JPH0448894B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for constructing a jet grout type underground retaining wall that is applied to excavation work, shield work, building foundations, etc. decrease,
This invention relates to a method for constructing a jet grout type underground retaining wall that can shorten the construction period and reduce the amount of hardened material used, as well as omit the chisel work of removing a part of the hardened retaining wall along the excavation surface.

<Conventional technology> Generally, when performing foundation work or excavation work on soft ground such as sandy soil, gravelly soil, or clay soil, hardening materials are injected into the soil and hardened in order to stop water and strengthen the ground. Ground improvement will be carried out. The jet grout underground retaining wall construction method is one of these ground improvement methods, and it forms an unhardened retaining wall by continuously constructing unhardened cylindrical columns underground. , is a method of constructing a retaining wall underground by hardening this unhardened retaining wall, and representative construction methods include the JSG construction method and the column jet construction method.

In the JSG method, an injection pipe turning/lifting drive device and an ultra-high-pressure hardening material supply device are installed on the ground, and ultra-high pressure water is injected from the tip of the hardening material injection pipe to drill a vertical hole while moving the hardening material injection pipe to the ground. Insert the hardening material into the tube to the target depth, activate the hardening material ultra-high pressure supply device, press the hardening material into the hardening material injection pipe from the hardening material inlet at the upper part of the pipe, and force the hardening material into the hardening material injection pipe from the hardening material nozzle at the bottom of the pipe in the radial direction of the pipe. At the same time, the hardening material injection pipe is pulled up while being turned in one direction by continuously ejecting it at an extremely high pressure of about 200 to 700 times the atmospheric pressure, and the above-mentioned injection pipe turning/lifting drive device is activated. This procedure is adopted. This creates a space in the soil by destroying the ground with the energy of the jet stream made up of ultra-high pressure hardening material. At that time, this space is filled with hardening material such as cement milk to improve the ground. A hardened column is created. Then, an unhardened retaining wall is created underground by forming a large number of unhardened pillars horizontally one after another, and by hardening this unhardened retaining wall, an underground retaining wall is constructed. Ru.

In the column jet grouting method, a vertical hole is drilled in advance using a boring machine or the like into which a hardening material injection pipe is inserted, and a driving device for turning and lifting the injection pipe and a hardening material ultra-high pressure supply device are installed on the ground. The injection pipe is suspended in a vertical hole and inserted to the target depth underground, and ultra-high pressure water is injected from the ultra-high pressure water inlet at the top of the hardening material injection pipe, and from the ultra-high pressure water nozzle at the bottom of the pipe, the water is directed outward in the radial direction of the pipe. At the same time, the hardening material is injected under ultra-high pressure from the hardening material inlet at the top of the hardening material injection pipe, and continuously in the radial direction of the pipe from the hardening material nozzle located below the high-pressure water nozzle at the bottom of the pipe. A procedure is adopted in which the hardening material injection tube is pulled up while being spun while the hardening material is spouted out. As a result, ultra-high pressure water is continuously jetted from the ultra-high pressure water nozzle into the ground in the radial direction outward of the hardening material injection pipe, and as the ultra-high pressure water jet is drawn up while swirling, the ultra-high pressure The jet force of the water jet cuts the ground around the hardening material injection pipe into a nearly cylindrical shape to form a space, and the hardening material is continuously jetted outward in the radial direction of the pipe from the hardening material nozzle to create the space. An unhardened column is created by filling the column. An unhardened retaining wall is created underground by forming a large number of unhardened pillars horizontally one after another, and a retaining wall is constructed underground by hardening this unhardened retaining wall. Ru.

<Problems to be Solved by the Invention> In these conventional jet grouting underground retaining wall construction methods, each unhardened column is formed into a cylindrical shape with a vertical axis. It needs to be set larger than the thickness. For this reason, the construction cross-sectional area becomes larger, the construction period becomes longer, and
A problem arises in that the amount of hardening material used also increases.

For example, when forming a reinforced retaining wall for a deep foundation, the diameter of the pitch circle P1 connecting the position where the hardening material injection pipe is driven into the ground, as shown by the imaginary line in Figure 4, is
Since D1 needs to be larger than the diameter D of the deep foundation, a larger number of unhardened columns are created compared to the case where the hardening material injection pipe is inserted along the circumference of the deep foundation. This creates the problem that the construction period becomes longer and the amount of hardening material used increases.

