JP3710991B2 - Ground reinforcement method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a natural ground reinforcement method suitable for use as a leading construction for reinforcing a natural ground in front of a face when a tunnel is constructed.
[0002]
[Prior art]
Conventionally, when excavating a tunnel in a natural ground with poor geological conditions, the tunnel is being dug while reinforcing the natural ground. Then, as a natural ground reinforcement method when excavating a tunnel while reinforcing the preceding natural ground, a long arch is formed from the face to the outer periphery of the tunnel prior to excavation to reinforce the natural ground ahead of the face. There is a long point receiving method, and this long point receiving method is an injection type receiving method using a steel pipe that can be easily constructed using standard drilling equipment such as a hydraulic drill jumbo used in the mountain tunnel method. is there.
[0003]
And as said injection-type tip receiving construction method, for example, a drilled steel pipe having a diameter of about 100 mm by a double pipe method is drilled by a diameter expanding bit attached to the tip of a drilling rod or a ring bit provided at the tip of a steel pipe. There is a method of reinforcing the natural ground by injecting a solidified material such as a chemical solution into the surrounding natural ground through a discharge hole in the peripheral wall of the steel pipe, and driving it at a predetermined elevation angle. The construction method can be used for various ground conditions and can receive a long tip, so it is widely used for the purpose of suppressing the preceding displacement of the ground, preventing loosening of the ground, and ensuring the safety of construction. Yes.
[0004]
FIG. 10 shows a state in which the above-described injection type pre-receiving method has been applied to the natural ground. In the tunnel space 21, a steel pipe 23 is driven into the natural ground 22 from the face 22a, and the steel pipe 23 thus placed is provided. A consolidated region 24 is formed around the periphery. In this construction method, the steel pipe 23 is filled with a space 25 between the steel pipe 23 and the hole wall of the natural ground 22 in which the steel pipe 23 is cast, so that the steel pipe 23 and the natural hole wall are in close contact with each other. By infiltrating the chemical solution injected into the natural ground 22 and increasing the bonding force between rock fragments or soil particles to form the consolidated region 24, an arch-shaped natural ground improvement body is formed in the natural ground in front of the face. .
[0005]
In placing the steel pipe 23 in the above method, a pilot hole having a diameter slightly larger than that of the steel pipe 23 is drilled about 300 mm on the outer periphery of the face, and the steel pipe 23 is cast for a predetermined length while adding the steel pipe 23 from the lower hole. Thereafter, a caulking material is filled in the lower hole, and a urethane-based or a cement-based chemical solution is injected into the steel pipe 23 to form a consolidated region 24 around the steel pipe 23.
[0006]
As an example of injecting a chemical solution, for example, there is a chemical solution injection method shown in FIG. In this example, an insert pipe 23a is installed in the steel pipe 23, three chemical liquid injection hoses 23b are inserted in the insert pipe 23a, and a static mixer 23c is provided at the tip of each chemical liquid injection hose 23b. The tip of each chemical solution injection hose 23b is arranged at a position separated by a predetermined distance in the insert tube 23a. Further, a mouth caulking 27a is provided between the end of the specular spray concrete 26 and the steel pipe 23, and a pipe caulking 27b is provided between the end of the steel pipe 23 and the chemical solution injection hose 23b. And a chemical | medical solution is inject | poured from the chemical | medical solution injection hose 23b, and a chemical | medical solution osmose | permeates in the surrounding natural ground 22 from the insert pipe | tube 23a and the steel pipe 23. FIG.
[0007]
[Problems to be solved by the invention]
However, in addition to the natural weakness of the natural ground that requires the above-mentioned local ground receiving method, the natural ground in the vicinity of the face that has been damaged by excavation is further loosened. After the injection is completed, a so-called leak may occur in which the chemical liquid overflows to the brittle face through cracks or voids, and the injection improvement effect may be impaired. For example, in FIG. 12A, the arrow indicates the traveling direction of the chemical solution, and the chemical solution injected from the tunnel space 21 into the steel pipe 23 penetrates into the natural ground 22 to form a consolidated region 24, but toward the face 22a side. When the leak occurs, the chemical solution does not partially rotate around the entire length of the steel pipe 23. As a result, there is a disadvantage that an appropriate ground improvement effect cannot be obtained.
