JP2014001545A - Synthesized substitution column and device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthesized substitution column which is more rational and economical for more harmonizing a balance between a bearing power to be determined from a foundation and a bearing power to be determined from material strength than a conventional technology, and for, concretely, increasing the foundation bearing power of the substitution column in the conventional technology and a device and method for manufacturing the synthesized substitution column.SOLUTION: A synthesized substitution column is configured such that a columnar hydraulic solidifying material liquid substitution columnar body is disposed at the axial center of a soil cement columnar body such that their axial centers can be almost matched, and the hydraulic solidifying material liquid substitution columnar body is formed to penetrate through the soil cement columnar body, and protrude downward.

Description

  The present invention relates to a composite replacement column in which a soil cement columnar body and a hydraulic solidifying material liquid replacement columnar body are synthesized as a basic construction method for a building such as a small-scale building or a detached house, or a soil slab, and a building apparatus and method for the same. .

As a basic construction method for buildings such as relatively small-scale buildings and detached houses and soil slabs, a column construction method using a deep mixed processing method is generally adopted. However, since the column method generally used mixes and mixes the ground in place and cement slurry, a co-rotation phenomenon occurs when working on viscous soil with high adhesive strength, resulting in poor quality due to poor mixing. There is a problem in that solidification failure occurs depending on the type of ground such as organic soil.
In order to solve this problem, the applicants previously provided a method for constructing a hydraulic solidifying material liquid replacement column and a construction apparatus for a hydraulic solidifying material liquid replacement column (see Patent Document 1) in Japanese Patent Application Laid-Open No. 2011-106253. ing.
According to the present invention, the applicant's subsequent research and development have changed the basic structure of the hydraulic solidifying material liquid replacement column, and have newly invented the building apparatus and the building method.

JP 2011-106253 A

In recent years, environmental problems have become a social problem, and soil removal in construction works has a negative impact on the environment. Basic construction methods with a large amount of soil removal (generated soil volume) have been avoided even when construction costs are low. I came. In the prior art shown in Patent Document 1, since a replacement column can be constructed almost without soil by using a drilling rod having a flat side surface, an example in which the type is employed has increased.
However, with a small construction machine for a detached house foundation, the excavation rod with a flat side with no soil removal function has a large resistance to excavation of the ground, so the column diameter that can be used to build a replacement column is at most about 20 to 30 cm. It was difficult to increase the diameter. Therefore, in the conventional replacement column technology, the support force determined from the material strength of the replacement column and the vertical support force of the replacement column determined from the ground are unbalanced. In other words, the replacement column with a small outer diameter has a relatively small ground supporting force, while the replacement column is made of pure hydraulic solidification liquid and its strength is much greater than that of ordinary soil cement. The vertical bearing force determined by the strength was relatively large, and as a result, the bearing force determined by the ground and the bearing force determined by the material strength were greatly separated and unbalanced, which was an uneconomical state. In other words, the excellent material strength of the replacement column could not be utilized effectively.
The present invention harmonizes the balance of the support force determined from the ground and the support force determined from the material strength more than that of the prior art, specifically, to increase the ground support force of the replacement column according to the prior art, A more rational and economical synthetic replacement column and its building equipment and method are provided.

The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and the invention of claim 1 provides a cylindrical hydraulic solidifying material liquid-substituted columnar body in the axial center of a soil cement columnar body. A soil cement column and a hydraulic solidifying material liquid, characterized in that they are arranged so that their axial centers substantially coincide, and the hydraulic solidifying material liquid replacement columnar body protrudes downward through the soil cement columnar body. It is a synthetic replacement column for a hardened column.
According to a second aspect of the present invention, there is provided a synthetic replacement column of a soil cement column and a hydraulic solidified material liquid-cured column, wherein the hydraulic solidified material liquid is mixed with a bleeding reducing material in the first aspect of the invention. It is.
The invention of claim 3 is the invention of claim 1 or claim 2, wherein the downward protrusion of the hydraulic solidifying material liquid replacement columnar body is a columnar shape, and the length of the columnar protruding portion is equal to the diameter of the protruding portion. It is a synthetic replacement column of a soil cement column and a hydraulic solidifying material liquid-cured column characterized by being at least 1.5 times the length.
According to a fourth aspect of the present invention, there is provided a drilling head having a hydraulic solidifying material liquid flow path at the lower end of a shaft portion having a hydraulic solidifying material liquid flow passage at the upper end and a joint portion with a drilling rod at the upper end. And at least two stirring blades are fixed to the shaft portion, and the length of the lower shaft portion from the position of the lowermost stirring blade is at least 1.5 times the diameter of the shaft portion. This is a building equipment.
The invention according to claim 5 is the invention according to claim 4, wherein the shaft portion has a co-rotation preventing blade mounted rotatably, and the rotation diameter of the co-rotation preventing blade is larger than that of the stirring blade, and An apparatus for building a synthetic replacement column, characterized in that it is installed in the vicinity of the stirring blade fixing position.
The invention of claim 6 is the invention of claim 4 or 5, wherein the excavation head has a conical shape facing downward, and spiral wings oriented to move excavation earth and sand upward during forward rotation A synthetic replacement column characterized in that it is fixed and has a maximum rotation diameter of the spiral blade that does not exceed the shaft diameter, and a discharge port for hydraulic solidifying material liquid is provided on the side surface. It is a building device.
A seventh aspect of the present invention is the spiral blade according to any one of the fourth to sixth aspects, wherein the excavated sediment is moved upward at the time of forward rotation from at least the lowermost stirring blade position to the lower shaft side surface. Is an apparatus for building a synthetic replacement column.
The invention of claim 8 is the synthetic replacement column building device according to any one of claims 4 to 7, wherein the excavation head is detachably connected to the shaft portion. .
According to a ninth aspect of the present invention, the synthetic replacement column construction device according to any one of the fourth to eighth aspects is connected to the lower part of the excavation rod, and the central portion of the excavation head tip below the construction device is positioned at the pile center position of the ground. And then proceeding to the excavation head while discharging the hydraulic solidification liquid from the discharge port of the excavation head, and after the excavation head reaches a predetermined depth, discharging the hydraulic solidification liquid And a method for building a synthetic replacement column of a soil cement column and a hydraulic solidifying material liquid-cured column that are pulled up while the building device is rotated forward or backward.
A tenth aspect of the present invention relates to the construction device for a synthetic replacement column according to any one of the fourth to eighth aspects, wherein a construction device for a synthetic replacement column according to any one of the fourth to eighth aspects is connected to a lower portion of a drilling rod having a continuous or intermittent spiral blade fixed on a peripheral side surface. Set the center of the lower excavation head tip at the pile center position of the ground, stir and mix the ground around the excavation rod while discharging the hydraulic solidification liquid from the discharge port while digging while rotating the construction device forward The soil cement column and the hydraulic solidifying material liquid, which are formed into a soil cement and are pulled up while the construction device is rotated forward or backward while discharging the hydraulic solidifying material liquid after the excavation head reaches a predetermined depth. This is a method of building a synthetic replacement column for a hardened column.
The invention of claim 11 is the invention of claim 9 or 10, wherein the hydraulic solidifying material liquid is discharged while pulling up the synthetic replacement column building device, and the liquid level of the discharged hydraulic solidifying material liquid is at a predetermined upper position. Before reaching, the synthetic replacement column building device is pulled upward, and further, the hydraulic solidifying material liquid is discharged, and the hydraulic solidifying material liquid level is adjusted so as to substantially coincide with the predetermined position. This is a method for constructing a synthetic replacement column of soil cement pillars and hydraulic solidifying material liquid-cured pillars.
According to a twelfth aspect of the present invention, in the invention according to any one of the ninth to eleventh aspects, a soil cement pillar and water that are mixed with magnesium carbonate for reducing bleeding in the hydraulic solidifying material liquid. This is a method for constructing a synthetic replacement column of a hard-curing material liquid-cured column.

The present invention has the following effects.
(1) Since the soil cement columnar body is arranged concentrically around the hydraulic solidifying material liquid replacement columnar body in the invention according to claim 1, the peripheral surface supporting force of the ground is the hydraulic solidification material liquid replacement columnar shape. Since it occurs on the side surface of the soil cement columnar body having an outer diameter larger than that of the body, the effect of increasing the peripheral surface supporting force is obtained due to the area effect. In addition, since the lower part of the synthetic replacement column is a hydraulic solidifying material liquid replacement columnar body having a small outer diameter, it is easy to penetrate into a relatively good ground so-called support layer. At the same time, there is an effect that the cost performance is improved in the direction in which the large support force of the support layer and the material strength of the hydraulic solidifying material liquid replacement columnar body are balanced.

(2) The invention according to claim 2 is characterized in that, in the invention of claim 1, a bleeding reducing material is mixed in the hydraulic solidifying material liquid to be replaced. If the hydraulic solidifying material liquid replaced after the construction of the synthetic replacement column bleeds and the top end level decreases, the resulting shape becomes poor. Therefore, it is necessary to inject additional hydraulic solidifying liquid. Therefore, since it is necessary to inject a hydraulic solidifying material liquid additionally, construction work in the subsequent process is generated. If the post-process is shifted to the next day after the construction date, the joint portion may become a cold joint in some cases, and the synthetic replacement column itself may be of poor quality. In some cases, the work period may be extended by one day for post-process work, and the construction cost may increase. By mixing bleeding reducing material with hydraulic solidifying material liquid, the hydraulic solidifying material liquid additional injection process is substantially eliminated or the additional injection work is overwhelmingly simplified to prevent the occurrence of cold joints. There is an effect of preventing the construction cost from being increased by suppressing the extension of the construction period.

(3) The invention according to claim 3 is the invention according to claim 1 or claim 2, wherein the downward protrusion of the hydraulic solidifying material liquid replacement columnar body is a columnar shape, and the length of the columnar protruding portion is the protrusion. The length is at least 1.5 times the diameter of the part. This is to avoid the phenomenon that the outer diameter of the hydraulic solidifying material liquid replacement columnar body built in the soil cement columnar body becomes thin when the projecting portion length becomes shorter. If the diameter is at least 1.5 times the diameter, there is an effect that the phenomenon that the outer diameter of the hydraulic solidifying material liquid-substituted columnar body in the soil cement columnar body becomes thin can be avoided.

(4) The invention according to claim 4 is an apparatus for building a synthetic replacement column, and has at least two agitating blades fixed to the shaft portion (side surface). When rotating while discharging the material liquid, the hydraulic solidified material liquid is stirred and mixed with the raw ground by the stirring blades to form a cylindrical soil cement portion. After that, when reaching a predetermined depth, while discharging the hydraulic solidification material liquid from the excavation head, when pulling up while rotating the building device, due to the kneading effect of the lower shaft portion side from the lowermost stirring blade position, A cylindrical space almost the same diameter as the shaft part is formed in the soil cement and below the soil cement part, and at the same time filled with the hydraulic solidifying material liquid, so the synthetic replacement column of the soil cement columnar body and the hydraulic solidifying material liquid columnar body Can be built. At this time, even if two stirring blades are used, a soil cement columnar body is formed, but empirically two or four or more stirring blades are preferable. In addition, if the length of the lower shaft portion from the position of the lowermost stirring blade is short, the kneading effect on the side surface of the shaft portion is reduced, so that the pore wall wall is not stable, and therefore, the outer side of the hydraulic solidified liquid curing column is not stable. The diameter is not stabilized, and a hydraulic solidified material liquid-cured column is formed in a thin state as shown in FIG. Therefore, the length of the lower shaft portion from the position of the lowermost stirring blade is required to be at least 1.5 times the shaft diameter. In order to make the void hole wall more stable, it is preferable that the length of the shaft portion is at least twice the shaft diameter. The shaft length at this time includes the length of the same diameter portion as the shaft portion diameter of the excavation head connected to the lower end of the building apparatus.