In addition, since the diameter d1 of the unhardened columns 13' needs to be set larger than the required average retaining wall pressure, if the retaining wall is built all the way to the boundary with the adjacent land, the inner normal of the retaining wall There is also the problem that the building is set far inward from the boundary, which limits the building's floor space.

In addition, in order to increase the floor space of a building, when the retaining wall is lifted up to the excavation surface after hardening, it is necessary to spend a great deal of labor and time on this lifting work, which shortens the construction period and reduces costs. There is also the problem that it becomes even more disadvantageous when trying to achieve this goal.

Furthermore, especially in the JSG method, the hardened material injection pipe is bent underground due to the reaction force of the jet of hardened material, and the jetting direction of the hardened material becomes more inclined as it goes deeper into the ground, causing the unhardened pillars to become more inclined. Another problem is that the closer you get to the bottom, the smaller the diameter is.

In addition, particularly in the JSG method, there is a problem in that the hardening material injection pipe is bent underground due to the reaction force of the jet of hardening material, increasing its rotational resistance and reducing drive efficiency.

The present invention has been made in consideration of the above circumstances, and it is possible to reduce the construction cross-sectional area of retaining walls by half, shorten the construction period and reduce the amount of hardened material used. When forming closed retaining walls such as A jet grout type site that allows for a large floor area by reducing the thickness of the retaining wall, and also makes it possible to omit chisel work by forming at least one side of the formed retaining wall into a substantially flat surface or a curved surface along the excavation surface. The purpose of this paper is to provide a method for constructing a retaining wall.

<Means for Solving the Problems> As shown in FIGS. 1a to 1e or 7a to 7f, for example, the present invention provides an injection tube turning/pulling drive device 1 and an ultra-high pressure supply of hardening material on the ground. The hardening agent injection pipe 5 is inserted from the ground surface GL to the target depth underground, and the hardening material ultra-high pressure supply device 2 is activated to feed the hardening material G into the hardening material injection pipe 5 at ultra-high pressure. The hardening material is press-fitted from the hardening material inlet 6a at the top of the pipe, and is continuously ejected from the hardening material nozzle 7e at the bottom of the pipe in the radial direction of the pipe, and the injection pipe turning/lifting drive device 1 is operated.
By pulling up the hardening material injection pipe 5 while rotating it, a hardening material jet stream 12 is continuously ejected underground from the hardening material nozzle 7e in the radial direction of the pipe at an extremely high pressure.
is pulled up while swirling, and the hardening material jet 12
In addition to cutting the surrounding ground with the jet force of
A hardening material G is injected into the cutting area 11 to create unhardened pillars 13 in the cutting area 11, and a large number of unhardened pillars 13 are arranged side by side and continuous to create an unhardened retaining wall 14. In order to achieve the above objective, the following steps are taken as a premise of the jet grout type underground retaining wall construction method, which consists of the steps of constructing the retaining wall 14 underground by hardening the unhardened retaining wall 14. I have the means.

That is, in the tube turning and pulling process in which the injection tube turning and lifting drive device 1 drives and pulls up the hardening agent injection tube 5, the hardening agent injection tube 5 is driven to turn back and forth through an angular range of approximately half a rotation. By repeating this, the cross-sectional shape of the unhardened pillars 13 created in the cutting area 11 is formed into a substantially half-moon shape, and the unhardened retaining wall 14 is created by arranging a large number of unhardened pillars 13 horizontally and consecutively. In the unhardened retaining wall construction process, a large number of unhardened pillars 13 having a substantially half-moon cross section are created so that the longitudinal direction of the cross-sectional shape is substantially along the direction in which the unhardened pillars 13 continue.

<Function> In the present invention, in the tube turning and pulling process, the cross section of the unhardened column 13 created in the cutting area 11 is improved by repeatedly turning the hardening material injection tube 5 back and forth through an angular range of approximately half a rotation. Since the shape is formed into a substantially semicircular shape, the construction cross-sectional area can be reduced to half as much as possible compared to the conventional example where the cross-sectional shape is circular. Further, since the cross-sectional shape of the unhardened pillars 13 is formed into a substantially semicircular shape, and the unhardened pillars 13 are constructed with the longitudinal direction of the cross-sectional shape substantially along the direction in which the unhardened pillars 13 continue, the retaining wall 14 can be made thinner. Furthermore, unhardened pillar 13
By arranging the substantially planar portion of the retaining wall 14 along the direction in which the uncured pillars 13 continue, at least one side of the retaining wall 14 can be formed into a substantially planar surface.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

FIGS. 1A to 1E are explanatory diagrams sequentially showing the steps of a method for creating unhardened columns of a deep foundation reinforced retaining wall according to an embodiment of the present invention.

