JPH1171983A - Boring method of deep well - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method of boring a deep well having no filled up state by pulling out an inner pipe, inserting a protecting pipe having a strainer wound with fabric after pulling out an inner pipe, and placing a sand of filter material having a predetermined grain size and grout material to the upper impermeable layer. SOLUTION: Boring is executed to a lower impermeable layer by a double pipe, and thereafter, an inner pipe 12 is pulled up. In the next place, a protecting pipe 21 is inserted to the bore bottom. A strainer 22 is arranged on the protecting pipe 21, and fabric 30 is wound round its outer periphery to then be stuck thereto by rubber paste. Following this, as pulling out an outer pipe, a sand of grain size of about 1-2 mm is placed therein. At the lower end of the protecting pipe 21, a sand trap 23 having its clogged lower end is disposed, and a pair of claws 51, 51 penetrating through a sand trap 23 is provided in a curved manner. After that, a grout material of cement is put and then cured to the depth of an upper impermeable layer (c) for forming a seal grout 61. In this way, blinding is avoided, and a pumping property is precluded from lowering due to clogging of the well with sand.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for excavating a deep well in which surface water on the ground and spring water from a low-quality surface water layer in a shallow part are not mixed.

[0002]

2. Description of the Related Art Conventionally, in order to excavate a deep well, Japanese Patent Application No.
As disclosed in US Pat. No. 3,310,025 "Method of drilling a well", a protective tube 2 having a slit 2a at a lower portion is inserted into a well hole 1 shown in FIG. The filter member 3a having a relatively large particle size such as gravel, the seal member 3b having a small particle size such as sand, and the solidified material 3c mixed with cement milk are filled in the upper portion from the bottom. , And pumps water through the pumping pipe 4 through the slit 2a, and the intermediate sealing member 3b is for sealing the permeation of domestic wastewater and cement milk etc. of the solidified material 3c. is there. The protective tube 2 is usually 60 mm in outer diameter.
PVC pipe with a nominal size of about 50 mm (hereinafter VP)
50) is used.
The size of a is limited to 2 to 3 mm, and therefore, the size of the packed gravel, that is, the particle size of the filter member 3a is determined based on the size of the slit 2a instead of the size from the water collection layer particles. Therefore, the so-called trisection (about 9 mm)
, Or two-part gravel (under a sieve of about 6 mm), and only relatively coarse ones could be used. In other words, regardless of whether the sampling layer is a gravel layer or a sand layer, regardless of the size, the filling gravel and the size of the strainer slits 2a had to be all uniform, and as a result, there were many wells where sand came out. Was.

In order to solve the above-mentioned disadvantage, Japanese Patent Application No. 8-12 / 1996
No. 6303 is filed for a method for excavating wells and a filter for a protective tube used therefor (hereinafter referred to as Invention A), and a Japanese Patent Application No. 8-162388 is filed for a "water-blocking packer" (hereinafter referred to as Invention B). Was. In the invention A, as shown in FIG. 10, a well hole 6 having a depth reaching a deep groundwater layer is drilled, and a protection pipe 7 is inserted into this hole. At the lower end of the protective tube 7, a plurality of slits 7a are formed in the outer peripheral surface,
On its outer periphery, a cylindrical shape of a predetermined thickness made of non-woven fabric,
The fibers were piled up in a tongue-and-blade manner, and this nonwoven fabric was provided with a protective tube filter 7b whose inside was dense and gradually coarsened toward the outside. Then, along the outer circumference of the protective tube 7, the seal ring 8 is
It was inserted to a predetermined depth at the inner upper portion, and the space between the inner wall of the hole and the outer periphery of the protective tube 7 was sealed to the ground surface with a cement-based solidifying material 8a. The pumping pipe 9a was inserted into the protection pipe 7, and the upper end thereof was connected to the well pump 9b on the ground.