[0008]
Further, in such a natural ground tip receiving method, for example, as shown in FIG. 12B, the steel pipe 23 is built later from the inside of the steel support 28a in the tunnel face 22a provided with the specular shot concrete 26. In order to place the steel pipe 23 at a minimum distance to the back of the steel support 28b in front of the cut face to be inserted, the steel pipe 23 is placed in the natural ground 22 with an elevation angle of about 4 to 5 degrees from the tunnel space 21. To do. In order to maintain this placement angle T, it is necessary to provide a section widening section S of about 6 m corresponding to the guide cell length of the drill jumbo. In this case, the secondary lining concrete placement space 29 increases. As a result, an extra material such as concrete for expanding the cross section of the tunnel is required, and the amount of work such as tunnel excavation increases.
[0009]
Although there is a natural ground tip receiving method that does not provide a cross-section widening section S, in this method, the pipe at the end of the steel pipe is made of a resin pipe such as a vinyl chloride pipe, and the resin pipe at the end of the pipe is built in front of the face. The steel support works in the overlap section are separated from the steel pipes that have already been placed in order to bury them in a natural ground in the range of about 3 steel support works and place them at an elevation angle of about 10 degrees. Depending on the natural ground condition, the natural ground under the steel pipe is loosened, which causes anxiety about the strength of the resin pipe at the end. Furthermore, if a leak to the face side such as the mouth portion described above occurs in this state, it is difficult to say that the natural ground improvement effect is sufficient.
[0010]
The present invention has been made in view of the above problems, and can prevent the occurrence of leaks in the ground receiving work for injecting the consolidated material, and it is not necessary to widen the cross section during tunnel excavation work. An object of the present invention is to provide a natural ground reinforcement method capable of obtaining a natural ground improvement effect.
[0011]
[Means for Solving the Problems]
The natural ground reinforcement method of the present invention comprises a plurality of pipes connected to each other by placing a plurality of pipes, each having a discharge hole formed in a peripheral wall, by sequentially connecting them to a natural ground at a predetermined elevation angle. In a natural ground reinforcement method in which a reinforcing pipe is formed and a consolidated material is injected through the reinforcing pipe to form a consolidated region in a front ground around the reinforcing pipe, at least a mouth pipe in the reinforcing pipe Is formed of a porous tube, and a bulkhead region is formed in the ground surrounding the porous tube with the consolidated material injected and leaked from a predetermined position in the porous tube, and then the consolidated region It is characterized by forming. It is possible to improve the natural ground by preventing the occurrence of leak from the back side of the hole where the reinforcement pipe is placed by the bulkhead region, and it is easy to cut the mouth pipe by adopting the porous pipe as the mouth pipe It is not necessary to widen the cross section when tunneling.
[0012]
Furthermore, the present invention provides the above-mentioned ground reinforcement method, wherein the aperture ratio of the hole formed in the porous tube is such that the porous tube can be cut with a blade of an excavating machine, and the porous tube has a required strength as a reinforcing tube. It is set to a predetermined value to be maintained. By setting the aperture ratio of the holes to a predetermined value, the porous tube can function as a reinforcing tube, and can be cut during excavation work, thereby improving the workability of tunnel excavation work. Furthermore, it is preferable that the aperture ratio of the hole be a predetermined value that allows the consolidated material to be quickly leaked from a tube other than the mouth tube.
[0013]
Further, in the above ground reinforcement method, the porous pipe is assumed to have rigidity and the required strength, and preferably the porous pipe is made of expanded metal or punched metal. By making the porous tube have a required strength such as an expanded metal or a punching metal, it is possible to maintain the strength required as a reinforcing tube while facilitating cutting, and to ensure sufficient stability of the natural ground.
[0014]
Further, the present invention provides the above ground reinforcement method, wherein the injection of the consolidated material is performed by an insert pipe provided in the reinforcement pipe, and the insert pipe can be excised and has a strength equivalent to that of the reinforcement pipe. It is characterized by becoming. By using the insert tube made of a material that can be excised and has a strength similar to that of the reinforcing tube, the strength of the porous tube can be supplemented while achieving the same effect as described above. Therefore, it is possible to freely increase the aperture ratio of the perforated tube or to construct the perforated tube with a material that can be easily cut.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the natural ground reinforcement method according to the present invention will be described based on specific embodiments shown in the drawings. 1 to 3 show an outline of the construction state in the natural ground reinforcement method of the present invention, FIG. 4 shows a reinforcing pipe used in the present invention, and FIGS. 5 to 9 show construction procedures of the natural ground reinforcement method of the present invention. It is a longitudinal cross-sectional view along line.