In this embodiment, the installation process shown in FIG. 1A, the drilling process shown in FIG. 1B, the test process shown in FIG.

First, in the installation process, as shown in Figure 1a,
A jet grout underground retaining wall construction device M is installed at a predetermined construction location.

This jet grout type underground retaining wall construction device M
consists of an injection tube rotation/elevating drive device 1, a curing material ultra-high pressure supply device 2, an ultra-high pressure water supply device 3, a compressed air supply device 4, and a double pipe supported by the injection tube rotation/elevation drive device 1. A curing agent injection pipe 5 is provided. A swivel 6 is connected to the upper end of the hardening material injection pipe 5 and connects the hardening material injection pipe 5 with the hardening material ultra-high pressure supply device 2, ultra-high pressure water supply device 3, and compressed air supply device 4. A monitor mechanism 7 is connected to.

As shown in FIG. 2, the swivel 6 has a jet inlet 6a that opens on its upper circumferential surface, and a jet passage 6b that extends from the jet inlet 6a to the center and communicates with the lower end surface along the axis. , an air inlet 6c opened on the circumferential surface of the intermediate height portion, and an air passage 6d. This air passage 6d is communicated with the air inlet 6c at the upper end, and is connected to the air inlet 6c at the upper end.
It is formed in a concentric ring shape independent from the jet passage 6b around a portion along the axis of the jet passage 6b.

As shown in FIG. 3, the monitor mechanism 7 includes:
A jet passage 7a passing through the center vertically, an ultra-high pressure water nozzle 7b formed at the lower end of the jet passage 7a, a check valve 7c provided at the entrance of the ultra-high pressure water nozzle 7b, and a ball valve seat 7d on the upstream side thereof. , a hardening material nozzle 7e connected to an intermediate portion of the jet passage 7a and opening radially outward; and a hardening material nozzle 7e.
The monitor mechanism 7 includes an air nozzle 7f that spouts air radially outward from the periphery of the monitor mechanism 7, and an air passage 7g that is formed around the jet passage 7a and communicates with the air nozzle 7f from the upper end of the monitor mechanism 7. Further, on the outer circumferential surface of the monitor mechanism 7, a blade bit 8 is provided which projects downwardly from the curing agent nozzle 7e and the air nozzle 7f in a jet shape in the outer radial direction.

In the next drilling process, a vertical hole drilling process and an injection pipe insertion process are performed in parallel. That is, as shown in FIG. 1b, the hardening material injection pipe 5 is vertically erected at a predetermined construction position (here, approximately on the periphery of the deep foundation), and the ultra-high pressure water supply device 3 is connected to the jet inlet 6a of the swivel 6.
is connected, and an ultra-high pressure water jet W of about 200 to 400 atmospheres is ejected downward from the ultra-high pressure water nozzle 7b of the monitor mechanism 7 to make a hole in the ground, while the injection tube is rotated by the injection tube turning/lifting drive device 1. The turning/elevating drive device 1 is operated to rotate the curing agent injection pipe 5 at a rotation speed selected according to the geological conditions and lower it at a stroke speed selected according to the geological conditions.
At the same time, the hardening material injection pipe 5 is inserted into the ground to a predetermined depth.

When the vertical hole 9 is drilled to the planned depth and the hardening material injection pipe 5 is inserted to the depth underground, an injection test process is performed. In the injection test process, first,
A steel ball 10 is introduced through the jet inlet 6a, and the ball valve seat 7d is closed (see FIG. 3).

After that, as shown in FIG. 1c, the hardening material ultra-high pressure supply device 2 is connected to the jet inlet 6a of the swivel 6, and the compressed air supply device 4 is connected to the air inlet 6c, and the injection tube is rotated and raised/lowered. Activate the device 1 and repeat driving the curing agent injection pipe 5 in a reciprocating manner at a trially set rotational speed through an angular range of approximately half a rotation outward from the tangent to the periphery of the deep foundation; Perform an injection test by increasing the rising stroke speed set on a trial basis.

