JP3363099B2 - Supporting ground improvement method for existing structures - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support ground improvement method for improving soft ground existing directly under existing structures such as buildings and levees to stabilized ground.

[0002]

2. Description of the Related Art Conventionally, for example, in order to improve soft ground such as sandy ground that is liquefied by the occurrence of an earthquake, a chemical solution, which is a ground improving agent, is injected into the soft ground layer to improve the soft ground. However, if a structure such as a building is already built on this soft ground, it is possible to drive the chemical liquid injection pipe through the existing structure to the soft ground layer directly below the structure. It's extremely difficult. For this reason, the chemical solution injection pipe is driven obliquely from the ground surface around the existing structure until it reaches the soft ground layer below the existing structure, and then the chemical solution is injected into the soft ground layer through the chemical solution injection pipe. It is being appreciated.

[0003]

However, according to the above-mentioned prior art, since the straight chemical liquid injection pipe is driven in the direction intersecting the thickness of the soft ground layer, the range of improvement in the plane direction of the soft ground layer is improved. Will be small. Therefore, it is necessary to change the driving angle of the chemical liquid injection pipe to shift the position of the tip nozzle portion of the chemical liquid injection pipe in the plane direction of the soft ground layer, which is extremely difficult and the work efficiency is poor, In addition, there is a possibility that a ground portion in which the chemical solution is not injected may be generated, resulting in lack of certainty.

The present invention has been made in view of the above problems, and an object thereof is to improve the ground existing from one side of the ground surface sandwiching the existing structure to directly below the existing structure. It is an object of the present invention to provide a method for improving the supporting ground of an existing structure capable of uniformly and efficiently improving a layer in a horizontal direction toward the other ground surface side over a wide range.

[0005]

In order to achieve the above object, the invention according to claim 1 uses a drill rod having a drill head mounted at its tip as a starting side with respect to one side ground surface of an existing structure as a starting side. After launching into the ground from the ground surface and propelling it in the ground layer to be improved immediately below the existing structure, it reaches the ground surface on the other side of the existing structure, and then the tip of this drill rod is given flexibility. Having a large number of chemical liquid injection holes that are provided and penetrate through the inner and outer peripheral surfaces, after connecting the chemical liquid injection pipe, the drill rod is pulled back to the starting side ground surface to improve the above-mentioned chemical liquid injection pipe immediately below the existing structure. It is laid on the ground layer to be improved, and after that, a chemical solution that is a ground improving agent is supplied from the ground surface side into the chemical solution injection pipe and injected into the ground layer to be improved from the chemical solution injection hole provided in the chemical solution injection pipe. It is characterized by that.

According to a second aspect of the present invention, in the method for improving the ground for supporting the existing structure according to the first aspect, the inside of the chemical liquid injection pipe is laid in a ground layer to be improved immediately below the existing structure by using a drill rod. In advance, a chemical solution supply pipe having a chemical solution supply nozzle at the tip is inserted, and after the chemical solution injection pipe is laid in the ground layer to be improved, the chemical solution that is a ground improvement agent from the surface side into the chemical solution supply pipe. While feeding back the chemical liquid supply pipe and injecting the chemical liquid from the chemical liquid supply nozzle into the ground layer to be improved through the chemical liquid injection hole of the chemical liquid injection pipe corresponding to the chemical liquid supply nozzle portion. Is.

According to a third aspect of the present invention, in the method for improving the ground for supporting an existing structure according to the second aspect, a drill rod is used to lay a chemical injection pipe in a ground layer to be improved immediately below the existing structure. At this time, draw the wire rope instead of the chemical solution injection pipe, and after laying the chemical solution injection pipe, the chemical solution supply attached to the tip of the chemical solution supply pipe at the end of the wire rope reaching the land surface side. After connecting the nozzle, pull the wire rope back from the ground surface of the starting side to insert the chemical solution supply nozzle into the chemical solution injection pipe, while the chemical solution supply nozzle is passing through the chemical solution injection tube directly below the existing structure, the chemical solution supply pipe from the arrival side A chemical solution which is a ground improvement agent is supplied to the ground and the chemical solution which is poured out from the chemical solution supply nozzle is injected into the ground layer to be improved through the chemical solution injection hole of the chemical solution injection pipe corresponding to the chemical solution supply nozzle portion. And it is characterized in and.

In the method for improving the supporting ground of an existing structure according to claim 1, claim 2, or claim 3, claim 4
The invention according to claim 1, when laying a chemical injection pipe in the ground layer to be improved under the existing structure using a drill rod, excavates a laying hole of the chemical injection pipe having a diameter larger than that of the drill rod. It has the characteristics of. That is, the chemical injection pipe is connected to the tip of the drill rod reaching the ground surface on the arrival side through the excavating means, and then the drill rod is pulled back to the ground surface on the starting side to lay a hole for laying the chemical injection pipe by the excavating means. The chemical liquid injection pipe following the drill rod is laid in the laying hole while excavating.

According to a fifth aspect of the invention, in the invention according to the second or third aspect, the chemical liquid supply pipe inserted into the chemical liquid injection pipe laid in the ground layer to be improved immediately below the existing structure. The injection means for injecting the chemical solution into the ground layer to be improved from the chemical solution supply nozzle provided at the tip of the chemical solution supply pipe through the injection hole of the chemical solution injection pipe part facing the chemical solution supply nozzle while moving the lengthwise direction. Therefore, a packer that slides in contact with the inner peripheral surface of the chemical liquid injection pipe is installed on the outer peripheral surface of the tip of the chemical liquid supply pipe inserted into the chemical liquid injection pipe at an appropriate interval in the front and rear, and the chemical liquid supply pipe between these front and rear packers A chemical solution supply nozzle is bored at the tip of and the chemical solution discharged from the chemical solution supply nozzle is filled in the annular space between the facing surfaces of the chemical solution supply pipe and the chemical solution injection pipe between the front and rear packers and the filled chemical solution. Injecting liquid medicine Are configured to be implanted into the ground layer to be improved through the injection holes are drilled in.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION On the ground surfaces on both sides of an existing structure, one ground surface is used as a starting side ground surface, and the other ground surface is used as a reaching side ground surface. After diagonally launching the drill rod equipped with, toward the bottom of the existing structure, propelling it to the ground layer to be improved under the existing structure while controlling the propulsion direction of the drill head, It is further propelled toward the arrival side, passes through the ground layer to be improved immediately below the existing structure, and then reaches the arrival side ground surface. The drill rod is formed by successively adding rod bodies of unit length, and the drill rod is propelled while rotating.

