JP2016089377A - Ground improvement method, and boring rod and ground improvement device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground improvement method capable of constructing a columnar ground improvement pile with a high bearing force, downsizing a diameter and a length of the columnar ground improvement pile compared to a conventional one, decreasing an amount of a binder to be used, and reducing a sand production that has to be removed to the ground.SOLUTION: A ground improvement method comprises the processes of: forming a drilling hole (40) in which sand production (41) remains by drilling a ground (4) to a required depth by a drilling means; mixing and agitating the sand production (41) in the drilling hole (40) and a liquid binder by an agitation means to produce a fluid mixture 5 in the drilling hole (40); forming a spiral groove (42) on a porous wall of the drilling hole (40) by drilling to a required depth in a lengthwise direction of the drilling hole (40); and solidifying the fluid mixture (5) in the drilling hole (40).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a ground improvement method, an excavation rod used in the ground improvement method, a columnar ground improvement pile, a ground improvement device, and a method for monitoring a spiral groove forming operation. More specifically, a ground improvement method that excavates a hole in the ground at the construction site, mixes and agitates the excavated soil and binder in the hole and solidifies it into a columnar shape, builds a columnar ground improved pile, and strongly improves the ground, In the excavation rod, columnar soil improvement pile and ground improvement device used in the ground improvement method, it is possible to construct a columnar soil improvement pile with excellent strength. The present invention relates to a material that can be made smaller than a short length, can reduce the amount of binder used, and can reduce excavated soil that must be discharged to the ground.

  When constructing a structure such as a house on a soft ground such as a reclaimed land, ground improvement for strengthening the ground is performed. There are various ground improvement methods, and one of them is a pile method that builds a pile inside the soil and strengthens the ground. In addition, the pile construction method also includes a construction method in which many existing piles such as wooden piles and concrete piles are built inside the soil, and a liquid binder (solidification material) such as cement milk inside the hole while excavating the soil. There is a construction method in which excavated soil is mixed and stirred and solidified in a columnar shape to construct a large number of pile structures that are concrete structures. Among these pile methods, as an example of the latter, there is a construction apparatus and construction method for a columnar ground improved pile disclosed in Patent Document 1.

  An apparatus for constructing a columnar ground improvement pile described in Patent Document 1 includes a drilling device in which a driving device is provided with a drilling blade at a lower end portion via a shaft, and a screw device that carries soil to the upper side of a hole while mixing with a binder. A combination is provided, and the soil mixed with the binding material is moved upward from the bottom of the excavation hole by a screw device, and the mixing action is favorably performed while moving the soil up and down in the hole.

  Moreover, the construction method of the columnar ground improved pile is that, when constructing the columnar ground improved pile, the binding material used for the pile is placed in the hole provided by removing the soil not used for the pile, and the hole is excavated. The soil excavated while being dug down is mixed with the binder, and the pile is efficiently constructed without pressing the binder. And the pillar-shaped ground improvement pile constructed | assembled by this becomes a cylindrical thing only as FIG. 4 of patent document 1 shows.

JP 2011-137298 A

However, the conventional columnar ground improvement pile construction apparatus and construction method, and the columnar ground improvement pile constructed thereby, have the following problems.
That is, the columnar ground improvement pile to be constructed is simply a columnar shape. For example, in order to obtain a greater proof stress (supporting force), it is necessary to increase the diameter of the pile or increase the length of the pile. was there. However, in this case, since the pile itself becomes large, the amount of binder used such as cement milk for solidifying the soil increases, and the amount of excavated soil that must be discharged to the ground increases accordingly. It was.

  The present invention was devised in view of the above points, excavating a hole in the ground at the construction site, mixing and agitating the excavated soil and binder in the hole to solidify it into a columnar shape, Construction of a column improvement ground with excellent strength in the ground improvement method to build and improve the ground firmly, the excavation rod used in the ground improvement method, the columnar soil improvement pile, the ground improvement device and the monitoring method of the spiral groove formation work With the same proof strength, the columnar ground improved pile can be made smaller and smaller than before, and the amount of binder used can be reduced and discharged to the ground. The object is to provide something that can reduce the excavated soil that must be soiled.

(1) The present invention includes a step of excavating the ground to a required depth by excavation means to form an excavation hole in which excavation soil remains, and the excavation soil and liquid binder inside the excavation hole are mixed by an agitation means Mixing and stirring to form a fluid mixture in the borehole, and forming a spiral groove drilled at a required depth in the lengthwise direction of the borehole in the borehole wall A ground improvement method comprising a step and a step of solidifying the fluid mixture inside the excavation hole.