In the injection test process, it is determined based on the amount of sludge discharged from the upper end of the vertical hole 9 whether cutting has been performed over the range necessary to form the predetermined cutting area 11, and the optimum cutting area is determined. A turning speed and a stroke speed are set.

In the injection test process, when the optimum rotation speed and stroke speed are set, the process moves to the creation process.

In the creation process, the hardening material nozzle 7 of the monitor mechanism 7
A hardening material injection step is set in which hardening material is jetted out at ultra-high pressure from e to crush the ground over a predetermined cutting area 11, and the hardening material is filled into the cutting area 11, and a hardening material injection pipe 5 is set. A turning and pulling-up process is performed in parallel, in which the object is pulled up while being turned at a turning speed.

That is, as shown in FIG. 1d, in the hardening material jetting step, for example, 20
The hardening material G is supplied to the jet inlet 6a at a high pressure of 400 atmospheres, and is jetted radially outward into the soil from the hardening material nozzle 7e, while ultra-high pressure air is supplied from the compressed air supply device 4 to the air inlet 6c, The hardening material is jetted radially outward around the hardening material jet 12 from the air nozzle 7f. Although jetting out ultra-high pressure air is not essential to the present invention, it is known that by jetting out ultra-high pressure air from around the hardening material at the same time, the reach of the hardening material can be dramatically increased. There is.

While performing this hardening material spouting process, the hardening agent injection pipe 5 is rotated at a predetermined turning speed by operating the injection pipe turning/elevating drive device 1 to rotate the hardening agent injection pipe 5 in an angular range of approximately half a turn outward from the tangent to the periphery of the deep foundation. Repeat reciprocating and turning, and pull up at a predetermined stroke speed. As a result, the hardening material jet 12 ejected from the hardening material injection pipe 5 is pulled up while reciprocating in an angular range of approximately half a rotation, and the fourth
As shown in the figure, the ground around the monitor mechanism 7 is crushed over a predetermined semi-cylindrical cutting area 11 whose plane part circumscribes the periphery of the deep foundation, and hardened material G is applied to the cutting area 11. is filled. The mud from the crushed earth is pushed out to the ground through the vertical hole 9 by the hardening material jetted from the hardening agent nozzle 7e. Then, by filling the cutting region 11 with the hardening material G, unhardened pillars 13 are created in the soil.

When the construction of one unhardened column 13 is completed, as shown in FIG. 1e, a pulling and cleaning step is performed, in which the hardening agent injection pipe 5 is pulled out above ground and the inside of the pipe is washed with fresh water. Thereafter, move to the next creation point and create approximately cylindrical unhardened pillars 13 in the soil using the same procedure.

As shown in Fig. 4, the construction point is such that on the outer circumferential circle P of the deep foundation 16, parts of a large number of unhardened pillars 13 formed in the soil are successively arranged horizontally so as to overlap with each other. is set to
Since each unhardened pillar 13 is formed in a semi-cylindrical shape with a flat part circumscribing the periphery of the deep foundation, the unhardened retaining wall 1 formed by the continuous unhardened pillars 13
4 is formed into a cylindrical shape whose inner peripheral surface is bent into a polygonal shape and is in contact with the deep foundation 16. Then, the retaining wall 14 is created underground by hardening this unhardened retaining wall 14, and then the ground inside the retaining wall 14 is excavated.

In this embodiment, since the cross-sectional shape of each uncured column 13 is formed into a substantially semicircular shape, the construction cross-sectional area can be reduced by half compared to the conventional example where the cross-sectional shape is circular, and the construction period can be shortened. With,
The amount of hardening material G used can be halved.

In addition, when creating each unhardened column 13, the insertion point of the hardened material column entry pipe 5 is set approximately on the periphery of the deep foundation 16, so that the cylindrical unhardened column 13 shown by the imaginary line in FIG. The diameter and circumference of the pitch center circle P connecting the insertion points of the hardening material injection pipes 5 are shorter than in the case where the hardening material injection pipe 5 is inserted, and the number of unhardened pillars 13 to be created can be reduced. Therefore, the construction period can be further shortened, and the amount of hardening material G used can be further reduced.

