JPH04237720A - Water stop method at excavation of pit - Google Patents

Abstract

PURPOSE:To reduce the cost for constructing a pit and prevent intrusion of subsoil water into the pit without causing ground subsidence. CONSTITUTION:A trench 21 is excavated till a non-permeative layer I in such a way as surrounding the ground G in which a pit 10 is to be constructed, and a non-permeative sheet 20 is placed in this trench 21. This non-permeative sheet, 10 prevents intrusion of subsoil water into the pit 10.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water stoppage method for preventing groundwater from entering a shaft when a shaft is excavated in the ground.

0002

BACKGROUND OF THE INVENTION When carrying out the deep foundation construction method or the shield construction method, a vertical hole or a vertical shaft, which is one type of a vertical hole, is sometimes excavated in the ground in which a deep foundation pile is to be constructed. To explain the deep foundation construction method as an example, this construction method is a construction method in which a circular vertical hole in plan view is manually excavated in the ground, and the hole is dug one by one while being stopped. Then, by filling the pit with concrete, it can be used as the foundation of a structure. Since the excavation is done manually, the generation of spring water and gas becomes a problem. Therefore, when constructing deep foundation piles, it is necessary to prevent groundwater from entering the shaft from the bottom of the excavation. The same applies to the construction of vertical shafts and other shafts. Conventionally, in order to prevent groundwater from entering a pit, water is pumped up using a deep well 1, as shown in FIG. 3. In the figure, symbol G is the ground, and symbol 2 is a pit.

0003

[Problems to be Solved by the Invention] However, the prior art has the following problems.

[0004] Groundwater pumping using deep wells requires
There was a problem in that it required a high amount of money to construct the pit because of the increased costs associated with operating the drainage pump. In addition, there was a problem that ground subsidence may occur because groundwater is pumped up.

The present invention has been made in view of the above problems, and its purpose is to reduce the cost required for constructing a pit compared to the prior art, and to drain underground water from the pit without causing ground subsidence. An object of the present invention is to provide a water stoppage construction method when excavating a vertical hole, which can prevent water from seeping into the interior.

[0006]

[Means for Solving the Problems] The gist of the present invention is a water stoppage method during excavation of a shaft, which prevents groundwater from flooding into the shaft when the shaft is excavated in the ground. This method consists of excavating a trench that extends to the impermeable layer surrounding the ground to be excavated, and erecting an impermeable sheet within the trench.

[0007]

[Function] The drainage pump connected to the deep well is operated to pump up groundwater, which does not prevent groundwater from seeping into the pit; instead, the impermeable sheet prevents groundwater from seeping into the pit. There will be no increase in drainage costs during excavation, and no ground subsidence will occur.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the component parts described in this example are as follows:
Unless specifically stated, the scope of the present invention is not intended to be limited thereto, and these are merely illustrative examples.

[0009] A water stop method during excavation of a pit according to this embodiment will be explained with reference to FIGS. 1 and 2. This water stop method was applied when constructing deep foundation piles in ground G. First, the deep foundation pile related to the water stop method will be explained. A deep foundation pile is a pile constructed by the deep foundation method, which is a construction method in which a 1.4 to 3.5 m circular vertical hole 10 in plan view is excavated in the ground G, and the pile is dug while stopping the pile. . The shaft 10 is then filled with concrete to serve as the foundation of the structure.

Next, the steps of the water stop method will be explained. First, as shown in FIG. 1, a trench 21 is excavated in the ground G where the deep foundation pile is to be constructed so as to surround the deep foundation pile. As shown in FIG. 2, the groove 21 has no hexagonal outline in plan view with the deep foundation pile to be constructed located at the center, and its lower end reaches the impermeable layer I. As a method for excavating the trench 21, the method for constructing a water stop wall (
It may be constructed using a material suitable for carrying out the present invention, such as Japanese Patent Application No. 1-286833. In addition, in the figure, the reference numeral indicates the advance hole 22 into which the guide of the wire saw is inserted. Next, a water-impermeable sheet 20 such as a vinyl sheet is inserted into the groove 21. A method for constructing a water-stop wall as a method for installing the impermeable sheet 20 (Japanese Patent Application No. 1-28683
No. 3), etc., which are suitable for carrying out the present invention may be used. The groove 21 in which the water-impermeable sheet 20 is placed is filled with a water-impermeable material such as mortar. As described above, it is possible to prevent groundwater from infiltrating into the pit 10 in which the deep foundation pile is to be constructed. In addition, in order to construct a deep foundation pile, after the above-mentioned process, it is sufficient to manually dig the pile while using the pile-stopping material 11 in the same manner as in the conventional construction method. At this time, if groundwater existing in the ground G surrounded by the impermeable sheet 20 floods into the pit 10, it may be drained by a drainage means such as a drainage pump. Next, the operation of the water stop method constructed as above will be explained. The impermeable sheet 20 built into the groove 21 prevents groundwater from invading from the ground G outside the impermeable sheet 20 to the ground G inside. In addition, since the lower end reaches the impermeable layer I, groundwater flows from below the impermeable sheet 20 into the vertical hole 1.
Prevent water from entering the room. Next, the effects of the water stop method will be explained. Since the impermeable sheet 20 prevents groundwater from seeping into the pit 10, drainage costs will not increase during excavation of the pit 10 due to operation of a drainage pump, etc., and subsidence of the ground G will not occur. , the cost required for constructing the pit 10 is reduced compared to the conventional technology, and the ground G
Underground water can be prevented from infiltrating into the pit 10 without causing subsidence.

[0011] In this example, the above-mentioned water stop method was applied to the construction of deep foundation piles, but the scope of the present invention is not limited thereto. Anything suitable for carrying out the present invention, such as a shaft, can be used. Further, the scope of the present invention is not limited to the case of constructing a vertical hole, but the present invention can be applied to a diagonal hole, etc.

0012

[Effects of the Invention] Since the present invention is constructed as described above, it achieves the following effects. Since the impermeable sheet prevents groundwater from seeping into the pit, there is no need to increase drainage costs during pit excavation due to the operation of a drainage pump, etc., and ground subsidence does not occur, making it easier to drill a pit than with conventional technology. It is possible to reduce the cost required to construct a pit and prevent groundwater from flooding into the pit without causing ground subsidence. As a result, according to the present invention, construction costs can be reduced compared to conventional techniques, and a pit can be constructed even in places where pumping of groundwater is regulated.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view showing a state in which a water-impermeable sheet according to an embodiment of the present invention is built into the ground.

FIG. 2 is a plan view showing a state in which the same water-impermeable sheet is built into the ground.

FIG. 3 is a vertical cross-sectional view of a pit in which a deep foundation pile is to be constructed, according to a conventional example.

[Explanation of symbols]

G Ground I Impermeable layer 10 Pit 20 Water impermeable sheet 21 Groove.

Claims (1)

[Claims] Claim 1: A water-stopping construction method for preventing groundwater from infiltrating into a shaft when a shaft is excavated in the ground, the method comprising: a water-stopping construction method for preventing groundwater from infiltrating into the shaft; A water stop method when excavating a vertical hole, which is characterized by excavating a trench down to the layer and placing an impermeable sheet inside the trench.