(2) The present invention is configured to include a step of forming, in the circumferential direction, a circular groove excavated at a required depth at a hole wall of the excavation hole at substantially the same position in the length direction of the excavation hole. You can also.

  In this case, when the columnar ground improved pile is formed inside the ground, a circular strip formed in the circumferential direction at substantially the same height is formed horizontally in the improved pile in addition to the spiral strip. Since this circular strip is formed horizontally, the vertical resistance to the hole wall is greater at the same length than the spiral groove inclined with respect to the vertical direction. Therefore, in addition to or mixed with the spiral groove on the improved pile, the circular ridge is formed, so that the proof stress is further improved.

(3) In the present invention, the formation of the groove is performed by a groove excavation part longer than an excavation blade included in the excavation means in which the excavation hole is formed, and the groove excavation is performed on the return path after the forward path forming the groove. It can also be set as the structure provided with the process in which a part reversely traces the groove | channel formed in the said outward path.

  In this case, when the excavating means is extracted from the excavation hole, the groove can be left clean without breaking the groove and the portion other than the groove on the hole wall. Thereby, when the columnar ground improved pile is formed inside the ground, the strip such as the spiral strip is formed neatly, so that the improved pile can exhibit sufficient proof stress.

(4) The present invention includes a step of excavating the ground to a required depth by excavation means to form excavation holes in which excavation soil remains, and mixing and agitation of excavation soil and binder inside the excavation holes by stirring means And it can also be set as the structure which performs the process of making the mixture which has fluidity | liquidity inside the said excavation hole simultaneously or in parallel.

  In this case, the formation of the excavation hole and the supply (injection) of the binder and the mixing and stirring of the excavated soil and the binder can be performed in one stroke (one stroke) from the start of excavation to the end of the formation of the excavation hole. Excellent work efficiency.

(5) The present invention includes a step of excavating the ground to a required depth by excavation means to form excavation holes in which excavation soil remains, and mixing and agitation of excavation soil and binder inside the excavation holes by stirring means And forming a fluid mixture in the borehole, forming a recess having a required depth in a hole wall of the borehole, and a fluid mixture in the borehole. It is a ground improvement construction method provided with the process to solidify.

  In this case, since a concave portion is formed in the hole wall, a mixture of excavated soil and binder having fluidity enters the concave portion, and solidified columnar ground improvement piles have protrusions on the surface. These protrusions increase the vertical resistance against the hole wall. Therefore, the improved pile formed in the ground can exhibit sufficient proof stress. In addition, the shape of the recess may be any shape other than a groove or a hole, and is not particularly limited.

(6) The present invention is used in the ground improvement method described in (1) to (5) above, and has a rod having a flow path through which a liquid binder is passed, and a circular excavation in the ground provided at the tip of the rod. A drilling member that forms a hole, a stirring member provided on the rod, a steadying member that is provided on the rod so as to be rotatable in the axial circumferential direction of the rod, and has a diameter larger than the rotation diameter of the drilling member; A drilling rod used in a ground improvement method provided at a tip of a rod, comprising a nozzle that discharges a binding material, and a groove forming tool that can be attached to and detached from the tip of the drilling member and extends the drilling member when attached. is there.

  In this case, when forming the excavation hole in the ground, a normal drilling operation is performed without attaching a groove forming tool to the excavation member of the excavation rod. And after forming a drilling hole, a groove formation tool is attached to the drilling member of the drilling rod extracted from the drilling hole, and it extends from a drilling member. In this state, the position of the rod, which is the center of rotation, is adjusted to the center of the drilling hole, and the rotational speed and the lowering speed are controlled by the control means, and the length direction of the drilling hole ( In the depth direction, a spiral groove can be formed at a required depth.

(7) In the present invention, the ground is excavated to a required depth by excavating means to form an excavation hole in which excavated soil remains, and the excavated soil and the binder inside the excavated hole are mixed and stirred by the stirring means, It is obtained by creating a fluid mixture inside the borehole, forming a spiral groove of a required depth on the bore wall of the borehole, and solidifying the fluid mixture inside the borehole. A columnar ground improvement pile having a spiral strip on the outer periphery of the column main body.

The columnar ground improvement pile has a spiral strip on the outer periphery of the column main body, and the spiral strip is cut into the hole wall of the excavation hole inside the ground. Thereby, a spiral strip part becomes resistance when the load from the upper part is added to the columnar ground improvement pile, and proof stress improves compared with the conventional simple cylinder improvement pile.
That is, if it is the same yield strength, it is possible to make the columnar ground improved pile smaller and smaller than the conventional one. Further, along with this, the amount of the binder to be used can be reduced, and the construction cost can be reduced accordingly.

