JPH0288899A - Consolidation process of viscous soil layer - Google Patents

Abstract

PURPOSE:To enable execution in a viscous soil layer by a method wherein a guiding hole is formed around a main hole shaped to the viscous soil layer, chemicals for consolidation are forced into a packer inserted into the main hole and discharged into the main hole and the chemicals permeate into the induction hole from the main hole. CONSTITUTION:A plurality of upward main holes are formed to a roof section 5 composed of a viscous soil layer at the nose of a tunnel facing, and a plurality of guiding holes 7 are shaped around the main holes 6. Cloth impregnated with a urethane resin liquid is stuffed into the openings of the induction holes 7, and the opening sides of the guiding holes 7 are blocked. Cloth is wound on the rear end sides of the packers 1, a hose 10 for a urethane-resin liquid press-in pump is connected at the rear end section of the cloth, and the packers 1 are inserted into the main holes 6 under the state in which the cloth is impregnated with the resin liquid. When the resin liquid is forced into the packers 1 through the hose 10, the resin liquid permeates toward the guiding holes 7 from the main holes 6 and cured, thus shaping a consolidated region A.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for consolidating a clayey soil layer, which improves a soft clayey soil layer into a firm clayey soil layer by using a chemical solution for clayey soil consolidation. .

[Conventional technology]

Conventionally, in geological zones such as soft rock (other mountains) or crushed ground, in order to prevent the top of the tunnel face from collapsing, a ceiling plate is installed at the top of the tunnel face. The first construction method is used, which involves drilling holes along the arch, inserting rock bolts into the holes, and solidifying them with mortar. In addition, methods such as the pipe roof construction method and the chemical injection method are also being used to strengthen the ground. However, this conventional method causes major damage to equipment, takes time and effort to install machines and prepare for injection, and -
Furthermore, there was a problem in that the work at the site had to be stopped for a considerable period of time to carry out these works.

[Problem that the invention seeks to solve]

Therefore, in order to solve this problem, the present inventors used rock drilling equipment such as a rock drill to drill multiple holes along the arch of the ceiling at the tip of the tunnel face. We have already proposed a technology in which packers made of hollow pipes are inserted into these holes, and urethane resin liquid is injected into the packers and then discharged from the tip of the packer to the outside and penetrated into the rock (patent application). (Sho 58-144024). In this case, in order to prevent the chemical solution from leaking from the hole and to fix the packer in the hole, a cloth or the like is wrapped around the base of the packer, and this is impregnated with urethane resin liquid, etc., and when the packer is inserted, the cloth is A method of foaming a urethane resin impregnated with a hole, etc., to prevent a gap between the wall of the hole and the outer periphery of the packer, and at the same time to fix the packer to the wall of the hole.

However, the above method is aimed at other mountains with high permeability such as fault-fractured areas, talus, or sandy soil, and if it is carried out on clayey soil layers with low permeability, the urethane discharged from the packer will The problem arises that the resin intensively penetrates into the low-density parts of the cohesive soil layer that have relatively many voids, making it impossible to consolidate the entire cohesive soil layer. Therefore, it has been difficult to carry out the above construction method on clayey soil layers with low water permeability.

The present invention was made in view of these circumstances, and its purpose is to provide a consolidation method that can be applied even to clayey soil layers with low water permeability.

[Means for Solving the Problems] In order to achieve the above object, the method for consolidating a clayey soil layer of the present invention involves drilling a main hole in the clayey soil layer and forming guide holes around the main hole. A hollow vibrator-shaped packer with a discharge hole formed on the tip side is inserted into the main hole, and a chemical solution for cohesive soil consolidation is press-fitted into the packer, and the liquid is forced into the main hole through the discharge hole. The discharged chemical solution permeates the outer periphery of the main hole and reaches the guide hole, and further permeates the outer periphery of the guide hole and hardens, thereby leaving the packer in the main hole while The structure is such that the clay layer around the main hole and guide hole is consolidated.

(Operation) In other words, the method of the present invention does not allow the urethane resin discharged from the packer into the hole to penetrate into the rock only by its discharge pressure, as in the conventional example, but instead of infiltrating the urethane resin into the rock mass only by the discharge pressure. A guide hole is drilled in the hole so that the chemical solution for cohesive soil consolidation can easily penetrate from the main hole toward the guide hole.Therefore, the chemical solution for cohesive soil consolidation is discharged from the packer into the main hole. Then, at the initial stage, the chemical solution permeates through the clayey soil layer in a vein pattern due to its discharge pressure and reaches the guide hole, but once this permeation path is formed, the amount of permeation increases rapidly and further. A new permeation path branches out from this permeation path, so that the chemical liquid permeates around the main hole, between the main hole and the guide hole, and around the guide hole, and hardens. As a result, even if the clay layer is a layer of clay that is difficult to penetrate with the chemical solution for cohesive soil consolidation, the above-mentioned area can be consolidated in a substantially uniform state.

Next, the present invention will be explained in detail based on examples.