When the drill head reaches the reaching surface,
Remove the drill head from the tip of the drill rod, connect the end of the flexible chemical injection pipe such as synthetic resin pipe to the tip of the drill rod on the ground on the arrival side, and then pull the drill rod on the starting side. It pulls back toward the ground surface on the starting side. By this pullback of the drill rod, the chemical injection pipe is laid in the propulsion trace of the drill rod from the ground surface on the arrival side to immediately below the ground surface on the starting side, passing directly below the existing structure.

As described above, the drill rod arranged from the ground surface on the starting side to the ground surface on the reaching side through the ground layer to be improved below the existing structure is replaced with the chemical liquid injection pipe. As usually, since a pipe of the same diameter as the drill rod or a large diameter is used, when burying this chemical injection pipe in the trace of the pullback of the drill rod, the drill rod and the chemical injection pipe are connected via the excavating means. It is desirable to connect. Then, by pulling back the drill rod, the excavating means digs a through hole, which is a trace of passage of the drill rod, into a large-diameter embedded hole in which the chemical liquid injection pipe can be embedded, and the chemical liquid injection pipe is embedded in the embedded hole.

After the chemical solution injection pipe is buried in the ground layer to be improved below the existing structure across both ground surfaces sandwiching the existing structure, a ground improvement agent is applied to the inside of the chemical solution injection pipe from one ground surface side. By injecting and supplying a certain chemical solution and injecting the chemical solution into the ground layer to be improved through the injection hole formed in the chemical solution injection pipe, the ground layer is improved to a stable support ground layer.
At this time, in order to improve the ground layer immediately below the existing structure and the peripheral portion just below the existing structure, it is necessary to form the chemical liquid injection hole only in the length portion of the chemical liquid injection pipe embedded in the ground layer portion. Good.

Further, when the area of the ground layer to be improved is large, the driving position of the drill rod is moved in parallel in the lateral direction so that there is a predetermined distance from the previously buried chemical solution injection pipe in the ground layer to be improved. In the same manner as above, the chemical solution injection pipes are embedded in parallel with each other, and a plurality of chemical solution injection pipes are arranged in parallel according to the width of the ground layer to inject the chemical solution into the ground layer. Further, when the layer thickness of the ground to be improved is large, the chemical solution injection pipes are arranged in parallel in the vertical direction in the ground layer and embedded, and the ground layer is improved by chemical solution injection.

When the chemical solution is injected into the ground layer to be improved from the chemical solution injection hole of the chemical solution injection pipe, the chemical solution is directly supplied to the chemical solution injection pipe from the surface side, so that the chemical solution injection pipe is longitudinally and circumferentially. The chemical solution may be poured out from all the chemical solution injection holes provided at predetermined intervals, but as described in claim 2 or claim 3, it penetrates the ground layer to be improved immediately below the existing structure. Then, insert the chemical solution supply pipe with the chemical solution supply nozzle at the tip into the chemical solution injection pipe embedded between the ground surfaces on both sides of the existing structure, and supply the chemical solution to the chemical solution supply pipe from the ground surface side. Then, the chemical solution is discharged from the chemical solution supply nozzle into the chemical solution injection pipe where the chemical solution supply nozzle is located, and the ground to be improved through the chemical solution injection hole corresponding to the chemical solution supply nozzle portion while moving the chemical solution supply nozzle in the chemical solution injection pipe. Inject into layers Good.

In order to inject the chemical liquid, which is discharged from the tip supply nozzle of the chemical liquid supply pipe, into the soft ground layer to be improved from the injection hole of the chemical liquid injection pipe in which the nozzle is located, as described in claim 5, A packer is attached to the tip of the chemical liquid supply pipe with the supply nozzle sandwiched between them, and the supply nozzle is provided between the packers that are in sliding contact with the inner peripheral surface of the chemical liquid injection pipe while moving the chemical liquid supply pipe in the length direction inside the chemical liquid injection pipe. The chemical solution is supplied through the through-hole and the chemical solution is injected into the ground layer to be improved from the injection holes of the chemical solution injection pipes corresponding to the packers.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a concrete embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 4 show an embodiment of a method for improving the supporting ground of an existing structure according to the present invention. The existing structure 1 is built on a stable ground layer 2 such as an embankment layer or a clay layer, and below the stable ground layer 2 is a soft ground layer such as a sandy ground that is liquefied when an earthquake occurs and should be improved. 3 is present.

In order to improve the soft ground layer 3 into a stable support ground, first, on the ground surface sandwiching the existing structure 1, one ground surface is used as the starting side ground surface 4 and the other ground surface is reached. A drill rod propulsion device 6 is installed on the starting side ground surface 4 as a side ground surface 5, and a drill rod 7 made of a hollow tube having a drill head 7A attached to the tip thereof is used by using this propulsion device 6 to start side ground surface. After starting from 4 to the ground and propelling the soft ground layer 3 directly below the existing structure 1 in the horizontal direction,
The arrival side ground surface 5 is reached.