[0004] Next, as shown in Fig. 11, in the invention B, as shown in Fig. 11, the protection pipe 7 of the invention A has a position immediately below the solidified material 8a of the surface layer A, a position of the intermediate clay layer c, and a position above the lower end strainer 7c. A water-blocking packer 8b was provided to prevent surface water at position A and contaminated water from the gravel layer B above it at position c. E is a pebble layer. At this position, there is a lower end of the protection tube 7, where a strainer 7c around which a filter 7b for the protection tube is wound is installed. The sediment from the ground and the spring water from above were cut off, and the spring water that was not contaminated only by the pebble layer E, which was the lowest layer, was collected.

[0005]

However, the conventional "well drilling method" shown in FIG. 9 not only has a large amount of sand penetrating into the well protection tube 2 as described above, but also has a well hole 1
After excavation, the protective tube 2 is inserted into the outer tube, and when the gravel of the filter member 3a is filled while removing the outer tube, the gravel becomes wedge-shaped in the gap between the outer tube and the protective tube 2, and the outer tube is pulled out. In some cases, the protection tube 2 is in an up state and the protection tube 2 cannot be installed.

In the case of using a cylindrical sponge-shaped protection tube filter 7b made of non-woven fabric for the strainer 7c as in the inventions A and B, fine sand hardly permeates into the protection tube 7. However, as shown in FIG. 12, gravel-like pebbles 8c having a large particle size are fitted between the outer fibers 7d,
There was a drawback of clogging.

Further, in the case where gravel is used as the filter member 3a shown in FIG.
In the case of the invention B, since the protective tube filter 7b has a cylindrical shape and a large thickness, the inner diameter of the outer tube is 3 to more than the outer diameter of the protective tube 2, 7 when the respective well holes 1 and 6 are excavated. I had to make it bigger than 4 inches.

[0008] The present invention has been made in view of the above-described circumstances, and the amount of fine sand entering the strainer is small.
In addition to providing a method of excavating a deep well in which a filter wound around a strainer has less clogging, the diameter of an outer tube for drilling a well hole can be reduced, and a protective tube does not rise during construction. It is.

[0009]

In order to achieve the above object, a method for excavating a deep well according to the present invention comprises: (1) a step of drilling a well hole having a predetermined depth in the ground with a double pipe; (3) a step of removing the inner pipe to the ground while leaving the pipe as it is, (3) a step of inserting a protective tube in which a woven fabric is wound around the lower strainer outer periphery and affixed to the outer pipe to the bottom of the hole, (4) A step of introducing sand that is a filter material having a particle size of about 1 to 2 mm from between the outer tube and the protective tube while removing the outer tube, (5) a well hole to a depth of an upper impermeable layer below the surface water layer; And (6) a step of inserting a pumping pipe into the protection tube to a predetermined depth.

The woven fabric has a thickness of about 2 mm or less and is formed of continuous glass fibers.
It is 60 plain weaves.

[0011] The woven fabric has a thickness of about 2 mm or less, and is formed of continuous synthetic fiber.
It is 60 plain weaves.

A sand trap is provided at the lower end of the protective tube, and a claw protrudes obliquely upward from the outer circumference thereof, and a plurality of anchors having the outer diameter of the tip substantially the same as the outer tube are protruded.

Further, the protective tube is provided with a plurality of grout hoses extending from the upper end to predetermined positions having different depths and attached to the protective tube. In some cases, the grout material is injected through the hose.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The method for excavating a deep well according to the present invention includes:
First, a well hole having a predetermined depth is drilled in the ground with a double pipe. The predetermined depth is up to the lower impermeable layer shown by e in FIG.
In this case, it is efficient to use a rotary percussion drill. Next, as shown in FIG. 4, the inner pipe 12 is pulled up to the ground. In the figure, reference numeral 11 denotes an outer tube.

Next, as shown in FIG. 5 and FIG.
1 is inserted into the outer tube 11 to the bottom of the hole.
A strainer 22 is provided at the lower part of the woven fabric. A woven fabric 60 is usually wound once around the outer periphery of the strainer 22 and attached with rubber glue or the like, and its cross section is as shown by reference numeral 30 in FIG. ing. However, the woven fabric 30 may not be attached to the entire surface of the strainer 22, but may be glued only to the joint where the upper and lower ends of the strainer 22 and the woven fabric partially overlap. In the opening of the strainer 22, holes of 20 mm diameter are formed at a pitch of 60 mm.
It is sufficient that 0 is not drawn in and the strength of the strainer 22 is maintained. FIG. 2 is a diagram in which the woven fabric 30 is wound around the strainer 22 and shows a case where a slit 22a is provided.

