JPH10102477A - Method for improving confined ground right under existing structure and water sealing device for use in the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently improving the ground on a foundation slab concrete by sealing underground water right under the foundation slab concrete to prevent the water from being discharged. SOLUTION: A lower water seal member S, which can be closed by sliding and moving a shutter plate 2 supported by a support plate 1, is set on a toundation 12 of an existing structure on the ground 14, in which underground water is confined. And an upper water seal member P, in which a plurality of water seal rubber packings 3 having therein an insertion hole 4 having a smaller diameter than the diameter (w) of an excavation pipe 1 are stacked through washers 5 in a case 6, is set on the member S. And the pipe 7 is inserted into the hole 4 and in the watertight conditions sealed with the packings 3, a through hole 15 is formed in the foundation 12 by means of the pipe 7 and after excavating the ground 14, injection agent is injected into the hole 15 to improve the ground as far as the foundation 12. The pipe 7 is lifted and the plate 2 is moved by sliding it to close the through hole 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for removing a pressurized ground immediately below a foundation slab of an existing structure on a ground being pressurized by groundwater (hereinafter, sometimes referred to as a pressurized ground). The present invention relates to a method of improving soil by a ground improvement consolidation method without discharging the same, and a water stop device used on a foundation slab concrete to suppress the spouting of groundwater or the like.

[0002]

2. Description of the Related Art Conventionally, when an existing structure inclined by liquefaction or the like is jacked up and restored, a ground improvement body which becomes a reaction force immediately below a foundation slab is constructed by a ground improvement consolidation method,
After jacking up, it is common to inject an injection material under the foundation slab. Also, when liquefaction of the supporting ground of the existing structure is expected, the ground may be similarly improved to reinforce the ground immediately below the foundation slab. However, as shown in FIG. 8, the ground g under the foundation slab b
When the ground is caught by the groundwater c and the ground improvement is performed by directly penetrating the foundation slab b with the drilling pipe d or the like, the groundwater c and the earth and sand e erupt from around the drilling pipe d. Therefore, the injected material of the improved body f during the ground improvement flows out or is diluted, the quality of the improved body f cannot be secured, and the ground improvement work is stagnated.

[0003] In such a case, with the existing technology, the following method is conceivable in which the underground water level is lowered by using a deep well h or the like as shown in FIG.
That is, a water-stopping retaining wall i is constructed on the outer periphery of the building a,
After the water level of the groundwater c is lowered, the outer periphery of the building a is excavated from the ground to just below the foundation slab concrete b, and the ground improvement is performed on the excavated bottom surface (FIG. 9).
In this method, after the groundwater level is lowered, the foundation slab concrete of the building is penetrated, and the ground is improved (not shown).

In recent years, the following method shown in FIG. 10 (see Japanese Patent Application Laid-Open No. 5-112927) has also been developed. An injection pipe is inserted into the improved ground to jet a jet jet (see FIG. 10C), and the discharge pressure of the sludge rising from the periphery of the injection pipe j is determined to be appropriate using the pressure adjusting device x, whereby the amount of the sludge is discharged. This is a method of improving the ground while controlling the
Injection pipe j and drilling pipe d for accommodating and drilling injection pipe j
The mouth packer device k has two upper and lower stages at the upper end, a packer ring q for a drilling pipe and a packer ring r for an injection pipe.
The lower end is formed with a fitting portion n to be fitted into a construction base (concrete) m constructed in the shaft, an opening / closing valve y is interposed in the middle portion, and from below the opening / closing valve y in the middle portion,
The drainage pipe z is branched via the pressure adjusting device x and the opening / closing valve y ′ to discharge groundwater and earth and sand.

[0005]

The above-mentioned ground improvement method requires a space on the outer periphery of the building a where the retaining wall i can be constructed and a waterproof layer v necessary for stopping water. The impossible is often the case. In addition, since work is not performed on the foundation slab concrete b of the building a, there is a problem that work efficiency is extremely poor.