[0016]
As shown in FIG. 1 to FIG. 3, in the tunnel under construction using the present invention, spray concrete 2 is applied to the mirror face 1a of the ground 1, and the tunnel space 3 that has already been excavated and formed behind the face 1a. Is covered with shotcrete that is not shown in the figure so as to cover the side wall and the rock surface of the arch part, and the steel support 4 along the cross-sectional shape of the tunnel on the inner side, For example, it is built at predetermined intervals such as every 1 m.
[0017]
In the upper part of the periphery of the tunnel space 3, a receiving work 5 constructed prior to the excavation work is provided at predetermined intervals in the excavation direction, and is formed in an arch shape and disposed in the natural ground 1. The receiving work 5 includes a reinforcing pipe 6 that is a natural ground reinforcing material placed at a predetermined pitch along the transverse cross-sectional shape of the tunnel and at a predetermined interval in the digging direction, and a consolidation injected through the reinforcing pipe 6. It consists of a bulkhead region 7 and a consolidated region 8 of the natural ground 1 consolidated by a material. Further, a leading work 5 under construction is provided in an arch shape from the outer periphery of the face 1a toward the natural ground 1 ahead.
[0018]
As shown in FIG. 4, the reinforcing pipe 6 of the receiving work 5 is connected to a plurality of steel pipes 62 connected by a coupler 61 and a steel pipe 62 closest to the mouth portion at the rearmost end of the connected steel pipes 62. It consists of a mouth tube 63. The steel pipe 62 is provided with a plurality of small holes 62a, which are discharge holes, on its peripheral wall, and a thread groove 62b is formed at the end thereof. In this embodiment, four steel pipes 62 having a diameter of 100 mm and a length of 3 m are formed. Are used by being screwed into the coupler 61. The mouth tube 63 has a large number of holes 63a, and is a porous tube made of the expanded metal of FIG. 4 (a), the punching metal of FIG. 4 (b), and the like. Has a shape that can be connected to the steel pipe 62 via the coupler 61 or the like. In this embodiment, a mouth pipe 63 having a length of 3 m is used. As the perforated pipe of the mouth pipe 63, a perforated pipe having an optimum opening ratio is selected according to the geological situation and the optimum length is selected from about 1 to 5 m depending on the geological situation. . The material of the tube forming the reinforcing tube 6 is metal in this embodiment, but other materials may be used as long as they have the required strength.
[0019]
In addition, when the binder is injected, if the insert tube provided in the reinforcing tube 6 as a chemical injection hose is GFRP or the like that can be excised and has the strength equivalent to that of the reinforcing tube 6, the strength is compensated accordingly. It is also possible to use a porous tube having no required strength, such as a resin lattice molded product, for the tube 63.
[0020]
As shown in FIGS. 1 to 3, in the receiving work 5, the bulkhead region 7 and the consolidated region 8 are formed in the natural ground 1 around the reinforcing pipe 6. 8 is formed by a consolidated material injected into the surrounding natural ground 1 through the reinforcing pipe 6. The caking agent in this embodiment is a urethane type chemical solution such as urethane, silica resin, inorganic composite urethane, etc., which has a relatively short curing time, but it is also possible to use a cement type chemical solution as the caking agent. .
[0021]
1 to 3, 9 is a drill jumbo, 1 b is a planned drilling area, and L is a length to be cut together with the mouth tube 63 in the bulkhead area 7.
[0022]
Next, the construction procedure of the receiving work 5 will be described with reference to FIGS. 5 to 9, the shotcrete 2 and the like are omitted.
[0023]
At the time of construction of the front receiving work 5, first, as shown in FIG. 5, a diameter of 160 mm and a depth of 160 mm from the predetermined position at the lower end of the steel support 4 built just before the face 1a toward the front natural ground 1 A pilot hole 10 having a length of about 300 mm is drilled, and a steel pipe 62 constituting the reinforcing pipe 6 is attached to a guide cell 9 a of a drill jumbo (rock drill) 9.
[0024]
The ring bit 11 is attached to the tip of the steel pipe 62, and the drilling jumbo 9 is hit from the drill bit 12 passing through the steel pipe 62 through the ring bit 11 and the tip bit 13 attached to the tip of the drill rod 12. Drilling holes by transmitting force and rotational force. According to the method of drilling using the ring bit 11 attached to the tip of the steel pipe 62 as described above, the drilling and driving are performed in such a manner that the ring bit pulls the entire steel pipe 62. Construction can be performed without striking the mouth pipe 63 connected to the rear end portion of the steel pipe 62, and even if the mouth pipe 63 is long, the mouth pipe 63 bears a burden due to the impact of the placement. You do n’t have to.
