JPH0516493B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method and apparatus for forming well the wall of a deep hole excavated underground and improving its water permeability in the deep well construction method. Regarding.

[Conventional technology] The deep well construction method involves drilling a deep well with a diameter of 30 to 40 cm into a permeable layer, which pumps up groundwater and lowers the groundwater table, thereby preventing spring water and reducing water pressure. This is what we aim to do.

Here, an example of the construction procedure of the deep well construction method will be briefly explained using FIGS. 3 and 4. In the figure, reference numeral 1 is the ground on which the predetermined construction work is to be performed.

First, a deep hole 3 is excavated in the ground 1 using an excavator 2. At this time, bentonite 5 is press-fitted into the deep hole 3 from the cutting edge 2a of the excavator 2 in order to prevent the hole wall 4 of the deep hole 3 from collapsing and to discharge the excavated earth and sand to the ground. The bentonite 5 press-fitted from the cutting edge 2a of the excavator 2 is discharged into the bentonite settling pond 6 on the ground together with the excavated earth and sand. The bentonite 5 discharged into the bentonite settling tank 6 is recycled into the excavator 2 by the pump 7 installed in the settling tank 6 when the sediment mixed in the bentonite 5 settles in the settling tank 6 and becomes pure bentonite 5. , and is press-fitted into the deep hole 3 from the cutting edge 2a and circulated.

In this way, the excavation of deep hole 3 is completed.
When the steel pipe 8 is completed, a steel pipe 8 having a strut (not shown) is installed in the deep hole 3.
Small gravel 9 for a filter is placed between the hole wall 4 of the deep hole 3 and
Fill it. Next, the submersible pump 11 is attached to the tip of the lift pipe 10, the lift pipe 10 is added, and the submersible pump 11 is installed at a predetermined location within the steel pipe 8.

When the deep well is completed according to the construction procedure described above, groundwater 12 contained in the ground around the deep hole 3 is collected into the deep hole 3. Groundwater 12 collected in the deep hole 3 passes between the small gravel filters 9, flows into the steel pipe 8, and is discharged to the ground by the submersible pump 11.

[Problem that the invention seeks to solve]

However, in the conventional deep well construction method described above, the bentonite used when excavating the deep hole adheres to the hole wall of the deep hole, worsening the water permeability of the hole wall and significantly reducing the water collection and drainage capacity of the deep well. There was a problem in that it caused a decline in the construction period and delayed the construction period.

This invention was made in view of the above circumstances, and provides a hole wall forming method in a deep well construction method that removes bentonite from the hole wall of a deep hole to improve the water permeability of the hole wall and shorten the construction period. The purpose is to provide equipment.

[Means for solving problems]

In order to solve the above-mentioned problems, the method according to the present invention provides a cutting part at the tip of a steel pipe, and when the steel pipe is installed in a deep hole, the cutting part sequentially cuts the deep hole toward the bottom. Bentonite attached to the hole wall is removed by cutting. Further, the device according to the present invention includes a first steel pipe installed inside the hole wall of the deep hole at a slight distance from the hole wall, and a first steel pipe whose axis is also attached to the tip of the steel pipe. , a second steel pipe having an outer diameter approximately the same as the diameter of the deep hole, and cutting blades fixed to the outer circumference of the second steel pipe at predetermined intervals along the circumferential direction of the steel pipe. This is what happens.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a hole wall forming device in the deep well construction method according to the present invention;
The figure is a diagram for explaining a hole wall forming method in the deep well construction method according to the present invention. In these figures, the same elements as those shown in FIGS. 3 and 4 are designated by the same reference numerals.

In Fig. 1, a deep hole 3 is excavated in the ground 1, and the deep hole 3 is equipped with a hole wall forming device (hereinafter simply referred to as "device") in the deep well construction method.
20 are installed. The device 20 is constructed by attaching a cutting part 22 to the tip of a steel pipe 21 installed in a deep hole 3. The steel pipe 21 has an outer diameter that can be inserted into the deep hole 3 and a length that is approximately the same as the depth of the deep hole 3, and has struts 23, 23, ...is being formed. The cutting part 22 includes a steel pipe 24 that has the same axis as the axis of the steel pipe 21 and has an outer diameter that is substantially the same as the inner diameter of the deep hole 3, a mounting part 24a that connects the steel pipe 24 and the steel pipe 21, and a steel pipe Cutting blades 2 fixed at predetermined intervals along the circumferential direction of the upper end outer periphery of 24
5, 25, and a plurality of openings 26, 26, . . . for discharging cutting soil, which are opened in the steel pipe 24 near the tips of the cutting blades 25, 25, .

Next, a second method of cutting and removing bentonite 5 adhering to the hole wall 4 of the deep hole 3 from the hole wall 4 using the apparatus 20 configured as described above will be described.
This will be explained using FIG.