[0006] Since the above method is carried out without constructing the retaining wall, there is a possibility that the surrounding ground will sink. In addition, if the amount of groundwater discharged is large, ground improvement becomes impossible.
The method of the above is, when drilling the excavation pipe d and the injection pipe j, installing the injection pipe j, or pulling out the excavation pipe d, etc. e is allowed to be discharged. Therefore, the opening and closing valves y and y 'must be operated to control the discharge of groundwater and the like while adjusting the drainage pressure with the pressure adjusting device x, or the packer ring q for the excavation pipe and the packer ring r for the injection pipe must be operated alternately. And that work is very troublesome and troublesome. Moreover, the packer device k is complicated, and the equipment cost increases. Furthermore, in this case, usually, a construction base m is provided in advance at a predetermined depth position in the shaft, and the construction base m
There is also a problem that the work efficiency is poor because the mouth packer device k is installed and constructed on top of the work.

[0007] An object of the present invention is to solve the above-mentioned problems by improving the ground under the foundation slab concrete of an existing structure which is under pressure with groundwater by the ground improvement consolidation method. It is an object of the present invention to provide a method for efficiently and rationally improving the ground on a foundation slab concrete of a structure without completely stopping and discharging water, and a water stopping device suitable for implementing the method.

[0008]

Means for Solving the Problems As means for solving the above-mentioned problems of the prior art, the method of improving the ground under pressure immediately below an existing structure according to the first aspect of the present invention includes the following steps. The lower water stopping member S, which is configured so that the shutter plate 2 slides and slides to close the through hole 15, is installed on the foundation slab concrete 12 of the existing structure on the ground 14 that is under pressure with the groundwater 13. And b) the pipe diameter w of the drilling pipe 7 having a bit at the tip
A water-stopping rubber packing 3 having an insertion hole 4 with a slightly smaller diameter t formed substantially at the center thereof is housed in a case 6 in a stacked state via a washer 5 in a plurality of upper water-stopping members P. C) inserting the drilling pipe 7 into the insertion hole 4 of the upper water-stopping member P from above, and maintaining the watertight state by the water-stopping rubber packing 3 with the drilling pipe 7 A step of forming a through hole 15 having a required minimum diameter in the foundation slab concrete 12, drilling the ground 14 to a desired depth, injecting an injection material, and performing ground improvement from the depth position to the level position of the foundation slab concrete 12. D) After the ground improvement is completed, the excavation pipe 7 is raised at least above the shutter plate 2 of the lower water stopping member S, and the shutter plate 2 is slid to move the through hole 1. 5), and e) removing the upper water stopping member P and injecting the injection material 9 from the injection port 8 provided in the shutter plate 2.

According to a second aspect of the present invention, there is provided a method of improving a ground under pressure immediately below an existing structure, wherein the reinforcing material is placed on the lower water stopping member S after the injection of the injection material 9 in the step e) of the first aspect. It is characterized in that the holding concrete 16 is cast. The water stopping device used in the method for improving the ground under pressure according to the invention of claim 3 is a lower water stopping member S installed on a foundation slab concrete 12 of a structure such as a building 11 being pressed by groundwater 13. And an upper water-stopping member P detachably mounted on the lower water-stopper S. The lower water-stopper S penetrates through the horizontal movement of the shutter plate 2 supported by the support plate 1. The upper water-stopping member P is configured such that the insertion hole 4 having a diameter t slightly smaller than the pipe diameter w of the excavation pipe 7 is formed substantially at the center of the water-stopping rubber member 3. A plurality of the water-stopping rubber packings 3 are housed in the case 6 in a stacked state with the
It is characterized in that it is configured to stop water in close contact with the excavation pipe 7 inside.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The method for improving the ground under pressure immediately below an existing structure according to the present invention is a method for improving the ground under the foundation slab concrete of a building 11 or the like which is under pressure with groundwater. In the improvement by the method, it is carried out by using a water stop device used on the foundation slab concrete while suppressing spouting of groundwater or the like.

