JP2013133630A - Excavation rod and construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excavation rod which allows the amount of earth removal to be reduced in pile construction, and a construction method.SOLUTION: An excavation rod 3 includes a main shaft 31 which is rotated by a driving force, an excavation bit 32 disposed at the tip 31a of the main shaft 31, and a corotation prevention blade 33, a first agitation blade 34, a second agitation blade 35, and propeller-like agitation blades 36 and 37, which are arranged in this order from the tip side. The agitation blades 36 and 37 having opposing slopes with gradients different from each other in circumferential direction include at least a pair of propeller-like vanes 361 and 371 which allow the distance between the opposing slopes to be gradually reduced toward circumferential direction. The agitation blades 36 and 37 are rotated coaxially with the main shaft 31 and exert a pushing force on the surplus excavated soil or the like toward outside.

Description

  The present invention relates to a drilling rod and a construction method. More specifically, the present invention relates to an improvement of construction technology using ground improvement in combination.

  Conventionally, a method of embedding a steel pipe or the like as a reinforcing member in a column (column body) in the ground constructed by ground improvement to make a pile body (composite pile) has been used.

  As such a method, the ground and hardened material such as cement milk are agitated, and the inside of the excavation hole is soil cemented to a predetermined depth, and the pile provided with spiral blades (extended blades) is rotated before the soil cement solidifies. A technique for constructing soil cement composite piles (synthetic piles) by burying them while being buried is known. In addition, a technique that uses a stirring bar and an earth-pressing plate to suppress the rise of soil while stirring, a technique in which a stirring effect is achieved by a stirring blade attached to the upper part of the anti-rotation blade has been proposed (for example, a patent) References 1 and 2).

Japanese Patent No. 3069874 Japanese Patent No. 3621971

  However, the conventional construction techniques as described above do not involve the point of reducing the amount of soil discharged during excavation (the amount of surplus excavated soil discharged to the ground surface). Excess excavated soil is industrial waste, which increases the burden on the environment and increases treatment costs. Therefore, it is important to reduce the amount of soil discharged when constructing piles. Yes.

  Then, an object of this invention is to provide the excavation rod and construction method which reduced the amount of earth removal at the time of pile construction.

  In order to solve this problem, the present inventor has made various studies. For example, in a conventional constant speed construction method using a stirring and mixing jig as in the prior art, the construction time increases depending on the hardness and water permeability of the target ground, and the amount of soil is often increased. This amount of soil removal varies widely from about 15% to 45% of the excavation volume, and it is difficult to predict reliably. Focusing on this point, a method for better agitation has heretofore been proposed, but there is still no excavation jig or excavation method having a technique for reducing the amount of soil removal. The present inventor who has further studied from such a viewpoint has come to obtain new knowledge that leads to the solution of such problems.

  The present invention is based on such knowledge, and in the excavation rod for excavating the ground to be excavated, the main shaft that rotates by receiving driving force, the excavation bit provided at the tip of the main shaft, and the inclination in the circumferential direction are different from each other. It consists of at least a pair of propeller blades that have opposing inclined surfaces, and the interval between these opposing inclined surfaces gradually decreases in the circumferential direction, and is provided on the main shaft and rotates coaxially with the main shaft to remove excess excavated soil, etc. And a stirring blade for applying a force pushing out to the side.

  In such a drilling rod, when the main shaft is rotated during excavation, the stirring blade provided on the main shaft rotates in a predetermined direction in the ground. At this time, between the pair of propeller blades (blades) The surplus excavated soil that has entered (including the excavated soil in the ground as well as a mixture of the excavated soil and a hardener such as cement milk) receives a downward force from the opposed inclined surface of the upper blade, In addition, an upward force is received from the opposed inclined surface of the lower blade. In this way, surplus excavated soil or the like, which is pressurized from above and below, is driven to the outer peripheral side (outside in the radial direction) and kneaded while being pressed against the hole wall side of the excavation hole. As a result, the amount of generated residual soil is reduced by the volume of surplus excavated soil kneaded on the hole wall, and the load on the environment is reduced. Moreover, since the increase in the peripheral frictional force of the composite pile can be expected, the performance as a pile can be improved.