(5) The invention according to claim 5 is the invention according to claim 4, further comprising a co-rotation preventing blade rotatably attached to the shaft body, and the rotation diameter of the co-rotation prevention blade is a stirring blade. Is a synthetic replacement column building device characterized in that it is installed in the vicinity of the stirring blade fixing position, and the hydraulic solidifying material liquid discharged from the drilling head discharge port during excavation When the original ground is agitated and mixed, the co-rotation preventing wings are stopped in the ground by being prevented from synchronous rotation with the excavating rod due to ground resistance. Furthermore, by installing the co-rotation preventing blade in the vicinity of the stirring blade, the soil mass excavated by the lowermost stirring blade can be efficiently shredded. Therefore, the so-called co-rotation preventing effect is effectively exhibited, and the hydraulic solidifying material liquid and the original ground are reliably stirred and mixed, so that a good soil cement columnar body is formed. In addition, even when the soil cement portion that has already been formed is re-stirred and mixed even when it is pulled up after reaching a predetermined depth, the effect of preventing co-rotation is effectively exhibited again, so that the stirring and mixing state is even better. It will be something.
The installation position of the co-rotation preventing blade is set in the vicinity of the stirring blade, but it is preferable that the stirring blade is fixed near the upper and lower sides of the co-rotation preventing blade if possible. This is because the excavated soil mass is shredded at two locations on the upper and lower surfaces of the co-rotation preventing wing, so that the efficiency of stirring and mixing is doubled.
The smaller the distance (gap) between the swirl prevention blade and the stirring blade, the higher the shredding effect on the excavated soil mass. However, there is a high probability that foreign matter such as gravel will bite during the construction, and the swirl prevention blade will become a stirrer blade. A co-rotation phenomenon that rotates in synchronization with the rotation occurs. Therefore, in actual construction, it is better to secure a distance (gap) between the co-rotation prevention blade and the stirring blade of about 2 cm or more. Further, since the present invention is intended for a comparatively small diameter synthetic replacement column, if the distance exceeds about 10 cm at most, the shredding effect of the soil block is reduced, which is not preferable. The preferred distance is 2 to 5 cm.
The rotation radius of the co-rotation preventing blade needs to be larger than that of the stirring blade due to its principle. The necessary difference depends on the ground conditions, but at least 2 cm is necessary. The difference is preferably about 5 cm for application to general soils.

(6) The invention according to claim 6 is the invention according to claim 4 or 5, wherein the excavation head has a conical shape facing downward, and the side surface of the excavation head is moved upward during forward rotation. The spiral blade is fixed, the maximum rotation diameter of the spiral blade is a size that does not exceed the shaft diameter, and a discharge port for hydraulic solidifying material liquid is provided on the side surface. This is a synthetic replacement column building device. The excavation head has a conical shape facing downward, and spiral wings are installed on the side to move the excavation sediment upward during forward rotation. It excels in excavation and relatively hard ground can be excavated, and at the time of excavation, almost all of the soil to be excavated is forcibly removed upward and laterally due to the inclination of the conical side of the excavation head and the effect of the spiral blades. Since the adhering effect of the earth and sand adhering to the excavation head is further enhanced by the adhesion force and the spiral blades on the side of the excavation head when the excavation head is pulled up, it does not peel off from the excavation head. There is no quality defect caused by the presence of a soil mass in the replacement part.
Since the maximum rotational diameter of the spiral blade does not exceed the shaft diameter, the hole wall surface formed by kneading on the side surface of the shaft does not disturb when the construction apparatus is pulled up.
In addition, by providing a discharge port on the side of the conical section of the excavation head, even if a check valve is provided on the discharge port, if the height is lower than the height of the spiral blade fixed on the side, Since the outlet or the check valve does not directly contact the original ground, there is an effect that the check valve is excellent in durability.

(7) The invention according to claim 7 is the invention according to any one of claims 4 to 6, wherein the excavated sediment is moved upward at least from the position of the lowermost stirring blade to the side surface of the lower shaft portion during forward rotation. This is a synthetic replacement column erection device characterized by the fact that the spiral wing of the direction is fixed.For hard ground and dense sand layer, only the spiral wing fixed to the cone of the drilling head is used to move the excavated soil to the side. Even when it is difficult to eliminate, the excavated earth and sand can be removed by moving upward with a spiral blade provided in the shaft portion, so that there is an effect that construction up to a predetermined depth can be reliably performed. Furthermore, if there is a structure that easily deforms, such as a retaining wall, in the vicinity of the construction site, if the construction device is connected with an excavating rod that is also provided with a spiral blade on the side, it will be discharged by the spiral blade. Due to the earth effect, lateral deformation pressure generated with construction can be reduced, and deformation of retaining walls and the like can be prevented.

(8) The invention according to claim 8 is the invention according to any one of claims 4 to 7, wherein the excavation head is detachably connected to the shaft portion, so that the excavation head is built from its function. Although it is easy to wear compared with the apparatus, even if it is worn out, only the excavation head can be replaced, so that the total construction cost can be reduced.

(9) In the invention according to claim 9, the construction device of the synthetic replacement column is connected to the lower side of the excavation rod, the center of the excavation head tip below the construction device is set at the pile center position of the ground, and the construction device is Excavating while discharging the hydraulic solidification liquid from the discharge port of the excavation head while rotating forward, and after the excavation head reaches a predetermined depth, the construction device is rotated forward or while discharging the hydraulic solidification liquid. Since it is a method for constructing a synthetic replacement column of a soil cement column and a hydraulic solidifying material liquid-curing column that are pulled up while rotating in the reverse direction, the lower is a hydraulic solidifying material liquid replacement columnar body corresponding to the diameter of the shaft of the construction device However, on the upper side, it is possible to construct a synthetic replacement column in which a soil cement surrounds the periphery of the hydraulic solidifying material liquid replacement columnar body in a cylindrical shape. By this method, a pillar of high quality pure hydraulic solidification liquid is formed in the center without mixing clumps, and the soil cement in which the hydraulic solidification liquid and the original ground are stirred and mixed in the upper part is a cylinder. A synthetic replacement column is formed in a simple manner in one step. Therefore, compared to a relatively small diameter hydraulic solidifying material liquid replacement column, a large-diameter soil cement column is formed, so that a high vertical support force is exhibited.
Furthermore, the invention according to claim 9 uses the building apparatus according to claims 4 to 8, so that when it is pulled up, the original ground portion and the soil cement are produced by the kneading effect by the side of the lower shaft portion from the lower end of the stirring blade. It becomes possible to build a strong hole wall in the part, and it is possible to construct a hydraulic solidified liquid column with a stable outer diameter.

(10) The invention according to claim 10 is characterized in that the synthetic replacement column building apparatus according to any one of claims 4 to 8 is connected to a lower portion of a drilling rod having a continuous or intermittent spiral blade fixed on a peripheral side surface. The center of the excavation head at the bottom of the construction device is set at the pile center position of the ground, and the ground around the excavation rod is discharged while discharging the hydraulic solidification material liquid from the discharge port while moving forward while rotating the construction device. After stirring and mixing to form soil cement and the excavation head reaches a predetermined depth, the soil cement pillar and water are pulled up while discharging the hydraulic solidifying material liquid and rotating the construction device forward or backward. Because it is a method of building a synthetic replacement column of hard solidifying material liquid hardening column body, it is effective for continuous or intermittent spiral blade fixed to the drilling rod when the drilling rod is rotating forward during excavation and pulling up etc. Construction has been soil cement Ri can be discharged to the ground.
When constructing a synthetic replacement column, the hydraulic solidification liquid injected into the ground during excavation, the excavating rod, and the force equivalent to the volume of the building equipment are pushed out to the side. A phenomenon may occur in which a wall or the like is pushed out and deformed. In such a case, according to the invention according to claim 10, since the soil cement can be discharged to the ground during the construction of the synthetic replacement column, the force for pushing the ground to the side can be reduced. Deformation of neighboring structures such as retaining walls can be prevented.

(11) The invention according to claim 11 is the invention according to claim 9 or 10, wherein the hydraulic solidifying material liquid is discharged while pulling up the synthetic replacement column building apparatus, and the liquid level of the discharged hydraulic solidifying material liquid is upward. Before reaching the predetermined position, the synthetic replacement column building apparatus is pulled upward, and then the hydraulic solidifying material liquid is further discharged so that the liquid level of the hydraulic solidifying material substantially coincides with the predetermined position. It is a method of constructing a synthetic replacement column of soil cement column and hydraulic solidifying material liquid curing column characterized by adjusting, so that the hydraulic solidification material liquid column has high compressive strength after curing and is difficult to deburring Since the construction level (top level) of the head of the body can be almost determined at the time of construction, there is no need for a chipping work at the time of leveling of the hydraulic solidified liquid column head in the post process, and the post process Is easier and more efficient Damage accident of synthetic replacement column can be eliminated also.

(12) The invention according to claim 12 is the soil cement according to any one of claims 9 to 11, wherein the hydraulic solidifying material liquid is mixed with magnesium carbonate for reducing bleeding. Since it is a method of building a synthetic replacement column between a column and a hydraulic solidifying material liquid-cured column, magnesium carbonate can reduce the amount of bleeding of the hydraulic solidifying material liquid, so hydraulic solidification after building a synthetic replacement column The work of adding an amount equivalent to the bleeding of the material liquid is minimized or unnecessary, and the construction is simplified. In addition, magnesium carbonate as used in the field of this invention shall be used by the broad concept containing basic magnesium carbonate.