[0011] As described in claim 2, the water stop device is as follows.
The lower water stop member S and the upper water stop member P which is detachable on the lower water stop member S are configured. The lower water stopping member S has a configuration in which the shutter plate 2 supported by the support plate 1 slides in the horizontal direction so that a through hole 15 described later can be closed (see FIG. 2A). As shown in FIG. 3B, the support plate 1 generally has an upper plate 1c having a square shape in plan view and having a pipe hole 10c at the center, and a lower plate having the same shape and size as the upper plate 1c and having a pipe hole 10a. 1a (see FIG. 2A), two rail plates 1b and 1b are sandwiched. And the pipe hole 2a
Is disposed between the rail plates 1b and 1b so as to be slidable in the horizontal direction. Each plate 1
c, the diameter u of the pipe holes 10c, 10a, 2a of 1a, 2
(See FIG. 3D) is a pipe diameter w of the excavation pipe 7 (FIG. 3A).
Reference). Oil such as grease is applied to the shutter plate 2 as necessary to enhance the water stopping performance and lubricity, such as the magnitude of the pressure.

As shown in FIG. 2B, the upper water stopping member P has a plurality of insertion holes 4 having a diameter t slightly smaller than the pipe diameter w of the excavation pipe 7 (see FIG. 3A) formed substantially at the center. The waterproof rubber packings 3 are housed in the case 6 in a stacked state with a washer 5 interposed between the vertically overlapping ones. Hereinafter, based on FIG. 2 to FIG. 5, a construction procedure of a method (claim 1) for improving the pressurized ground immediately below an existing structure using the water stopping device will be described.

FIG. 2 shows a stage of installing the water stopping device on the foundation slab concrete. First, as shown in FIG. 2A, the lower water stopping member S of the water stopping device is placed on the foundation slab concrete 12 immediately below the existing pressurized ground 14 immediately below the existing building (see FIG. 1). . At this time, it is desirable that water be stopped between the lower plate 1a of the support plate 1 and the foundation slab concrete 12 with a sealing material. Then, the lower water stopping member S is fixed on the base slab concrete 12 by using the chemical anchor 20 which is connected to the base slab concrete 12 from above the upper plate 1c of the support plate 1. Next, as shown in FIG. 2B, the upper water stopping member P of the water stopping device is installed on the lower water stopping member S.

FIG. 3 shows a construction stage of insertion of a drilling pipe and ground improvement. First, the shutter plate 2 is slid so that the pipe hole 2a of the shutter plate 2 is located at the descent position of the excavation pipe 7 (FIG. 3).
B). A drill bit (not shown) is attached to the lower end of the drill pipe 7. The excavation pipe 7 is lowered from above and inserted into the insertion hole 4 of the upper water stopping member P (FIG. 3A). Then, the drill pipe 7
Is tightly adhered to by a plurality of waterproof rubber packings 3 forming an insertion hole 4 having a diameter t smaller than the pipe diameter w, and a watertight state (waterproof state) is maintained. While maintaining the watertight state, the excavation pipe 7 descends and passes through the pipe holes 1c and 1a of the lower water stopping member S, penetrates the foundation slab concrete 12 with the excavation bit at the lower end by coring, and has a required minimum diameter. Is formed, and the ground 14 is further drilled to the planned depth for improvement. Then, by a so-called ground improvement consolidation method, an injection pipe (not shown) is inserted into the drilling pipe 7, and the injection pipe is slightly protruded from the tip while pulling up the drilling pipe 7 from the depth position to be improved. The injection material 9 is injected, and the foundation slab concrete 12 is injected.
The ground 14 under the pressurized water up to the level position is improved (FIG. 1). More precisely, as shown in FIG. 3C, the inside of the through hole 15 of the foundation slab concrete 12 is also positively improved. In the unlikely event that the groundwater 13 or earth and sand rises when the excavated pipe 7 penetrates the foundation slab concrete 12 or drills the ground 14, even if the groundwater 13 or the earth and sand rises, the required minimum diameter of the through hole 15 is reduced. And the drilling pipe 7 located in the through hole 15 has almost no gap, so that the rise of the groundwater 13 and the like can be stopped. Even if the gap is raised, the water is stopped by hitting the plurality of waterproof rubber packings 3 and does not blow out onto the foundation slab concrete 12. After the ground improvement is completed,
C, the excavation pipe 7 is pulled out of the foundation slab concrete 12 and, when it is pulled out above the shutter plate 2 of the lower water stopping member S, the shutter plate 2 is immediately slid and moved to the through hole 15.
Completely occlude the top.