  In the excavation rod as described above, it is preferable that the plurality of blades are arranged at equal intervals in the circumferential direction.

  Moreover, it is preferable that the projected area of the blade in the main axis direction is 1/8 to 1/6 of the area of the circle drawn by the tip of the blade.

  Furthermore, it is preferable that the diameter of a blade | wing is smaller than the internal diameter of the hole wall of the excavation hole formed by excavating with an excavation bit.

  Moreover, it is also preferable that what is located above among the opposing blade | wings is formed in the shape wider than what is located below. In this case, the blades positioned above among the opposed blades may be formed in a shape in which the rear in the rotation direction of the blades is wider than the front side.

  Moreover, it is also preferable that at least one of the blades has an inclined surface having a steep slope at the rear in the rotation direction of the blade.

  Moreover, it is also preferable that at least one of the blades has an inclined surface with a gentle slope near the outer periphery in the radial direction of the blade.

  Furthermore, it is preferable that the main shaft has a larger shaft diameter between the opposing blades in the main shaft than the shaft diameter in other portions.

  Further, the construction method according to the present invention has opposed inclined surfaces having different inclinations in the circumferential direction, and a stirring blade composed of at least a pair of propeller blades in which the interval between the opposed inclined surfaces gradually decreases in the circumferential direction. And when excavating the ground to be excavated with the excavation rod using the excavation rod provided with a main shaft that rotates by receiving a driving force and a excavation bit provided at the tip of the main shaft, or A force for pushing the mixture of the earth and sand and the cement milk to the outer peripheral side is applied by a stirring blade.

  According to the present invention, the amount of soil discharged during pile construction can be reduced.

It shows the procedure of construction method of composite piles. (A) Pile core alignment by pile driver, (B) Soil cement column construction by mixing and mixing cement milk and ground, (C) Construction completion of soil cement column , (D) Steel pipe pile erection, (E) Steel pipe pile pile alignment, verticality confirmation, (F) Steel pipe pile rotary embedding in soil cement column, (G) Steel pipe pile pile head level It is a figure showing each process of confirmation. It is a side view of the excavation rod which shows one Embodiment of this invention. It is a top view which shows the form example of a drilling rod. It is the figure of the blade | wing seen from the radial direction outer side which shows the form example of a propeller-shaped stirring blade. It is a top view which shows the other form of a propeller-shaped stirring blade. It is the schematic of the propeller-shaped stirring blade (only one side of a main shaft) which has an inclined surface which changes so that it may become a steep slope toward the back rather than the rotation direction front. It is the figure which looked at the propeller-shaped stirring blade (only one side of a main axis | shaft) which has the inclined surface twisted so that it might become a gentle slope near the radial direction outer periphery of a blade | wing from the radial direction outer side.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 4 show an embodiment of a drilling rod and construction method according to the present invention. Below, the structure of the excavation rod 3 and the pile driving machine 10 is demonstrated first, and the construction method of the composite pile using this excavation rod 3 is demonstrated after that.

  2 and 3, reference numeral 3 denotes a drilling rod that is driven to rotate by the auger 13 and excavates the excavation hole 4 in which the steel pipe pile 5 is embedded. The main shaft 31 of the excavation rod 3 has a hollow structure and also serves as a pipe for passing a liquid or the like. The tip 31a of the main shaft 31 of the excavation rod 3 is provided with a nozzle (not shown) that ejects cement milk (an example of a hardened material as a ground improvement material) when the excavation rod 3 performs prior excavation. Yes. Further, a drilling bit 32 that excavates the ground G and stirs and mixes the cement milk and the excavated soil is provided on the proximal end side of the distal end portion 31a of the main shaft 31. On the base end side of the excavation bit 32, a co-rotation preventing blade 33, a first stirring blade 34, a second stirring blade 35, and propeller-shaped stirring blades 36 and 37 are provided on the main shaft 31 in order from the distal end side.

