JPH11209998A - Impermeable construction method of underground structure by self-standing type double impermeable walls - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent floating of an underground structure by arranging a drain well in the part surrounded by inside/outside impermeable walls of self-standing type double impermeable walls and lattice-like beams, and constructing the underground structure by excavating th ground stranded by a water impermeable bottom plate and the inside inpermeable wall. SOLUTION: Self-standing type double impermeable walls 2 using the bottom part as a drain layer 3 are constructed by connecting an inside impermeable wall 2a and an outside impermeable wall 2b arranged on a water impermeable bottom plate 1 in a radial shape by lattice-like beams 2c. Next, an underground structure B is constructed by excavating the ground A' surrounded by the water impermeable bottom plate 1 and the inside impermeable wall 2a after sufficiently lowering underground water level in an execution work area by operating a pumping well. In this case, since the self-standing type double impermeable walls 2 are high in rigidity by being constituted of the impermeable walls 2a, 2b and the lattice-like beams 2c, the underground structure B can be constructed at an interval from the inside impermeable wall 2a to use the interval 6 as a dry area. Therefore, impermeable performance can be excellently secured over a long period at earthquake time to prevent floating of the underground structure by water pressure and buoyancy of underground water after execution work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the construction of an underground structure (including an above-ground structure having an underground structure portion) on a ground having a shallow groundwater level and a highly permeable gravel layer or sand layer. In this case, it belongs to the technical field of a water-blocking method implemented so that the adverse effects of groundwater and rainwater do not affect the construction of the underground structure and the soundness after construction. An underground structure that surrounds underground structures with self-supporting double impermeable walls and also has a drainage function, maintains stable impermeable performance for a long time, and can be found (identified) and repaired early if an impermeable wall should be damaged. The present invention relates to a method for impermeable construction of structures.

[0002]

2. Description of the Related Art When constructing an underground structure on a ground composed of a gravel layer or a sand layer having a shallow groundwater level and high permeability, it is necessary to block water during ground excavation (realize dry work during earthwork) and For the purpose of preventing floating of the underground structure due to the water pressure or buoyancy of the groundwater after the construction, a water shielding method of the underground structure has been implemented. As shown in FIGS. 3 and 4, the conventional general water-blocking method first employs the weight of the underground structure B and the ground A ′, and poorly permeable water with sufficient strength and thickness against possible shaking such as an earthquake. The base 1 ′ is formed as an improved ground at a predetermined depth below the underground structure B by a chemical injection method or the like. Subsequently, a water-impervious wall 2 ′ that surrounds the outer periphery of the underground structure B as viewed in a plan view is formed by the ground improvement method or the like, with its bottom being rooted in the poorly permeable bottom 1 ′. Next, the ground A 'surrounded by the impermeable base 1' and the impermeable wall 2 'is excavated, and the underground structure B is constructed there.

Next, attention was paid to the effect of preventing the deterioration of the soundness of the underground structure due to the infiltration of groundwater and the effect of preventing the discharge of waste liquid and the like to the ground around the underground structure as a secondary effect generated by the water shielding method. The following technology has been proposed as an application of a structure impervious method to a special facility called an underground oil storage base. Japanese Patent Publication No. 59-31632 discloses a water-impervious wall which is provided along the outer periphery of a tank group yard and reaches a water-impermeable layer (impervious bottom), and a bottom and a side provided on an open cut site inside the water-impervious layer. Part has a filter layer (a drainage layer through which spring water such as rainwater can move freely), and a drainage pipe for draining the spring water from the filter layer is connected to a service tunnel, and is fixed with backfill embankment There is disclosed an underground oil storage base constructed on a soft ground having a permeable layer, which is characterized by being composed of a group of tanks.

[0004]

According to the prior art described above, the impermeable wall is not strong enough to function as a self-supporting mountain stay for a long period of time, and after the underground structure is constructed, It has a structure that plays its part as a cutting beam. In other words, impermeability during excavation (realization of dry work during earthwork)
The main purpose of this method was to construct a temporary structure, which did not guarantee long-term or water-tightness in the event of an earthquake. For this reason, there is a problem that the effect of preventing the floating of the underground structure due to the water pressure and buoyancy of the groundwater after the construction described above cannot be guaranteed for a long term and during an earthquake.

[0005] As described above, the prior art described above has the effect of preventing soundness deterioration of an underground structure due to infiltration of groundwater as a secondary effect produced by the method of impermeable construction of an underground structure,
Attention is paid to the effect of preventing the discharge of waste liquid etc. to the ground around the underground structure, and furthermore, it has a drainage function, measures against spring water due to rainwater, etc., and the problem of outflow of internal waste liquid from the underground structure to the outside ground (In this case, the problem of oil spill inside the tank) It can be appreciated that attention has been paid to improving measures. In addition, although it is designed to have sufficient strength against earthquakes, etc., if the construction of the underground structure has been completed for a long time,
It is conceivable that the water-blocking performance is reduced. At that time, there is no disclosure of a technique for finding (identifying) and repairing a water leakage point.