FIG. 4 shows the stage of removing the upper water stopping member and injecting the injection material. That is, the basic slab concrete 1 is formed by the shutter plate 2 of the lower water stopping member S.
Since the through hole 15 formed in 2 is closed, the upper water stopping member P becomes unnecessary and is removed. After the improved ground 14 is hardened and contracted by breathing or the like, an injection material 9 ′ is injected using the injection port 8 of the shutter plate 2,
The gap created between the upper surface of the improved ground 14 and the shutter plate 2 is filled.

Further, as described in claim 2, reinforcement finishing by casting concrete is performed as necessary. That is, as shown in FIG. 5, the reinforced concrete 16 is constructed on the foundation slab concrete 12 so as to completely cover the lower water stopping member S. Above the through hole 15, the upper water blocking member P is removed and there is nothing, so that the reinforced concrete 1 having substantially the same thickness as the foundation slab concrete 12 is provided.
This is to reinforce with 6, and to resist long-term pressure. In addition, although not shown, the base slab concrete 12 below the lower water stopping member S is previously formed slightly lower, and after the injection material 9 is injected, the upper surface is covered with mortar or the like, and the lower water stopping member S It is also preferable that the upper surface of the foundation slab concrete 12 is smoothed.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The waterproof rubber packing 3 used for the upper waterproof member P is made of abrasion-resistant rubber, and in the illustrated example, five are laminated, but the number is not limited to this. The basic shape of the waterproof rubber packing 8 does not matter, but a square or a circle is preferable. Rail plate 1 of lower water stopping member S
b and the shutter plate 2 can be implemented, for example, in a mode as shown in FIG. FIG. 6A shows that the U-shaped rail plate 1b and the inside of the center of the U-shaped rail plate 1b can be slid and closed only from one direction (in the illustrated example, from the near side) in a plan view. 3 shows a shutter plate 2 without a pipe hole. FIG. 6B
Shows an example in which two rectangular rail plates 1b 'and 1b' are installed in parallel when viewed from a plane direction, and a longer shutter plate 2 'can slide between the front and rear directions to close between them. . FIG. 6C has almost the same configuration as the example of FIG. 6B, but has two rectangular rail plates 1.
An example is shown in which a shutter plate 2 'that moves between b' and 1b 'is formed to be short, and a pipe hole 2a is provided at an end of the shutter plate 2', and thus slides only from one direction.

Although not shown, the rail plate 1b is not used, and a rail (groove) in which the shutter plate 2 is slidably formed is formed on one support plate 1. It is also possible to form (grooves) in the upper plate 1c and implement it as two upper and lower plate types. 6B and 6C, the injection port 8 provided in the shutter plate 2 is formed by forming a plurality of injection ports penetrating vertically, and from the outer end face of the plate, as in the injection port 8 'shown in FIG. 6D. It may be perforated in the horizontal direction and hung downward. A countersunk bolt 16 as shown in FIG. 7 is preferably used for the inlet 8 penetrated up and down so that the surface does not protrude.