  The co-rotation preventing wing 33 is a wing formed to have a length exceeding the hole diameter of the excavation hole 4, and both ends thereof enter the ground 3 so as not to rotate together with the excavation bit 32. Although not shown in detail, the co-rotation preventing wing 33 is attached to be able to rotate relative to the main shaft 31 via a pipe or the like. Further, the co-rotation preventing wing 33 and the excavation bit 32 are arranged at a narrow interval to some extent so as to be suitable for shearing and finely pulverizing the soil (see FIG. 2), which contributes to the formation of a good quality improved body. To do.

  The first stirring blade 34 and the second stirring blade 35 are blades made of a rod-like member fixed to the main shaft 31 of the excavation rod 3, and rotate together with the main shaft 31 of the excavation rod 3. (See FIG. 2). In this embodiment, the rod-shaped members arranged so as to be orthogonal to each other are the first stirring blade 34 and the second stirring blade 35, respectively, but the number and shape of these blades are not particularly limited, and other modes It can also be.

  The propeller-shaped stirring blades 36 and 37 are configured by a pair of propeller-shaped blades disposed so that the inclined surfaces 36a and 37a face each other. In this embodiment, two propeller blades 361 arranged at intervals of 180 degrees constitute a propeller-like stirring blade 36 on the axial front end side, and similarly, two propeller-like blades arranged at intervals of 180 degrees are formed. A propeller-like stirring blade 37 on the axial base end side is constituted by the blade 371 (see FIG. 3).

  The tip side (lower side) blade 361 and the base end side (upper side) blade 371 have opposed inclined surfaces 36a and 37a having different inclinations in the circumferential direction, respectively (see FIG. 4). More specifically, the blade 361 on the distal end side has an upward inclined surface 36a that pushes up excess excavated soil when the excavating rod 3 rotates clockwise, and the blade 371 on the proximal end side is excavated. When the rod 3 rotates in the clockwise direction, it has an opposing inclined surface 37a having a downward reverse inclination that pushes down the excess excavated soil or the like (see FIGS. 3 and 4). The blades 361 on the distal end side and the blades 371 on the proximal end side are arranged so that the distance between the opposed inclined surfaces 36a and 37a gradually decreases in the circumferential direction (see FIG. 4).

  The distance between the opposed inclined surfaces 36a, 37a in the blade 361 on the distal end side and the blade 371 on the proximal end side is not particularly limited, depending on the size and properties of the target ground G, the structure of the excavation rod 3, and the like. It can be set appropriately. Here, if an example of the space | interval of the said opposing inclined surfaces 36a and 37a is shown, it will be about 10 cm-20 cm.

  In addition, the size (projection area in the axial direction) of the blades 361 on the distal end side and the blades 371 on the proximal end side can be set as appropriate. If a suitable example is shown, the tips of these blades 361 and 371 are drawn. It is preferable that it is about 1/8 to 1/6 of the area of the circle (the region that can be stirred by the propeller-like stirring blades 36 and 37). If the size of the blades 361 and 371 is about this level, the operation of pushing the surplus excavated soil etc. to the side of the hole wall 4a while moving the surplus excavated soil and the like in a range in which the resistance during rotation of the excavating rod 3 does not become excessively large. Easy to express.

  Furthermore, the diameters (propeller diameters) of the blades 361 on the distal end side and the blades 371 on the proximal end side are larger than about 80% of the hole wall diameter of the drilling hole 4 formed by drilling with the drilling bit. It is preferably smaller than the wall diameter. In the present embodiment, the diameters of the blades 361 and 371 are set to about 90% of the hole wall diameter (see FIG. 2 and the like).

  The pile driving machine 10 has a leader 12, an auger 13, a steady rest device 14, and the like, excavates the ground G, and rotates and embeds a pile (for example, a steel pipe pile 5) while standing in the excavation hole 4. (See FIG. 1).