It is the front view (a) and top view (b) of the synthetic | combination replacement column which show embodiment of this invention. It is an explanatory front view explaining the peripheral frictional force which arises in a hydraulic solidification material liquid substitution column (a) and a synthetic substitution column (b). It is explanatory drawing (a) (b) of the thinning condition of the hydraulic solidification material liquid substitution columnar body in a soil cement columnar body. It is explanatory drawing (a) (b) (c) of the cold joint by the bleeding state of hydraulic solidification material liquid, and additional injection | pouring. It is a front view which illustrates (a) (b) (c) (d) the construction apparatus (including excavation head) of the synthetic | combination replacement column which shows embodiment of this invention. It is a front view (a) (b) of a conical excavation head which shows an embodiment of the invention, and is a case (a) and a case (b) of a truncated cone as a cone. It is explanatory drawing which shows the construction process of the synthetic | combination replacement column construction which concerns on this invention in process order (a) (b) (c) (d) (e). It is a front view which illustrates the excavation rod used by this invention (a) (b) (c). It is explanatory drawing which shows the construction process which builds a synthetic | combination replacement column using the excavation rod with a spiral blade in process order (a) (b) (c) (d) (e). It is explanatory drawing shown to process order (a) (b) (c) (d) (e) (f) (g) in the case of adding a hydraulic solidification material liquid and constructing it by construction of a synthetic substitution column. They are the front view (a) which shows the synthetic | combination replacement column building apparatus which concerns on Example 1 of this invention, and the front view (b) which shows the synthetic | combination replacement column building apparatus which concerns on the comparative example 1. FIG. It is explanatory drawing which shows the relationship between the time and depth of a construction process in the synthetic | combination replacement column construction apparatus which concerns on Example 1 of this invention. It is explanatory drawing which shows the relationship between the time of the construction process in the substitution column construction apparatus which concerns on the comparative example 1, and depth. The photograph (a) after drawing of the synthetic | combination replacement column built with the synthetic | combination replacement column manufacturing apparatus of Example 1 of this invention and the photograph (b) after drawing | extracting of the substitution column built with the substitution column construction apparatus of the comparative example 1 It is. It is a photograph figure which shows the section situation after pulling out the synthetic substitution column built by Example 1 of the present invention, and crushing. It is a front view which shows the synthetic | combination replacement column building apparatus which concerns on Example 2, and is a construction apparatus which removed the common rotation prevention wing | blade from the synthetic | combination replacement column building apparatus of Example 1 shown to Fig.11 (a), and is using a common rotation prevention wing | blade. It is a synthetic replacement column building device that does not have. It is explanatory drawing which shows the relationship between the time of the construction process in the synthetic | combination replacement column construction apparatus which concerns on Example 1 and Example 2 shown to Fig.11 (a), and depth. It is the photograph figure which shows the section situation after pulling out the synthetic substitution column built with the synthetic substitution column construction device of Example 2, and crushing. It is a photograph figure which shows the cross-sectional condition after pulling out the synthetic | combination replacement column built with the synthetic | combination replacement column construction apparatus of Example 1 shown to Fig.11 (a), and crushing. It is a front view which shows the synthetic | combination replacement column construction apparatus which concerns on the comparative example 2. FIG. It is explanatory drawing which shows the relationship between the time of the construction process in the synthetic | combination replacement column building apparatus which concerns on Example 1 shown to Fig.11 (a), and depth. It is explanatory drawing which shows the relationship between the time of the construction process in the synthetic | combination replacement column construction apparatus which concerns on the comparative example 2, and depth. It is a photograph figure (a) (b) which shows the section situation after pulling out the synthetic substitution column built with the synthetic substitution column construction device concerning Example 1 shown in Drawing 11 (a), and crushing. It is a photograph (a) (b) which shows the section situation after pulling out the synthetic substitution column built with the synthetic substitution column construction device concerning comparative example 2, and crushing.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view (a) and a plan view (b) of a synthetic replacement column showing an embodiment of the present invention.

  In the figure, a synthetic replacement column 1 is a synthetic replacement column of a soil cement columnar body 2a and a hydraulic solidifying material liquid replacement columnar body 3a. A cylindrical hydraulic solidifying material liquid is formed at the axial center of the soil cement columnar body 2a. The replacement columnar body 3a is arranged so that the axial centers thereof substantially coincide with each other, and the hydraulic solidifying material liquid replacement columnar body 3a is formed so as to project downward 4 through the soil cement columnar body 2a.

The soil cement columnar body 2a is formed by stirring and mixing the in-situ ground and the hydraulic solidifying material liquid. The quality of the soil cement column 2a depends on the soil quality of the in-situ ground, especially the uniaxial compressive strength. In the case where the soil composition varies depending on the depth, even if the ground has the same soil or the same soil, the quality of the soil cement columnar body 2a varies. On the other hand, the hydraulic solidified liquid columnar body 3a is characterized in that the quality after curing is high quality and stable because stirring and mixing with the in situ ground is not performed. However, since the raw ground is not stirred and mixed unlike the soil cement columnar body 2a, all the hydraulic solidifying material liquid replacement columnar bodies 3a are composed of the hydraulic solidifying material liquid, so that the material cost occupies the cost. For this reason, it is difficult to increase the diameter of the hydraulic solidifying material liquid-substituted columnar body 3a for economic reasons. As a result, since the hydraulic solidifying material liquid replacement columnar body 3a has a relatively small diameter, its peripheral area is also small, so that the peripheral surface supporting force of the ground is also small. For this reason, the supporting force determined from the ground and the supporting force determined from the material strength are unbalanced, and the material strength cannot be made effective.
However, in the synthetic replacement column 1 according to the present invention, since the soil cement columnar body 2a is disposed concentrically around the hydraulic solidifying material liquid replacement columnar body 3a, the peripheral surface supporting force of the ground is hydraulically solidified. Since it occurs on the side surface of the soil cement columnar body 2a having an outer diameter larger than that of the material liquid replacement columnar body 3a, the peripheral surface support force is increased by the area effect. FIG. 2 (a) is a front view of the hydraulic solidifying material liquid replacement column 3a, and FIG. 2 (b) is a front view of the synthetic replacement column 1. Even if the circumferential frictional force degree t of the ground is the same, a small diameter is shown. It can be well understood that the peripheral support force Pb of the soil cement columnar body 2a of the synthetic replacement column 1 having a larger diameter than the peripheral support force Pa exhibited by the hydraulic solidifying material liquid replacement column 3a is larger. Therefore, by using the synthetic replacement column 1 obtained by synthesizing the soil cement columnar body 2a and the hydraulic solidifying material liquid replacement columnar body 3a on the same axis, the peripheral surface is obtained by the peripheral area effect of the large-diameter soil cement columnar body 2a. Support force increases. By appropriately selecting the outer diameter of the soil cement columnar body 2a, it becomes possible to balance the supporting force determined from the ground of the synthetic replacement column 1 and the supporting force determined from the material strength, and a synthetic replacement with high quality and stable quality. It is possible to provide a rational basic column that can fully demonstrate the performance of the column.

In addition, the length H of the columnar protrusion 4 below the hydraulic solidifying material liquid replacement columnar body 3 a in the synthetic replacement column 1 is at least 1.5 times the diameter D of the protrusion 4. When the length H of the protrusion 4 is short and less than 1.5 times the diameter D of the protrusion 4, the outer diameter of the hydraulic solidifying material liquid replacement column 3a to be built in the soil cement column 2a is thin, for example. The tendency to get confused becomes smaller. When the length H of the projecting portion 4 is 1.5 times or more of the diameter D, the outer diameter of the hydraulic solidifying material liquid-substituted columnar body 3a in the soil cement columnar body 2a is almost equal to the plasticity of the hole wall. It is uniform and approaches the outer diameter of the protrusion 4. Preferably, the length H of the protrusion 4 is at least twice the diameter D of the protrusion 4. In order to ensure the outer diameter of the hydraulic solidifying material liquid replacement columnar body 3a in the soil cement columnar body 2a and to keep it constant, the longer the length H of the protrusion 4 is, the better. As a result, the synthetic portion of the synthetic replacement column 1 becomes relatively small, the expected effect of improving the supporting force is reduced, and it becomes necessary to allow the protruding portion 4 to penetrate into a relatively hard supporting layer, resulting in difficult construction. The case that becomes. Accordingly, it is preferable that the length H of the protruding portion 4 is 6 times or less the diameter D of the protruding portion 4 at the longest.
FIG. 3A shows a case where the length H of the protruding portion 4 below the hydraulic solidifying material liquid replacement columnar body 3 a of the synthetic replacement column 1 is 1.5 times or more the diameter D of the protruding portion 4. , Shows a state in which the hydraulic solidifying material liquid replacement columnar body 3a in the soil cement columnar body 2a is normally constructed, and (b) shows the length H of the downward projecting portion 4 and the diameter D of the projecting portion 4. The outer diameter of the hydraulic solidifying material liquid replacement columnar body 3a in the soil cement columnar body 2a is disordered and thinned and becomes smaller. As described above, the length H of the protrusion 4 below the hydraulic solidifying material liquid replacement column 3a of the synthetic replacement column 1 is preferably 1.5 times or more and 6 times or less the diameter D of the protrusion 4.

  Further, a bleeding reducing material is mixed in the hydraulic solidifying material liquid for constructing the synthetic replacement column 1. If the hydraulic solidifying material liquid replaced after the construction of the synthetic replacement column 1 bleeds and the top end level is lowered, the resulting shape becomes poor. Therefore, it is necessary to additionally inject the hydraulic solidifying material liquid. Therefore, since the hydraulic solidifying material liquid has to be additionally injected, a labor for construction in the subsequent process is generated. If the post-process is shifted to the next day after the construction date, the joint portion may become a cold joint in some cases, and the synthetic replacement column 1 itself may have poor quality. In some cases, the work period may be extended by one day for post-process work, and the construction cost may increase. By adding a bleeding reducing material to the hydraulic solidifying material liquid, the additional injection process of the hydraulic solidifying material liquid is substantially eliminated, or the additional injection operation is overwhelmingly simplified to prevent the occurrence of cold joints. In addition, it is possible to prevent the construction cost from increasing by suppressing the extension of the construction period.

FIG. 4A shows the composite replacement column 1 in which the top end level L of the soil cement columnar body 2a and the hydraulic solidifying material liquid 3b after construction is normal, and FIG. 4B shows the hydraulic solidified material after construction. 3c shows the synthetic replacement column 1 in a state where the liquid 3b is bleeding and the top end level L is lowered, and (c) is a hydraulic solidification because the hydraulic solidifying material liquid 3b is bleeding after the work and the top end level L is lowered. The synthetic replacement column 1 in a state where the material liquid 3c is additionally injected is shown, and the cold joint is generated at the joint 5 between the hydraulic solidification material liquid 3b and the additionally injected hydraulic solidification material liquid 3c.
In this way, if the bleeding reducing material is not mixed with the hydraulic solidifying material liquid 3b, the hydraulic solidifying material liquid 3b causes bleeding, and after the construction of the synthetic replacement column 1, the top end of the hydraulic solidifying material liquid replacement columnar body 3a. Level L will drop and must be repaired after construction. Therefore, the construction period is delayed and the cost is increased. If the bleeding reducing material is appropriately mixed with the hydraulic solidifying material liquid 3b, the solidified solid replacement column 1 is solidified in a state where the top end level L of the hydraulic solidifying material liquid replacement columnar body 3a is in a predetermined position. Can be built.

  Next, an embodiment of a synthetic replacement column building apparatus according to the present invention will be described. FIGS. 5A, 5B, 5C, and 5D are front views illustrating an apparatus for building a synthetic replacement column showing an embodiment of the present invention.

Synthetic replacement column building apparatus 10A shown in FIG. 5 (a) includes a shaft portion 11 having a hydraulic solidifying material liquid channel therein, a joint portion 12 that connects the excavation rod 20 to the upper end of the shaft portion 11, An excavation head 13 connected to the lower end of the shaft portion 11 and a stirring blade 16 fixed to the side surface of the shaft portion 11 are provided.
The shaft portion 11 has the same outer diameter as the excavation rod 20 to be connected, and has a joint portion (not shown) at the lower end of the shaft portion 11 to which the excavation head 13 is connected. The excavation head 13 has a downward conical shape (conical shape or truncated cone shape), and a hydraulic solidifying material liquid discharge port 14 is provided on a side surface. A hydraulic solidification material liquid flow path is provided in the shaft portion 11 and communicates with the discharge port 14. The hydraulic solidification material liquid supplied by the flow channel in the excavation rod 20 passes through the flow path of the shaft portion 11. From the discharge port 14. A check valve (not shown) for preventing reverse inflow of excavated earth and sand is installed at the discharge port 14. This check valve may be fixed or detachable.
Further, a spiral blade 15 is fixed to the outer peripheral surface of the conical excavation head 13 in such a direction that the excavation rod 20 pushes the excavation earth and sand upward when the excavation rod 20 rotates forward. The maximum rotation diameter of the spiral blade 15 is a size that does not exceed the outer diameter D of the shaft portion 11.