First, as shown in Fig. 3, a deep hole 3 is excavated in the ground 1 by an excavator 2 while circulating bentonite 5 in order to prevent the collapse of the hole wall 4 and discharge the excavated earth to the ground. do. Therefore, bentonite 5 is attached to the hole wall 4 of the excavated deep hole 3.

Once the deep hole 3 is completed, the device 20 is then installed within the deep hole 3, as shown in FIG. That is, the device 20 is inserted into the deep hole 3 sequentially from the top to the bottom. At this time, the device 20 may be inserted straight into the deep hole 3, or may be inserted while rotating the device 20. When the device 20 is inserted into the deep hole 3, the device 20
The steel pipe 24 of the cutting part 22 is cut along the hole wall 4.
The cutting blade 25 of the cutting part 22 advances while sliding.
25, . . . proceed while cutting the hole wall 4 to a predetermined thickness. At this time, the cut hole wall 4 is discharged into the deep hole 3 through the openings 26, 26, . . . formed in the steel pipe 24. At the same time, the submersible pump 11 is installed at a predetermined location inside the device main body 20 (for example, between the tip of the cutting blade 25 and the submersible pump 11
Align the tips of the ) By doing so, it is possible to keep the bentonite 5 in the lower part of the device main body 20. That is, by discharging the bentonite 5 below the cutting blade 25 to the outside by the submersible pump 11, the bentonite 5 is prevented from adhering again to the clean hole wall 4 from which the bentonite 5 adhering to the hole wall 4 has been removed by the cutting blade 25. This is to prevent Then, cut with the cutting blade 25,
A portion of the deep hole 3 having a clean hole wall 4 with good water permeability is filled with fresh water. Here, since the bentonite 5 has a higher specific gravity than the fresh water 27, it does not rise to the top and mix into the fresh water 27. Further, the device 20 is installed in the deep hole 3, and small gravel 9 for a filter is filled between the steel pipe 21 of the device 20 and the hole wall 4. The small gravel filter 9 widens the effective diameter of the deep well, prevents fine sand from entering the deep well, prevents the area around the deep well from collapsing and causing damage to the device 20, and has the effect of increasing pumping efficiency. There is.

In this way, when the device 20 is installed in the deep hole 3, the groundwater 12 contained in the ground 1 around the deep hole 3 is collected in the deep hole 3. At this time, since bentonite 5, which inhibits the permeability of groundwater, has been almost completely removed from the hole wall 4 of the deep hole 3, the hole wall 4
has good water permeability.

Furthermore, the groundwater collected in the deep hole 3 passes between the small gravel filter 9, flows into the device 20 through the struts 23, 23, . . . of the steel pipe 21, and is pumped by the pump 11. It is discharged to the ground.

In addition, in order to keep the liquid level of bentonite 5 below the device 20, a submersible pump 11 is installed inside the device 20.
However, instead of the submersible pump 11, a pump may be installed on the ground, and a pipe connected from the pump may be installed near the cutting blade 25 of the device 20.

〔Effect of the invention〕

As described in detail above, according to the present invention, in the deep well construction method, a cutting part is provided at the tip of the steel pipe, and when the steel pipe is installed in a deep hole, the cutting part sequentially moves the steel pipe toward the bottom. Since bentonite adhering to the walls of the deep hole is removed by cutting, the water permeability of the hole wall is improved, and the water collection and drainage capacity of the deep well is significantly improved.
It is possible to shorten the construction period and reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the main parts of the device used in this invention, Fig. 2 is a sectional view showing bentonite adhering to the wall of a deep hole is being removed by this invention, and Fig. 3 , FIG. 4 is an explanatory diagram for explaining the deep well construction method. 1...Ground, 2...Excavator, 3...Deep hole, 4...
...hole wall, 5...bentonite, 8...steel pipe, 9...
...Filter (small gravel), 11...Submersible pump, 1
2... Groundwater, 20... Hole wall forming device, 21...
Steel pipe (first steel pipe), 22...Cutting part, 24...
Steel pipe (second steel pipe), 25...cutting blade.

Claims (1)

[Claims] 1. A deep hole is dug in the ground using bentonite, a steel pipe is installed inside the deep hole, and small gravel for a filter is placed between the steel pipe and the wall of the deep hole. In the deep well construction method, a submersible pump is installed inside the steel pipe in the deep hole, and the groundwater collected in the deep hole by this submersible pump is drained to the surface.A cutting part is provided at the tip of the steel pipe. , hole wall formation in a deep well construction method, characterized in that, when the steel pipe is installed in a deep hole, bentonite adhering to the hole wall of the deep hole is sequentially cut and removed toward the bottom by the cutting section; Method. 2. A first steel pipe installed inside the hole wall of the deep hole at a slight distance from the hole wall, and a first steel pipe installed at the tip of this steel pipe with the same axis as this first steel pipe, A second steel pipe having an outer diameter that is approximately the same as the diameter, and cutting blades fixed to the outer periphery of the second steel pipe at predetermined intervals along the circumferential direction of the steel pipe. A hole wall forming device for the deep well construction method.