  The auger (pile rotating device) 13 is provided so as to be movable along the leader 12 standing upright in the vertical direction, and moves up and down along the longitudinal direction of the leader 12 (see FIG. 1). The steel pipe pile 5 is connected to the auger 13 directly or via a yatco (not shown), and the steel pipe pile 5 is also rotated and penetrated into the ground G when the auger 13 is driven to rotate. In this embodiment, the steel pipe pile 5 in which the spiral blade 5b for penetration is provided at least at the tip is used. By rotating the steel pipe pile 5 in this way, the steel blade pile 5b is generated into the ground. The steel pipe pile 5 is penetrated into the excavation hole 4 using a propulsive force. When the steel pipe pile 10 penetrates the ground G, the auger 3 also descends along the leader 2.

  Subsequently, a series of operations until the ground G is excavated by using the excavation rod 3 and the steel pipe pile 5 is buried in the excavation hole 4 will be described in order (see FIG. 1 and the like).

  First, the ground G is excavated by rotating the excavating rod 3 (see FIGS. 1A and 1B). When excavating, for example, cement milk is supplied to a pipe provided inside the excavating rod 3 from a plant (not shown) or the like installed on the ground, and discharged from a nozzle located at the tip of the pipe. The discharged cement milk is agitated by the excavation bit 32 and mixed with the surplus excavation soil of the ground G to form a slurry, and the soil cement column 40 is constructed. Thereafter, the excavation rod 3 is pulled out from the excavation hole 4 (see FIG. 1C).

  Subsequently, the steel pipe pile 5 is built in the excavation hole 4. In order to build the steel pipe pile 5, first the base end (pile head) of the steel pipe pile 5 is lifted by the pile driving machine 10 (see FIG. 1 (D)), and the vertical alignment of the steel pipe pile 5 is confirmed. (See FIG. 1E). Thereafter, the steel pipe pile 5 is rotated and embedded in the soil cement column 40 (see FIG. 1 (F)), and once embedded, the pile head level (vertical position of the pile head) of the steel pipe pile 5 is confirmed (FIG. 1 ( G)). In the present embodiment, the steel pipe pile 5 having a helical blade 5a that enhances the adhesion of the steel pipe pile 5 to the soil cement is embedded in the soil cement column 40 in the excavation hole 4 while rotating the steel pipe pile 5 around it. ing. Thus, the construction of the composite pile (soil cement steel pipe composite pile) 1 in which the steel pipe pile 5 is embedded as a reinforcing member in the soil cement column 40 in the ground G constructed by the ground improvement is completed.

  According to this embodiment constructed using the excavation rod 3 as described above, the following operational effects can be achieved. That is, when excavating the ground G with the excavation rod 3, the propeller-shaped stirring blades 36 and 37 provided on the main shaft 31 are used, and the surplus excavation soil or the like (in addition to the surplus excavation soil, the (Including a mixture of surplus excavated soil and hardened material) upward and toward the upper slanted hole wall 4a, and the surplus excavated soil or the like is moved downward and slanted by the blade 371 on the base end side (upper side). The action of moving to the wall 4a side can be brought about (see the oblique arrow in FIG. 2 and the arrow in FIG. 4). Since the blades 361 on the front end side and the blades 371 on the base end side gradually decrease the distance between the opposed inclined surfaces 36a, 37a in the circumferential direction, excess excavated soil between the propeller-shaped stirring blades 36, 37, etc. Receives pressure from above and below, loses escape and is pushed to the outer periphery. Therefore, according to the excavation rod 3 of the present embodiment, the surplus excavation soil and the like can be stirred in a flat and three-dimensional manner, and at the same time, the surplus excavation soil and the like can be kneaded while being pressed toward the hole wall 4a. (See horizontal arrow in FIG. 2).

  As a result, according to the excavation rod 3 of the present embodiment, the amount of generated residual soil is reduced by the volume of surplus excavated soil and the like kneaded on the hole wall 4a, thereby reducing the burden on the environment.

  In addition, the use of the propeller-shaped stirring blades 36 and 37 also leads to an improvement in the efficiency of stirring and mixing such as surplus excavated soil. According to this, it becomes possible to realize a ground improvement body that suppresses variations in the ground improvement body and is more uniform and of higher quality. And since the increase in the peripheral frictional force of the composite pile 1 can be anticipated, the intensity | strength and quality of the said composite pile 1 can be improved.

