JP4057440B2 - How to improve natural ground - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for improving natural ground, and more particularly, to a method for reinforcing a natural ground by burying a bent pipe in the natural ground around a tunnel by a curved boring method.
[0002]
[Prior art]
Generally, when excavating a tunnel on soft ground, it is necessary to reinforce the natural ground beforehand. Therefore, a method is used in which a hole is formed by curved boring in a natural mountain that is an arch portion of a tunnel, and a drug such as a ground solidifying agent is injected into the hole to be reinforced. When forming such a drilling hole, for example, as shown in FIGS. 7A and 7B, a steel pipe to be inserted into the natural ground 60 is a bent steel pipe (hereinafter referred to as an injection hole 51h) on its side surface. A distal end provided with a distal end bit 53b that is rotated by a motor 53a at the distal end of the inner tube 52. A curved boring device 50 is used in which the device 53 is attached and the ground 60 is excavated and the outer pipe 51 is inserted into the ground 60 and buried. In this curved boring device 50, the outer tube 51 and the inner tube 52 are coupled by the swivel 54 in the advanced guiding shaft 61, and the outer peripheral surface of the outer tube 51 is held by the holder 55 </ b> H of the propulsion device 55 for propulsion. The outer pipe 51 and the inner pipe 52 are simultaneously inserted into the natural ground 60 while excavating the natural ground 60 with the tip device 53.
[0003]
Then, while repeating the step of propelling the outer tube 51 and the inner tube 52 by excavating the natural ground 60 and the step of extending the double tube by connecting the inner tube 52 and the outer tube 51 respectively, After the tube 51 is inserted to a predetermined length, the tip device 53 and the inner tube 52 are recovered, and a packer 56p is provided in the outer tube 51 before and after the discharge port 56h as shown in FIG. The injection pipe 56 is inserted, and the ground solidifying agent pumped through the injection liquid transfer pipe 57 connected to the rear end portion of the injection pipe 56 is discharged into the outer pipe 51, The ground solidifying agent is injected from the provided injection hole 51h into the ground 60 around the tunnel to reinforce the ground 60 (for example, Patent Documents 1 and 2, Non-Patent Document 1, etc.).
[0004]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2000-160980 (pages 2, 3 and 1, 3)
[Patent Document 2]
Japanese Patent Laid-Open No. 2002-242581 (pages 2, 3 and 1-3)
[Non-Patent Document 1]
Yoshitomo Kameoka, Taro Sugaya, “Development of Curve Boring Method (TURIP Method)”, Journal of Japan Society of Civil Engineers, April 1995 issue [0005]
[Problems to be solved by the invention]
However, in the above conventional method, since a rotating mechanism is used for excavation of the natural ground 60, the cross-sectional shape of the bent steel pipe (outer pipe 51) to be embedded is limited to a circular one. Further, in the curved boring device 50, since the motor 53a, the tip bit 53b, and further devices such as a rotational force transmission mechanism need to be housed in the inner tube 52, the inner space of the inner tube 52 is narrow. Therefore, there was a problem that the excavated mud could not be discharged efficiently.
[0006]
The present invention has been made in view of the conventional problems, and with a simple configuration, a bent steel pipe is efficiently inserted and embedded in a natural ground around a tunnel, and an injection material is inserted from the bent steel pipe into the natural ground. It aims at providing the method of injecting into the above-mentioned natural ground.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, a bent pipe having a plurality of injection holes on the side surface is inserted into the ground from the side wall of the advanced guiding shaft and buried, and the ground solidifies from the injection hole into the ground. A method for improving a natural ground by injecting a material to reinforce the natural ground, wherein a cylindrical guide blade along the outer periphery of the curved pipe is attached to a distal end portion of the curved pipe and disposed in the curved pipe. A jet water spray nozzle is attached to the tip of the outer peripheral portion of the inner pipe and inside the guide blade, and jet water from the jet water spray nozzle is sprayed into the natural ground from the inner space side of the guide blade. The bent pipe is inserted into the natural ground while excavating a mountain and discharging the mud excavated by the jet water through the inner pipe . As a result, the degree of freedom in the shape of the cross-section of the hole is increased, and it is possible to embed a curved pipe or a curved steel material other than a round pipe such as a square pipe or H steel with a simple configuration. Become. Further, since there is no need to install a drilling device or the like in the pipe, the efficiency of soil removal is improved, so that the construction efficiency can be greatly improved . Moreover, since jet water can be intensively ejected by this , a natural ground can be excavated efficiently.