(8) The present invention includes a work implement main body, a lifting / lowering drive device provided in the work implement main body, and an excavation rod used for the ground improvement method of (6) above attached to the lift / rotation drive device. It is a ground improvement device provided.

(9) In the present invention, in the hole wall of the excavation hole, the vertical axis represents the depth representing the position in the depth direction of the groove excavation part that forms the spiral groove in the hole wall, and the circumferential position of the groove excavation part is defined as Plotting the forward movement trajectory of the groove excavation part that forms the spiral groove with the angle represented as the horizontal axis, and in the return path after the forward pass, the groove excavation part reverses the spiral groove formed by the forward path. This is a method of monitoring the spiral groove forming work by plotting and displaying the movement trajectory that traces back and forth.

  In this case, since the operator can visually confirm the position of the groove excavation part at the time of forming the spiral groove with a monitor of the work vehicle, the worker does the work when forming the spiral groove in the hole wall of the excavation hole. It is easy to prevent or reduce failures.

(Function)
The operation of the ground improvement method, the ground improvement device, and the columnar ground improvement pile of the present invention will be described.
Excavation rod attached to an ascending / descending rotation drive device using a ground improvement device having an excavation rod provided with excavation means (excavation member), agitation means (agitation member), and means for supplying a binder (rod and nozzle) The soft ground is excavated to the required depth to form an excavation hole in which excavated soil remains.

When the excavation hole is formed, the steadying member can prevent the rod from shaking when the excavation rod rotates, so that stable excavation can be performed.
An appropriate amount of a liquid binder such as cement milk is supplied by means for supplying the binder into the borehole. The excavated soil and the binding material inside the excavation hole are mixed and agitated by the agitating means to create a fluid mixture inside the excavation hole.

  The drilling rod is raised and exposed to extract the drilling member from the mixture in the drilling hole. Note that the supply (injection) of the liquid binding material is not performed when the excavation member is lowered, but can be performed when the excavation member is raised. Then, the groove excavator is fixed to the exposed excavating member, and the excavating member is extended.

  Again, the drilling member is immersed in the fluidized unsolidified mixture in the drilling hole, and the rotation speed and lowering speed of the drilling rod are controlled by the control means, and the drilling hole is drilled into the hole wall of the drilling hole by the groove forming tool. A spiral groove is formed at a required depth in the length direction (depth direction). At the same time as the spiral groove is formed, the fluid mixture enters the spiral groove.

  By repeating the above steps, a necessary number of columnar objects that have not yet solidified are applied at a predetermined depth inside the ground. And the columnar ground improvement pile which solidifies the mixture which has fluidity inside each excavation hole by carrying out curing for a predetermined period, and has a spiral strip part (the part which the mixture which entered the spiral groove solidified) in the perimeter part. Form. Thereby, the soft ground can be improved to a solid ground.

  The columnar ground improvement pile formed as described above has a spiral strip portion on the outer peripheral portion, and the spiral strip portion has a form that bites into the hole wall of the excavation hole. Thereby, a spiral strip part becomes resistance when the load from the upper part is added to the columnar ground improvement pile, and proof stress improves compared with the conventional simple cylinder improvement pile.

  That is, if the columnar ground improved pile has the same proof stress, the columnar ground improved pile can be made smaller and shorter than the conventional one. Further, along with this, the amount of the binder to be used can be reduced, and the construction cost can be reduced accordingly.

  The present invention excavates a hole in the ground at the construction site, mixes and agitates the excavated soil and binder in the hole and solidifies it into a columnar shape, constructs a columnar ground improved pile, and improves the ground strongly, In the excavation rod, the columnar ground improvement pile, the ground improvement device and the spiral groove forming work monitoring method used for the ground improvement construction method, it is possible to construct a columnar ground improvement pile with excellent strength. To provide a material that can be smaller in diameter and smaller in length, can reduce the amount of binder used, and can reduce excavated soil that must be discharged to the ground. Can do.