The propulsion device 6 has a carriage 6a which is movable and movable, and a starter table 6b which is inclined toward the ground surface 4 on the starting side and is mounted so that the inclination angle thereof can be changed. A drill rod gripping tool 6c that reciprocates by an extension / contraction mechanism (not shown) such as a jack is provided, and a guide member 6d for the drill rod is erected and fixed at the tilted lower end of the tilt start base 6b. The gripping tool 6c is configured to rotate by a rotating mechanism (not shown) to rotate the drill rod 7.

The propulsion device 6 is stopped at a predetermined position on the ground surface 4 on the starting side with the tilting direction inclined toward the lower end of the starting base 6b toward the driving direction of the drill rod 7, and the drill head 7A is attached to the tip. The base end portion of the drill rod 7 to which is attached is gripped by the gripping tool 6c, and the tip end of the drill rod 7 is inserted into the guide member 6d in the driving direction. The drill rod 7 is formed into a long drill rod 7 by successively adding bending-deformable short drill rods 7a, and the drill head 7A is attached only to the tip of the drill rod 7a that is first driven. .

Then, the first short drill rod 7a is placed on the starting table 6b as described above, and the base end thereof is held by the holding tool 6c, and then the holding tool 6c is started. Of the starting side ground surface 4 toward the lower side of the existing structure 1 by moving the drill rod 7a in the longitudinal direction while moving the drill rod 7a by the gripping tool 6c while moving the drill rod 7a toward the lower end of the slope.
Drive diagonally into. After driving of driving the short drill rod 7a, a holding tool 6c for the base end of the short drill rod 7a is provided.
After releasing the grip, the gripping tool 6c is retracted to its original position, and the tip of the next short drill rod 7a is connected to the proximal end of the short drill rod 7a that has been previously hammered in, and the short length is increased. A short drill rod 7a in which the proximal end of the drill rod 7a is gripped by the gripping tool 6c, and the gripping tool 6c is rotated and moved toward the inclined lower end of the starting base 6b so that the short drill rod 7a is first driven. Followed by and promoted into the ground.

As described above, the short drill rods 7a are successively added to form the long drill rods 7 while the drill rods 7 are moved from the ground surface of the starting side ground surface 4 toward the lower side of the existing structure 1. When the drill head 7A reaches the soft ground layer 3 by obliquely propelling the ground, the propulsion direction is gradually directed to directly below the existing structure 1 in the horizontal direction, and then as shown in FIG. After passing through the soft ground layer 3 immediately below the object 1 almost horizontally and passing through the soft ground layer 3 immediately below the existing structure, gradually reach the reaching ground surface 5 with the drill head 7A facing upward. Let

In order to control the direction of the drill head 7A, a transmitter is built in the rear part of the drill head 7A, and the radio wave transmitted from this transmitter is received on the ground to enable the drill head 7A to operate.
Detects the depth and direction of the tip of the drill head 7A from the ground
The directional control mechanism built in is sent to control the direction.

When the drill head 7A reaches the reaching-side ground surface, the drill head 7A is removed from the tip of the drill rod 7 and is combined with the tip of the drill rod 7 projecting on the reaching-side ground surface 5 on the reaching-side ground surface 5. One end of a flexible liquid medicine injection pipe 8 such as a resin pipe is connected. At this time, if the chemical injection pipe 8 has a diameter larger than that of the drill rod 7, the tip of the drill rod 7 is easily inserted so that the chemical injection pipe 8 can be easily buried in the ground by retracting the drill rod 7. Excavating means 9 for excavating a hole having a diameter slightly larger than that of the chemical liquid injection pipe 8.
And the chemical injection pipe 8 is connected and connected to the excavating means 9 via the rotary joint 10.

As shown in FIG. 5, the excavating means 9 has a plurality of bits 9b projecting from the conical surface of a truncated cone shell reamer 9a and a lubricant discharge hole communicating with the hollow chamber of the shell reamer 9a. This shell reamer 9a is made by drilling 9c.
The distal end opening portion of the drill rod 7 is detachably connected to the distal end opening portion so that it can be integrally rotated with the drill rod 7. Further, a shaft 9d is provided in the center of the disc-shaped rear plate of the shell reamer 9a, and the shaft 9d and the center of a closing plate 11 that closes the open end of the chemical liquid injection pipe 8 are provided so as to project. The shafts 12 are connected by the rotary joint 10. Therefore, the rotation of the drill rod 7 causes the shell reamer to rotate.
The chemical liquid injection pipe 8 does not rotate even when the 9a is rotated.

In this way, after the chemical liquid injection pipe 8 is connected to the tip of the drill rod 7 through the excavating means 9 and the rotary joint 10, the base end portion of the drill rod 7 is gripped on the starting side ground surface 4 side. While rotating the gripping tool 6c of the propulsion device 6, the inclined starting base 6b is moved backward from the lower end to the upper end. Then, the drill rod 7 is pulled back in the longitudinal direction toward the starting side ground surface 4 by the retraction of the gripping tool 6c, and the chemical solution injection pipe 8 integrally connected to the drill rod 7 is moved from the reaching side ground surface 5 to the drill rod 7. When the drill rod 7 is pulled back, the drill rod 7 travels along the propulsion buried trace and enters the ground.

At this time, the shell reamer 9a of the excavating means 9 is rotated by the rotation of the gripping tool 6c of the propulsion device 6, and the chemical liquid injection pipe 8 is excavated so as to expand the diameter of the propulsion buried trace of the drill rod 7. The chemical solution injection pipe 8 is inserted into the embedded hole 14 while forming the embedded hole 14. On the other hand, by supplying a lubricant 13 such as muddy water into the hollow inside of the drill rod 7 from the base end portion of the drill rod 7 on the starting side ground surface 4 side, the shell reamer of the excavating means 9 is provided from the tip of the drill rod 7.
The lubricant 13 is filled in the 9a, discharged from the discharge hole 9c to the excavation face, and made to flow through the annular gap between the chemical liquid injection pipe 8 and the buried hole 14 toward the arrival side ground surface 5 side to fill the chemical liquid in the buried hole 14. The injection tube 8 can be easily propelled and the shell reamer
The earth and sand excavated by 9a are lubricated by the lubricant 13 and the ground surface 5 on the arrival side
Discharge to the side.