[0008]
According to a second aspect of the present invention, in the method for improving a natural ground according to the first aspect, in order to efficiently propel the bent steel pipe, the bent steel pipe is inserted while applying vibration to the guide blade. It is characterized by that.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a view showing an embodiment of the present invention, in which 10 is an advanced excavated in advance to construct two adjacent tunnels (main shafts) 11 and 12 in parallel. A central shaft 20, which is a shaft, is installed in the central shaft 10. From the shoulders 14 a and 14 b of the support 14 of the central shaft 10, the arch portion of the main shafts 11 and 12 to be excavated This is a curved boring device for inserting and embedding cylindrical bent steel pipes 30 and 30 in the natural ground 15.
2 and 3 are diagrams showing the details of the curved boring apparatus 20, wherein 21 is an inner pipe disposed concentrically with the bent steel pipe 30 in the bent steel pipe 30, which is an outer pipe, and 22 is the bent. A cylindrical guide blade 23 attached to the tip of the steel pipe 30 along the outer periphery of the bent steel pipe 30 is a jet installed between the bent steel pipe 30 and the inner pipe 21 inside the guide blade 22. A nozzle 24 is connected to the rear end of the inner pipe 21, and a rock drill 25 for propelling the inner pipe 21 is mounted with the rock drill 24, and the rock drill 24 is connected to the ground 15. A guide cell for sliding in a direction. As shown in FIG. 1, the guide cell 25 is configured such that at least the slide surface of the rock drill 24 has a curved surface having the same curvature as that of the bent steel pipe 30. Further, 26 is a swivel provided at the rear end of the bent steel pipe 30 to connect the bent steel pipe 30 and the inner pipe 21, 27 is a water supply pipe for pumping high-pressure water to the jet nozzle 23, and 28 is the above-mentioned This is a soil removal outlet provided at the rear end of the inner pipe 21. The water supply pipe 27 is piped along the outer peripheral portion of the inner pipe 21 inside the bent steel pipe 30. The other end of the water pipe 27 is connected to an inlet for high-pressure water pumped from a high-pressure water pumping means (not shown).
[0012]
Next, a method for improving natural ground will be described.
First, a bent steel pipe 30 having a guide blade 22 attached to the distal end side is inserted into a face 15a of a ground 15 which has been excavated in advance, and an inner pipe having a jet nozzle 23 attached to the distal end of the outer peripheral portion thereof in the bent steel pipe 30. 21 is inserted. Then, high-pressure jet water is ejected from the jet nozzle 23 provided inside the guide blade 22 into the natural ground 15 to excavate the natural ground 15, and the rock drill 24 is moved along the guide cell 25. The inner pipe 21 is propelled by moving in the direction of the natural ground 15, and the bent steel pipe 30 and the inner pipe 21 are simultaneously inserted into the natural ground 15.
By the way, when the guide blade 22 is not attached to the distal end side of the bent steel pipe 30, the jet water spreads beyond the width of the bent steel pipe 30, as shown in FIG. The direction perpendicular to the traveling direction of the steel pipe 30 is also excavated. As described above, when the jet water spreads, not only the digging force by the jet water itself is lowered and the propulsion speed is slowed, but also the surroundings of the bent steel pipe 30 are caused by voids due to excessive digging, the jet water The problem is that the ground is weakened due to excessive absorption of water by the ground. On the other hand, in this example, since the guide blade 22 is attached to the distal end side of the bent steel pipe 30, the jet water is concentrated in a region substantially close to the width of the guide blade 22 as shown in FIG. And then erupted. Therefore, the natural ground 15 can be excavated efficiently. Further, it is difficult to form a void due to excessive digging around the bent steel pipe 30 serving as the preceding support work, and the water of the jet water does not diffuse. Therefore, since the ground is not weakened, it is possible to construct the preceding support work quickly and reliably.
At this time, for example, an ultrasonic vibrator is attached to the guide blade 22 to give vibration to the guide blade 22, or to the guide blade 22 by a rock drill, while bending the pipe. If the 30 and the inner pipe 21 are propelled, the excavation efficiency of the natural ground 15 can be further improved.