It is explanatory drawing which shows one Embodiment of the ground improvement apparatus of this invention. The excavation head of a ground improvement apparatus is shown, (a) is explanatory drawing at the time of excavation, (b) is explanatory drawing at the time of spiral groove formation. The 1st Example of the ground improvement construction method of this invention is shown, (a) is explanatory drawing which shows a motion of an excavation head, (b) is a graph which shows transition of the height corresponding to the motion of an excavation head. It is explanatory drawing in the middle of the outward path formation which shows the formation method of the spiral groove by the excavation head in the ground improvement construction method of this invention. It is explanatory drawing at the time of the completion | finish of an outward path | route which shows the formation method of the spiral groove by the excavation head in the ground improvement construction method of this invention. It is explanatory drawing during the return path formation which shows the formation method of the spiral groove by the excavation head in the ground improvement construction method of this invention. It is explanatory drawing after completion | finish of return path | route formation which shows the formation method of the spiral groove by the excavation head in the ground improvement construction method of this invention. The 2nd Example of the ground improvement construction method of this invention is shown, (a) is explanatory drawing which shows a motion of an excavation head, (b) is a graph which shows transition of the height corresponding to the motion of an excavation head. The monitoring method of spiral groove formation work is shown, (a) is explanatory drawing which shows the outline of the locus | trajectory of a groove formation tool, (b) is explanatory drawing which shows the detail of the locus | trajectory of a groove formation tool, (c) is an illustration of a groove formation tool. It is explanatory drawing which shows a circumference position.

The present invention will be described in detail based on the embodiments shown in the drawings.
Please refer to FIG. 1 and FIG.
First, the ground improvement apparatus A used in the ground improvement construction method will be described.
The ground improvement device A includes an underground drilling machine 1, a guide cell 2 included in the underground drilling machine 1, and a drilling rod 3 that moves up and down along the guide cell 2 to excavate the ground to form a drilling hole. Yes.

  The underground drilling machine 1 includes a crawler type drilling machine main body 10 and a guide body 12 attached to a front portion of the drilling machine main body 10 via a hydraulic cylinder 11 in the vertical direction. The drilling machine main body 10 is provided with an outrigger 13 for stabilizing the ground improvement device A.

  The angle of the guide body 12 can be adjusted by the hydraulic cylinder 11. A guide cell 2 is attached to the guide body 12 such that the guide cell 2 can be adjusted up and down within a certain range along the guide body 12 by a hydraulic cylinder (hidden in the guide cell 2 and not visible in the figure). Further, the guide cell 2 is provided with a winch 21 for suspending an excavation rod 3 described below with a wire.

  The guide cell 2 has a guide portion 20 provided on the front side thereof over almost the entire length. A drifter 30, which is an elevating and rotating drive device using a hydraulic motor as a drive source, is attached to the guide unit 20 so as to be movable up and down along the guide unit 20. The drifter 30 holds the excavation rod 3 having a predetermined length, and the rod 31 of the excavation rod 3 is suspended in a substantially vertical direction.

  An excavation head 33 constituting excavation means is fixed to the tip of the rod 31. The excavation head 33 includes a nozzle 32 having a triangular plate-shaped bit 330 fixed at the tip thereof and two excavation blades 331 fixed at a right angle to the rod 31 above the nozzle 32. The excavation blade 331 constitutes an excavation member and has a plurality of excavation teeth 332 fixed at regular intervals in the length direction, and each excavation tooth 332 is inclined downward at a required angle in the forward rotation direction. (Refer to AA sectional view of FIG. 2).

  Among the two excavation blades 331, one (right side in FIG. 2) of the excavation blades 331 is formed with bolt through holes 333 at two locations through the upper and lower surfaces. A groove excavator 39, which will be described later, can be fixed to the excavation blade 331 via a fixing bolt 38 that passes through the bolt through hole 333. A semicircular cutout (not shown) is formed in the center of the fixed side of the bit 330 so as not to block a discharge port connected to a flow path 310 to be described later.

The nozzle 32 has a structure that can be attached and detached.
As shown in FIG. 2, the excavation head 33 has a nozzle attachment portion 37 at the tip of the rod 31. The excavation blade 331 is fixed to the outer peripheral portion of the nozzle mounting portion 37. The nozzle mounting portion 37 has a fitting hole 370 that is open on the tip side. The fitting hole 370 is connected to a flow path 310 through which the binding material passes.

  The nozzle mounting portion 37 is formed with pin holes 371 and 372 penetrating between the outer peripheral surfaces so as to partially lie at two portions of the fitting hole 370 opposite to the upper and lower sides. A nozzle 32 is detachably attached to the nozzle attachment portion 37. In addition, the nozzle attached to the nozzle attachment part 37 is not limited to this, It can replace | exchange suitably for the various nozzles prepared for others.

  The nozzle 32 has a cylindrical body portion 320, and a cylindrical insertion portion 322 is formed in the base portion of the body portion 320. A channel (not shown) connected to the channel 310 is formed at the center of the body 320 and the fitting portion 322. The front end of the flow path is opened at the front end of the body part 320 to form a discharge port (not shown).