On the starting side ground surface 4 side, the first short drill rod 7a forming the last pipe portion of the drill rod 7 is pulled up on the starting table 6b by retracting the gripping tool 6c of the propulsion device 6. , Disconnecting the short drill rod 7a, advancing the gripping tool 6c to the lower end of the tilt of the starting base 6b, gripping the base end of the next short drill rod 7a, and rotating the drill rod 7 again in the same manner as above. By pulling back, the excavation means 9 excavates the buried hole 14 of a certain length, and the chemical solution injection pipe 8 enters and is buried in the buried hole 14.

Thus, while the drill rod 7 is being rotated, it is pulled back toward the ground surface 4 on the starting side, and at the time of pulling back, the excavation means 9 excavates the buried hole 14, and the chemical liquid is introduced into the buried hole 14 as shown in FIG. By injecting and burying the injection pipe 8 and removing the entire drill rod 7 to the starting side ground surface 4 side, the existing structure 1 is sandwiched between the starting side ground surface 4 and the reaching side ground surface 5. Then, the chemical solution injection pipe 8 is buried in the soft ground layer 3 below the existing structure 1. The drilling means 9 is also removed from the rotary joint 10 when the drill rod 7 is removed.

The chemical solution injection pipe 8 has a central portion buried below the existing structure 1 in the soft ground layer 3 to be improved.
A large number of injection holes 15 are formed at small intervals in the circumferential direction and the length direction, and the inside of one end of the pipe length portion, in which the injection holes 15 are formed, preferably the end on the arrival side ground surface 5 side. Stopper
Further, it is closed by 16 in advance, and a chemical liquid supply device 17 having a chemical liquid tank 18 which is a ground improving agent such as grout is installed on the arrival side ground surface 5 along with the propulsion device 6.

The supply hose of this chemical supply device 17
After connecting 19 to the tip of the chemical solution injection pipe 8 and connecting them, the chemical solution 20 such as grout in the chemical solution tank 18 is supplied to the chemical solution injection pipe 8 by operating the chemical solution supply device 17. The connection between the supply hose 19 and the chemical liquid injection pipe 8 is performed through a closing plate 11 that closes the open end of the chemical liquid injection pipe 8. At this time, the connecting plate is projected from the center of the closing plate 11. This is done by setting the above-mentioned shaft 12 as a hollow shaft communicating with the chemical liquid injection pipe 8 and connecting a supply hose 19 to the hollow shaft 12.

The chemical liquid supply device 17 is operated to activate the chemical liquid tank 18.
When the chemical solution 20 therein is press-fitted and supplied into the chemical solution injection pipe 8, the chemical solution 20
3 fills the chemical liquid injection pipe 8 and then sprays from the injection hole 15 into the soft ground layer 3 around the chemical liquid injection pipe 8 below the existing structure 1 as shown in FIG. 3 and penetrates into the soft ground layer 3. Then, the soft ground layer 3 is improved into a stable support ground layer 3A as shown in FIG. 4 by hardening in a state of being mixed with sand particles. In addition, a filler such as mortar may be filled inside the length portion from the stopper 16 in the chemical liquid injection pipe 8 to the end portion that opens to the reaching-side ground surface 5.

The soft ground layer 3 below the existing structure 1
Is present over a wide range, the propulsion device 6 is laterally moved from the driving position of the drill rod 7 to a position at a certain interval, and at that position, the removed short drill rods 7a are moved. Using the same again as above, the drill rod 7 is propelled by horizontally penetrating the soft ground layer 3 into the ground between the starting-side ground surface 4 and the reaching-side ground surface 5, and the chemical solution is reached at the reaching-side ground surface 5. The injection pipe 8 is drilled by a drilling means 9 and a rotary joint.
The chemical liquid injection pipe 8 is embedded in parallel with the previously embedded chemical liquid injection pipe 8 by connecting the same through 10 and pulling back the drill rod 7, and then the chemical liquid injection pipe 8 is embedded by the chemical liquid supply device 17.
The chemical solution 20 may be supplied to the inside and injected into the soft ground layer 3 through the injection hole 15 to improve the soft ground layer 3 between the adjacent chemical solution injection pipes 8 into the support ground layer 3A. This work is performed on the existing structure 1 It may be performed at a predetermined interval in the horizontal direction with respect to the soft ground layer 3 below.

Further, when the soft ground layer 3 has a large layer thickness, the tilting angle of the starting base 6b of the propulsion device 6 is appropriately changed to adjust the driving depth of the drill rod 7 to inject the previously embedded chemical solution. After the chemical solution injection pipe 8 is embedded above or below the pipe 8 in the same manner as described above, the chemical solution 20 is supplied into the chemical solution injection pipe 8 by the chemical solution supply device 17, and the soft ground layer 3 is injected from the injection hole 15.
The chemical solution 20 is injected into the above to improve the soft ground layer 3 between the vertically adjacent chemical solution injection pipes 8, 8 into the support ground layer 3A.

When the chemical solution 20 is injected into the soft ground layer 3 from the chemical solution injection hole 15 of the chemical solution injection pipe 8, the chemical solution 20 is directly supplied into the chemical solution injection tube 8 in the above construction method.
The chemical solution 20 was simultaneously injected into the soft ground layer 3 through all the chemical solution injection holes 15 formed in the central portion of the chemical solution injection pipe 8 buried below the soft ground layer 3, but below the existing structure 1. The soft ground layer 3 in 3 may be injected into each fixed length portion of the chemical liquid injection pipe 8.