The strainer 22 is located in the aquifer d shown in FIG. As shown in FIG.
Of the woven fabric 30 while the well is in use.
Is flat, and particles of the sand 41 (particle diameter: about 1 to 2 mm) abut on the outside of the yarn 31, so that the particles do not get caught in the eyes of the yarn 31, so that clogging does not occur. The spring water passes between the fibers 31a of the yarn 31.

The thickness of the woven fabric 30 is about 2 mm.
In the following plain weave, the yarn 31 is 15 to 60 per 25 mm in length and width.
The fibers 31a of the yarn 31 are preferably continuous fibers (filaments), and the fiber 31a of the yarn 31 is preferably a fiber generally called a glass fiber cloth. It may be made of fiber.

Next, as shown in FIG. 7, the buried material having a grain size of about 1 to 2 mm as shown by an arrow f from the ground between the outer tube 11 and the protective tube 21 while pulling out the outer tube 11. Sand 41
Input. The protection tube 21 has an outer diameter of 60 mm in this embodiment.
A VP 50 is used, and a sand trap 23 having the same material (or another material) and a cylindrical lower end closed as shown in FIGS. 1 and 3 is integrated with or separate from the strainer 22 at the lower end thereof. At its lower part, two pairs of anchors 5 projecting obliquely upward from the outer periphery and having the same outer diameter as the outer tube 11 are provided.
0,50 protrudes. As shown in FIGS. 3 (a) and 3 (c), the structure is such that a pair of claws 51, 51 which penetrate the sand trap 23 and project outward and obliquely upward, are bent. The material of the anchor 50 may be 0.
A stainless plate having a thickness of 2 to 0.5 mm is preferable. Anchor 50
Is to prevent the protective tube 21 from rising together when the sand 41 is charged while removing the outer tube 11.
It may not be necessary depending on the case. Further, the sand trap 23 may not be provided only by extending the lower portion of the strainer 22.

Next, as shown in FIG. 1, the well hole 60 and the protective pipe 21 are extended to the depth of the upper impermeable layer c below the surface water layer b.
During this time, a cement grout material is introduced from the ground surface and solidified to form a seal grout 61. In this case, as shown in FIGS. 1 and 3A and 4B, four grout hoses 71 to 74 are extended from the upper end of the protective tube 21 to predetermined positions having different depths, and Is pasted on. The open positions of the lower ends of the grout hoses 71 to 74 are distributed and arranged at a depth up to the upper water-impermeable layer c, and even if a hole wall of a certain depth collapses during construction of the seal grout 61,
A cement grout material is injected from a grout hose 70 having a lower end opened above and below, and a seal grout 61 is formed.
Can be formed. The grout hose 70 may be a vinyl-based commercial product. The grouting hose 70 is not required on the ground where there is no risk of collapse of the hole wall, but the provision of the grouting hose 70 can ensure the work.

Next, a pumping pipe (not shown) is inserted into the protection pipe 21 to a predetermined depth. A deep well pump (not shown) installed on the ground is connected to the pumping pipe.

The pumping will be described with reference to FIG. Since the seal grout 61 is constructed up to the upper impervious layer b, the sewage flowing on the ground surface, the sewage that has permeated the topsoil layer a, and the sewage flowing out from the surface water layer b are separated by the seal grout 61 and the upper impervious layer c. Will be shut off. Then, the spring water of the uncontaminated aquifer d passes through the sand 41 of the buried material, flows into the protective tube 21 via the woven fabric 30 → the strainer 22, and
It is pumped to the ground by a deep well pump via a water pump. A small amount of fine sand passing through the woven fabric 30 accumulates in the sand trap 23.

[0022]

According to the present invention described in detail above,
The following effects are obtained. (1) In the conventional method of digging a well filled with a gravel filter member between a protective tube and a well hole, the protective tube often rises when the outer tube is pulled out, but in the case of the present invention,
Since the filter material is filled with sand having a particle size of about 1 to 2 mm instead of gravel, there is no rise. In addition, a sand trap is provided at the lower end of the protection tube, and a structure in which a plurality of anchors are protruded from the sand trap completely prevents the rise.