In addition, since the cross-sectional shape is approximately semicircular and the unhardened pillars 13 are constructed with the longitudinal direction of the cross-sectional shape substantially along the direction in which the unhardened pillars 13 continue, the thickness of the retaining wall 14 can be reduced. It can be made thinner, the cross-sectional area of the deep foundation 16 formed within the land for constructing the retaining wall 14 can be increased, and the land can be used more effectively.

Furthermore, by arranging the substantially flat portions of the unhardened pillars 13 in the direction in which the unhardened pillars 13 continue, that is, along the periphery of the deep foundation 16, the inner circumferential surface of the retaining wall 14 has a substantially planar polygonal shape. In addition, the outer periphery of each unhardened column 13 is connected to the outer periphery of the adjacent unhardened columns 13 on the inner peripheral surface of the retaining wall 14, and the outer periphery of each unhardened column 13 is formed in a shape connected to the other unhardened columns 13 in order, and is uneven due to changes in the strata or fluctuations in discharge pressure. Since they overlap, there is no need to cut out the inner peripheral surface of the constructed retaining wall 14. As a result, the chisel work can be omitted, significantly shortening the construction period, and a great deal of labor can be saved.

The present invention can be applied, for example, to the construction of retaining walls for reinforcing main pile side piles. In this case, for example, the fifth
As shown in the figure, it is also possible to create a structure in which the cross-sectional directions of adjacent unhardened pillars 13 out of a large number of unhardened pillars 13 are in the same direction, and for example, as shown in FIG. As shown, a large number of unhardened columns 13
It is also possible to create such that the cross-sectional directions of adjacent uncured pillars 13 are opposite to each other.

FIGS. 7a to 7e are explanatory diagrams sequentially showing the steps of a method for creating unhardened columns of a deep foundation reinforced retaining wall according to another embodiment of the present invention. .

Hardening material injection pipe 5 used in this example
As shown in FIG. 10, the swivel 6 is composed of a triple pipe, and the swivel 6 connected to the upper end is connected to a jet inlet 6a for both ultra-high pressure water and curing material, which is opened on the upper circumferential surface as shown in FIG. A jet passage 6b extends from the jet inlet 6a to the center and communicates with the lower end surface along the axis, an air inlet 6c opens on the lower circumferential surface, and an air inlet 6c formed on the circumferential surface of the intermediate height section. It includes a high-pressure water inlet 6e, an ultra-high-pressure water passage 6f, and an air passage 6d. The ultra-high pressure water passage 6f is an annular passage formed around and independently of the jet passage 6b, and its upper end communicates with the ultra-high pressure water inlet 6e. The air passage 6d is formed further outside the ultra-high pressure water passage 6f as an annular passage independent of the jet passage 6b and the ultra-high pressure water passage 6f, and communicates with the air inlet 6c at its upper end.

In addition, the monitor mechanism 7 connected to the lower end of the hardening material injection pipe 5 has a jet passage 7a for both ultra-high pressure water and hardening material that passes vertically through the center, and a jet passage 7a, as shown in FIG. Ultra-high pressure water nozzle 7b formed at the lower end of the ultra-high pressure water nozzle 7b
The check valve 7c provided at the inlet of the check valve 7c and the ball valve seat 7d on the upstream side thereof, and the check valve 7c provided on the lower circumferential surface of the monitor mechanism 7 radially outward and provided in the jet passage 7a on the upstream side of the ball valve seat 7d. A hardening material nozzle 7e that communicates with the hardening material nozzle 7e, an air nozzle 7f that jets air radially outward from around the hardening material nozzle 7e, and a hardening material nozzle on the lower peripheral surface of the monitor mechanism 7 at a higher position than the hardening material nozzle 7e. Jet nozzle 7h for ultra-high pressure water that opens in the opposite direction to the opening direction of 7e.
The jet nozzle 7 is formed around the jet passage 7a as an annular passage independent from this, and the jet nozzle 7 is formed at the lower end.
h, and an air passage 7g formed around the jet passage 7a and the ultra-high pressure water passage 7i as an independent annular passage, the lower end of which communicates with the air nozzle 7f. We are prepared. In addition, the swivel 6 and the hardening material injection pipe 5
In order to easily check the rotational phase of the monitor mechanism 7, the cross-sectional profile of the monitor mechanism 7 is formed into a polygon (here, a hexagon), as in the case of the hardening material injection pipe 5 shown in FIG. 10, for example. . In Figure 10,
5a is a jet passage for both ultra-high pressure water and hardening material;
b is an inner circumferential wall, 5c is an ultra-high pressure water passage, 5d is an intermediate wall, 5e is an air passage, and 5f is an outer circumferential wall.