In this way, the excavation head 13 has a conical shape facing downward, and a spiral blade 15 that moves the excavation earth and sand upward is fixed on the side surface of the excavation head 13 according to the prior art. It excels in excavation performance compared to the excavation head, enables relatively hard ground excavation, and at the time of excavation and advancement, almost all of the excavation target sand and sand is inclined on the side of the conical portion of the excavation head 13 and the effect of the spiral blade 15. The excavation head 13 can remove excavation upward and sideward, and the adhering effect of the earth and sand adhering to the excavation head 13 is further enhanced by the adhesion force and the spiral blades 15 on the side of the excavation head 13 when the excavation head 13 is pulled up. Since there is almost no peeling from the excavation head 13, quality defects may occur due to the presence of soil blocks in the hydraulic solidifying material liquid replacement part. There is no.
Since the maximum rotation diameter of the spiral blade 15 does not exceed the outer diameter of the shaft portion 11, the hole wall surface formed by kneading on the side surface of the shaft portion 11 is not disturbed when the synthetic replacement column building apparatus 10A is pulled up. .
Further, by providing the discharge port 14 on the conical side surface of the excavation head 13, even if a check valve is provided on the discharge port 14, the position of the discharge port 14 and the check valve is fixed on the side surface. If it is lower than the height of the spiral blade 15, the discharge port 14 or the check valve does not directly contact the original ground during rotary excavation, so that the durability of the check valve is improved.

  Two pairs of stirring blades 16 are fixed on the side surface of the shaft portion 11 in two stages. In this example, the stirring blades 16 have two pairs of two stages. However, the present invention is not limited to this example, and three pairs of three or more stirring blades may be used, or one stirring blade per stage. A plurality of wings may be fixed. The rotating diameter of the stirring blade 16 is preferably about 1.5 times the diameter D of the shaft portion 11 even if it is small because of the stirring and mixing properties of the soil cement. If the length of the stirring blade 16 becomes shorter than this, the stirring and mixing of the hydraulic solidifying material liquid and the excavated earth and sand becomes poor, and the quality of the soil cement may be deteriorated.

Further, the length H from the lower end of the lowermost stirring blade 16 to the position of the lowermost end where the outer diameter of the joint portion 19 of the excavation head 13 is D is preferably 1.5 to 6 times the outer diameter D. .
From the lower end of the lowermost stirring blade 16 in the shaft portion 11 to the position of the lowermost end where the outer diameter of the joint portion 19 of the excavation head 13 is D, the hydraulic solidified material liquid replacement columnar body 3a of the synthetic replacement column 1 is provided. It is a part which contributes to forming the protrusion part 4 below. When the synthetic replacement column 1 is constructed with a length H from the lower end of the lowermost stirring blade 16 in the shaft portion 11 to the position of the lowermost end where the outer diameter of the joint portion 19 of the excavation head 13 is D, the hydraulic solidified material The length H of the protrusion 4 below the liquid replacement columnar body 3a is determined. Therefore, both lengths were set to H. Moreover, the diameter D of the protrusion part 4 below the hydraulic solidifying material liquid replacement columnar body 3a is determined by the diameter D of the shaft part 11. Therefore, both diameters were set to D.

  Using the synthetic replacement column building device 10A, when rotating while discharging the hydraulic solidifying material liquid from the discharge port 14 during excavation, it is stirred and mixed with the ground soil by the stirring blade 16 fixed on the side surface of the shaft portion 11, As the excavation progresses, a soil cement portion is formed around the excavation rod 20. When the construction device 10A is pulled up while the discharge of the hydraulic solidifying material liquid from the discharge port 14 is continued after reaching a predetermined depth, the soil cement portion is re-stirred by the stirring blade 16 and the mixing degree is improved. In addition, a hole having substantially the same diameter as the diameter D of the shaft portion 11 is formed in the soil cement by the kneading effect by the side surface of the shaft portion 11 protruding downward from the lowermost stirring blade 16 of the building apparatus 10A. The holes are filled with a hydraulic solidifying material solution, and when the soil cement and the hydraulic solidifying material solution are cured, a synthetic replacement column is formed. That is, by using the synthetic replacement column building apparatus 10A, it is possible to build the synthetic replacement column 1 in which the soil cement columnar body 2a and the hydraulic solidifying material liquid replacement columnar body 3a are synthesized in one step of digging and lifting.

  When the protruding length of the shaft portion 11 from the lowermost stirring blade 16 of the synthetic replacement column building device 10A is 1.5 times or less the diameter D of the shaft portion 11, the soil cement is raised in the lifting process of the building device 10A. The effect of kneading to the part is reduced, and the holding force of the hole wall is weakened, so that the shrinkage of the hole wall = cross-sectional shrinkage easily occurs, resulting in the phenomenon that the outer diameter of the hydraulic solidifying material liquid replacement part is thinned and thinned. There is. On the other hand, even if the protruding length of the shaft portion 11 is longer than 10 times the diameter D of the shaft portion 11, the effect of kneading the hole wall does not increase linearly. On the other hand, if the protruding length of the shaft portion 11 is too long, the length of the soil cement columnar body becomes relatively short, so that the length of the finished shape as the synthetic replacement column becomes small. The protruding length of the shaft portion 11 is preferably about 1.5 to 6 times the diameter D of the shaft portion 11.

  The synthetic replacement column building apparatus 10B shown in FIG. 5B is provided between the upper and lower stirring blades 16 and the stirring blades 16 provided on the shaft portion 11 in the synthetic replacement column building apparatus 10A shown in FIG. The co-rotation preventing wing 17 is rotatably provided, and the other components are the same as those in the embodiment of the synthetic replacement column building apparatus 10A shown in FIG. Other detailed explanations are omitted.

  The co-rotation prevention blade 17 is rotatably mounted on the shaft portion 11, and the rotation diameter thereof is larger than the rotation diameter of the stirring blade 16 and is installed in the vicinity of the fixed position of the stirring blade 16. In this example, it is provided between the upper and lower stirring blades 16 and the stirring blades 16. Therefore, in this synthetic replacement column building apparatus 10B, when the hydraulic solidifying material liquid discharged from the discharge port 14 of the excavation head 13 and the original ground soil are stirred and mixed at the time of excavation, the co-rotation prevention blade 17 is in the ground. Synchronous rotation with the excavation rod 20 (shaft portion 11) is prevented by the ground resistance, and it stops. Further, by installing the co-rotation preventing blade 17 in the vicinity of the stirring blade 16, the soil mass excavated by the lowermost stirring blade 16 can be efficiently shredded. Therefore, the so-called co-rotation preventing effect is effectively exhibited, and the hydraulic solidifying material liquid and the original ground soil are reliably agitated and mixed to form a good soil cement columnar body. In addition, even when the soil cement part that has already been formed is re-stirred and mixed even when it is pulled up after reaching a predetermined depth, the effect of preventing co-rotation is effectively exerted again, so that the state of stirring and mixing is even better. It will be something.

The installation position of the co-rotation preventing blade 17 is set in the vicinity of the stirring blade 16, but preferably, the stirring blade 16 is fixed in two stages in the vicinity of the co-rotation preventing blade 17. This is because the excavated earth lump is shredded at two locations on the upper and lower surfaces in the vicinity of the co-rotation preventing wing 17 so that the efficiency of stirring and mixing is doubled.
The smaller the distance (interval) between the co-rotation impeller 17 and the stirring impeller 16, the higher the shredding effect on the excavated soil mass, but the higher the probability that foreign matter such as gravel will bite during the construction, thereby preventing co-rotation. A co-rotation phenomenon in which the blade 17 rotates in synchronization with the stirring blade 16 occurs. Therefore, in actual construction, it is better to secure a distance (interval) of about 2 cm or more between the co-rotation preventing blade 17 and the stirring blade 16. Since the present invention is intended for a relatively small-diameter synthetic replacement column, if the distance (interval) exceeds about 10 cm at most, the shredding effect of the soil mass is reduced, which is not preferable.
Further, the rotation diameter of the co-rotation prevention blade 17 needs to be larger than the rotation diameter of the stirring blade 16 from the principle. The necessary difference depends on the ground conditions, but at least 2 cm is necessary. The difference is preferably about 5 cm for application to general soil quality.

  A synthetic replacement column building apparatus 10C shown in FIG. 5C is obtained by replacing the conical excavation head 13 in the synthetic replacement column building apparatus 10B shown in FIG. 5B with a sword blade-shaped excavation head 13a. The others are the same as those in the embodiment of the composite replacement column building apparatus 10B shown in FIG. 5B, and therefore, the same components are denoted by the same reference numerals and other detailed descriptions are omitted. The hydraulic solidifying material liquid discharge port 14 is provided on the bottom surface of the shaft portion 11. This sword blade-shaped excavation head 13a has the advantage that the manufacturing cost is lower than that of the conical excavation head 13, and the discharge direction of the hydraulic solidified liquid is directly below, so that the hole wall is less likely to be disturbed during discharge. There is. However, if the earth and sand of the excavation ground is sandy soil, the sword-blade excavation head 13a has a defect that excavation becomes difficult because it does not have a function of discharging the excavation earth and sand sideways or upward.

A synthetic replacement column building apparatus 10D shown in FIG. 5 (d) is provided with a spiral blade 18 on the outer peripheral surface of the shaft portion 11 in the synthetic replacement column building apparatus 10B shown in FIG. 5 (b). Since it is the same as that of embodiment of the synthetic | combination replacement column building apparatus 10B shown to 5 (b), the same code | symbol is attached | subjected to the same component and other detailed description is abbreviate | omitted.
The spiral blade 18 is mainly provided below the lowermost stirring blade 16 of the shaft portion 11, but may exist on the shaft portion 11 above the uppermost stirring blade 16. The rotational diameter of the spiral blade 18 is the same as the outer diameter of the excavation rod 20. Accordingly, the outer diameter of the shaft portion 11 in this case is smaller than the outer diameter of the excavation rod 20. In this synthetic replacement column building apparatus 10D, a function of discharging the excavated earth and sand excavated by the excavating head 13 by fixing the spiral blade 18 in a direction to move the excavated earth and sand at the time of forward rotation to the shaft portion 11 is fixed. Therefore, the digging performance is improved as compared with the building apparatuses 10A and 10B shown in FIGS. 5 (a) and 5 (b). This synthetic replacement column building apparatus 10D is particularly excellent in digging in sandy ground, and is combined with a continuous spiral screw 25 or a drill rod 20 with an intermittent spiral screw 25a shown in FIGS. 8B and 8C described later. As a result, even in the sandy ground that is difficult to dig with the building apparatuses 10A, 10B, and 10C shown in FIGS. The width of the spiral blade 18 is required to be at least about 10 mm in order to exhibit the soil removal function of excavated soil. As described above, according to the composite replacement column building apparatus 10D of this example, the spiral blade 18 is provided on the outer peripheral surface of the shaft portion 11 in addition to the operation and effect of the composite replacement column building apparatus 10B shown in FIG. Therefore, the soil removal function is improved, and the excavation performance is good even if the excavated soil is sandy soil.