(2) In the present invention, since the woven fabric is wound around the strainer and its outer periphery is filled with sand of about 1 mm to 2 mm, there is no clogging and the well (in the protection tube)
Is not clogged with sand and the pumping performance does not fall.

(3) Since the woven fabric is thinner than the conventional fender-shaped filter for a protective tube and the filter member is made of sand instead of gravel, the inner diameter of the outer tube is smaller than the outer diameter of the protective tube when drilling. Drilling efficiency is improved because it is only necessary to be about 10 to 20 mm larger.

(4) When grouting hoses having different lengths for grouting material injection are provided above the protective tube, the grouting material can be injected to a required depth even if the hole wall is collapsed.

[Brief description of the drawings]

FIG. 1 is a cross-section after construction showing one embodiment of the present invention.

FIGS. 2A and 2B are diagrams in which a woven fabric is wound around a strainer used in the excavation method of the present invention, wherein FIG. 2A shows a longitudinal section, and FIG. 2B shows a side surface excluding a part of the woven fabric.

3A and 3B are explanatory views of a grouting hose and an anchor used in the present invention, wherein FIG. 3A shows an arrangement of a grouting hose and an anchor, and FIG. 3B shows a plane on which the grouting hose is attached to a protective tube. , (C) show cross sections in which the anchor is attached to the sand trap.

FIG. 4 is an explanatory view showing a process of the present invention.

FIG. 5 is an explanatory view showing a process of the present invention.

FIG. 6 is an explanatory view showing a process of the present invention.

FIG. 7 is an explanatory view showing the process of the present invention.

FIG. 8 is an explanatory diagram of a use state of a woven fabric used in the present invention.

FIG. 9 is a cross-sectional view illustrating a conventional well excavation method.

FIG. 10 is a cross-sectional view illustrating a conventional well excavation method.

FIG. 11 is an explanatory view in a case where a water-blocking packer is used in a conventional well excavation method.

FIG. 12 is an explanatory diagram of a use state of a protective tube filter used in a conventional well excavation method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Outer pipe 12 Inner pipe 21 Protective pipe 22 Strainer 23 Sand trap 30 Woven cloth 31 Thread 31a Fiber 41 Sand 50 Anchor 51 Claw 60 Well hole 61 Seal grout 70, 71, 72, 73, 74 Hose for grout b Surface water layer c Upper impermeable layer

Claims (5)

[Claims] 1. A method for drilling a deep well by the following steps: (1) drilling a well hole of a predetermined depth in the ground with a double pipe, (2) extracting the inner pipe to the ground while leaving the outer pipe as it is (3) a step of inserting a protective tube in which a woven fabric is wound around the lower strainer outer periphery and affixed to the bottom of the hole into the outer tube, and (4) the outer tube and the protective tube while removing the outer tube. (5) grouting material from the ground surface between the well hole and the protective tube to the depth of the upper impermeable layer below the surface water layer, (6) a step of inserting a pumping pipe to a predetermined depth in the protective tube, 2. The woven fabric has a thickness of about 2 mm or less, and is formed of continuous fiber glass fibers. 2. The method for excavating a deep well according to claim 1, wherein the excavation is a plain weave. 3. The woven fabric has a thickness of about 2 mm or less, and 15 to 60 yarns of 25 mm in length and width, which are made of synthetic fibers of continuous fibers, are not twisted or slightly laid. 2. The method for excavating a deep well according to claim 1, wherein the excavation is a plain weave. 4. A sand trap is provided at the lower end of the protective tube, a claw projects diagonally upward from the outer circumference thereof, and a plurality of anchors having a tip whose outer diameter is substantially the same as that of the outer tube are provided. The method for excavating a deep well according to claim 1, 2, or 3, wherein: 5. A plurality of grout hoses extending from the upper end to predetermined positions having different depths are attached to the protective tube, and are provided with a plurality of grout hoses. 5. The method for excavating a deep well according to claim 1, wherein the grout is injected through the hose.