  The fitting portion 322 can be fitted into the fitting portion 370 with almost no gap. Pin grooves (reference numerals omitted) are linearly formed in the fitting portion 322 at two locations on the outer peripheral surface of the fitting holes 371 and 372 opposite to each other when the fitting portion 370 is fitted. Yes.

  Then, the pin hole 371, the pin hole 372 and the pin groove are aligned, and the pin P is inserted into each, so that the nozzle 32 can be rotated integrally with the rod 31 so as not to come out of the nozzle mounting portion 37. Can be fixed.

  The nozzle 32 constitutes a binder injection means, and discharges cement milk (or a cement-based solidifying agent solution) that is a binder (column body material). The nozzle 32 has a structure in which cement milk is supplied from a mixer plant (not shown) through a flow path 310 inside the rod 31 by known means (not shown).

  In the rod 31, a steadying blade 34, which is a steadying member that can freely rotate in the axial circumferential direction around the rod 31, is provided slightly above the excavation head 33. The steady-rest blade 34 does not move in the length direction of the rod 31, and the direction of the two blades (not shown) is a direction perpendicular to the rod 31 and the diameter line direction, and its diameter (length) is It is formed to be slightly longer than the excavation blade 331.

  In the rod 31, an agitating member 35 that constitutes an agitating means is fixed in three stages at a substantially constant interval in the vertical direction above the steady brazing blade 34. Each stage of the agitating member 35 is composed of two blade members (reference numerals omitted) provided on the rod 31, and the direction thereof is perpendicular to the rod 31 and in the diameter line direction, and is further adjacent to the upper and lower sides. The members 35 are shifted by 90 ° in the axial circumferential direction of the rod 31.

  A connecting member 22 is formed at the lower end of the guide cell 2 toward the front. A cylindrical steady rest 23 that is rotatably held through the rod 31 is fixed to the tip of the connection member 22. The steady rest 23 has a structure that can open and close the center hole (details are omitted), and the center hole can be opened to insert the middle portion of the rod 31 from the side.

  Further, when the ground improvement device A forms the spiral groove 42 that is a recess in the hole wall of the excavation hole, the excavation blade 331 is attached with a groove excavator 39 that becomes a spiral groove forming portion. The groove excavator 39 is placed on the front side of the excavation blade 331 as shown in FIG. The groove excavator 39 is composed of an upper plate 391, a tip plate 392, a front plate 393, and a rear plate 394, and fitting recesses 396 for avoiding the excavation teeth 332 are formed at two locations on the front side.

  The upper plate 391 is formed with two through holes 395 that are combined with the bolt through holes 333. Further, the upper plate 391, the tip plate 392, and the front plate 393 are formed so as to be slightly narrowed toward the front side, and a large number of protrusions 390 are formed on the front side surface.

  After the groove excavator 39 is put on the front side of the excavation blade 331, the through holes 395 and the bolt through holes 333 are aligned and fixed by fastening bolts 38 and nuts 380. In the fixed state, the tip plate 392 of the groove excavator 39 protrudes from the tip of the excavation blade 331 and further protrudes outward from the tip of the blade 34. The structure and attachment / detachment structure of the groove excavating tool 39 are not limited to the above, and well-known means can be appropriately employed.

(Function)
The operation of the ground improvement device A and the first embodiment of the ground improvement method using the ground improvement device A will be described mainly with reference to FIG. 3, FIG. 4, FIG. 5, FIG. 4 to 7, for the sake of convenience, illustration of a mixture of excavated soil and binder (cement milk) existing in the excavation hole during the process is omitted.
Further, in the following work, the rotation speed and the lifting speed of the excavation head 33 are not particularly limited, and are adapted to the soil soil quality at the site, or to the type of drilling work or spiral groove forming work. Are set as appropriate.

(1) The ground improvement device A is installed at a place where the ground improvement is performed (on the soft ground).
(2) The excavation rod 3 of the ground improvement device A is lowered while rotating, and the excavation head 33 starts excavation of the soft ground 4 (see (1) in FIG. 3A). The excavation head 33 is used in a form in which the groove excavator 39 is not attached as shown in FIG.

(3) Further, excavation by the excavation head 33 is advanced. At this time, the tip portions on both sides of the steady blade 34 longer than the inner diameter of the excavation hole 40 excavated by the excavation head 33 enter so as to pierce the hole wall of the excavation hole 40, and the rotation of itself stops. While moving to the deep part, it functions as a steady rest (maintenance of the rotation center) of the rod 31.