[0025]
It is also possible to adopt a drilling method other than the above, and a diameter expansion bit (not shown) is attached to the tip of the hole drilling rod 12 passed through the steel pipe 62, and this diameter expansion bit is attached to the tip of the steel pipe 62. It is good also as a system etc. which drive the steel pipe 62, making it drill, drilling by transmitting the striking force and rotational force of the drill jumbo 9 connected to the drilling rod 12 to the diameter expansion bit.
[0026]
At the time of drilling and placing, the guide cell 9a is set at a predetermined elevation angle of 3 to 6 degrees, preferably about 5 degrees, and the ring bit 11 is directed from the lower hole 10 toward the natural ground 1 located in front of the face 1a. The steel pipe 62 is driven while drilling. When a predetermined number of steel pipes 62, four in this embodiment, are connected while being connected by the coupler 61, the mouth pipe 63 is connected to the rearmost end for further driving. As shown in FIG. The steel pipe 62 and the mouth pipe 63 are placed in the front ground 1 of the face 1a as a reinforcing pipe 6 having a predetermined length. After the reinforcement pipe 6 is placed by the placement, the caulking material 14 such as a caulking capsule and waste cloth is filled in the portion of the lower hole 10 to perform caulking.
[0027]
In this state, for example, a chemical solution injection hose (insert tube) is set in the reinforcing tube 6 in the manner shown in FIG. 11, and the chemical solution is consolidated from the chemical solution injection hose having a discharge port at a predetermined position in the mouth tube 63. When the material is injected, as shown in FIG. 7, in the portion of the mouth tube 63 made of a porous tube at the start of pouring, the consolidated material quickly leaks from the numerous holes 63a of the mouth tube 63, and the leaked consolidation The material penetrates and solidifies in the natural ground 1 around the mouth tube 63. That is, by using a porous tube for the mouth tube 63, the consolidated material is actively leaked to the periphery of the mouth tube 63 in the initial stage of injection, and the bulkhead region 7 is formed in a limited region around the mouth tube 63. .
[0028]
Thereafter, as shown in FIG. 8, when the caking material is injected into the back side of the hole that has been laid, it gradually solidifies at a relatively moderate speed from the small hole 62 a on the peripheral wall of the steel pipe 62 constituting the reinforcing pipe 6. The binding material leaks, and the leaked consolidation material consolidates the surrounding natural ground 1 to form a consolidated region 8. At this time, even if cracks or voids are formed in the surrounding natural ground 1 by first forming the bulkhead region 7 in the mouth portion where the natural ground 1 is roughened by drilling. Further, it is possible to prevent the chemical liquid as the consolidated material from overflowing to the brittle face 1a side through these cracks and voids, and to obtain an appropriate ground improvement effect over the entire length of the reinforced reinforcement tube 6. .
[0029]
The front receiving work 5 is applied in an arch shape along the outer periphery of the face 1a in the tunnel. When the arch-shaped tip receiving work 5 is constructed on the outer periphery of the face 1a, the stability of the natural ground 1 scheduled to be excavated located below is secured. Then, the tunnel is further excavated to advance the face 1a, and the tunnel excavation work is proceeded while the supporting work 4 is built in order as the face 1a advances.
[0030]
When the excavation work is performed, the natural ground 1 where the mouth portion of the prior receiving work 5 placed immediately before is also excavated. At this time, as shown in FIG. The mouth tube 63 is excised. Since the mouth pipe 63 is a porous pipe such as an expanded metal or a punching metal, it can be easily cut with a blade of an excavating machine. In addition, since the mouth tube 63 is limited to a predetermined length, it can be easily detached from the coupler 61 connecting the mouth tube 63.
[0031]
In the tunnel excavation work in which a receiving work is performed, the support pipe 4 can be built in the same cross section without performing the cross section widening, while the mouth pipe 63 made of a porous pipe Although it is easy to cut, it is made of a material having a predetermined strength such as the rigidity of the steel material, and the strength against the axial force as the reinforcing tube 6 is sufficiently secured. Furthermore, since the penetration of the consolidated material into the surrounding natural ground 1 is reliably achieved, the stability of the natural ground 1 is sufficiently ensured and the excavation work can be performed safely.
[0032]
Note that the screw-in type coupler 61 shown in FIG. 4 is used for the connection of the reinforcing pipe 6 in the present embodiment, but it is not a type of screwing outside the reinforcing pipe 61 as in the illustrated example, but a coupler in which a male screw is formed. May be connected by being screwed into the inside of the reinforcing pipe formed with the female thread. Furthermore, other connection methods are possible, for example, the connection between the steel tube 62 and the mouth tube 63 constituting the reinforcing tube 6 is not a screw method in order to facilitate removal after the mouth tube 63. The coupler 61 that can be easily removed may be used by means such as a plug-in type. That is, when placing the rearmost end portion of the reinforcing pipe 6 on the ground 1, the burden on the coupler 61 is light and the strength of the coupler 61 does not have to be removed by the placement. Also, the couplers in other parts can be made into couplers that are not screw type.
