JP2001020291A - Groundwater draining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a draining method which does not cause a factor responsible for degradation of working efficiency. SOLUTION: The draining method is employed when underground walls 12 are constructed so as to be opposite to each other under the ground 10 and the ground inside the underground walls 12 is excavated while the groundwater level being lowered. The underground wall 12 is formed by excavating an excavated groove 14 in the ground, building a cage in the excavated groove 14, and placing concrete therein. At this time, a draining means 16 is embedded in the underground wall 12, which lowers the underground water level. The embedded draining means 16 includes water collecting sections 18, drainage pipes 20, and a suction pump. The water collecting sections 18 are arranged at respective internal lower ends of the underground wall 12, along an extending direction of the wall 12 at predetermined intervals. The drainage pipes 20 are erected in the vertical direction of the underground wall 12. Each pipe 20 has its lower end communicate with the water collecting section 18 and has its upper end extend up to the ground, and the upper end of each pipe 20 is connected to the suction pump and communicates with the same on the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for draining groundwater.

[0002]

2. Description of the Related Art When constructing a structure in the ground deeper than the groundwater level, an underground wall for retaining the ground is constructed, and the inside of the underground wall is excavated while lowering the groundwater level, and excavation is performed to a root cut surface. There is known a method of constructing a structure in a cut and opened state.

In this case, the method of lowering the groundwater level is as follows:
Although various proposals have been made, the deep well method of lowering the groundwater level by driving a steel pipe for collecting water into the stagnant ground, installing a drainage pump inside, and pumping water is a simple method. Relatively many are adopted.

However, such a conventional deep well method has the following technical problems.

[0005]

In other words, in the deep well method, the location of the water collecting steel pipe is designed inside or outside the excavation so as not to interfere with the column member or the beam member of the structure to be constructed. It is set with consideration.

However, when installed inside the excavation,
As the excavation progresses, as the excavation surface becomes deeper, the water collecting steel pipe gradually exposes upward from the excavation surface and rises up, and in such a state, there is an obstacle to the operation of heavy machinery and the like. And reduced the work efficiency.

In the case of external installation, it is necessary to secure an installation site.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an inexpensive groundwater drainage method which does not cause a reduction in work efficiency. To provide.

[0009]

In order to achieve the above object, the present invention provides a method for constructing an underground wall in the ground and excavating the inside of the underground wall while lowering the groundwater level. A drainage means is built in the underground wall, and the groundwater level is lowered through the built-in drainage means. According to the drainage method for groundwater configured as described above, the drainage means for lowering the groundwater level is built in the underground wall, so that the excavation work is performed as in the conventional deep-well steel pipe for collecting water. It does not affect the operation of heavy machinery at the time. The drainage means is provided at a lower end side of the underground wall, and a water collecting section for collecting groundwater, one end communicates with the water collecting section, and is vertically installed inside the underground wall and the other end side is provided. A drain pipe extending to the ground,
A drainage pump installed at a lower end of the drainage pipe, or a suction pump connected to the other end of the drainage pipe, wherein the water collecting part and the drainage pipe are reinforced cages for constructing the underground wall. Can be locked. According to this configuration, since the water collecting portion and the drainage pipe are locked and built into the reinforcing steel cage for the construction of the underground wall, the drainage means can be built into the inside at the same time as the construction of the underground wall. In addition, the drainage means can be efficiently formed. The water collecting portion includes a casing having an opening on an outer surface side of the underground wall, a water-permeable plate installed inside the casing to separate a passage along a bottom surface of the casing, and a water-permeable plate on the water-permeable plate. And a water-permeable filter layer that is placed on the casing and is provided so as to cover the front side of the filter layer and that contacts the excavation wall surface of the underground wall. And can be composed of According to the water collecting section configured as described above, since the water-impermeable water-impermeable sheet has water-impermeable property until it comes into contact with hot water of a predetermined temperature, cast concrete or muddy water enters the filter layer. Can be prevented. The hot water dissolvable water-blocking sheet is made of a synthetic resin sheet whose dissolution temperature can be selected, and the dissolution temperature can be set in accordance with the temperature rise during the hydration reaction of the cast concrete. According to this configuration, when the concrete starts to harden and the temperature of the mud rises due to the hydration reaction of the cement, the temperature rise causes the hot water solubility to be set to the temperature at the time of the hydration reaction of the cast concrete. Water sheet can be dissolved automatically. In this case, at the stage where the temperature rises due to the hydration reaction of the cast concrete, the cast concrete has hardened and its fluidity has almost disappeared. Does not penetrate into the filter layer. The dissolving temperature may be set to be equal to or higher than the rising temperature of the cast concrete during the hydration reaction, and hot water heated to the dissolving temperature may be supplied into the casing via the drain pipe. In the case of this configuration, the melting temperature is set to be equal to or higher than the rising temperature of the casting concrete during the hydration reaction. The certainty of dissolution can be increased as compared with the case of dissolution. The drainage means can be selected from either a drainage pump installed in the lower end of the drainage pipe or a suction pump connected to the other end of the drainage pipe.