6 to 10 show an embodiment of the construction method, in which a short drill rod 7a is successively added from the starting side ground surface 4 side to form a long drill rod 7 while the propulsion device 6 is used. The process (shown in FIG. 6) of propelling the drill rod 7 from the starting side ground surface 4 to the reaching side ground surface 5 after horizontally propelling the soft ground layer 3 below the existing structure 1 is the same as the above-mentioned construction method. The difference from the above construction method is that when the chemical liquid injection pipe 8 is connected to the tip of the drill rod 7 reaching the reaching side ground surface 5 through the excavating means 9 and the rotary joint 10, the inside of the chemical liquid injection pipe 8 is At this point, a flexible chemical solution supply pipe 21 having a chemical solution supply nozzle 22 at its tip is inserted.

The chemical liquid supply pipe 21 has a diameter smaller than that of the chemical liquid injection pipe 8. As shown in FIG. 11, a short pipe 23 having the same diameter as the chemical liquid supply pipe 21 is connected and communicated with the distal end thereof as shown in FIG. twenty three
A plurality of the above-mentioned supply nozzles 22 are bored. further,
The tip of the short pipe 23 is closed 24, and the rubber packer 25 is slidably and closely attached to the outer peripheral surface of the distal end and the outer peripheral surface of the base end of the short pipe 23. , 25 are fixed to form a space 26 having an annular cross section with the packers 25, 25, the outer peripheral surface of the short pipe 23 and the inner peripheral surface of the chemical liquid injection pipe 8 corresponding to the outer peripheral surface of the short pipe 23. There is.

In this way, with the chemical solution supply pipe 21 inserted into the chemical solution injection pipe 8, the drill rod 7 is rotated toward the start side ground surface 4 side by the gripping tool 6c on the start side ground surface 4 side. By pulling back the chemical liquid supply pipe 21, the chemical liquid injection pipe 8 having the chemical liquid supply pipe 21 installed therein is introduced into the embedding hole 14 excavated by the excavation means 9 along the embedding trace of the drill rod 7 as shown in FIG. To the soft ground layer 3 below the existing structure 1 between the starting-side ground surface 4 and the reaching-side ground surface 5 with the existing structure 1 sandwiched between the starting-side ground surface 4 side and the starting-side ground surface 4 side. The chemical injection pipe 8 having the pipe 21 inside is embedded. The drilling means 9 is also removed from the rotary joint 10 when the drill rod 7 is removed.

As shown in FIG. 8, the chemical liquid supply pipe 21 is wound around a winding drum 27 installed on the ground surface 5 on the arrival side, and is drawn out from the winding drum 27 to be inserted into the chemical liquid injection pipe 8. A large number of injection holes formed by the short pipe 23 in the chemical liquid injection pipe 8.
The chemical liquid supply device 17 'is inserted in a state of being disposed at a position passing through 15, and has the base end wound on the winding drum 27 installed integrally with the winding drum 27 on the arrival side ground surface 5.
It communicates with the chemical liquid tank 18 'via.

When the chemical liquid supply device 17 'is operated to supply the chemical liquid 20 in the chemical liquid tank 18' to the chemical liquid supply pipe 21,
The chemical solution 20 fills the annular space 26 between the packers 25 and 25 from the plurality of supply nozzles 22 formed in the short pipe 23, and then the space 26 corresponds to the length of the space 26. As shown in FIG. 9 after being injected into the soft ground layer 3 through the plurality of injection holes 15 of the chemical liquid injection pipe 8, the soft ground around the length portion of the chemical liquid injection pipe 8 corresponding to the length of the space 26. Improve layer 3 to a stable supporting ground layer 3A.

After injecting the chemical liquid 20 into the surrounding soft ground layer 3 in the fixed length portion of the chemical liquid injection pipe 8, the winding drum
By rotating 27 in the winding direction and pulling back the chemical liquid supply pipe 21 to the arrival side ground surface 5 side by a length equal to the length dimension between the front and rear packers 25, 25, the front and rear packers 25, 25 are fed. While being slid on the inner peripheral surface of the liquid medicine injection pipe 8, the liquid medicine injection pipe 8 is moved to the next length portion, and the medicine liquid 20 is passed through the annular space portion 26 from the injection hole 15 formed in the length portion. Inject into the soft ground layer 3 around 26. As described above, by winding the chemical liquid supply pipe 21 at a constant length around the winding drum 27, the supply nozzle 22 formed in the short pipe 23 at the tip of the chemical liquid supply pipe 21 is moved in the chemical liquid injection pipe 8 to form an annular space. From the injection hole 15 corresponding to the annular space portion 26 through the portion 26 to the soft ground layer 3
The chemical solution 20 is injected into the existing structure 1 as shown in FIG.
This is to improve the soft ground layer 3 around the central portion of the supply pipe 21 below.

An injection hole 15 formed in the chemical liquid injection pipe 8
As shown in FIG. 11, it is closed by a rubber sleeve 28 fitted on the outer peripheral surface of the chemical liquid injection pipe 8 to prevent pressurized water such as groundwater from entering the chemical liquid supply pipe 21 through the injection hole 15. Yes, at the time of ground improvement, the liquid pressure of the liquid medicine 20 filled in the annular space portion 26 is increased through the supply nozzle 22 drilled from the liquid medicine supply pipe 21 to the short pipe 23, and the liquid medicine 20 is poured out from the liquid medicine injection hole 15. The pressure is applied to cause the rubber sleeve 28 to expand and deform, and the rubber sleeve 28 is injected into the soft ground layer 3 from an injection nozzle 29 formed in the peripheral surface of the central portion of the rubber sleeve 28.