(4) In this way, the excavation holes 40 are gradually formed deeper, and excavated soil 41 generated by the soil being shaved remains in the excavation holes 40. In parallel, cement milk as a binder is injected from the nozzle 32 into the excavation hole 40 and mixed with the excavation soil 41. Further, the cement milk is mixed and agitated with the excavated soil 41 by the rotating excavation head 33 and the respective agitating members 35, thereby creating a fluid mixture 50. When the excavation hole 40 is formed to a predetermined depth, the descent of the excavation head 33 is stopped (see (2) in FIG. 3A).

(5) In the deep part of the mixture 50 having fluidity, the excavation head 33 is finely moved up and down while rotating, and the deep part of the mixture 50 is mixed and stirred. Next, the excavation head 33 is gradually raised to expose the excavation head 33 so as to be extracted from the mixture 50 while further stirring the mixture 50 (see (3) in FIG. 3A). At this time, it is preferable that the amount of the mixture 50 is slightly larger than the capacity of the excavation hole 40 in consideration of the amount entering the spiral groove 42 in a later step. Note that cement milk for mixing and stirring is not performed when the excavation head 33 is lowered, but can also be performed when the excavation head 33 is raised.

(6) Then, the groove excavator 39 is fixed to the exposed excavation blade 331 of the excavation head 33 with the two fixing bolts 38 as described above (see (3) in FIG. 3A).
(7) The excavation head 33 is again immersed in the fluid mixture 50 in the excavation hole 40 and is lowered while being controlled by the control means (not shown) by the control means (not shown). The grooved excavator 39, which is extended and has a tip on the outside, excavates the hole wall (side wall) of the excavation hole 40 to form a spiral groove 42 having a required depth (see FIG. 4). With the formation of the spiral groove 42, the fluid mixture 50 already in the excavation hole 40 enters the spiral groove 42.

(8) Further, the excavation head 33 is lowered while being controlled and rotated, and is positioned at the inner bottom of the excavation hole 40. At the inner bottom, the excavation head 33 is rotated while maintaining the height, so that a horizontal groove 42a having the same height is formed over the entire circumference (see (4) and FIG. 5 in FIG. 3A). Thus, the outward path for forming the spiral groove is completed. In the present embodiment, the groove excavator 39 is attached to only one excavation blade 331. However, if the groove excavator 39 is attached to both excavation blades 331, the spiral groove can be a double helix.

(9) After the formation of the horizontal groove 42a, the groove excavator 39 raises the excavation head 33 while controlling and rotating the excavation head 33 in the opposite direction to the lowering while controlling the spiral groove 42 in the opposite direction to the above ( (See FIG. 6). Accordingly, the rod 31 and the excavation head 33 can be extracted from the fluid mixture 50 in the excavation hole 40 without breaking the spiral groove 42 with the excavation tool 39 (see FIG. 7). As a result, the return path for forming the spiral groove is completed. At this point, the mixture 50 is in the spiral groove 42 and the horizontal groove 42a (see (5) in FIG. 3A).

(10) By repeating the above process (work), the necessary number of columnar objects that have not yet been solidified are applied to a predetermined depth inside the ground 4. The mixture 50 having fluidity inside each of the excavation holes 40 is hardened by curing for a predetermined period, and the spiral strip 51 (the portion where the mixture 50 that has entered the spiral groove 42 is solidified) is formed on the outer periphery. A columnar ground improvement pile 5 (see (5) in FIG. 3 (a)) having a strip 52a (a portion where the mixture 50 that has entered the horizontal groove 42a is solidified) is formed. Thereby, the soft ground 4 can be improved to a strong ground.

  The columnar ground improved pile 5 formed as described above has a spiral strip 51 and a horizontal strip 52a on the outer periphery, and the spiral strip 51 and the horizontal strip 52a are holes of the excavation hole 40. It is in the form of biting into the wall. Thereby, the spiral strip portion 51 and the horizontal strip portion 52a become resistance when a load from above is applied to the columnar ground improved pile 5, and the proof stress is improved as compared to a conventional cylindrical improved pile. To do. In addition, in FIG. 3 (and FIG. 8 mentioned later), the code | symbol with a parenthesis is provided about each part of the columnar ground improvement pile after solidification.

  That is, if it is the same yield strength, it is possible to make the columnar ground improved pile smaller and smaller than the conventional one. Further, along with this, the amount of the binder to be used can be reduced, and the construction cost can be reduced accordingly.

A second embodiment of the ground improvement method of the present invention will be described with reference to FIG.
In addition, in the following description, description is abbreviate | omitted about the same process which overlaps with the 1st Example of the said ground improvement construction method, and only a different process is demonstrated.