[0010]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG.
FIG. 3 to FIG. 3 show an embodiment of a method of draining groundwater according to the present invention.

The drainage method shown in FIG. 1 is employed when the underground wall 12 is constructed in the ground 10 so as to face the ground and the inside of the underground wall 12 is excavated while the groundwater level is lowered. The underground wall 12 is, for example, a waterproof type constructed by an underground continuous wall method, and after excavating and forming an excavation groove 14 in the ground and embedding a steel cage in the excavation groove 14, concrete Is formed.

At this time, in the drainage method of the present embodiment, the drainage means 16 is built in the underground wall 12, and the built-in drainage means 16 lowers the groundwater level. The built-in drainage means 16 includes a water collecting part 18, a drainage pipe 20, and a suction pump (not shown). A plurality of the drainage means 16 are arranged at predetermined intervals along the extension direction of the underground wall 12. I have.

The water collecting portion 18 is provided on the inner side of the lower end of the underground wall 12 and is provided at a predetermined interval along the extending direction of the underground wall 12. In this embodiment, the water collecting section 18
Are provided only on the inner surfaces of the pair of underground walls 12 facing each other, but may also be provided on the outer surfaces of the respective underground walls 12.

The details of the water collecting section 18 are shown in FIGS. The water collecting part 18 shown in FIG.
It has a water-permeable filter layer 18b and a hot water-soluble water-blocking sheet 18c.

The casing 18a has a rectangular box shape formed of a flat steel plate having one end opened on the excavation wall surface side of the excavation groove 14, and has a water-permeable plate separating the passage space 18d above the bottom surface. 18e are fixedly provided at predetermined intervals.

As the water permeable plate 18e, for example, a plate material or a wire mesh having a large number of holes or slits is used. The filter layer 18b is housed in the casing 18a so as to be placed on the water permeable plate 18e. For example, the filter layer 18b is formed by randomly entangled coiled synthetic resin fibers having a relatively large diameter. A mat (manufactured by Toyobo Co., Ltd., trade name) can be used.

The hot water decomposable water-blocking sheet 18c is dissolved by contact with hot water at a predetermined temperature. For example, a synthetic resin sheet whose dissolution temperature can be selected;
Solbron (trade name, manufactured by Nichibi Co., Ltd.) can be used.

In the case of the present embodiment, the dissolution temperature of the impermeable sheet 18c is determined by the melting temperature corresponding to the rising temperature during the hydration reaction of the concrete cast in the excavation groove 14, for example,
A dissolution temperature of about 20 ° C. is used.

The waterproof sheet 18c is engaged with the casing 18a so as to cover the outer surface of the filter layer 18b housed in the casing 18a.
In this case, the impermeable sheet 18c is
The filter layer 18b may be provided so as to surround the outer periphery of the filter layer 18b stored in the filter layer 18a.

The drainage pipe 20 is formed of a hollow cylindrical steel pipe or the like, and is vertically suspended from the underground wall 12, and is disposed so that the lower side reaches the lower end thereof along the back surface of the casing 18a. ing.

The lower part of the drain pipe 20 along the back surface of the casing 18a communicates with the passage space 18d of the water collecting part 18 at a plurality of places, and the upper end is extended to the ground part. An omitted suction pump is connected in communication.

The means for discharging groundwater from the drainage pipe 20 is not limited to this suction pump. For example, a drainage pump may be incorporated at the lower end of the drainage pipe 20.

The water collecting section 18 and the drain pipe 20 having the above-described configuration.
When the underground wall 12 is constructed, it is locked at a predetermined position of the reinforcing rod cage built in the excavation groove 14 and is built together with the reinforcing rod cage in the excavating groove 14, and then concrete is inserted in the excavating groove 14. Is installed, the underground wall 12 is constructed.

In the case of the present embodiment, when the muddy water rises to a predetermined temperature due to the hydration reaction of the cement in the poured concrete, the hot water decomposable water-blocking sheet 18c of the water collecting section 18 is hit. It dissolves in the early stage of setting concrete hardening, and the filter layer 18b is exposed.

When the filter layer 18b is exposed, when the suction pump connected to the drain pipe 20 or the drain pump is driven, groundwater in the ground is sucked through the filter layer 18b, and the ground water is discharged from the drain pipe 20 to the outside. Is discharged.