The chemical liquid supply pipe 21 is successively wound around the winding drum 27 at a constant length so that the short pipe 23 is intermittently moved in the chemical liquid injection pipe 8 by a constant length toward the arrival side ground surface 5 side. The portion corresponding to the intermittent movement of the supply nozzle 22 in the soft ground layer 3 is sequentially improved, but the short pipe 23 of the chemical liquid supply pipe 21 is continuously moved in the chemical liquid injection pipe 8 to supply the supply nozzle 22.
The chemical solution 20 may be successively poured into the soft ground layer 3 through the annular space portion 26 from the injection hole 15 corresponding to the annular space portion 26 to continuously improve the soft ground layer 3.

12 to 17 show another ground improvement method in the present invention. In the method shown in FIGS. 6 to 10, the chemical solution supply pipe 21 is inserted into the chemical solution injection pipe 8 in advance. Although it was embedded in the embedding hole 14 at the same time as the chemical liquid injection pipe 8, in this construction method, the chemical liquid supply pipe 21 is inserted into the chemical liquid injection pipe 8 after the chemical liquid injection pipe 8 is embedded.

That is, while the short drill rods 7a are sequentially added from the starting side ground surface 4 side to form the long drill rod 7, the drill rods 7 are moved from the starting side ground surface 4 to the existing structure 1 by the propulsion device 6. The step of propelling the lower soft ground layer 3 in the horizontal direction and then penetrating it to the reaching side ground surface 5 (shown in FIG. 12) is the same as the above method, but the difference from the above method is the reaching side ground surface. Drill rod 7 reached 5
A liquid injection pipe 8 is provided at the tip of the via a drilling means 9 and a rotary joint 10.
The wire rope wound around the winch 30 installed on the ground surface 5 on the arrival side in the chemical injection pipe 8 when connecting the
31 is inserted and the tip thereof is connected to the tip closing plate 11 of the liquid medicine injection pipe 8, and after the liquid medicine injection pipe 8 is embedded, the liquid medicine supply pipe 21 is inserted into the liquid medicine injection pipe 8 using this wire rope 31. That is the point.

More specifically, first, the wire rope 31 is inserted into the chemical liquid injection pipe 8 and is connected to the ground liquid 4 and the ground surface 4 on the starting side.
By pulling back toward the starting side ground surface 4 side while rotating the drill rod 7 by the gripping tool 6c on the side, the chemical liquid injection pipe 8 is removed as shown in FIG. The drill rod 7 is made to penetrate into the buried hole 14 excavated by the excavation means 9, and the entire drill rod 7 is moved to the starting surface 4
By embedding the existing structure 1 between the ground surface 4 on the start side and the ground surface 5 on the arrival side by removing the existing structure 1, it is embedded in the soft ground layer 3 below the existing structure 1 as shown in FIG. .

Next, when the drill rod 7 is removed, the excavation means 9 and the rotary joint 10 that have reached the starting side ground surface 4 side are removed, the tip closing plate 11 of the chemical solution injection pipe 8 is removed, and the tip end opening of the chemical solution injection tube 8 is removed. The tip of the wire rope 31 is pulled out from the section, and the chemical liquid supply pipe 21 wound around the winding drum 27 installed on the ground surface 4 on the starting side is also pulled out, and the chemical liquid supply pipe 21
After connecting the short pipe 23 provided at the tip of the wire rope 31 to the tip of the wire rope 31, the wire rope 31 is unwound by operating the winch 30 on the arrival side ground surface 5 side, as shown in FIG. By returning, the chemical liquid supply pipe 21 is inserted into the chemical liquid injection pipe 8 while sliding the front and rear packings 25 mounted on the outer peripheral surface of the distal short tube 23 thereof.

Then, the unwinding of the wire rope 31 is stopped at a position where the short pipe 23 passes through the central portion of the chemical liquid supply pipe 21 which is buried in the soft ground layer 3 below the existing structure 1,
After that, the chemical liquid supply device 17 'installed integrally with the winding drum 27 is operated to activate the chemical liquid 20 in the chemical liquid tank 18'.
Is supplied to the inside of the chemical liquid supply pipe 21 through the base end of the chemical liquid supply pipe 21 wound around the winding drum 27, and between the plurality of supply nozzles 22 bored in the short pipe 23 and the packers 25, 25. After filling the annular space portion 26 with the chemical liquid 20, the chemical liquid 20 is filled in the soft ground layer 3 from the space portion 26 through a plurality of injection holes 15 of the chemical liquid injection pipe 8 corresponding to the length of the space portion 26. By gradually injecting the chemical liquid supply pipe 21 around the winding drum 27 as shown in FIG. 16 and FIG.
The soft ground layer 3 around the length portion of the chemical solution injection pipe 8 corresponding to the length of the above is continuously or intermittently improved to a stable support ground layer 3A for each fixed length dimension.

When the injection of the chemical liquid 20 into the soft ground layer 3 below the existing structure 1 is completed in this way, the chemical liquid supply pipe 21 is wound around the winding drum 27 and the soft ground layer below the existing structure 1 is wound. 3 is to be used for the injection of the chemical liquid in the next part, and the wire rope 31 has both ends thereof at the start-side ground surface 4 and the arrival-side ground surface 5 when the chemical liquid supply pipe 21 is pulled out from the chemical liquid injection pipe 8. Since it can be inserted into the chemical solution injection pipe 8 in a state of being projected to the end, the chemical solution supply pipe 21 is connected to the tip of the wire rope 31 projecting to the starting side ground surface 4 side again, and then the reaching side ground surface. The chemical solution supply pipe 21 is inserted into the chemical solution injection pipe 8 by pulling the wire rope 31 from the 5 side until the tip nozzle 22 reaches a desired position in the chemical solution injection pipe 8, and the soft ground layer 3 is formed in the same manner as above.
It is possible to inject the drug solution 20 into a desired position of the.