  In this ground improvement method, the lowering speed of the excavation head 33 is slowed in the course of the spiral groove formation by the groove excavator 39, and the horizontal grooves 42c, 42b, 42a having the same height are arranged at a predetermined interval over the entire circumference. The spiral groove 42 is formed while forming in order. In the return path, the groove excavator 39 traces the spiral groove 42 and the horizontal grooves 42a, 42b, and 42c in reverse to the forward path. According to this, the groove excavator 39 does not break the spiral groove 42 or the portion other than the groove of the hole wall, and the groove can be left clean. In addition, you may enable it to visually confirm the condition where the groove excavation tool 39 is returning in this return path on the operator's monitor.

  The columnar ground improvement pile 5a (see (5) in FIG. 8A) formed thereby has a spiral strip 51 and horizontal strips 52a, 52b, 52c on the outer periphery, and the spiral strip. The part 51 and the horizontal strips 52 a, 52 b, 52 c are in the form of biting into the hole wall of the excavation hole 40. In addition, a horizontal horizontal strip has a larger resistance when a load from above is applied than an inclined spiral strip. As a result, the columnar ground improved pile 5a has more resistance to the load from the upper side by the amount of the horizontal horizontal strips 52a, 52b, 52c than the columnar ground improved pile 5, and the proof stress is further increased than the columnar ground improved pile 5. improves.

With reference to FIG. 9, the monitoring method of spiral groove formation work is demonstrated.
FIG. 9A is an explanatory diagram showing an outline of the trajectory of the groove forming tool, FIG. 9B is an explanatory diagram showing details of the trajectory of the groove forming tool, and FIG. 9C is an explanatory diagram showing a turning position of the groove forming tool. At least the same display as these is displayed on a work vehicle, that is, a construction management device monitor (not shown) provided in the driver's seat of the underground drilling machine 1.

  First, in FIG. 9B, in the hole wall of the excavation hole 40, the depth representing the position in the depth direction of the groove excavation tool 39 forming the spiral groove 42 in the hole wall is taken as the vertical axis (unit: m), and the groove An angle representing the circumferential position of the excavator 39 is taken as a horizontal axis (full width: 180 °).

  Then, a forward movement trajectory 421 that forms the spiral groove 42 in the hole wall of the groove excavator 39 is plotted, and on the return path after the outward path, the spiral groove 42 formed by the groove excavator 39 in the outward path is traced in reverse. The return movement locus 422 is plotted and displayed.

  Thereby, the movement of the groove excavator 39 in the spiral groove forming operation of the excavation rod 3 is displayed in real time by the pointer 43, and the spiral groove forming operation can be monitored. The plotted position of the groove excavator 39 is an estimated value calculated from the rotational speed of the excavation head 33 and the ascending / descending speed.

  In addition, FIG. 9A monitors the entire spiral groove forming operation of the excavation hole, but this is a schematic display unlike FIG. In FIG. 9, although the case where the depth of the excavation hole is about 1.5 m is described, the case of a deep excavation hole can also be monitored in the same manner. In such a case, FIG. 9B is also adapted by switching the screen or by sequentially moving the screen.

  FIG. 9C shows the position of the groove forming tool in the circumferential direction monitored by the pointer 43a. The movement of the pointer 43a in the circumferential direction is synchronized with the movement of the pointer 43 in FIG.

  For example, by adjusting the rotational speed of the excavation head 33 and the lifting speed, the operator can perform the work while checking the construction management apparatus monitor provided in the driver's seat of the underground drilling machine 1. By making the movement locus 422 of the groove excavator 39 not greatly deviate from the movement locus 421 of the forward path, that is, within the allowable error, the spiral groove 42 can be formed cleanly, and the excavation rod 3 The excavation head 33 can be extracted from the excavation hole 40.

  Thus, the operator can visually confirm the position of the groove excavator 39 when forming the spiral groove on the construction management device monitor of the underground drilling machine 1, so It is easy to work when forming the spiral groove 42, and it is possible to prevent or reduce failures.

  Also, when submitting the work report to the contractor, print the same display as shown in Fig. 9 (b) (the work is completed and the state of the overlap between the forward path and the return path is displayed) Then, since it is possible to visually indicate that the formation of the spiral groove has been completed without any problem, it is possible to give the construction owner a sense of security.

  The terms and expressions used in this specification are merely explanatory and are not limiting at all, and exclude terms and expressions equivalent to the features described in this specification and parts thereof. There is no intention to do. Further, it goes without saying that various modifications are possible within the scope of the technical idea of the present invention.