[0019]

According to the method for improving the pressurized ground immediately below an existing structure according to the first and second aspects of the present invention, the water stopping device according to the third aspect of the present invention can be used on a foundation slab concrete of an existing structure. Since the groundwater and the like are completely stopped by using this method, and the ground under the pressurized water is improved by the ground improvement consolidation method, rational and efficient ground improvement is achieved, and liquefaction countermeasures and seismic reinforcement are achieved. The ground is improved without draining any groundwater, so there is no effect on the surrounding ground. In addition, since all operations can be performed on the foundation slab concrete by the water stop device having a simple configuration, no large-scale temporary construction is required at all, and a reduction in construction cost and a shortening of the construction period are achieved.

[Brief description of the drawings]

FIG. 1 is an overall view showing a point of ground improvement.

FIG. 2A is a cross-sectional view showing the installation state of a lower water stopping member,
B is a cross-sectional view showing the installation state of the upper water stopping member.

FIGS. 3A and 3B are a cross-sectional view and a partially omitted plan view showing the state of penetration of the excavation pipe, and C and D are a cross-sectional view and a partially omitted plan view of the state of withdrawal of the excavation pipe.

FIG. 4 is a cross-sectional view showing an injection step of an injection material.

FIG. 5 is a cross-sectional view showing a state of placing concrete.

6A to 6D are plan views showing variations of a rail plate and a shutter plate.

FIGS. 7A and 7B are a cross-sectional view and a plan view showing the manner in which the injection port is closed.

FIG. 8 is a cross-sectional view showing a conventional example.

FIG. 9 is a cross-sectional view showing a different conventional example.

10A to 10C are cross-sectional views of different conventional examples.

[Explanation of symbols]

 S Lower water stopping member P Upper water stopping member 1 Support plate 2 Shutter plate 3 Waterproof rubber packing 4 Insertion hole 5 Washer 6 Case 7 Drilling pipe 8 Injection 9 Injection material 11 Building 12 Foundation slab concrete 13 Groundwater 15 Through hole 16 Presser concrete

Claims (3)

[Claims] A) a shutter plate supported by a support plate is slid to move a lower water stopping member configured to be capable of closing a through hole; B) a water-stop rubber packing having an insertion hole having a diameter slightly smaller than the diameter of the drilling pipe having a bit at the tip formed substantially at the center thereof, and being stacked in the case through a washer. Installing a plurality of upper water-stopping members on the lower water-stopping member, and c) inserting a drilling pipe from above into the insertion hole of the upper water-stopping member, and watertight by water-stopping rubber packing. Forming a through hole with a required minimum diameter in the foundation slab concrete with the excavated pipe while maintaining the state, drilling the ground to a desired depth, and then injecting an injection material to improve the ground; d) ground After the improvement is completed, raising the excavation pipe at least above the shutter plate of the lower water stopping member, sliding the shutter plate to close the through hole, and e) removing the upper water stopping member; Injecting an injection material from an injection port provided in a shutter plate. A method for improving a pressurized ground immediately below an existing structure, comprising: 2. The existing structure according to claim 1, wherein after the upper waterproofing member is removed and the injection material is injected, a holding concrete for reinforcement is cast on the lower waterproofing member. A method for improving the ground directly under pressure. 3. A lower water stopping member installed on a foundation slab concrete on the ground which is under pressure with groundwater, and an upper water stopping member detachably mounted on the lower water stopping member, The lower water stop member is configured such that the shutter plate supported by the support plate slides in the horizontal direction to be able to close the through hole, and the upper water stop member has an insertion hole having a diameter slightly smaller than the pipe diameter of the excavation pipe. A plurality of waterproof rubber packings formed substantially at the center are housed in the case in a stacked state via washers, and the waterproof rubber packing is configured to adhere to a drilling pipe in an insertion hole to stop water. Characterized by the water stop device used in the method for improving the ground under pressure.