In the above embodiments, the description has been made on the improvement of the sandy ground (soft ground) which is liquefied due to the occurrence of an earthquake. However, the ground improvement method of the present invention improves such sandy ground. Not only the underpinning work when constructing an underground structure such as a tunnel directly under the existing structure, that is, the improvement of the ground below the existing structure as a support ground stabilization work for the existing structure, and the existing structure. Improvements to prevent loosening of the ground in shield tunnel construction that passes directly below may also be implemented. In addition, existing structures are not limited to buildings constructed on the ground surface, but also landscaping of bridge piers, roads, parks, etc., obstacles such as rivers and ponds, or underground such as tunnels and buried pipes. Structures can be targeted.

[0051]

As described above, according to the method for supporting ground improvement of an existing structure of the present invention, a drill rod having a drill head attached to the tip thereof is used as a starting side with one side ground surface of the existing structure as a starting side. After launching into the ground from the surface and propelling it in the ground layer to be improved immediately below the existing structure, it reaches the ground surface on the other side of the existing structure, and then the tip of this drill rod has flexibility. And, after connecting the chemical liquid injection pipe formed by drilling a large number of chemical liquid injection holes penetrating the inner and outer peripheral surfaces, the above chemical liquid injection pipe is improved immediately below the existing structure by pulling back the drill rod to the ground surface on the starting side. Since it is laid in the desired ground layer, it is possible to reliably and easily bury the chemical solution injection pipe in the substantially horizontal direction over the entire length in the desired portion of the ground layer to be improved below the existing structure. After that, one surface of the earth Since the chemical solution which is the ground improving agent is supplied into the end of the chemical solution injection pipe projecting on the ground surface, the chemical solution can be smoothly supplied into the chemical solution injection pipe and the chemical solution is supplied into the chemical solution injection pipe. The chemical solution can be uniformly injected into the ground layer to be improved around the chemical solution injection pipe from a large number of injection holes of the chemical solution injection pipe which is embedded horizontally in the ground layer to be improved. The ground layer around the can be efficiently improved over the entire length of the chemical injection pipe.

Further, the driving position of the drill rod that penetrates the ground layer to be improved below the existing structure from the ground surface on the starting side to reach the ground surface on the reaching side is laterally moved to inject the previously buried chemical solution. The embedding position of the next chemical solution injection pipe with respect to the pipe can be performed in parallel at a predetermined interval according to the chemical solution treatment range, and therefore the plane direction and the vertical direction with respect to the ground layer to be improved below the existing structure can be performed. By performing ground improvement by embedding multiple chemical solution injection pipes in the direction,
Even if the ground layer to be improved below the existing structure is wide and the layer thickness is large, the entire structure can be improved uniformly and efficiently.

In the above-mentioned method for supporting ground improvement of an existing structure, the chemical solution may be directly injected into the chemical solution injection pipe to inject the chemical solution into the ground layer to be improved from the injection hole formed in the chemical solution injection pipe. As described in claim 2 or 3, the chemical liquid supply pipe having the chemical liquid supply nozzle at the tip is inserted into the chemical liquid injection pipe, and the chemical liquid is supplied to the chemical liquid supply pipe from one ground surface side to supply the chemical liquid. Pour the liquid medicine from the nozzle,
It may be possible to inject into the ground layer to be improved through the injection hole of the chemical liquid injection pipe corresponding to this chemical liquid supply nozzle portion. According to this construction method, the ground layer to be improved is fixed to a certain length of the chemical liquid injection pipe. While dividing into the corresponding ground part,
The ground part can be improved and the injection amount is increased in some parts, and the injection amount is decreased in some parts and the next ground part is processed without injecting into parts that do not require improvement. Therefore, it is possible to perform an improvement treatment according to the properties of the ground layer around the chemical injection pipe.

According to the invention of claim 4, in the support ground improvement method for the existing structure, the distribution from the ground surface on the starting side to the ground surface on the arrival side through the ground layer to be improved under the existing structure is performed. When replacing the installed drill rod with the chemical injection pipe, since the chemical injection pipe is connected to the drill rod through the excavation means, it is a trace of passage of the drill rod by the excavation means by pulling back the drill rod. While enlarging the through hole, the chemical liquid injection pipe can be inserted and embedded in the enlarged excavation hole, and the chemical liquid injection pipe can be efficiently and reliably embedded.

In addition, in the method for improving the ground for supporting existing structures, the chemical solution poured from the tip supply nozzle of the chemical solution supply pipe is injected into the ground to be improved from the injection hole of the chemical solution injection pipe in which the nozzle is located. As described in claim 5, a packer is attached to the tip of the drug solution supply pipe with a supply nozzle interposed therebetween, and the drug solution supply pipe is moved in the longitudinal direction inside the drug solution injection pipe. By supplying the chemical solution through the supply nozzle between the packers in sliding contact with the peripheral surface, the chemical solution can be accurately injected into the ground layer to be improved from the injection hole of the chemical solution injection pipe corresponding to the space between the packers.

[Brief description of drawings]

FIG. 1 is a simplified vertical sectional side view showing a propelled state of a drill rod in a support ground improvement method of the present invention,

FIG. 2 is a simplified vertical sectional side view showing a process of burying a chemical liquid injection pipe,

FIG. 3 is a simplified vertical cross-sectional side view of a state in which a chemical solution injection process is being performed,

FIG. 4 is a simplified vertical side view after improvement,

FIG. 5 is a simplified side view of the excavating means,

FIG. 6 is a simplified vertical sectional side view showing a propelling state of a drill rod in another supporting ground improvement method of the present invention;

FIG. 7 is a simplified vertical sectional side view showing a step of burying a chemical solution injection pipe having a chemical solution supply pipe inside.

FIG. 8 is a simplified vertical sectional side view showing the buried state,

FIG. 9 is a simplified vertical cross-sectional side view showing a state where a chemical solution injection process is being performed.