〔Example〕

FIG. 1 shows a packer used in one embodiment of the invention. That is, this packer 1 has an open rear end,
It is formed in the shape of a hollow pipe with a sharp tip, and has an outer diameter of 27 mm, an inner diameter of 14 mm, and a total length of approximately 3 m. and,
A plurality of discharge holes 2 are bored at predetermined intervals on the circumferential surface of the distal end side. Further, the packer 1 is divided into two parts, a front side and a rear side, with a substantially central portion as a boundary, and these parts are joined by a threaded joint (not shown). A step is provided on the inner circumferential side of the joint part on the front side, and a stationary mixer 3 shown in FIGS. The base ring 4 is inserted with the ring facing toward the distal end thereof, and is fixed by engaging the base ring 4 with the stepped portion. The stationary mixer 3 has V-shaped double blades 13b tilted at regular intervals on the left half of the center about a linear central axis 3a extending forward (in the direction of arrow X) from the center of the root side ring portion 4. On the right half, single-ply blades 3c are tilted at regular intervals, and the urethane resin liquids A and B press-fitted into the backer 1 are received on the left and right halves, respectively, and both liquids are directed in the same direction. (It is designed to be transferred while turning in the direction of arrow AB force. In this case, a single blade 3c is provided on the right half, a V-shaped double blade 3b is provided on the left half, and the urethane resin liquid is transferred to the right half. When you turn around to the left half, you will see a V-shaped double wing m3 with a wide entrance side and a narrow exit side.
The flow velocity is increased by the action of b, and returns to the initial velocity when returning from the left half to the right half. That is, liquids A and B are mixed while rotating in the same direction due to the difference in flow velocity between the left half and the right half, and are mixed and sent forward while maintaining the initial flow velocity at the time of injection. Therefore, when press-fitting a urethane resin liquid that hardens extremely quickly, the urethane resin liquid can be mixed and transferred without being hardened midway, and can be smoothly discharged from the tip. Further, a threaded portion is formed at the rear end of the packer 1 for engaging a joint with a check valve (not shown). .

This invention uses the packer 1 described above to consolidate a clayey soil layer. That is, in the configuration, first, as shown in FIGS. 3 and 4, using a rock drill or the like, an upward (
Holes 6 are drilled at predetermined intervals (only one is shown in the figure) at an angle θ = 10 to 2°), and four guide holes 7 are formed around the holes 6. The holes are kept at intervals of 1 to 3 times the diameter of the holes, and at a constant distance from each other. Next, a cloth 8a (see FIG. 5) impregnated with urethane resin liquid is stuffed into the opening of the guide hole 7 to close the opening side of the guide hole 7, and a cloth 8b is wrapped around the rear end of the packer 1. A hose (not shown) of a urethane resin liquid injection pump is connected to the rear end. Next, the cloth 8b
The packer 1 is impregnated with urethane resin liquid, and the packer 1 in this state is inserted into the hole 6 provided in the top plate 5. At the same time, the urethane resin liquid is pressurized into the packer 1 from a press-in pump via a hose. As a result, as shown in FIG. 5, the urethane resin liquid is discharged from the discharge hole 2 of the packer 1 into the hole 6, filling the hole 6, and then forming veins toward the guide hole 7. After it permeates through the ceiling portion 5 and fills the guide hole 7, it further permeates from the guide hole 7 toward its surroundings and hardens there. In FIG. 5, the area indicated by the chain line is the solidified area of the urethane resin. As a result, the packer 1 is fixed in the hole 6, and the portion indicated by the chain line A is firmly fixed by the urethane resin. At this time, the openings of the holes 6 and the guide holes 7 are closed by the cloths 8b and 8a, respectively, so that the urethane resin liquid is prevented from leaking from the openings of the holes 6 and the guide holes 7. In this way, the solidified area A of the urethane resin is
By forming the packer 1 continuously on the ceiling of the top plate 5 as shown in the figure or continuously along the arch of the top plate 5 as shown in FIG. will be reinforced. In FIG. 6, 9 is a unit for joining the chemical solution to the packer 1, 10 is its hose, and 11 is a support.

As described above, in the method for consolidating a cohesive soil layer of the present invention, when the urethane resin liquid is discharged from the packer 1 into the hole 6, the urethane resin liquid forcibly penetrates toward the guide hole 7 due to the discharge pressure. A permeation region is formed between the hole 6 and the guide hole 7 and around the guide hole 7, and then hardened. As a result, even a clayey soil layer with low water permeability can be sufficiently penetrated and consolidated in a substantially uniform -Φ state. Therefore, it becomes possible to use the Bakker method even for clayey soil layers, which were previously considered impossible.

〔Effect of the invention〕

As described above, the method for consolidating a cohesive soil layer of the present invention involves drilling a guide hole around the main hole and discharging a chemical solution for cohesive soil consolidation into the main hole using a packer. The solidifying chemical solution is forced to penetrate toward the guide hole and further penetrate the outer periphery of the guide hole. Therefore, the chemical solution for cohesive soil consolidation does not permeate only a part of the cohesive soil layer, and the cohesive soil layer can be consolidated in a substantially uniform state. As a result, it can be applied even to clayey soil layers with low water permeability, making the effective range extremely wide.

[Brief explanation of drawings]

Figure 1 is a front view of the packer used in this invention, Figure 2 (
a) is a perspective view of a stationary mixer disposed within the packer;
FIG. 2(b) is a side view of the same, FIG. 3 is a joint cross-sectional view of the top plate section where holes and guide holes are provided, FIG. 4 is a front view thereof, and FIG. 5 is an explanatory diagram of how to use the packer. FIG. 6 is a longitudinal cross-sectional view showing the construction state, and FIG. 7 is a cross-sectional view thereof. 1...Backer 2...Discharge hole 5...Top plate part
6... Hole 7... Induction hole patent applicant Tokai Rubber Industries Co., Ltd. Representative Patent attorney Yukihiko Nishi (a) Mo (b)

Claims (1)

[Claims] (1) A main hole is drilled in the clayey soil layer, a guide hole is drilled around the main hole, and a hollow pipe-shaped packer with a discharge hole formed at the tip is inserted into the main hole. A chemical solution for cohesive soil consolidation is pressurized into the packer and discharged from the discharge hole into the main hole, and this discharged chemical solution permeates the outer periphery of the main hole and reaches the guide hole. A method for consolidating a cohesive soil layer, characterized by solidifying the cohesive soil layer around the main hole and the guide hole while leaving the packer in the main hole by infiltrating and hardening the outer periphery of the guide hole. .