JPH05287724A - Check valve for casing pipe for grout - Google Patents

Abstract

PURPOSE:To conduct boring work and the impregnation of a grout smoothly by installing a closing sheet having strength not damaged by the pressure of boring water onto the inner circumferential surface of a casing pipe for the grout and covering a discharge opening. CONSTITUTION:In a check valve 4 composed of a discharge opening 34, a valve sheet 41 closing the inside and outside of the discharge opening and a closing sheet 42, the closing sheet 42 has strength, in which the sheet 42 is not damaged at slime discharge pressure and damaged for the first time at grout impregnation pressure higher than the slime discharge pressure at the time of boring. Boring and grout impregnation operation are conducted by using a casing pipe 2 with such a check valve 4. Consequently, the state of the closing of the discharge opening 34 is maintained by the working of the closing sheer 42 at the time of boring, thus preventing an outflow to the bedrock side of slime 5. When grout is impregnated, the closing sheet 42 is broken and the inside of the discharge opening 34 is opened when the pressure of a grout material is increased and made larger than the rupture strength of the closing sheet 142, and the grout material elastically deforms the valve sheet 41 and infiltrates into a bedrock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a check valve for a grout casing pipe.

[0002]

2. Description of the Related Art A grout casing pipe is a hollow pipe having both a boring function and a grout injection function, and is provided with a check valve for discharging grout material while preventing backflow from the peripheral surface. In this check valve, a rubber ring is arranged on the outer peripheral surface of the casing pipe to cover the discharge hole, or a valve seat provided inside the discharge hole and a valve ball urged in the seating direction of the valve seat. A valve mechanism constituted by

[0003]

Problems to be Solved by the Invention The conventional check valve of this type has the following problems. <B> When the casing pipe is used as the outer pipe for perforation by a double pipe method, the space between the peripheral surfaces of both pipes serves as a discharge path for slime containing drilling water. Therefore, when the pressure of drilling water is applied from the inside of the check valve, the check valve easily opens. When the check valve opens, drilling water flows out to the natural ground side through this check valve, and drilling becomes impossible. <B> In addition, since slime containing cutting soil also forms a discharge path between the outer periphery of the casing pipe and the hole-drilling wall, foreign matter is trapped and the check valve function is impaired. Cause trouble.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to ensure the reliability of a check valve with a simple improvement and to perform drilling work and grout. It is intended to provide a check valve for a casing pipe for grout, which can smoothly perform an injection work.

[0005]

DISCLOSURE OF THE INVENTION The present invention is directed to a reverse casing of a grout casing pipe in which a discharge hole formed in the peripheral surface of a grout casing pipe is covered with a valve seat to prevent backflow from the outside to the inside of the pipe. In the stop valve, a check valve for a grout casing pipe is characterized in that a sealing sheet having a strength that does not damage at least the pressure of drilling water is attached to the inner peripheral surface of the pipe to cover the discharge hole.

[0006]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings.

<A> Overall Structure FIG. 1 shows an example of a casing pipe 2 in which an inner rod 1 for drilling is inserted. The casing pipe is a tubular body whose both ends are open, and is connected via a coupling 3 to adjust the total length. In this embodiment, a case where a check valve 4 is formed at a connecting portion between a casing pipe 2 and a coupling 3 will be described.

<B> Casing Pipe Both ends of the casing pipe 2 are formed with a large inner diameter to form a fitting port 21, and a female screw which can be screwed into the coupling 3 is formed on the peripheral surface of the fitting port 21. It is engraved. The casing pipe 2 has a plurality of discharge holes 22 formed in the circumferential surface of at least one end thereof in the circumferential direction. Further, a concave groove 23 is formed facing the discharge hole 22 on the inner peripheral surface of the fitting port 21 where no ridge is formed. The groove 23 is an annular space between the peripheral surfaces of the casing pipe 2 and the coupling 3 for allowing elastic deformation of the valve seat 41, which will be described later.

<C> Coupling The coupling 3 is a connecting cylinder for connecting the casing pipes 2, and has a large diameter portion 31 equal to the outer diameter of the casing pipe 2 and small diameter portions formed on both sides of the large diameter portion 31. 32a, 3
2b and. Male threads are engraved on the outer peripheral surfaces of both the small diameter portions 32a and 32b, but one small diameter portion 32a is not engraved over a certain range from the end. As shown in FIGS. 2 and 3, in the vicinity of the end of the outer peripheral surface of the small diameter portion 32a in which no screw is engraved, a housing groove 33 is provided in the circumferential direction and faces the housing hole 33. A plurality of discharge holes 34 are opened. An endless type valve seat 41 is externally mounted on the housing groove 33 to close all the discharge holes 34 from the outside. In consideration of the wall thickness of the valve seat 41, the recessed depth of the housing groove 33 is set at least to a depth at which the valve seat 41 does not protrude from the outer peripheral surface of the small diameter portion 32a. Also, the small diameter part 3
An annular groove 35 is provided along the circumferential direction on the inner peripheral surface corresponding to the accommodation groove 33 of 2a, and a tape-shaped sealing sheet 42 is attached to this annular groove 35 to close the discharge hole 34 from the inside. ing. Since the annular groove 35 functions to prevent the sealing sheet 42 from protruding from the inner peripheral surface of the coupling 3 so as to be difficult to peel off, if the sealing sheet 42 can be attached so as not to easily peel off, the annular groove 35 In some cases, 35 may be omitted. Incidentally, reference numeral 36 in the figure denotes a seal material mounted on the outer periphery of the end of the small diameter portion 32a.