FIG. 10 is a simplified vertical sectional side view after improvement,

FIG. 11 is an enlarged vertical side view of the supply nozzle portion,

FIG. 12 is a simplified vertical sectional side view showing a propelled state of a drill rod in still another supporting ground improvement method of the present invention;

FIG. 13 is a simplified vertical cross-sectional side view showing a step of burying a chemical liquid injection pipe containing a wire rope.

FIG. 14 is a simplified vertical sectional side view showing the buried state,

FIG. 15 is a simplified vertical sectional side view showing a state where the chemical liquid supply pipe is drawn in;

FIG. 16 is a simplified vertical cross-sectional side view showing a state where a chemical liquid injection process is being performed.

FIG. 17 is a simplified vertical sectional side view after improvement.

[Explanation of symbols]

1 Existing structure 3 Soft ground layer 4 Start side ground surface 5 Arrival surface 6 propulsion devices 7 drill rod 7A drill head 8 Chemical injection tube 9 Excavation means 10 rotary joint 14 buried hole 15 injection hole 20 chemicals 21 Chemical supply pipe 22 Supply nozzle 31 wire rope

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-1-10895 (JP, A) JP-A-9-88005 (JP, A) JP-A-8-120661 (JP, A) JP-A-63- 118496 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) E02D 3/12 101

Claims (5)

(57) [Claims] 1. A ground layer to be improved immediately below the existing structure by launching a drill rod having a drill head at its tip from one side of the existing structure to the starting side into the ground from this starting side ground surface. After propelling the inside, it reaches the ground surface on the other side of the existing structure, and then the drill rod has a large number of flexible chemical injection holes penetrating its inner and outer peripheral surfaces. After connecting the chemical injection pipe, pull the drill rod back to the ground surface on the starting side to lay the above chemical injection pipe in the ground layer to be improved immediately below the existing structure, and then improve the ground from the ground side to the inside of the chemical injection pipe. A support ground improvement method for an existing structure, which comprises supplying a chemical solution as an agent and injecting it into the ground layer to be improved from the chemical solution injection hole provided in the chemical solution injection pipe. 2. A ground layer to be improved immediately below the existing structure by launching a drill rod having a drill head at its tip from one side of the existing structure to the starting side into the ground from this starting side ground surface. After propelling the inside, it reaches the ground surface on the other side of the existing structure, and then the drill rod has a large number of flexible chemical injection holes penetrating the inner and outer peripheral surfaces. After connecting the chemical solution injection pipe and inserting the chemical solution supply pipe having the chemical solution supply nozzle at the tip into this chemical solution injection pipe, the chemical solution injection pipe with the above-mentioned chemical solution supply pipe inside by pulling back the drill rod to the ground surface on the starting side is already installed. Laying on the ground layer to be improved immediately below the structure, and then supplying the chemical solution which is the ground improving agent into the chemical solution supply pipe from the ground side and pulling out the chemical solution from the chemical solution supply nozzle while pulling back the chemical solution supply pipe. A method for supporting ground improvement of an existing structure, characterized by injecting into a ground layer to be improved through a chemical solution injection hole of a chemical solution injection pipe corresponding to a chemical solution supply nozzle portion. 3. A ground layer to be improved immediately below the existing structure by launching a drill rod having a drill head at its tip from one side of the existing structure to the starting side into the ground from this starting side ground surface. After propelling the inside, it reaches the ground surface on the other side of the existing structure, and then the drill rod has a large number of flexible chemical injection holes penetrating its inner and outer peripheral surfaces. After connecting the chemical injection pipe and pulling the wire rope into this chemical injection pipe, pull back the drill rod to the ground surface on the starting side to improve the chemical injection pipe with the above wire rope inserted directly under the existing structure. After laying on the ground layer to be reached, connect the chemical solution supply nozzle attached to the tip of the chemical solution supply pipe to the wire rope that has reached the reaching surface side, and then pull back the wire rope from the starting surface to pull the chemical solution into the chemical solution injection pipe. While inserting the supply nozzle, the chemical solution supply nozzle supplies the chemical solution which is a ground improvement agent to the chemical solution supply pipe from the arriving side while the chemical solution supply nozzle is passing through the inside of the chemical solution injection pipe immediately below the existing structure to supply the chemical solution to be poured out from the chemical solution supply nozzle. A method for supporting ground improvement of an existing structure, characterized by injecting into a ground layer to be improved through a chemical solution injection hole of a chemical solution injection pipe corresponding to the chemical solution supply nozzle portion. 4. A ground layer to be improved immediately below the existing structure by launching a drill rod having a drill head at its tip from one side of the existing structure to the starting side to the ground from this starting side ground surface. After propelling the inside, it reaches the ground surface on the other side of the existing structure, after removing the drill head, a large number of chemical liquids that have flexibility through the drilling means at the tip of the drill rod and penetrate the inner and outer peripheral surfaces A chemical injection pipe formed by forming an injection hole is connected, and then the drill rod is pulled back to the ground surface on the starting side, and the following chemical injection pipe is laid while excavating the chemical injection pipe laying hole by excavating means. The method for improving the supporting ground of an existing structure according to claim 1, 2 or 3, wherein the method is to lay in a hole. 5. A packer, which is slidably contacted with the inner peripheral surface of the chemical liquid injection pipe with an appropriate front and rear spacing, is attached to the outer peripheral surface of the tip of the chemical liquid supply pipe inserted into the chemical liquid injection pipe, and the chemical liquid between these front and rear packers is mounted. A chemical liquid supply nozzle is formed at the tip of the supply pipe to fill the annular space between the facing surfaces of the chemical liquid supply pipe and the chemical liquid injection pipe between the front and rear packers with the chemical liquid to be poured from the chemical liquid supply nozzle. The method for supporting ground improvement of an existing structure according to claim 2 or 3, wherein the chemical solution is injected into the ground layer to be improved through an injection hole formed in the chemical solution injection pipe.