  Here, from the viewpoint of expressing excessively excavated soil or the like by the propeller-shaped stirring blades 36 and 37 toward the hole wall 4a and a kneading function, the blades 361 and 371 of the main shaft 31 which are opposed to each other. It is also preferable to set the portion in the middle to a larger shaft diameter than the portions in the other portions (see reference numeral 31b indicated by a two-dot chain line in FIG. 2). In such a case, by forcibly eliminating the shaft side space between the propeller-like stirring blades 36 and 37, it is possible to increase the pressing action and kneading action on the outer excavated soil and the like on the outer peripheral side.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the propeller-like stirring blades 36 and 37 are illustrated such that the top blade 361 and the base blade 371 arranged vertically are overlapped in a plan view (see FIG. In addition, the front-side blades 361 and the proximal-side blades 371 may be shifted in the circumferential direction by leading or retracting the front-side blades 361. . As an example, when excavating soil having high viscosity and low fluidity, if the tip blade 361 and the base blade 371 are shifted in the circumferential direction in this manner, the upper and lower blades 361 and 371 are arranged. Since the two do not hit the excavated soil at the same time but alternately hit with a time difference, the resistance can be reduced.

  Further, in the above-described embodiment, the propeller-shaped stirring blades 36 having a plane-symmetric structure in which the tip-side blades 361 and the base-side blades 371 arranged vertically are arranged symmetrically across the horizontal plane. Although 37 is illustrated (see FIG. 4), this is also only a preferred example and may be an asymmetric structure. If an example is shown, the blade | wing 371 of the base end side (upper side) among the blade | wings 361 and 371 which opposes may be formed in the shape where the rotation direction back of the said blade | wing 371 was expanded rather than the front side (FIG. 4). Middle two-dot chain line and FIG. 5). Usually, the cement content with respect to the surplus excavated soil is about 70 to 80%, and the mixture having the cement content of about 100% has high fluidity. In the case of targeting a mixture with high fluidity (excess excavated soil, etc.), increasing the size of the blade 361 in some form is more effective for the stirring action and the pressing action on the hole wall side. It is suitable in that it can be made. In addition, increasing the size of only the base end (upper) blade 371 in this way is preferable in that it does not obstruct the lifting of the excavation rod 3 from the ground G (relatively less resistance is generated).

  Further, if a structural example in which the tip-side blade 361 and the base-side blade 371 are asymmetric is further shown, the tip-side blade 361 and the base-side blade 371 are inclined, although not particularly illustrated. The degree of inclination may be changed by providing a difference between the surfaces 36a and 37a.

  In the above-described embodiment, the specific form of the inclined surfaces 36a and 37a facing the blades 361 on the distal end side and the blades 371 on the proximal end side is not particularly mentioned, but these inclined surfaces 36a and 37a It can be set as appropriate according to the size and properties of G, the structure of the excavation rod 3, and the like. Specifically, the inclination angle (blade angle, propeller pitch) of the blades 361 (371) may be variable, or the inclination angles of the blades may be different from each other. Further, the inclined surfaces 36a and 37a may be smooth surfaces having a uniform angle or curved surfaces having a free curvature. If the example of the curved surface with a curvature is given, the blade | wing 361 (371) has the inclined surface 36a (37a) which changes so that it may become a steep slope back from the rotation direction front of the said blade | wing 361 (371). It is also possible (see FIG. 6). Or the inclined surface 36a (37a) twisted so that it may become a gentle slope near the radial direction outer periphery of the blade | wing 361 (371) may be sufficient (refer FIG. 7). If the inclined surface 36a (37a) changes so as to become a gentle slope toward the radially outer periphery of the blade 361 (371), pressure is applied to the surplus excavated soil or the like on the main shaft 31 side, and the outer peripheral side is closer to the outer peripheral side. The pressure is reduced. For this reason, it becomes possible to make it act more effectively, without inhibiting the operation which the inner peripheral side (axis side) surplus excavation soil etc. try to move largely from the inner periphery side to the outer periphery side.