[0013]
When the bent steel pipe 30 is extended and extended, the bent steel pipes 30 and 30 are connected by welding as usual, but the inner pipe 21 is connected to the connecting portion of the inner pipes 21 and 21 as shown in FIG. A flange 21F provided with a protruding piece 21k protruding in the direction of the bent steel pipe 30 is attached to the outer peripheral side at a position rotated by 45 ° with respect to the radius of curvature of the bent steel pipe 30. The protruding pieces 21k of the flange 21F are attached to each other. Are fastened and connected by bolts 21B. At this time, the tip of the protruding piece 21k is brought into substantially contact with the inner wall of the bent steel pipe 30. Thereby, even when the bent steel pipe 30 is deformed so as to be crushed in the radius direction of curvature in the ground 15 due to the pressure from the ground 15, the center position of the bent steel pipe 30 can be maintained. In addition, since the flange 21F does not mesh with the bent steel pipe 30, the bent steel pipe 30 can be smoothly inserted into the ground 15. For the same reason, the recovery of the inner pipe 21 after the bent steel pipe 30 is inserted can be performed smoothly. Further, even a bent steel pipe having an inferior roundness accuracy can be smoothly inserted into the ground 15.
Moreover, in this example, since the inner pipes 21 and 21 are connected by the protruding pieces 21k of the flange 21F, the water supply pipe 27 can be passed between the protruding pieces 21k and 21k in the connecting portion. Therefore, piping of the water supply pipe 27 is facilitated, and the space between the bent steel pipe 30 and the inner pipe 21 can be effectively utilized.
[0014]
The soil excavated from the natural ground 15 is discharged outside through the inside of the inner pipe 21. Specifically, as shown in FIG. 2, a soil removal outlet 28 is provided at the rear end of the inner pipe 21, and a soil removal pump (not shown) is attached to the soil removal outlet 28 so that the excavated mud Is discharged to the outside of the inner pipe 21. In this example, since there are no devices such as a digging device inside the inner pipe 21, the soil can be collected efficiently.
After the embedment of the bent steel pipe 30 is completed, the jet nozzle 23, the water supply pipe 27, and the inner pipe 21 are taken out from the bent steel pipe 30, and the bent steel pipe 30 is similar to the injection pipe 56 shown in FIG. The ground solidifying agent is injected into the ground 15 through an unillustrated injection hole of the bent steel pipe 30 to reinforce and improve the ground 15.
[0015]
Thus, in the present embodiment, the cylindrical guide blade 22 along the outer periphery of the bent tube is attached to the distal end portion of the bent steel tube 30 that is an outer tube, and the bent inside the guide blade 22. A jet nozzle 23 is attached between the steel pipe 30 and the inner pipe 21 disposed in the bent steel pipe 30, and high-pressure water is sent from the water supply pipe 27 to the jet nozzle 23, from the inner side of the guide blade 22. The bent steel pipe 30 and the inner pipe 21 are simultaneously inserted into the natural ground 15 while excavating the natural ground 15 by jetting high-pressure jet water into the natural ground 15. The natural ground 15 can be excavated efficiently without weakening the ground. Further, in this example, since excavation is performed only with jet water, there are no devices in the inner pipe 21, so that the discharged soil can be efficiently recovered.
In addition, an injection device is inserted into the bent steel pipe 30 embedded in the natural ground 15 in this manner, and a ground solidifying agent is injected into the natural ground 15 from an injection hole (not shown) of the bent steel pipe 30 to thereby form the natural ground 15. If it reinforces, the said natural ground 15 can be improved reliably.
[0016]
In addition, in the said embodiment, although the case where the cylindrical bent steel pipe 30 was embed | buried in the natural ground 15 was demonstrated, since the curved boring apparatus 20 of this example does not have a rotation part, the bent steel pipe embed | buried in the natural ground 15 is demonstrated. The cross-sectional shape can be arbitrarily selected.
FIG. 5 (a) is a diagram showing an example, and even if the bent steel pipe 31 has a rectangular cross-sectional shape, if the cylindrical inner pipe 21 is installed on the inner wall side of the bent steel pipe 31, It is possible to smoothly insert the bent steel pipe 31 and the inner pipe 21 into the natural ground 15. By the way, the magnitude of the pressure acting on the cross section of the bent steel pipe in the natural ground 15 is almost constant in the circumferential direction in the case of a straight pipe, but in the case of a curved pipe, the magnitude of the pressure is the same as that of the bent steel pipe. Since the direction of the radius of curvature is larger than the direction perpendicular thereto, as shown in FIG. 5B, a force that crushes the bent steel pipe in the direction of the radius of curvature acts on the cross section of the bent steel pipe. May be deformed and hinder propulsion. Therefore, in curved boring, it is necessary to increase the strength of the bent steel pipe. At this time, in the case where the bent steel pipe is a cylindrical bent steel pipe 30 as in the above example, a method of increasing the strength by increasing the thickness of the cylindrical radius of curvature is also conceivable. It is not practical to do. Further, if the thickness of the entire bent steel pipe 30 is increased, the cost is increased. However, in the present invention, since the cross-sectional shape of the bent steel pipe can be arbitrarily selected, for example, as shown in FIG. A curved steel pipe 31 having a rectangular cross-sectional shape, and an upper surface 31a having a large curvature among the surfaces in the radius direction of curvature (= the surface perpendicular to the radius direction of curvature and corresponding to the upper surface and the lower surface in the figure) 31a, 31b Can be bent without increasing the thickness of the entire pipe, if the thickness of the lower surface 31b or the surfaces (side surfaces in the figure) 31c and 32d in the direction perpendicular to the radius of curvature is thicker than the thickness of the entire tube. Since the strength of 31 can be improved, it is possible to construct a prior support work using a bent steel pipe that is inexpensive and has high strength. The portion where the thickness of the bent steel pipe 31 is changed is not limited to the upper surface 31a having a large curvature, and the thickness of the lower surface 31b having a small curvature may be increased. In this case, the strength can be further improved.