[0033]
【The invention's effect】
Natural ground reinforcing construction method of the present invention is a mouth Motokan the perforated pipe within the stiffening tube, bulkhead around the natural ground of the perforated tube in consolidation material injected to leak caking material from a predetermined position of the porous tube Since the area is formed and then the consolidation area of the front ground is formed, it is possible to prevent the occurrence of leaks at the ground receiving work where the solidified material such as chemical solution is injected, and the reinforcement pipe ( The solidified material reliably rotates over the entire length of the material, and as a result, a high injection effect can be obtained. Furthermore, it is not necessary to widen the cross section during tunnel excavation work, and the amount and cost of tunnel excavation work can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a tunnel showing a construction state of a natural ground reinforcement method according to the present invention.
FIG. 2 is a cross-sectional view of a tunnel showing a construction state of the natural ground reinforcement method of the present invention.
FIG. 3 is an enlarged cross-sectional view showing a face portion in a state where a tip receiving work is applied from the face of FIG. 1;
FIG. 4A is a front view showing a state in which the mouth pipe of the first embodiment is connected to a steel pipe.
(B) The front view which shows the state which connects the mouth pipe | tube of a 2nd Example to a steel pipe.
(C) The front view which shows the state which connects steel pipes.
FIG. 5 is a longitudinal sectional view showing a state where a reinforcement pipe is driven by the natural ground reinforcement method of the present invention.
FIG. 6 is a longitudinal sectional view showing a state in which caulking is applied to the mouth pipe by the natural ground reinforcement method of the present invention.
FIG. 7 is a longitudinal sectional view showing a state in which a bulkhead region is formed by the natural ground reinforcement method of the present invention.
FIG. 8 is a longitudinal sectional view showing a state where a consolidated region is formed by the natural ground reinforcement method of the present invention.
FIG. 9 is a longitudinal sectional view showing a state in which a mouth tube is excised by the natural ground reinforcement method of the present invention.
FIG. 10A is a longitudinal sectional view of a tunnel showing a construction state of a conventional natural ground reinforcement method.
(B) The cross-sectional view of the tunnel which shows the construction state of the conventional natural ground reinforcement construction method.
(C) The cross-sectional view which shows the steel pipe cast in the natural ground.
FIG. 11 is a longitudinal sectional view showing a state in which a chemical solution is injected by a conventional ground reinforcement method.
FIG. 12A is a longitudinal sectional view of a tunnel showing a leaking state by a conventional ground reinforcement method.
(B) The longitudinal cross-sectional view of the tunnel which shows the construction state expanded by the conventional natural ground reinforcement construction method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ground 1a Face 3 Tunnel space 4 Supporting work 5 Prior receiving work 6 Reinforcement pipe 61 Coupler 62 Steel pipe 62a Small hole 63 Mouth pipe 63a Hole 7 Bulkhead area 8 Consolidation area 10 Pilot hole 14 Caulking material

Claims (3)

A plurality of pipes having discharge holes formed in the peripheral wall are sequentially connected to a natural mountain at a predetermined elevation angle to form a reinforcing pipe composed of the connected plurality of pipes. In the ground reinforcement method for injecting the caking material through and forming a consolidation area in the front ground around the reinforcing pipe,
The mouth tube in the reinforcing tube is a porous tube made of a material having the required strength to perform the reinforcing function,
The opening rate of the discharge hole of the perforated pipe is set to a predetermined value that can be cut with a blade of an excavating machine, can maintain the required strength as a reinforcing pipe, and can quickly leak the consolidated material from pipes other than the mouth pipe Has been
A bulkhead region is formed in a ground around the perforated pipe with the caking material injected and leaked from a predetermined position in the perforated pipe, and then a consolidated area is formed around the reinforcing pipe. A natural ground reinforcement method characterized by this. 2. The natural ground reinforcement method according to claim 1, wherein the porous pipe is an expanded metal or a punching metal. The injection of the consolidated material is performed by an insert pipe provided in the reinforcing pipe, and the insert pipe is made of a material that can be excised and has a strength equivalent to that of the reinforcing pipe. Natural mountain reinforcement method.

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