When such drainage is continued, the groundwater level gradually decreases, and the inside of the underground wall 12 can be excavated in an open-cut state.

According to the groundwater drainage method configured as described above, since the drainage means 16 for lowering the groundwater level is incorporated in the underground wall 12, the conventional steel pipe for collecting water of the deep well method is used. In this way, it is possible to eliminate a factor that has been one of the causes of the reduction in the construction efficiency without protruding from the excavation surface and affecting the operation of the heavy equipment during the excavation work.

In the case of the present embodiment, the water collecting portion 18 and the drainage pipe 20 are engaged with the steel cage for constructing the underground wall 12 and are built in the excavation groove 14, so that concrete is At the same time that the underground wall 12 is constructed by casting, the drainage means 16 can be built therein, and the drainage means 16 can be formed efficiently.

Further, according to the water collecting section 18 of this embodiment,
The hot water-soluble water-blocking sheet 18c has water-blocking properties until it comes into contact with hot water at a predetermined temperature, so that it is possible to prevent cast concrete or muddy water from entering the filter layer.

The impermeable sheet 18c of this embodiment is made of a synthetic resin sheet whose melting temperature can be selected. The melting temperature is set in accordance with the rising temperature during the hydration reaction of the cast concrete. When the temperature of the mud rises due to the hydration reaction of the cement, the hardening of the cast concrete starts, and this temperature rise causes the hot water-soluble water-blocking sheet set at the temperature at the time of the hydration reaction of the cast concrete. 18
c can be dissolved automatically.

In this case, at the stage where the temperature rises due to the hydration reaction of the cast concrete, the cast concrete has hardened and its fluidity has almost disappeared. However, the concrete does not go around and enter the filter layer b.

The dissolving temperature of the hot water-soluble water-blocking sheet 18c can be set to a temperature higher than the rising temperature during the hydration reaction of the cast concrete. At the early stage of setting concrete hardening, warm water heated to the melting temperature is discharged through the drain pipe 20 to the casing 1.
8a, and the supply of the hot water causes the impermeable sheet 1
8c can also be dissolved.

In the case of this configuration, the melting temperature is set to be equal to or higher than the rising temperature of the cast concrete during the hydration reaction. The dissolution reliability can be increased as compared with the case of dissolving in accordance with (1).

[0034]

As described above in detail in the embodiments,
According to the method for draining groundwater according to the present invention, the groundwater level can be lowered smoothly and inexpensively without lowering work efficiency and without being restricted by land.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view of a construction state showing an embodiment of a method of draining groundwater according to the present invention.

FIG. 2 is a perspective view of a main part of FIG.

FIG. 3 is a sectional view of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ground 12 Underground wall 14 Excavation groove 16 Drainage means 18 Water collecting part 18a Casing 18b Filter layer 18c Waterproof sheet 18d Passage space 18e Water permeable plate

Claims (5)

[Claims] 1. An underground wall is built in the ground, and when excavating the inside of the underground wall while lowering the groundwater level, a drainage means is built in the underground wall. A method for draining groundwater, comprising lowering the groundwater level through the method. 2. The drainage means is provided at a lower end side of the underground wall, and has a water collecting part for collecting groundwater, one end communicating with the water collecting part, and being vertically installed inside the underground wall. A drainpipe, the other end of which is extended to the ground, and a drainpump installed at the lower end of the drainpipe, or a suction pump connected to the other end of the drainpipe, The method for draining groundwater according to claim 1, wherein a portion and a drain pipe are locked to the steel cage for constructing the underground wall. 3. The water collecting section, wherein a casing having an opening at one end on the outer surface side of the underground wall, and a water-permeable plate installed inside the casing so as to separate a passage along a bottom surface of the casing. A water-permeable filter layer placed on the water-permeable plate and housed in the casing; and a hot-water dissolving device provided so as to cover the front side of the filter layer and abutting on the excavation wall surface of the underground wall. The groundwater drainage method according to claim 2, further comprising a water-permeable sheet. 4. The water-impermeable water-blocking sheet is made of a synthetic resin sheet whose dissolution temperature can be selected, and the dissolution temperature is set in accordance with a rising temperature during a hydration reaction of the cast concrete. 4. The method according to claim 3, wherein
Groundwater drainage method as described. 5. The method according to claim 1, wherein the dissolving temperature is set to be equal to or higher than a rising temperature of the cast concrete during a hydration reaction, and hot water heated to the dissolving temperature is supplied into the casing via the drain pipe. The method for draining groundwater according to claim 3, wherein