An object of the present invention is to provide not only water shielding during ground excavation (realization of dry work during earthwork) but also good water shielding performance over a long period of time and during an earthquake. Of underground structures due to water pressure and buoyancy of water, prevention of deterioration of soundness of underground structures due to infiltration of groundwater or rainwater, and prevention of outflow of waste liquid etc. to the ground and underground water around underground structures It is an object of the present invention to provide an improved underground structure waterproofing method that can be found (specified) and repaired at an early stage in case of damage.

[0007]

As a means for solving the above-mentioned problems, a method for impermeable construction of an underground structure using a self-supporting double impermeable wall according to the first aspect of the present invention has a shallow groundwater level. In an impermeable construction method in which an artificially impervious base and impermeable walls are formed on the ground composed of a highly permeable gravel layer or sand layer, etc. An inner impermeable wall provided at a predetermined depth deeper than the underground structure and surrounding the outer periphery of the underground structure in a plan view, and an outer impermeable wall spaced apart from the inner impermeable wall at the bottom thereof. Rooted in the impervious bottom, and constructed, furthermore, a plurality of lattice-shaped beams radially connecting the outer impermeable wall and the inner impermeable wall, spaced apart in the longitudinal direction of the impermeable wall, The bottom is formed to a depth that allows a space to be used as a drainage layer between it and the upper surface of the poorly permeable bottom plate. To provide a self-supporting double impermeable wall, for each site surrounded by the inner and outer impermeable walls and the grid-like beams of the self-supporting double impermeable wall, one or more drainage pumping wells To the depth reaching the drainage layer, and excavating the ground surrounded by the poorly permeable bottom and the inner impermeable wall to construct an underground structure.

According to a second aspect of the present invention, there is provided a method for waterproofing an underground structure using a self-supporting double impermeable wall according to the first aspect, wherein the underground structure is slightly spaced from the inner surface of the inner impermeable wall. And forming the space portion as a dry area. According to a third aspect of the present invention, there is provided a method for impermeable construction of an underground structure using the self-supporting double impermeable wall according to the first or second aspect. It is characterized by installing a water pressure gauge for each part surrounded by beams and monitoring water leakage.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 and 2 by using a self-supporting double impermeable wall for an underground structure. INDUSTRIAL APPLICABILITY The method for impermeable construction of an underground structure according to the present invention is suitably implemented when an underground structure is constructed on the ground composed of a gravel layer or a sand layer having a low groundwater level and high permeability.

In the embodiment shown in FIGS. 1 and 2, first, the weight of the underground structure B and the ground A 'and the poorly permeable bottom 1 having sufficient strength and thickness against possible shaking such as an earthquake. Is formed at a position sufficiently deeper than the foundation bottom of the underground structure B by a ground improvement method using a ground improvement machine or a chemical liquid injection method.
Subsequently, the inner impermeable wall 2 surrounding the outer periphery of the underground structure B in plan view by the ground improvement method or the chemical liquid injection method.
a and the outer impermeable wall 2b spaced apart from the inner impermeable wall 2a are formed by piercing the bottom of the inner impermeable wall 2b into the poorly permeable bottom 1 respectively. The use of reinforcing materials such as reinforcing bars or steel frames is also performed as necessary. Further, the outer impermeable wall 2
are connected at equal intervals in the longitudinal direction of the water-impervious walls 2a and 2b, and the bottom and the upper surface of the poorly permeable bottom 1 are also spaced apart from each other. The self-supporting double impermeable wall 2 is constructed by constructing and constructing it by the ground improvement method or the chemical liquid injection method in the same manner as the impermeable walls 2a and 2b to a depth at which an interval used as the drainage layer 3 is provided. . In view of the fact that the facility is a permanent facility, the self-supporting double impermeable wall 2 (impermeable walls 2a, 2b and lattice beams 2c ...) can be formed as a concrete wall.

Further, the drainage pumping well 5 is separated from the surface of the ground by the unit of each closed portion 4 surrounded by the inner and outer impermeable walls 2a and 2b and the lattice-shaped beams 2c. It is provided to a depth that reaches the drainage layer 3. As shown in FIG. 2, in this embodiment, a total of four drainage pumping wells 5 are installed, one for each part 4 located at each corner, but this is not a limitation.

Next, after the drainage pumping well 5 is operated to sufficiently lower the groundwater level in the construction area, the ground A 'surrounded by the poorly permeable bottom 1 and the inner impermeable wall 2a is removed. Excavation is performed to construct the underground structure B. In this case, the self-supporting double impermeable wall according to the present invention has a configuration in which the inner and outer double impermeable walls 2a, 2b are integrally connected by a plurality of lattice beams 2c.
Since its rigidity is high and it also has a function as a self-supporting mountain retainer, the underground structure B can be constructed at a slight distance from the inner surface of the inner impermeable wall 2a. The thus formed interval portion 6 is formed as a dry area, and if there is a water leakage point in the inner impermeable wall 2a, the water leakage point is found (identified) by visual observation from above the dry area 6,
Use for immediate repair. Furthermore, even if the poorly permeable bottom 1 is damaged and groundwater infiltrates, the ground A 'at the bottom of the dry area 6 can be directly visually observed to be wet.