In this embodiment, as shown in FIGS. 7a and 7b, the installation process and the drilling process are performed in the same manner as in the above embodiment.

Then, when the vertical hole 9 is drilled to the planned depth and the hardening material injection pipe 5 is inserted into the ground to a predetermined depth, an injection test process is performed.

In the injection test process, first, the jet inlet 6a
A steel ball 10 is thrown in to close the ball valve seat 7d. After this, as shown in FIG. 7c, the hardening material ultra-high pressure supply device 2 is connected to the jet inlet 6a of the swivel 6, the ultra-high pressure water supply device 3 is connected to the ultra-high pressure water inlet 6e, and the compressed air supply device is connected to the air inlet 6c. 4
Connect each to the injection pipe turning/lifting drive device 1.
, the curing agent injection pipe 5 is repeatedly driven to swing back and forth in an angular range of about half a rotation outward from the tangent to the periphery of the deep foundation at a trially set rotation speed, and at the same time Raise at the rising stroke speed set to . In the injection test process, the ground around the curing agent injection pipe 5 is crushed by the ultra-high pressure water jet W ejected from the jet nozzle 7h and the curing agent jet 12 ejected from the curing agent nozzle 7e, and the ultra-high pressure water Jet stream W and curing agent jet stream 12
The sludge removed is discharged to the ground through the vertical hole 9. Therefore, depending on the amount of sludge discharged from the upper end of the vertical hole 9, it can be determined whether optimal cutting is being performed over the range necessary to form the predetermined cutting area 11. . Then, the turning speed and rising stroke speed of the hardening material injection pipe 5 in the next forming process are set to the turning speed and rising stroke speed at which optimal cutting is performed over the range necessary to form the predetermined cutting area 11. be done.

After this, the forming process is started, and in this forming process, as shown in FIG. 7d, the jet nozzle 7h
from the hardening material nozzle 7e, and the hardening material G from the hardening material nozzle 7e.
While injecting ultra-high-pressure air from the air nozzles 7f, the injection tube turning/elevating drive device 1 is activated, and the hardening material injection tube 5 is moved approximately halfway outward from the tangent to the periphery of the deep foundation at the set turning speed. It repeats reciprocating rotation angle range and turning drive, and raises at a set ascending stroke speed. As a result, underground, the ground is crushed into a semi-cylindrical shape by the ultra-high pressure water on the one hand, with the boundary in the diametrical direction where the hardening material injection pipe 5 is reversed, forming a space that is filled with ultra-high pressure water. On the other hand, the rock is crushed into a semi-cylindrical shape by the hardening material G, and the hardening material G is filled into the semi-cylindrical space created by the crushing. At the boundary between one semi-cylindrical shape and the other semi-cylindrical shape, the internal pressure of each semi-cylindrical space is balanced, and the hardening material G filled in the other semi-cylindrical space is filled into one semi-cylindrical space. It will not flow into the space where it is placed. Therefore, unhardened columns 13 are created in the semi-cylindrical cutting area 11 formed by the hardening material jet 12.

In the above injection test process and creation process,
Since ultra-high pressure water is injected from the jet nozzle 7h in the opposite direction to the hardening material G jetted from the hardening material nozzle 7e, the jetting reaction force of this ultra-high pressure water and the jetting reaction force of the hardening material G are balanced and the hardening material injection pipe 5 is prevented from bending in the direction opposite to the direction in which the hardening material G is sprayed. This prevents the injection direction of the hardening material G from being tilted downward and reducing the diameter of the unhardened pillars 13, increasing the dimensional accuracy of the unhardened pillars 13, and increasing the dimensional accuracy of the hardening material injection pipe 5. It reduces rotational resistance, increases drive efficiency, and further shortens construction time.