  In the above-described embodiment, the pair of propeller-shaped stirring blades 36 and 37 including the blades 361 on the front end side and the blades 371 on the base end side arranged on the top and bottom are illustrated (see FIG. 2). It is also possible to provide a multistage excavation rod 3 in which a plurality of pairs of blades 361 and 371 are arranged along the axial direction.

  Similarly, in the above-described embodiment, an example is shown in which the propeller-shaped stirring blade 36 (37) on the tip end side in the axial direction is configured by two propeller-shaped blades 361 (371) arranged at intervals of 180 degrees ( Of course, three or more blades can of course be arranged on the same plane. In this case, it is preferable that these blades are arranged at equal intervals in the circumferential direction. In addition, when the propeller-like stirring blades are multistage, the blades of different propeller-like stirring blades (different-stage propeller-like stirring blades) should not overlap (when projected in the main axis direction, the blades overlap) It is preferable that it is configured so that there is no or less). In this case, even if there is a slight increase in construction resistance, surplus excavated soil or the like can be kneaded to the hole wall 4a side with a greater pressing effect.

  Further, the blades 361 and 371 constituting the propeller-like stirring blades 36 and 37 may be plate-shaped blades having a uniform thickness, or may be blades having a triangular cross-section with varying thickness. Good. The point is that the specific shape of the propeller-like stirring blades 36, 37 is provided as long as it has the inclined surfaces 36a, 37a that cause the surplus excavated soil or the like to move sideways and push out to the hole wall 4a side. Is not particularly limited. Therefore, it is possible to constitute a propeller-like stirring blade even with a blade having a configuration in which a disc is divided and attached to the main shaft in an inclined state.

  The present invention is suitable for application when excavating the ground when constructing composite piles or the like.

DESCRIPTION OF SYMBOLS 1 ... Composite pile 3 ... Drilling rod 4 ... Drilling hole 4a ... Hole wall 31 ... Main shaft 31a ... Tip part 32 ... Drilling bit 36, 37 ... Propeller-shaped stirring blade (stirring blade)
36a, 37a ... inclined surfaces 361, 371 ... propeller blade G ... ground

Claims (10)

In the excavation rod that excavates the ground to be excavated,
A spindle that rotates upon receiving a driving force;
A drill bit provided at the tip of the spindle;
It has at least one pair of propeller-shaped blades having opposed inclined surfaces with different inclinations in the circumferential direction, and the interval between these opposed inclined surfaces gradually decreases in the circumferential direction, and is provided on the main shaft and rotates coaxially with the main shaft And a stirring blade for applying a force to push the surplus excavated soil etc. to the outer peripheral side,
A drilling rod comprising.   The excavation rod according to claim 1, wherein the plurality of blades are arranged at equal intervals in the circumferential direction.   The drilling rod according to claim 1, wherein a projected area of the blade in the principal axis direction is 1/8 to 1/6 of a circle drawn by a tip of the blade.   The drilling rod according to claim 1, wherein the diameter of the blade is smaller than the inner diameter of a hole wall of a drilling hole formed by drilling with the drilling bit.   The excavation rod according to claim 1, wherein among the opposed blades, an upper one is formed in a shape wider than that of a lower one.   The excavation rod according to claim 5, wherein the blade located above among the opposed blades is formed in a shape in which the rear in the rotation direction of the blade is wider than the front side.   The excavation rod according to claim 1, wherein at least one of the blades has an inclined surface whose rear surface in the rotation direction of the blade is a steep slope.   The excavation rod according to claim 1, wherein at least one of the blades has an inclined surface having a gentle slope near a radially outer periphery of the blade.   The excavation rod according to claim 1, wherein the main shaft has a larger shaft diameter between the opposing blades of the main shaft than a shaft diameter in other portions. Stirring blades composed of at least a pair of propeller blades having opposed inclined surfaces with different inclinations in the circumferential direction, and the interval between the opposed inclined surfaces gradually decreases in the circumferential direction, and a main shaft that rotates by receiving a driving force And a drilling rod provided with a drilling bit provided at the tip of the main shaft,
When excavating the ground to be excavated with the excavation rod, a construction method in which the stirring blades act to push the earth and sand in the ground or a mixture of the earth and sand and cement milk to the outer peripheral side.

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