[0017]
In addition, as shown in FIG. 6, a bent steel material 32 having an H-shaped cross section can be used instead of the bent steel pipes 30 and 31. In this case, cylindrical inner tubes 21 and 21 are respectively provided between the upper and lower flange portions 32F and 32F and the web 32W of the bent steel material 32. At this time, a plurality of injection holes 21h are provided in advance along the side surfaces of the inner pipes 21 and 21, and after the bent steel material 32 is embedded, an injection device is inserted into the inner pipe 21, and the injection is performed. What is necessary is just to reinforce the natural ground 15 by injecting a ground solidifying agent into the natural ground 15 through the hole 21h.
The bent steel material 32 having an H-shaped cross section is not only high in strength but also more easily available than the thick cylindrical bent steel pipe 30 and the bent steel pipe 31 having a rectangular cross-sectional shape, and also reduces costs. It has the advantage of being possible.
[0018]
【The invention's effect】
As described above, with mounting the guide blades on the distal end side of the bending steel pipe is inserted into the natural ground, fitted with a jet water spray nozzle on the tip of the outer peripheral portion of the bent inner tube disposed on the inner side of the steel pipe, the While the jet water from the jet water jet nozzle is jetted from the opening of the guide blade into the natural ground to excavate the natural ground, the bent steel pipe is inserted into the natural ground. The above-mentioned natural ground can be improved by inserting and embedding a bent steel pipe in the natural ground around the tunnel efficiently. Moreover, since drilling only by jet water which does not require a rotating mechanism, it is possible to rather large degree of freedom of the shape of the drilling section, the bending cross section other than circular tube, such as horned tube and H steel pipe or Curved steel can be embedded. Moreover, since it is not necessary to install a drilling device etc. in a pipe | tube, it can discharge | emit efficiently and construction efficiency can be improved significantly.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a curved boring apparatus according to the present embodiment.
FIG. 3 is a cross-sectional view of a main part of a curved boring apparatus.
FIG. 4 is a diagram showing a natural ground excavation method according to the present embodiment.
FIG. 5 is a view showing a method of inserting a bent steel pipe having a rectangular cross-sectional shape.
FIG. 6 is a view showing a method of inserting a bent steel pipe having an H-shaped cross section.
FIG. 7 is a diagram showing an outline of a conventional curved boring apparatus.
FIG. 8 is a view showing a method for injecting a ground solidifying agent.
[Explanation of symbols]
10 central shaft, 11, 12 main shafts, 14 central shaft support, 15 ground, 20 curved boring device, 21 inner pipe, 21F flange, 21k projecting piece, 21B bolt, 22 guide blade, 23 jet nozzle, 24 Jackhammer,
25 guide cell, 26 swivel, 27 water pipe, 28 earth removal outlet,
30 bent steel pipe.

Claims (2)

A ground pipe which has a plurality of injection holes on the side surface and is embedded in the ground from the side wall of the advanced guide shaft, and the ground is reinforced by injecting a solidified material into the ground from the injection hole. In the mountain improving method, a cylindrical guide blade along the outer periphery of the bent tube is attached to the distal end portion of the bent tube, and the tip of the outer peripheral portion of the inner tube disposed in the bent tube and the guide blade Install a jet water spray nozzle inwardly from the inner space side of the guide blades by injecting jets water from the jet water injection nozzle into the land Yamauchi excavating the natural ground, the mud which has been excavated by the jet water A method for improving a natural ground, wherein the bent pipe is inserted into the natural ground while discharging through the inner pipe . 2. The ground improvement method according to claim 1, wherein the bent pipe is inserted while applying vibration to the guide blade.

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