Further, in this embodiment, the jet nozzle 7h for high pressure water is opened above the hardening material nozzle 7e, so that when the hardening material injection pipe 5 is pulled up, the jet nozzle 7h is pulled up before the hardening material nozzle 7e. Therefore, the filled hardening material G
There is no fear that the unhardened pillars 13 will be washed out by high-pressure water, and dense unhardened pillars 13 can be created in the soil.

In each of the above embodiments, in the preceding process, ultra-high pressure water is spouted from the hardening material injection pipe 5 to form a vertical hole 9 in the ground.
However, prior to the installation process, a vertical hole 9 of a required depth is formed in the ground using, for example, a polling machine, and the hardening material injection pipe 5 is inserted into the vertical hole 9. You are free to change any part of the above procedure. Furthermore, if the water stop function is not required, it is not necessary to make the ends of adjacent unhardened columns 13 interpenetrate with each other.

<Effects of the Invention> As described above, according to the present invention, the cross section of the unhardened pillar formed underground is semicircular, so the construction cross-sectional area per unhardened pillar becomes small. As a result, the construction period can be shortened and the amount of hardening material used can be halved.

In addition, since the cross section of the unhardened pillars formed underground is semicircular, it can be used, for example, as a retaining wall for reinforcing deep foundations.
If the retaining wall is constructed so that its cross-sectional plane forms a closed plan shape, the longitudinal direction of the retaining wall is approximately semicircular in cross-section and is constructed approximately parallel to the direction in which the unhardened columns continue. The construction point where the injection pipe is inserted can be set on or very close to the periphery of a deep foundation, etc., which reduces the number of construction points by shortening the circumference of pitch lines such as pitch circles that connect the construction points. This makes it possible to further shorten the construction period and further reduce the amount of hardening material used.

In addition, since the cross section of the unhardened pillars formed underground is semicircular, by constructing the longitudinal direction of the almost semicircular cross section almost parallel to the direction in which the unhardened pillars continue, it is possible to create an unhardened retaining wall. 14 can be made smaller, and the available land for construction can be made larger, for example, the building floor area can be made larger. Moreover, by constructing the longitudinal direction of the nearly semicircular cross section in approximately parallel to the direction in which the unhardened columns continue, it is possible to make at least one side of the retaining wall continuous in a planar shape. The construction period can be significantly shortened by omitting the chisel work required to expand the site, and the labor involved can be greatly reduced.

In particular, in the present invention, the balancing liquid is injected under ultra-high pressure from the balancing liquid inlet in the upper part of the hardening material injection pipe, and from the balancing liquid nozzle in the lower part of the pipe, the direction opposite to the direction in which the hardening material is ejected from the hardening material nozzle. If the counterbalancing liquid discharge reaction force is to counteract the hardening material jetting reaction force that acts as a bending force on the lower part of the tube by continuously jetting it in the direction of Therefore, it is possible to prevent eccentricity to the side opposite to the discharge direction. As a result, the diameter of the uncured column is prevented from decreasing due to the downward inclination of the ejecting direction of the hardening material, improving construction accuracy, and reducing the rotational resistance of the hardening material injection pipe to improve its driving efficiency. This can further shorten the construction period. Also,
In this case, in particular, the balancing liquid nozzle is biased to a higher position than the hardening material nozzle, and in the tube turning and pulling process, the balancing liquid jet jetted from the balancing liquid nozzle is the hardening material jet jetted from the hardening material nozzle. In the case where the hardening material is placed in advance above the hardening material nozzle, there is no fear that the hardening material ejected from the hardening material nozzle will be washed away by the balancing liquid jet, and dense unhardened pillars can be created in the soil.

[Brief explanation of the drawing]

Figures 1a to 1e are explanatory diagrams sequentially showing the steps of a method for creating unhardened columns for a deep foundation reinforced retaining wall according to an embodiment of the present invention, and Figure 2 is a cross-sectional view of a swivel used in the above embodiment. Fig. 3 is a sectional view of the monitor mechanism used in the above embodiment, Fig. 4 is a cross-sectional plan view of the deep foundation reinforced retaining wall, and Fig. 5 is a main pile side pile reinforced retaining wall to which the present invention is applied. A cross-sectional plan view of the wall, FIG. 6 is a cross-sectional plan view of another main pile side pile reinforced retaining wall to which the present invention is applied, and FIGS. 7 a to 7 e are deep foundation reinforced retaining walls according to other embodiments of the present invention. 8 is a sectional view of a swivel used in the other embodiments described above, and FIG. 9 is a sectional view of a monitor mechanism used in the other embodiments described above. FIG. 10 is a cross-sectional plan view of a hardening material injection pipe used in the above-mentioned other embodiments. 1...Injection pipe turning/lifting drive device, 2...Hardening material ultra-high pressure supply device, 3...Ultra high pressure water supply device, 5
... Hardening material injection pipe, 6a ... Jet inlet, 6e
...Jet inlet, 7e...Hardening material nozzle, 7
e, 11... Cutting area, 12... Hardening material jet, 1
3... Unhardened column, 14... Retaining wall, 7h... Jet nozzle, G... Hardened material, GL... Ground surface, W...
Ultra high pressure water jet.