A ground improvement device 1 underground drilling machine 10 drilling machine main body 11 hydraulic cylinder 12 guide body 13 outrigger 2 guide cell 20 guide part 21 winch 22 connecting member 23 steady rest 3 excavating rod 30 drifter 31 rod 310 channel 32 nozzle 322 Insertion part 33 Excavation head 330 Bit 331 Excavation blade 332 Excavation tooth 333 Bolt through hole 34 Stabilizing blade 35 Stirring member 37 Nozzle attachment part 370 Fitting hole 371, 372 Pin hole P Pin 38 Fixing bolt 380 Nut 39 Groove excavator 390 Protrusion 391 Upper plate 392 Front plate 393 Front plate 394 Rear plate 395 Through-hole 396 Fitting recess 4 Ground 40 Excavation hole 41 Excavation soil 42 Spiral groove 421 Outward movement trajectory 422 Return path movement trajectory 43, 43a Pointer 5 Columnar ground improvement pile 50 Fluid mixture 51 Spiral Part 5a columnar ground improvement pile 52a, 52b, 52c horizontal-like portion

Claims (9)

A step of excavating the ground to a required depth by excavating means to form an excavation hole in which excavated soil remains;
Mixing and agitating the excavated soil and the liquid binder inside the excavation hole by an agitating means, and creating a fluid mixture inside the excavation hole;
Forming a spiral groove excavated at a required depth in the length direction of the excavation hole in the hole wall of the excavation hole;
And a step of solidifying the fluid mixture inside the excavation hole. The ground improvement method according to claim 1, comprising a step of forming, in a circumferential direction, a circular groove excavated at a required depth at a hole wall of the excavation hole at substantially the same position in the length direction of the excavation hole. The groove is formed by a groove excavation section that is longer than the excavation blade of the excavation means that forms the excavation hole, and the groove excavation section is formed by the forward path on the return path after the outward path forming the groove. The ground improvement construction method of Claim 1 or 2 provided with the process of tracing back a groove | channel and returning. A step of excavating the ground to a required depth by excavating means to form an excavation hole in which excavated soil remains, and excavating soil and binder inside the excavated hole are mixed and agitated by an agitating means, The ground improvement construction method according to claim 1, 2 or 3, wherein the step of forming a fluid mixture is simultaneously or concurrently performed. A step of excavating the ground to a required depth by excavating means to form an excavation hole in which excavated soil remains;
Mixing and agitating the excavation soil and the binder inside the excavation hole by an agitating means, and creating a fluid mixture in the excavation hole;
Forming a recess having a required depth in the hole wall of the excavation hole;
And a step of solidifying the fluid mixture inside the excavation hole. Used in the ground improvement method of claim 1 to 5;
A rod having a flow path for passing a liquid binder;
A drilling member provided at the tip of the rod and forming a circular drilling hole in the ground;
A stirring member provided on the rod;
An anti-sway member provided on the rod so as to be rotatable in the axial direction of the rod, and having a diameter larger than the rotational diameter of the excavating member;
A nozzle provided at a tip of the rod, for discharging a binding material;
The excavation rod used for a ground improvement construction method provided with the groove | channel formation tool which can be attached or detached to the front part of the said excavation member, and extends the said excavation member at the time of attachment. Excavating the ground to the required depth by excavating means to form a drilling hole in which excavated soil remains,
Mixing and stirring the excavation soil and the binder inside the excavation hole by a stirring means,
Making a fluid mixture in the borehole,
A spiral groove having a required depth is formed in the hole wall of the excavation hole,
Obtained by solidifying the fluid mixture inside the borehole,
A columnar ground improvement pile having a spiral strip on the outer periphery of the column body. The work machine body,
Elevating and rotating drive device provided in the working machine body;
A rod having a flow path for passing a liquid binder, attached to the lifting and rotating drive device, a drilling member provided at the tip of the rod and forming a circular drilling hole in the ground, and provided on the rod An agitating member, a rod that is provided on the rod so as to be rotatable in the axial direction of the rod, a steadying member that is larger in diameter than the rotating diameter of the excavating member, and a nozzle that is provided at the tip of the rod and that discharges the binding material And a excavation rod that can be attached to and detached from the tip of the excavation member and has a groove forming tool that extends the excavation member when attached. In the hole wall of the excavation hole, the vertical axis represents the depth representing the position in the depth direction of the groove excavation part forming the spiral groove in the hole wall, and the horizontal axis represents the angle representing the circumferential position of the groove excavation part, The movement trajectory of the forward path of the groove excavation part that forms the spiral groove is plotted, and on the return path after the forward path, the movement trajectory that the groove excavation part traces back the spiral groove formed in the forward path is returned. Plot and display How to monitor spiral groove formation.

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