FIG. 6 is a front view showing an embodiment of a conical excavation head, in which (a) is a conical shape and (b) is a truncated cone shape.
The conical excavation head 13 shown in (a) has a spiral blade 15 fixed to a side surface in a direction in which excavated earth and sand are pushed upward during normal rotation, and the height of the spiral blade 15 is about 20 mm. The spiral blade 15 may be made of flat steel, or may be made by winding a steel bar or by stacking multiple stages. Since the lowermost end portion of the spiral blade 15 is a portion where abrasion due to excavation is severe, it is preferable to weld a steel type with high hardness or to embed a cemented carbide tip to improve durability. The discharge port 14 for the hydraulic solidifying material liquid is formed on the side surface of the cone, and the discharge port 14 is provided with a check valve (not shown) in order to prevent the backflow of excavated soil. The check valve is detachably attached with an elastic plate such as synthetic rubber or synthetic resin. In some cases, a steel spring check valve may be used.

  FIG. 6B shows a frustoconical excavation head 13, and the conical excavation head 13 of FIG. 6A has a sharp tip and a reduced durability. It is a thing that raised. The cut-off height of the tip is preferably about 1 cm even if the diameter of the bottom surface of the cut-out cone is large. If the diameter is larger than this, it may be necessary to take measures to improve the digging performance such as providing a claw in the truncated cone part.

  The excavation head 13 has a conical shape (conical shape, truncated cone shape), and a spiral wing 15 that pushes the excavation earth and sand upward when it rotates in the forward direction. Excavation and excavation are good because it has the effect of removing excavated sediments not only upward but also laterally. This is because the excavated earth and sand are efficiently moved and removed laterally by the conical inclined side surface and the soil removal effect of the spiral blade 15. Therefore, even if the ground is difficult to move laterally, such as sandy ground, the excavation is good. Further, in the conical excavation head 13, when the excavated sediment is viscous soil, it can exist only in a relatively thin layer along the conical side surface up to the height of the spiral blade 15. Since the adhesion force with respect to the excavation head 13 is larger, when the excavation head 13 is pulled up, it adheres to the excavation head and is pulled up to the ground. Therefore, there is no possibility that the viscous soil falls from the excavation head 13 and remains in the replaced hydraulic solidification material liquid, resulting in poor quality. When the excavated soil is sandy soil, there is no adhesion, so it will not stick to the excavation head and be lifted upward.

The excavation heads 13 and 13a are preferably detachably connected to the shaft portion 11. The excavation heads 13 and 13a are easy to wear even in the synthetic replacement column building apparatuses 10A, 10B, 10C and 10D due to their functions, and even if they are worn out, only the excavation heads 13 and 13a can be replaced. It can be reduced.
6 (a) and 6 (b) are front views (a) and (b) showing an example of a configuration in which the excavation head 13 is detachably connected to the shaft portion 11, and the upper end portion of the excavation head 13 is a hexagonal male and female. The structure of the fitting type joint 19 is shown, and the case where the shaft part 11 is detachable is shown. (A) is a case where the excavation head 13 is a cone shape, (b) is a case where the excavation head 13 is a truncated cone type. The joint structure is not limited to this, and may be a flange connection type, a bolt connection type, or the like with relatively low cost.

FIG. 7 is an explanatory view showing a construction method for constructing a composite replacement column using the composite replacement column construction apparatus according to the present invention in order of steps (a), (b), (c), (d), and (e). This is a case where the synthetic replacement column building apparatus 10B shown in FIG. 5B is used as the synthetic replacement column building apparatus.
First, in step 1, the synthetic replacement column building apparatus 10B is connected to the lower end of the drilling rod 20, and the center position of the tip of the drilling head 13 of the building apparatus 10B is set to the pile center position of the ground (FIG. 7A). . Next, in step 2, the excavation rod 20 is gripped by a construction machine (not shown) equipped with an auger motor that can apply rotational force and can be advanced and retracted (advanced and retracted), and the synthetic replacement column building apparatus 10B is installed. Excavation is carried out while rotating forward, and the hydraulic solidification material liquid is discharged from the discharge port of the excavation head 13 after the lowermost position of the lowermost stirring blade 16 of the building apparatus 10B reaches the first predetermined depth (the lower end position of the hollow moat). And digging is continued in this state (FIG. 7B). The discharge amount of the hydraulic solidifying material liquid is set such that the quality of the soil cement portion 2b to be built satisfies the design required performance.
In the next step 3, when the excavation head 13 reaches a predetermined depth (at the lower end position of the synthetic replacement column to be built) (FIG. 7C), the rotation of the synthetic replacement column building apparatus 10B and the discharge of the hydraulic solidifying material liquid are performed. While continuing, the building apparatus 10B is pulled upward. At this time, the rotation direction is preferably forward rotation, but reverse rotation is also possible. Since reverse rotation may cause the earth and sand adhering to the side surface of the excavation head 13 to easily fall, forward rotation is preferable.
Further, in the next step 4, as shown in FIG. 7 (d), the synthetic replacement column building apparatus 10B is pulled up while continuing to rotate and discharge the hydraulic solidifying material liquid. At this time, the hydraulic solidifying material liquid is discharged. The quantity shall maintain the quantity which fills the space generated by pulling up the building apparatus 10B and does not generate suction (negative pressure). Further, at the position where the excavation head 13 of the building apparatus 10B reaches a predetermined depth, no soil cement part is formed below the lowermost stirring blade 16, so that the soil cement part 2b is lifted up from this position. Until formed, the hole formed by the shaft portion 11 and the excavation head 13 is filled with the hydraulic solidifying material liquid and pulled up, and the protruding portion 4 downward of the hydraulic solidifying material liquid replacement columnar body 3a. Is formed.
When the lower shaft portion 11 is positioned on the soil cement portion 2b from the lowermost stirring blade 16, the side surface of the lower shaft portion 11 is kneaded from the lowermost stirring blade 16 into the soil cement portion 2b. The hole is pulled up while forming a hole, and the hole is pulled up while being filled with the hydraulic solidifying material liquid that has been immediately discharged. At this time, the soil cement portion 2b is re-stirred by the stirring blade 16. In addition, since the hole formed in the soil cement part 2b at the time of pulling up is formed by kneading the side surface of the shaft part 11 below the lowermost stirring blade 16, the hole wall is firmly kneaded with the soil cement. It will be something.
Further, in step 5, as shown in FIG. 7 (e), the synthetic replacement column building apparatus 10B is pulled up to the ground, and the hydraulic solidifying material liquid replacement columnar body 3a is filled to a predetermined top end level L to complete the construction. .

Next, an example of the excavation rod used in the present invention is shown in FIGS. 8 (a), (b) and (c). The excavation rod 20 has a construction machine rod portion 22 having an outer diameter connectable to an auger motor of a construction machine (not shown) and a relatively large diameter forming a hydraulic solidifying material liquid replacement portion (in the case of a spiral screw, the outer diameter thereof). ) And a rod main body portion 21 for connecting the synthetic replacement column building apparatus to the lower end, and an adapter 23 for connecting them.
In FIG. 8 (a), since there is no function of discharging excavated earth and sand excavated by the excavating head 13 with the flat rod 20a having a flat side surface, when the construction is performed using the rod 20a, the generated residual soil is the smallest. .
FIG. 8B shows the excavation rod 20b in which the continuous spiral screw 25 is fixed to the side surface of the rod main body 21. Since the excavation soil excavated by the excavation head 13 is largely discharged to the ground, it is most effective for excavation. Although it is excellent, on the other hand, when it constructs using this rod 20b, the generated residual soil is the most.
FIG. 8C shows an excavation rod 20c in which an intermittent spiral screw 25a is fixed on the side surface of the rod main body 21, and the function of discharging excavated earth and sand excavated by the excavation head 13 to the ground is shown in FIG. It is intended to improve the balance between the excavation performance and the amount of generated residual soil by lowering than the excavation rod 20b having the screw 25. When the construction is performed using this rod 20c, both the excavation performance and the generated residual soil are (a ) And (b).

Next, the synthetic replacement column 10b shown in FIG. 5 (d) is connected to the excavation rod 20b in which the continuous spiral screw 25 is fixed to the side surface of the rod main body 21 shown in FIG. 8 (b). A column construction method will be described with reference to FIGS. 9A, 9B, 9C, 9D, and 9E. 9A, 9B, 9C, 9D, and 9E are shown in the order of steps. As shown in FIG. 5 (d), the synthetic replacement column building apparatus 10D has a conical shape having a spiral blade 15 on the side surface at the lower end of the shaft portion 11 having a stirring blade 16, a co-rotation preventing blade 17 and a spiral blade 18 on the side surface. The synthetic replacement column building apparatus 10D is connected to the drilling rod 20b.
At the time of construction, the excavation rod 20b is connected to an auger motor of a construction machine (not shown). The auger motor can grip the excavation rod 20b, transmit a rotational force, and move back and forth (advance and retreat). it can.

First, in the step (a), the center position of the tip of the excavation head 13 is set at the pile center position of the ground as shown in FIG.
Next, in step (b), as shown in FIG. 9 (b), the synthetic replacement column building apparatus 10D is dug while rotating forward through a drilling rod 20b connected to an auger motor of a construction machine (not shown). After the lowermost position of the stirring blade 16 reaches the first predetermined depth (empty excavation depth), the hydraulic solidified material liquid is discharged from the discharge port 14 of the excavation head 13, and the excavation is continued in this state. The discharge amount of the hydraulic solidifying material liquid is set such that the quality of the soil cement portion 2b of the columnar body to be built satisfies the design required performance. At this time, the soil cement is discharged to the ground by the soil removal effect of the continuous spiral screw 25 fixed to the excavation rod 20b, and becomes the generated soil. Due to this soil removal effect, the lateral displacement of the ground due to the construction of the synthetic replacement column is mitigated. Further, since the spiral blades 15 and 18 are fixed to the conical excavation head 13 and the shaft portion 11, the excavated earth and sand can be obtained even in a relatively hard ground or a sandy layer that is difficult to move laterally. Can be moved upward, so that the digging performance is good and the digging up to a predetermined depth can be performed reliably.
Next, in step (c), as shown in FIG. 9 (c), when the excavation head 13 reaches a predetermined depth (the depth that is the lower end position of the synthetic replacement column to be built), step (d) is performed as shown in FIG. 9 (d). As shown in (2), while continuing to rotate the synthetic replacement column building apparatus 10D and discharging the hydraulic solidifying material liquid, the building apparatus 10D is pulled upward. At this time, the rotation direction is preferably forward rotation, but reverse rotation is also possible. The discharge amount of the hydraulic solidifying material liquid while continuing the rotation of the building apparatus 10D fills the space generated by pulling up the building apparatus 10D and maintains an amount that does not cause suction (negative pressure).