In addition, a water pressure gauge is installed in units of each closed part 4 surrounded by the water barriers 2a, 2b inside and outside the self-supporting double water barrier 2 and the grid-like beams 2c. Monitor for leaks. If there is a leak point, the leak point can be found or specified quite accurately as a change in the water pressure measurement value of the water pressure gauge. Specifically, the outer impermeable wall 2
If a water pressure gauge is installed on the inner surface of b, it is possible to find (specify) a leak point of the outer impermeable wall 2b.

[0014]

[Effects of the present invention] According to the method for impermeable construction of an underground structure using a self-supporting double impermeable wall according to the present invention, the underground water level is shallow, and the ground is composed of a highly permeable gravel layer or sand layer. When constructing a structure, it is possible to carry out earthwork during soil excavation by dry work, as well as using a self-supporting double impermeable wall with high rigidity and drainage function, Even at times, good water barrier performance can be ensured. Therefore, it is possible to guarantee the prevention of the floating of the underground structure due to the water pressure and buoyancy of the groundwater after the construction, the deterioration of the soundness of the underground structure due to the infiltration of the groundwater and rainwater, and the prevention of the outflow of the waste liquid and the like to the ground around the underground structure and the groundwater. .

Even if a leak occurs, the leak location can be found (specified) and repaired at an early stage. In addition, it is possible to have sufficient time to take such measures. In terms of cost, the artificially impervious layer has only one layer, which is the same as the conventional one, so that the cost is low and it can be applied to small and medium-sized underground structures.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a method for impermeable construction of an underground structure using a self-supporting double impermeable wall according to the present invention.

FIG. 2 is a plan view showing an embodiment of a method for impermeable construction of an underground structure using a self-supporting double impermeable wall according to the present invention.

FIG. 3 is a vertical cross-sectional view showing a conventional water-blocking method for an underground structure.

FIG. 4 is a plan view showing a conventional method for impermeable construction of an underground structure.

[Explanation of symbols]

A Ground B Underground structure 1 Impervious bottom 2a Inner impermeable wall 2b Outer impermeable wall 2c Lattice beam 3 Drainage layer 2 Self-supporting double impermeable wall 4 Inner / outer impermeable wall of self-supporting double impermeable wall And the area surrounded by lattice beams 5 Pumping well for drainage 6 Dry area

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takaaki Shimizu 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside Takenaka Corporation Technical Research Institute (72) Inventor Yuji Taya 1-5-1, Otsuka, Inzai City, Chiba Prefecture Inside Takenaka Corporation Technical Research Institute (72) Inventor Hideo Namba 8-21-1, Ginza, Chuo-ku, Tokyo Inside Tokyo Main Office Takenaka Corporation (72) Inventor Masaro Odagawa 8-chome, Ginza, Chuo-ku, Tokyo No. 21 1 Takenaka Corporation Tokyo Main Store (72) Inventor Akira Morishima 8-21-1, Ginza, Chuo-ku, Tokyo Co., Ltd.

Claims (3)

[Claims] 1. A water-blocking method for forming an artificially impervious bottom plate and a water-blocking wall on a ground having a shallow groundwater level and a highly permeable gravel layer or sand layer in a form surrounding an underground structure. An impervious bottom plate having a required thickness is provided at a predetermined depth deeper than the underground structure, and an inner impermeable wall that surrounds the outer periphery of the underground structure in plan view and a space is provided outside the inner impermeable wall. Each of the outer impermeable walls is formed with its bottom portion embedded in the impervious bottom, and a plurality of lattice-shaped beams radially connecting the outer impermeable wall and the inner impermeable wall are formed by the impermeable wall. The self-supporting double water-impervious wall is provided by forming a bottom with a space between the upper surface of the impervious bottom plate and the upper surface of the impervious bottom plate at an interval in the longitudinal direction thereof. One or more drainage pumping wells for each site surrounded by the inner and outer impermeable walls and the lattice beams From the ground surface to the depth reaching the drainage layer, excavating the ground surrounded by the poorly permeable bottom and the inner impermeable wall, and constructing an underground structure, Water-blocking method for underground structures with double water-blocking walls. 2. The self-supporting double shield according to claim 1, wherein the underground structure is constructed with a small gap from the inner surface of the inner impermeable wall, and the gap is formed as a dry area. Water barrier method for underground structures using water walls. 3. A water pressure gauge is installed at each portion surrounded by the impermeable walls inside and outside the self-supporting double impermeable walls and the grid-shaped beams to monitor water leakage. 2. A method for impermeable construction of an underground structure using a self-supporting double impermeable wall described in 2.