Claims (1)

[Claims] 1. An injection pipe turning/lifting drive device 1 and a hardening material ultra-high pressure supply device 2 are installed on the ground, a hardening material injection pipe 5 is inserted from the ground surface GL to a target depth underground, and a hardening material injection pipe 5 is installed on the ground. The ultra-high pressure supply device 2 is activated, and the hardening material G is pressed into the hardening material injection pipe 5 at an extremely high pressure from the hardening material inlet 6a at the top of the pipe, and is continuously jetted out from the hardening material nozzle 7e at the bottom of the pipe in the radial direction of the pipe. At the same time, actuate the injection tube turning/lifting drive device 1,
By pulling up the hardening material injection pipe 5 while rotating it, a hardening material jet stream 12 is continuously ejected underground from the hardening material nozzle 7e in the radial direction of the pipe at an extremely high pressure.
is pulled up while swirling, and the hardening material jet 12
In addition to cutting the surrounding ground with the jet force of
A hardening material G is injected into the cutting area 11 to create unhardened pillars 13 in the cutting area 11, and a large number of unhardened pillars 13 are arranged side by side and continuous to create an unhardened retaining wall 14. In a jet grout type underground retaining wall construction method comprising a procedure of constructing a retaining wall 14 underground by hardening an unhardened retaining wall 14, a hardening material injection pipe 5 is connected to an injection pipe turning/lifting drive device 1. In the pipe turning and pulling process in which the hardening material injection pipe 5 is rotated and pulled up while being driven by the A large number of unhardened pillars 13 each having an approximately half-moon shape and a cross section are arranged side by side and continuous to form an unhardened retaining wall 14 during the unhardened retaining wall construction process. A method for constructing a jet grout type underground retaining wall, which is characterized in that the longitudinal direction of the approximately semicircular cross section is constructed approximately along the above-mentioned horizontally continuous direction. 2. The jet grout type underground retaining structure according to claim 1, wherein adjacent unhardened pillars 13, 13 among the plurality of pillars are constructed so that their substantially half-moon cross sections are oriented in the same direction. Wall construction method. 3. The jet grout type underground according to claim 1, characterized in that the substantially half-moon cross sections of adjacent unhardened pillars 13, 13 of the plurality of pillars are constructed in opposite directions. Retaining wall construction method. 4 The hardening material nozzle 7e is opened on one side of the circumferential surface of the lower part of the hardening material injection pipe 5, and the balancing liquid nozzle 7h is opened on the other side on the opposite side. A balancing liquid ultra-high pressure supply device 3 is installed in the pipe turning and pulling process, and the balancing liquid ultra-high pressure supply device 3 is operated to supply the balancing liquid at an ultra-high pressure to the upper part of the hardening material injection pipe 5 for balancing. By press-fitting the liquid into the liquid inlet 6e and continuously jetting it from the balancing liquid nozzle 7h at the lower part of the tube in the opposite direction to the direction in which the hardening material is ejected from the hardening material nozzle 7e, the hardening agent acts as a bending force on the lower part of the pipe. Claims 1 and 2 characterized in that a counterbalancing liquid discharge reaction force opposes the material jet reaction force.
Or the jet grout type underground retaining wall construction method described in 3. 5 The balancing liquid nozzle 7h is replaced with the hardening material nozzle 7e.
In the pipe turning and pulling step, the balancing liquid jet W jetted from the balancing liquid nozzle 7h precedes the hardening material jet 12 spouted from the hardening material nozzle 7e above. The method for constructing a jet grout type underground retaining wall according to claim 4.