At this time, since the soil cement portion is not formed below the lowermost stirring blade 16 at the position where the excavation head 13 reaches the predetermined depth (FIG. 9C), the soil is not lifted up from this position. Until the cement portion is formed, the hole formed by the shaft portion 11 and the excavation head 13 is pulled up while being filled with the hydraulic solidifying material liquid, and is lowered below the hydraulic solidifying material liquid replacement columnar body 3a. The protrusion part 4 will be formed.
When the lower shaft portion 11 is positioned in the soil cement portion from the lowermost stirring blade 16 by further lifting, the side surface of the lower shaft portion 11 is kneaded from the lowermost stirring blade 16 into the soil cement portion 2b. The hole is pulled up while forming a hole, and the hole is pulled up while being immediately filled with the hydraulic solidifying material liquid to be discharged. Since the hole formed in the soil cement portion 2b at the time of the pulling is formed by kneading the side surface of the shaft portion 11 below the lowermost stirring blade 16, the hole wall is firmly kneaded with the soil cement. However, the degree is not stronger than the flat rod 20a.
Further, in the step (e), as shown in FIG. 9 (e), the synthetic replacement column building apparatus 10D is pulled up to the ground, filled to the top end level L of the hydraulic solidifying material liquid, and the construction is finished.

  In this example, the excavation rod 20b having the continuous spiral screw 25 fixed thereto is used. However, when the amount of generated soil is larger than planned, the intermittent spiral screw as shown in FIG. Take measures such as changing the excavating rod 20c to 25a. Conversely, when the amount of generated soil is less than planned, measures such as increasing the number of revolutions of the excavating rod and slowing the excavation speed or the lifting speed are taken.

The synthetic replacement column 1 is constructed by pulling up the synthetic replacement column building apparatuses 10A, 10B, 10C, and 10D while discharging the hydraulic solidified material liquid from the discharge port 14 of the excavation head 13, but the normal replacement level (top) The level L) is adjusted to a predetermined position below the construction ground surface and the discharge of the hydraulic solidifying material liquid is stopped because the liquid level (top) cannot be seen at the time of construction. It is extremely difficult. As a result, if the liquid level (top end) of the hydraulic solidifying material liquid is lower than a predetermined position, additional filling of the hydraulic solidifying material liquid is required in a subsequent process. On the other hand, if the liquid level (top) is higher than a predetermined position, it is necessary to scoop it up using a handle before the hydraulic solidifying material liquid is cured, or to cut off the portion that is too high in the subsequent process. Since the hydraulic solidifying material liquid mainly composed of ordinary Portland cement exhibits a compressive strength exceeding 10 N / mm ² per day in the material example, if the subsequent process is delayed, the shaving operation itself becomes difficult. If it is forcibly scraped off with a backhoe or the like, the synthetic replacement column itself may even be damaged. In any case, if the liquid level (top) of the hydraulic solidifying material liquid cannot be adjusted to a predetermined position in the construction process of the synthetic replacement column, a post process occurs, leading to a delay in construction period and an increase in cost.

Next, in the construction for constructing the composite replacement column, the construction method for correcting the top end level L of the composite replacement column to a predetermined position is shown in FIGS. 10 (a) (b) (c) (d) (e) (f). (G) will be described.
The construction method for constructing the composite replacement column using the composite replacement column building apparatus 10B is the same as the construction process shown in FIGS. 7 (a), (b), (c), (d), and (e). Detailed description will be omitted.
First, the construction steps up to FIGS. 10 (a) (b) (c) (d) (e) are the same as FIGS. 7 (a) (b) (c) (d) (e). In this construction process, as shown in FIG. 10 (e), the discharge of the hydraulic solidifying material liquid 3b is stopped at a position lower than a predetermined top end level L, and the synthetic replacement column building apparatus 10B is lifted upward, (Top) L1 is a position lower than a predetermined top level L. At this time, when the construction apparatus 10B is pulled up, the forward rotation of the construction device 10B causes the soil cement portion 2b above the hydraulic solidifying material liquid filling position L1 to be placed below the lowermost stirring blade 16 of the construction apparatus 10B. Since the part 11 kneads the hole wall, the hole wall is stable and preferable.
As shown in FIG. 10E, when the liquid level (top end) L1 of the hydraulic solidifying material liquid is applied at a position lower than a predetermined top end level L as shown in FIG. The composite replacement column building apparatus 10B is pulled up, and the discharge of the hydraulic solidifying material liquid is resumed in a state where the hydraulic solidifying material liquid discharged from the discharge port 14 of the excavation head 13 is fixed in a position where the hydraulic solidifying material liquid is contained in the hole wall. As shown in FIG. 10 (f), the hydraulic solidifying material liquid is filled up to a predetermined top level L by visual observation from the ground. Since it is visually managed, the hydraulic solidifying material liquid can be easily filled in accordance with a predetermined position (predetermined top end level L).
Also, when the building apparatus 10B is in the way and visual management is not possible, after moving the building apparatus 10B as shown in FIG. 10 (g), the hydraulic solidifying material liquid is placed at a predetermined position (predetermined) using a handle or a bucket. To top level L). In this case, when the filling amount of the hydraulic solidifying material liquid is large, it may be filled by directly injecting it from a construction grout pump through a hose.

The hydraulic solidifying material liquid used in the present invention is a slurry mainly composed of various portland cements such as ordinary portland cement, blast furnace cement, fly ash cement, and cement-based solidifying material for ground improvement. This hydraulic solidifying material solution bleeds after filling. The amount of bleeding greatly depends on the composition of the hydraulic solidifying material liquid, particularly the water cement ratio. Increasing the water-cement ratio improves the fluidity of the slurry and improves the construction efficiency when pumping, but the amount of bleeding increases and the top level when solidifying the hydraulic solidification liquid is higher than that when filling. Decrease significantly. Therefore, it is necessary to increase the hydraulic solidification material liquid filling amount at the completion of construction in consideration of the bleeding amount, but the extra length is small when the top level is at a relatively shallow depth like a detached house, It is difficult to increase the filling amount of the hydraulic solidifying material liquid. Therefore, the work of filling the hydraulic solidifying material liquid has to be performed in the subsequent process, resulting in a delay in the construction period and an increase in cost. On the other hand, in order to suppress the bleeding amount to such an extent that a post-process is substantially unnecessary, it is necessary to reduce the water cement ratio to such an extent that the fluidity of the hydraulic solidifying material liquid is lost. However, if the water-cement ratio is reduced in such a manner, the hydraulic solidifying material liquid is no longer in the form of a slurry, and the pump cannot be pumped, and the construction itself cannot be performed.
Therefore, the above problem can be solved by using an admixture in which the hydraulic solidifying material liquid maintains fluidity as a slurry and reduces bleeding. Bentonite is generally used as a material for reducing bleeding, but bentonite requires a relatively large amount of admixture of about 10 to 20% with respect to cement, the effect of reducing bleeding significantly varies depending on the varieties, and mixing. There are drawbacks such as the variation of the bleeding rate from batch to batch and the decrease in compressive strength after hardening of the hydraulic solidifying material liquid when the amount of bentonite is increased, and there are many problems to be solved for use in the present invention. .

  In view of such points, in the present invention, magnesium carbonate is used as a bleeding reducing material. In the present invention, magnesium carbonate is used in a broad concept including basic magnesium carbonate. Mixing magnesium carbonate with the hydraulic solidification liquid increases the viscosity of the slurry, but if the amount is adjusted to the conditions such as the water cement ratio and slurry temperature, the amount of bleeding is reduced without impairing the fluidity of the slurry. I can do it. Furthermore, there is also a feature that the decrease in compressive strength is small compared to bentonite mixing.

  Next, examples and comparative examples of the present invention will be described in detail with reference to the drawings.

  Fig.11 (a) is a front view which shows Example 1 of the synthetic | combination replacement column construction apparatus based on this invention. The composite replacement column building device 10B of the first embodiment has the same configuration as the composite replacement column building device 10B shown in FIG. 5B, and the shaft portion 11 having an outer diameter of 216 mm is 500 mm above the lower end of the shaft portion 11. 4 stirrer blades 16 having a rotation outer diameter of 400 mm projecting above the position of the two, and a rotation prevention blade 17 having a rotation outer diameter of 500 mm is rotatably provided between the two stages of the stirring blades 16, 16. The excavation head 13 is connected to the lower end of the shaft portion 11. The stirring blade 16 has a gradient of 30 degrees with respect to the horizontal axis, the width (height) is 80 mm, the interval between the two stirring blades 16 and 16 is 240 mm, the width (height) of the co-rotation preventing blade 17 is 70 mm, The distance between the stirring blade 16 and the co-rotation preventing blade 17 is 45 mm. This synthetic replacement column building apparatus 10B is connected to a drilling rod 20 having an outer diameter of 216 mm.

Comparative Example 1

  FIG.11 (b) is a front view which shows the comparative example 1 of a hydraulic solidification material liquid substitution column construction apparatus. The hydraulic solidifying material liquid replacement column building apparatus 30A of Comparative Example 1 is provided with a drilling head 13 having a length (height) of 300 mm at the tip of a drilling rod 20 having an outer diameter of 216 mm. There are no stirring blades and anti-rotation blades.

  In both Example 1 and Comparative Example 1, the excavation head 13 secures excavation performance in the sand ground and does not cause the sediment adhering to the excavation head to fall off from the excavation head. A spiral blade 15 is provided on the side surface so as to move the excavated earth and sand upward during forward rotation, and a hydraulic solidifying material liquid discharge port 14 is provided on the side surface of the excavation head 13.

FIG. 12 is an explanatory diagram showing the relationship between the time and depth of a construction process for building a composite replacement column using the composite replacement column building apparatus 10B of the first embodiment shown in FIG. 11 (a). In this example, the synthetic replacement column construction apparatus 10B was used to construct a synthetic replacement column having a length of 4 m.
In the excavation process, W / C = 60% (W: water, C: cement) hydraulic solidifying material liquid is discharged from the discharge port 14 at a rate of 2.0 m / min while being discharged at a speed of 2.0 m / min. Digged and built the soil cement part. After reaching a predetermined depth, the hydraulic solidification material liquid is discharged from the discharge port 14 at a predetermined rotation rate of 44 liters per minute while maintaining the forward rotation, and the discharge is continued for 30 seconds at the predetermined depth position. In the process, the composite solidification column was constructed by pulling up at a speed of 1.2 m / min by normal rotation while keeping the discharge amount of the hydraulic solidifying material liquid from the discharge port 14 at 44 liters / min. Incidentally, the discharge amount of the hydraulic solidifying material liquid of excavation process, as the amount of adding the excavated soil 1 m ³ per 250 kg, were set the volume of the target soil outside diameter 400 mm, a cylindrical column having an inner diameter of 216 mm (excluding rod volume) . In addition, the discharge amount of the hydraulic solidifying material liquid in the pulling process was set to a discharge amount capable of filling an amount corresponding to the volume of an inner diameter of a hole generated when the pulling-up was performed at a speed of 1.2 m per minute, being 216 mm.

FIG. 13 is an explanatory view showing the relationship between the time and depth of the construction process for building a replacement column using the hydraulic solidifying material liquid replacement column building apparatus 30A of Comparative Example 1 shown in FIG. 11 (b). In this example, a hydraulic solidifying material liquid replacement column having a length of 4 m was built using a hydraulic solidifying material liquid replacement column building apparatus 30A.
In the excavation process, the excavation was performed in a forward rotation at a speed of 2.0 m / min without discharging the hydraulic solidifying material liquid. After reaching the predetermined depth, the hydraulic solidified material liquid was discharged from the discharge port 14 at a rate of 44 liters per minute while maintaining the forward rotation, and maintained at the depth position for 30 seconds, and then the pulling-up was started. In the pulling process, the hydraulic solidifying material liquid replacement column was constructed by pulling up at a speed of 1.2 m per minute by normal rotation while the discharge amount of the hydraulic solidifying material liquid from the discharge port 14 was 44 liters per minute.