<D> Check Valve The check valve 4 is composed of the discharge hole 34, the valve seat 41 that closes the inside and outside of the discharge hole 34, and the closing seat 42. The valve seat 41 that closes the outside of the discharge hole 34 is made of an elastic material such as rubber that blocks the entry of fluid from outside the tube into the tube. Further, as the sealing sheet 42 for sealing the inside of the discharge hole 34, a film or sheet having a strength not to be damaged under a certain pressure is used. The strength of the sealing sheet 42 will be described in more detail as long as the sealing sheet 42 has such strength that it will not be damaged by the slime discharge pressure at the time of punching and will be damaged only by the grout injection pressure higher than the slime discharge pressure. Blocking sheet 4
As the attaching means for No. 2, known attaching means such as adhesion or screwing can be adopted.

[0011]

Next, a method of using the casing pipe will be described.

<A> At the time of perforation A ring bit is attached to the tip of the casing pipe 2 shown in FIG. 1, and inner bits are attached to the tips of the inner rods 1 inserted in the casing pipe 2, respectively. Is applied to the casing pipe 2 at the same time, to the casing pipe 2 to start perforation. Upon drilling, the axial path of the inner rod 1 is used as a drilling water supply path. As shown in FIG. 1, the slime 5 including the ground soil is discharged as a mainstream discharge path between the inner surfaces of the inner rod 1 and the casing pipe 2.
The pressure P ₁ of this slime 5 (usually about 4 kg / cm ² )
As shown in FIG. 2, the blocking sheet 42 acts outward, but since the breaking strength of the blocking sheet 42 is set to be larger than the pressure P _{1 of the} slime 5, the blocking sheet 42 closes the discharge hole 34. Maintain the condition and prevent the slime 5 from flowing out to the natural side. Further, the slime 5 may pass between the casing pipe 2 and the hole wall, but since the valve seat 41 forming the check valve is stored inside the casing pipe 2, the valve seat 41 may be turned over. Without this, the discharge hole 34 is blocked to prevent the backflow of the slime 5.

<B> At the time of pouring grout In place of the inner rod 1, for example, a pouring pipe equipped with a double packer is inserted into the casing pipe 2, and grout material such as mortar is placed in a sealed space region defining the inner space of the casing pipe 2. When discharged at a high pressure, the pressure of the grout material acts on the inner surface of the sealing sheet 42 as a pressure P ₂ (usually about 20 kg / cm ² ) as shown in FIG. When the pressure P _{2 of the} grout material increases and becomes larger than the breaking strength of the blocking sheet 42, the blocking sheet 42 breaks and the inside of the discharge hole 34 is opened. Then, the grout material elastically deforms the valve seat 41 as shown by the arrow to open the discharge hole 34,
It penetrates into the ground through both discharge holes 34 and 22. Further, the valve seat 41 prevents the backflow of the grout material through the discharge hole 34, since it is the same as before, and the description thereof will be omitted.

[0014]

[Embodiment 2] As shown in FIG. 5, a valve seat 41 is mounted on the outer periphery of the end portion of the casing pipe 2 so as not to protrude from the peripheral surface of the casing pipe, and a sealing sheet 42 is attached to the inside of the casing pipe 2. Both sides of the discharge hole 22 may be closed.

[0015]

Since the present invention is as described above, the following effects can be obtained.

<a> Since the sealing sheet that seals the inside of the discharge hole protects the check valve without being broken by the slime pressure during perforation, the check valve functions normally when pouring grout material, and the check valve works normally. Improves reliability of valve function.

<B> Since the sealing sheet is set to have a strength to be broken by the grout injection pressure, there is no fear of adversely affecting the grout injection. Therefore, the boring work and the grout injection work can be performed smoothly.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a casing pipe for grout having a check valve.

FIG. 2 is an enlarged sectional view of a check valve.

FIG. 3 is a perspective view in which a part of the coupling is omitted.

FIG. 4 is an explanatory diagram of a check valve during grout injection.

FIG. 5 is an explanatory diagram of the second embodiment.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Takahiko Ohara 1-25-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Within Taisei Corporation (72) Inventor Haruo Kawai 3-700, Miyahara-cho, Omiya-shi, Saitama Nariwa Kiko Co., Ltd. Omiya Plant (72) Inventor Masatoshi Okabe 3-700 Miyahara-cho, Omiya City, Saitama Seiwa Kiko Co., Ltd. Omiya Plant

Claims (1)

[Claims] 1. A check valve of a grout casing pipe for covering a discharge hole formed in a peripheral surface of a grout casing pipe with a valve seat to prevent backflow from the outside to the inside of the pipe. A check valve for a casing pipe for a grout, characterized in that a sealing sheet having a strength that does not damage at least the pressure of drilling water is attached to the surface to cover the discharge hole.