In addition, in order to prevent the head (top end) of the hydraulic solidifying material liquid replacement part from bleeding and lowering the top end level after construction in both Example 1 and Comparative Example 1, the hydraulic solidifying material liquid is bleeding. Reducer (basic magnesium carbonate) is mixed. Table 1 shows a blending example of the hydraulic solidifying material liquid.
Further, in the column constructed in Example 1 and Comparative Example 1, a deformed bar with a screw node is inserted at the center position over the entire length of the column immediately after construction as a core material for pulling out with a mobile crane.

  Construction was carried out according to the construction steps shown in FIGS. 12 and 13 together with Example 1 and Comparative Example 1, and the excavation speed did not decrease even in sandy ground having a depth of 3.2 m or more. Moreover, bleeding was not seen by the head (top end) of the hydraulic solidification material liquid replacement part after construction.

Further, in both Example 1 and Comparative Example 1, three synthetic replacement columns and hydraulic solidifying material liquid replacement columns were constructed in the construction steps shown in FIGS. The synthetic replacement columns constructed in Example 1 are designated as Example columns 1 to 3, and the hydraulic solidifying material liquid substitution columns constructed in Comparative Example 1 are designated as Comparative Examples columns 1 to 3. Table 2 shows the measurement results of the pull-out resistance of the ground when pulled out using the mobile cranes of Examples Columns 1 to 3 and Comparative Examples Columns 1 to 3 that were implemented at the age of 28 days.
The pulling resistance shown in Table 2 was reduced by 8 kN in the synthetic replacement column (Example columns 1 to 3) and 2 kN in the hydraulic solidifying material liquid replacement column (Comparative Examples columns 1 to 3) as the column weight. Value.

  According to the test results, the average value of the example columns 1 to 3 is 231.1 kN, which is approximately 2.34 times the average value of the pulling resistance force of the comparative example columns 1 to 98.6 kN. The peripheral area ratio of the structures of the examples of the present invention and the comparative example is 1.87 times, the pulling force is larger than the peripheral area ratio, and the peripheral resistance force is 1.25 times. From the above, it can be said that the peripheral replacement force of the composite replacement column of the embodiment of the present invention is significantly improved as compared with the column of the comparative example.

  Next, Table 3 shows the results of the investigation on the finished shape of the example column 3 and the comparative example column 3.

  According to the results of the completed form investigation in Table 3, the finished diameter of the soil cement portion of the synthetic replacement column of the embodiment column 3 of the present invention is substantially equal to the outer diameter of the stirring blade 16 of the synthetic replacement column building apparatus 10B. I understand.

FIG. 14 is a photographic diagram showing a side situation of the column after pulling out the column 3 of the embodiment of the present invention and the column 3 of the comparative example, (a) is a synthetic replacement column of the column 3 of the embodiment according to the present invention, (b). Is a hydraulic solidifying material liquid replacement column of Comparative Example column 3.
FIG. 15 is a photograph showing a cross-sectional state after crushing of the synthetic replacement column of the embodiment column 3 of the present invention. It can be confirmed that a hydraulic solidifying material liquid replacement column having a diameter of about 200 mm, which is equivalent to the shaft portion 11 of the synthetic replacement column building apparatus 10B, is built at the center of the column section of the example column 3. There was no thinning of the hydraulic solidifying material liquid replacement column over the entire length.
In Examples Columns 1 to 3 and Comparative Examples Columns 1 to 3 of the present invention, no soil block was mixed in the hydraulic solidifying material liquid replacement part.

  FIG. 16: is a front view of the synthetic | combination replacement column construction apparatus which shows Example 2 of this invention. The synthetic replacement column building apparatus 10E of the second embodiment is obtained by removing the common rotation preventing wing 17 from the synthetic replacement column building apparatus 10B of the first embodiment shown in FIG. This is a synthetic replacement column building apparatus 10E. Synthetic replacement using the synthetic replacement column building apparatus 10E not equipped with the co-rotation preventing wing shown in the second embodiment and the synthetic replacement column building apparatus 10B equipped with the co-rotation preventing wing 17 shown in FIG. Built a column.

FIG. 17 is an explanatory diagram showing the relationship between the time and depth of the construction process for constructing this composite replacement column. In this example, a synthetic replacement column having a length of 4 m was constructed using a synthetic replacement column building apparatus 10B equipped with the co-rotation preventing wing 17 and a synthetic replacement column building apparatus 10E not equipped with the co-rotating prevention wing. In the excavation process, the hydraulic cement material liquid of W / C = 60% was discharged from the discharge port 14 at a rate of 41 liters per minute, and excavated at a speed of 2.0 m / min. . After reaching the predetermined depth, the discharge amount of the hydraulic solidification material liquid was continuously set to 44 liters per minute from the discharge port 14 while maintaining the forward rotation, and the discharge was continued for 30 seconds at the predetermined depth position. In the pulling up process, the composite solidification column was constructed by pulling up at a speed of 1.2 m / min by normal rotation while the discharge amount of the hydraulic solidifying material liquid from the discharge port 14 was 44 liters.
In addition, the discharge amount of the hydraulic solidifying material liquid in the excavation process was set to an amount for adding 250 kg per 1 m ^{3 of} excavated soil, and the volume of the target soil was set as a cylindrical shape with an outer diameter of 400 mm and an inner diameter of 216 mm (excluding the rod volume). . Further, the discharge amount in the pulling process was set to a discharge amount capable of filling an amount corresponding to the volume of the inner diameter of the hole generated when pulling up at a speed of 1.2 m per minute to be 216 mm.

In order to prevent the head (top end) of the hydraulic solidifying material liquid replacement part from bleeding and lowering the top end level after the construction, a bleeding reducing material is mixed in the hydraulic solidifying material liquid. Although basic magnesium carbonate is used for the bleeding reducing material, magnesium carbonate may be used. Bentonite, which is effective in reducing bleeding of cement milk, is not preferable because it causes a decrease in strength of the soil cement. The hydraulic solidifying material liquid has the same composition as in Table 1 above.
In addition, a deformed steel bar with a threaded joint is inserted at the center of the entire length of the column immediately after the construction of the synthetic replacement column as a core material for pulling out with a mobile crane after construction.

  Even when any of the synthetic replacement column building apparatuses 10B and 10E was used, the construction was performed according to the construction process shown in FIG. In addition, no bleeding was observed at the head of the hydraulic solidifying material liquid replacement part after construction.

As described above, the synthetic replacement column building apparatus 10B equipped with the co-rotation preventing wing 17 shown in FIG. 11A of the first embodiment and the synthetic replacement column construction not equipped with the co-rotation preventing wing shown in FIG. 16 of the second embodiment. A synthetic replacement column was built using the apparatus 10E, and after the construction, the synthetic replacement column was pulled out by a mobile crane at a material age of 28 days, and the finished shape was confirmed.
In the vicinity of the outer peripheral surface of the synthetic substitution column constructed using the synthetic substitution column construction apparatus 10E not equipped with the co-rotation prevention wing of Example 2, the hydraulic solidifying material liquid was solidified in a thin skin state. This is because the excavated soil and the hydraulic solidifying material liquid are not well agitated and mixed due to the occurrence of a so-called co-rotation phenomenon of the excavated soil in which the excavated soil rotates synchronously with the construction apparatus 10E.
FIG. 18 is a photographic view showing a cross-sectional state after fracture of a synthetic replacement column constructed using the synthetic substitution column building apparatus 10E of Example 2 in which no common rotation prevention wing is attached. It can be confirmed that a hydraulic solidifying material liquid replacement column having a diameter of about 200 mm, which is substantially equivalent to the shaft portion 11 of the building apparatus 10E, is built at the center of the column cross section. There is no thinning of the hydraulic solidifying material liquid replacement part over the entire length, and there is no mixing of soil blocks. However, it can be seen that the soil cement portion on the outside has a portion in which the hydraulic solidifying material liquid is solidified as it is and a soil block of the original ground soil, which is not well mixed with stirring.
However, as will be described below, the quality of the synthetic replacement column constructed using the synthetic replacement column construction apparatus 10B of Example 1 equipped with the co-rotation prevention wing 17 is better, but this example is also implemented. Although the quality is inferior to that of Example 1, depending on the raw ground soil, the quality can be implemented with little difference. For example, when the ground soil is sandy soil, co-rotation does not occur even if there is no co-rotation prevention wing, so that it is possible to build a synthetic replacement column with good quality.
FIG. 19 is a photographic view showing a cross-sectional state after fracture of the synthetic replacement column constructed using the synthetic substitution column construction apparatus 10B of Example 1 equipped with the co-rotation preventing wing 17. In the center of the synthetic replacement column, a hydraulic solidifying material liquid replacement column having a diameter of about 200 mm, which is substantially the same as the shaft portion 11 of the building apparatus 10B, is built, and the diameter ( It can be confirmed that a soil cement part having an outer diameter of 400 mm is built. It can be seen that the soil cement portion does not appear to co-rotate and is uniformly stirred and mixed. In the synthetic replacement column building apparatus 10B equipped with the co-rotation preventing wing 17, the protruding portion of the original ground of the co-rotation preventing wing 17 may have a digging resistance and the digging performance may be lowered. A uniform soil cement part can be built by preventing the co-rotation phenomenon of soil.

Comparative Example 2

FIG. 20 is a front view of the synthetic replacement column building apparatus showing the second comparative example. In the synthetic replacement column building apparatus 30B of the comparative example 2, the excavation head 13 having a length (height) of 300 mm is provided at the tip of the shaft portion 11 having an outer diameter of 216 mm. The excavation head 13 not only improves the excavation performance, but also prevents the sediment adhering to the excavation head from being peeled off from the excavation head 13, so that the excavation head 13 has a downward conical shape. A spiral wing 15 is fixed in the direction of movement. On the side surface of the excavation head 13, a discharge port 14 for hydraulic solidifying material liquid is provided.
On the shaft portion 11, two stages of four stirring blades 16 having a rotating outer diameter of 400 mm are fixedly provided above the position of 100 mm above the lower end of the shaft portion 11, and between the two stages of stirring blades 16, 16. A co-rotation prevention blade 17 having a rotation outer diameter of 500 mm is rotatably provided. The stirring blade 16 has a gradient of 30 degrees with respect to the horizontal axis, its width (height) is 80 mm, the interval between the two stages of the stirring blades 16, 16 is 240 mm, and the width (height) of the co-rotation prevention blade 17. Is 70 mm, and the distance between the stirring blade 16 and the co-rotation preventing blade 17 is 45 mm.
Synthetic replacement columns were constructed using the synthetic replacement column building device 30B shown in Comparative Example 2 and the synthetic replacement column building device 10B according to Example 1 shown in FIG. In the synthetic replacement column building apparatus 10B shown in Example 1, the length of the shaft portion 11 below the lower end of the lowermost stirring blade 16 is 300 mm, whereas the synthetic replacement column building apparatus 30B in Comparative Example 2 is The two are different in that the length of the shaft portion 11 below the lower end of the lowermost stirring blade 16 is 100 mm, and the others are the same.

FIG. 21 is an explanatory diagram showing the relationship between the time and depth of the construction process for building the synthetic replacement column by the synthetic replacement column building apparatus 10B of the first embodiment of the present invention, and FIG. 22 is the synthetic replacement column building apparatus of Comparative Example 2. It is explanatory drawing which shows the relationship between the time of the construction process which builds a synthetic | combination replacement column by 30B, and depth. In both cases, a synthetic replacement column having a length of 4 m was constructed.
In each of the excavation processes, a hydraulic solidification material liquid of W / C = 60% is discharged from the discharge port 14 at 57 liters per minute, and excavated at a speed of 2.0 m / min. Built. After reaching a predetermined depth, the discharge was continued at a discharge depth of 44 liters per minute with the hydraulic solidifying material liquid being 44 liters per minute while maintaining the forward rotation, and kept at a predetermined depth for 30 seconds, and then pulled up. In the pulling step, the composite solidification column was constructed by pulling up at a speed of 1.2 m / min while maintaining the normal rotation while keeping the discharge amount of the hydraulic solidifying material liquid from the discharge port 14 at 44 liters / min. The discharge amount of the hydraulic solidifying material liquid in the excavation process was set to an amount for adding 350 kg per 1 m ^{3 of} excavated soil, and the volume of the target soil was set as a cylindrical shape (excluding the rod volume) having an outer diameter of 400 mm and an inner diameter of 216 mm. In addition, the discharge amount in the pulling process was set to a discharge amount capable of filling an amount corresponding to the volume of a hole having a diameter of 216 mm generated when pulling up at a speed of 1.2 m per minute.
In addition, in the construction of the synthetic replacement column in Example 1 and Comparative Example 2, in order to prevent the head (top end) of the hydraulic solidifying material liquid replacement part from bleeding after construction and the top end level from being lowered. In addition, a bleeding reducing material is mixed in the hydraulic solidifying material liquid. The hydraulic solidifying material liquid has the same composition as in Table 1. In addition, a deformed steel bar with a threaded joint is inserted at the center of the entire length of the column immediately after construction as a core material for pulling out the synthetic replacement column after being built by a mobile crane.

  When the synthetic replacement column building apparatus 10B shown in Example 1 is used, construction is performed according to the construction process shown in FIG. 21, and when the synthetic replacement column building apparatus 30B shown in Comparative Example 2 is used, it is shown in FIG. Construction was performed according to the construction process. In addition, no bleeding was observed at the head (top end) of the hydraulic solidifying material liquid replacement part after construction.

The synthetic replacement column constructed above was pulled out with a mobile crane at the age of 28 days after construction, and the finished shape was confirmed.
FIG. 23 is a photograph (a) and (b) showing a cross section of a synthetic replacement column constructed using the synthetic substitution column construction apparatus 10B of Example 1 shown in FIG. 11 (a). It can be confirmed that a hydraulic solidifying material liquid replacement portion having a diameter of approximately 200 mm, which is substantially equivalent to the shaft portion 11 of the building device 10B, is built at the center of the column cross section. Although not shown in the drawing, the diameter of the hydraulic solidifying material liquid replacement part was partially less than 200 mm, but the diameter of about 200 mm was almost the same as the shaft part 11 of the building apparatus 10B over almost the entire length. Met. In this example, no soil clumps were found.
FIGS. 24A and 24B are photographic views (a) and (b) showing a cross section of a synthetic replacement column constructed using the synthetic substitution column construction apparatus 30B of Comparative Example 2. FIG. In the center of the column cross section, a hydraulic solidifying material liquid replacement part is built, and although no clumps are seen, the diameter is 150 mm, which is thinner than the diameter 216 mm of the shaft part 11 of the building apparatus 30B. Thinness was seen.

From the above results, the length (shaft protrusion length) H of the lower shaft portion 11 from the position of the lowermost stirring blade 16 is at least 1.5 times the diameter of the shaft portion 11, so that the hydraulic solidification is achieved. It can be said that the outer diameter of the material liquid replacement part can be stably constructed. In the soft silt ground as in this construction example, it can be said that the outer diameter of the hydraulic solidifying material liquid replacement part can be more stably constructed by further increasing the shaft protrusion length H.
However, if the protruding length H of the shaft portion is too long, the length of the soil cement columnar body becomes relatively short, so that the length of the finished shape as the synthetic replacement column becomes small, which is not preferable. Further, if the shaft protrusion length H exceeds 6 times the diameter of the shaft 11, the distance from the discharge port 14 to the stirring blade 16 is too far away, so that the stirring ground 16 is mixed with the ground soil by stirring. In addition, when the hydraulic solidifying material liquid deviates into the ground, there is a risk that the mixing degree of the hydraulic solidifying material liquid and the raw ground soil will be poor, and the finished shape of the soil cement part may be poor. Therefore, the protrusion length H of the shaft portion 11 is preferably up to about 6 times the diameter of the shaft portion 11.

The following can be said from the examples and comparative examples.
(1) With the synthetic substitution column construction apparatus and method of the present invention, it is possible to construct a synthetic substitution column having substantially the same diameter as the stirring blade outer diameter. Further, within the scope of this example, the fracture surface at the time of pulling out the synthetic replacement column occurs at the boundary between the soil cement part and the original ground, and the ratio is larger than the outer peripheral area ratio of the synthetic replacement column and the hydraulic solidifying material liquid replacement column. It is possible to improve the peripheral surface support force.
(2) By using a bleeding reducing agent, bleeding of the hydraulic solidifying material liquid replacement part head can be suppressed.
(3) The length of the lower shaft portion from the position of the lowermost stirring blade is set to 1.5 times or more the shaft diameter, and the columnar protrusion length of the hydraulic solidifying material liquid replacement columnar body is set to 1 of the protrusion diameter. By making the length 5 times or more, the thinning of the hydraulic solidifying material liquid replacement portion can be prevented.
(4) By mounting the co-rotation prevention wing so as to be rotatable with respect to the shaft body, the hydraulic solidifying material liquid and the original ground can be surely stirred and mixed, and the soil cement portion can be made homogeneous.
(5) The excavation head has a conical shape facing downward, and a spiral wing is attached to the side surface to move the excavation earth and sand upward during forward rotation, thereby ensuring excavation on hard ground. The earth and sand adhering to the excavation head is not peeled off from the excavation head, so that no soil block is mixed into the hydraulic solidifying material liquid replacement part.

DESCRIPTION OF SYMBOLS 1 Synthetic substitution column 2 Soil cement column 2a Soil cement column 2b Soil cement 3 Hydraulic solidification material liquid hardening column 3a Hydraulic solidification material liquid substitution column 3b Hydraulic solidification material liquid 3c Additional hydraulic solidification material liquid injected 4 Hydraulic solidification material liquid replacement columnar projecting part 5 Joint (cold joint)
10A, 10B, 10C, 10D, 10E Synthetic replacement column building apparatus 11 Shaft portion 12 Joint portion 13, 13a Drilling head 14 Discharge port 15 Spiral blade 16 Stirring blade 17 Co-rotation prevention blade 18 Spiral blade 19 Joint portions 20, 20a, 20b 20c Excavation rod 21 Rod body part 22 Construction machine rod part 23 Adapter 24 Joint part 25 Continuous spiral screw 25a Intermittent spiral screw

Claims (12)

  A columnar hydraulic solidifying material liquid replacement columnar body is disposed in the axial center portion of the soil cement columnar body so that the axial centers thereof substantially coincide with each other, and the hydraulic solidifying material liquid replacement columnar body disposes of the soil cement columnar body. A synthetic replacement column consisting of a soil cement column and a hydraulic solidifying material liquid-cured column, characterized by penetrating and projecting downward.   The composite replacement column of soil cement pillars and hydraulic solidifier liquid-hardened columns according to claim 1, wherein the hydraulic solidifier liquid is mixed with a bleeding reducing material.   The downward protrusion of the hydraulic solidifying material liquid replacement columnar body is cylindrical, and the length of the cylindrical protrusion is at least 1.5 times the length of the protrusion. Or the synthetic | combination substitution column of the soil-cement pillar body of 2 and a hydraulic solidification material liquid hardening pillar body.   An excavation head having a hydraulic solidification material liquid discharge port is attached to the lower end of the shaft portion having a hydraulic solidification material liquid flow path inside and a joint portion with a drilling rod at the upper end. An apparatus for constructing a synthetic replacement column, wherein at least two stirring blades are fixed, and a length of a lower shaft portion from the position of the lowermost stirring blade is at least 1.5 times the diameter of the shaft portion.   The shaft portion has a rotation preventing blade that is rotatably mounted, the rotation diameter of the rotation preventing blade is larger than that of the stirring blade, and is installed in the vicinity of the fixed position of the stirring blade. The apparatus for building a synthetic replacement column according to claim 4.   The excavation head has a conical shape facing downward, and a spiral blade is fixed to the side of the excavation head so that the excavation earth and sand is moved upward during normal rotation. 6. The synthetic replacement column building apparatus according to claim 4 or 5, wherein the apparatus has a size that does not exceed, and a discharge port for hydraulic solidifying material liquid is provided on the side surface.   The spiral blade of the direction which moves excavation earth and sand upwards at the time of forward rotation is fixed by the shaft side of the lower part from the position of the lowest stirring blade at least. The synthetic replacement column building device described in 1.   8. The synthetic replacement column building device according to claim 4, wherein the excavation head is detachably connected to the shaft portion.   The synthetic replacement column construction device according to any one of claims 4 to 8 is connected to the lower part of the excavation rod, and the central part of the excavation head tip below the construction device is set at the pile center position of the ground. While rotating forward, digging while discharging hydraulic solidifying material liquid from the discharge port of the drilling head, and after the drilling head reaches a predetermined depth, discharging the hydraulic solidifying material liquid and rotating the building device forward Alternatively, a method for constructing a synthetic replacement column of a soil cement column and a hydraulic solidified material liquid-cured column that are pulled up while rotating in reverse.   9. The synthetic replacement column building device according to claim 4 is connected to a lower part of a drilling rod having a continuous or intermittent spiral blade fixed on a peripheral side surface of the drilling rod. Set the center of the tip of the head at the pile center position of the ground, and dig while rotating the construction device forward, while stirring and mixing the ground around the excavating rod while discharging the hydraulic solidification liquid from the discharge port to make soil cement A soil cement column and a hydraulic solidified material liquid-cured column, which are pulled up while the construction device is rotated forward or backward while discharging the hydraulic solidified material liquid after the excavation head reaches a predetermined depth. How to build a synthetic replacement column.   The hydraulic solidifying material liquid is discharged while pulling up the synthetic replacement column building device, and before the liquid level of the discharged hydraulic solidifying material liquid reaches the upper predetermined position, the synthetic replacement column building device is pulled up. 11. The soil cement pillar and the water according to claim 9 or 10, wherein after that, the hydraulic solidifying material liquid is further discharged and adjusted so that the liquid level of the hydraulic solidifying material liquid substantially coincides with the predetermined position. A method for constructing a synthetic replacement column for a hard-solidifying material liquid-cured column.   12. The soil cement column and the hydraulic solidified liquid column according to claim 9, wherein the hydraulic solidified material liquid is mixed with magnesium carbonate for reducing bleeding. How to build a synthetic replacement column.

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