JP2010037742A - Return apparatus and rock bolt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a return apparatus capable of confirming both the concentration of a fluid and a fluid pressurizing situation and suitably used for work requiring confirmation of both of these characteristics. <P>SOLUTION: The return apparatus 32 includes an openable/closable first valve 41, a second valve 42 opened with a predetermined fluid pressure, and a branch pipe 43 connected to each of the first and second valves to lead a fluid to these valves. The second valve 42 includes: a cylinder part provided with an inlet passage at one end, and an outlet passage in the middle; a spring disposed inside the cylinder part, on the side opposite to the inlet passage; and a piston rod normally blocking a passage between the inlet passage and the outlet passage by the spring force of the spring and opening the passage between the inlet passage and the outlet passage by pressing in the spring with a predetermined fluid pressure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a return device and a lock bolt including the return device, and more particularly, to a return device suitable for use in injecting a fixing material after a lock bolt is installed and a lock bolt including the return device.

In tunnel construction such as mountains, as shown in FIG. 9, a natural space 1 is excavated to form a tunnel space 2, for example, sprayed concrete is applied to the walls of the tunnel space 2 as necessary, and the walls go into the bedrock. The lock bolt 4 is driven, and then a fixing material such as cement or resin is injected to fix the lock bolt to the ground. By doing as described above, the ground near the inner wall of the tunnel can be strengthened, and by supporting it with the ground inside the rock mass, it is possible to prevent the surrounding wall from collapsing.
10A and 10B are configuration diagrams of a conventional post-injection lock bolt with a packer. FIG. 10A is an overall view, and FIG. 10B is an enlarged view of the mouth. The post-injection type lock bolt with a packer includes a hollow bolt 11 installed in a hole (bore hole) HL opened in a natural ground, a packer 12 attached to the mouth of the hollow bolt 11 to close the hole, and a packer 12 Packer injection hose 13 for injecting under pressure and expanding in the radial direction, fixing material injection hose 14 for injecting a fixing material such as mortar and cement milk into the hole, and the mouth of the hollow bolt 11 (return) The valve 15 is connected to the mouth) so as to be freely openable and closed, and has a washer 16 and a nut (not shown) for pressing and fixing the lock bolt to the ground. The hollow bolt 11 is, for example, a hollow atypical screw node hollow rebar with a special screw formed on the outside.

  The construction of the post-injection lock bolt with a packer is to drill a hole in the ground, insert and set the lock bolt in the hole (bore hole) HL, then expand the packer 13 to close the hole, and then fix The material is injected into the hole, and the fixing material (return material) injected into the hole is returned from the tip of the hollow bolt 11 to the return port through the bolt hollow portion, so that the fixing material is filled to the back of the hole. Determine and close valve 15 to complete the injection. In addition to the configuration shown in FIG. 10, the post-injection type rock bolt with packer expands in the radial direction by pressurizing the packer, closely adheres to the hole wall, and pressurizes the cement milk as a fixing material to the surrounding soil. Have also been proposed (Patent Document 1).

By the way, when there is spring water at the place where the rock bolt is installed, that is, when groundwater is springing out from the ground behind the packer, in the above construction method, the injected fixing agent is washed away from around the bolt by the spring water. However, the fixing material in the bore hole is thinned and the fixing of the bolt becomes insufficient. Therefore, with a packer that fills the water-permeable packer with water-absorbing polymer powder and cement powder and closes the mouth of the borehole while blocking the water with the packer, and injects the fixing agent into the back of the hole A lock bolt has been proposed (Patent Document 2). Operations such as injection, stop, pressurization, and holding of the fixing material in the lock bolt are performed by opening and closing the valve 15 while an operator visually observes a pressure gauge provided in any of the flow paths.
JP-A-11-117698 JP 2006-118130 A

However, when there is a lot of spring water in the bore hole and the spring water pressure in the bore hole is high, even if the mouth of the bore hole is closed with a packer as in Patent Document 2, the water WT overflows in the back of the hole as shown in FIG. . For this reason, even if the operator determines that the fixing material has been sufficiently charged by confirming the return and completes the injection of the fixing material, the fixing material is diluted with water and the concentration of the fixing material in the hole is reduced. May be less than the appropriate value, and sufficient fixing strength may not be obtained. Therefore, if the return valve is closed to increase the injection pressure, a problem arises that the material pressure feed pump is subjected to a large load and the pump stops. In this way, when a viscous material such as a fixing material is pumped into a space where some pressure such as water pressure has already been applied to fill the space, a large load is applied to the material pump and the pump However, even if it can be pumped at a high pressure, the concentration of the actually filled material is diminished, and there is a problem that a reliable injection material filling operation is very difficult.
As described above, an object of the present invention is to provide a return device capable of filling a material of an appropriate quality while reducing the load applied to the material pressure pump as much as possible, and a lock bolt using the return device. .
It is an object of the present invention to provide a return device that can confirm both the concentration of fluid and the pressurization state of the fluid, and is suitable for work that requires confirmation of both characteristics. .

The present invention is a return device and a lock bolt including the return device.
Return Device The return device of the present invention is connected to each of the first valve that can be opened and closed, the second valve that opens at a predetermined fluid pressure, and the first and second valves, and fluid is supplied to these valves. And a branch pipe leading to The second valve includes a cylinder portion having an inlet passage at one end and an outlet passage in the middle, a spring disposed on the opposite side of the inlet passage in the cylinder portion, and usually a spring of the spring. A piston rod that closes the flow path between the inlet passage and the outlet passage by force and pushes the spring with the predetermined fluid pressure to open the flow path between the inlet passage and the outlet passage is provided. The fluid contact portion of the piston rod is formed in a spherical shape.

Lock bolt The lock bolt of the present invention includes a hollow main body installed in a hole, a packer attached to the mouth of the main body to close the hole, and an injection part for injecting a fixing material into the hole. A return device connected to the hollow body in a form communicating with the hole partitioned by the packer, the return device being opened and closed with a predetermined injection pressure. A second valve and a branch pipe connected to the hollow main body and guiding a return material flowing in from the hollow main body to each of the first and second valves are provided.

According to the return device of the present invention, the material is returned from the first valve that can be opened and closed regardless of the pressure in the flow path, the concentration of the return material is determined, and the return material reaches the appropriate concentration. Close the first valve, pressurize the flow path until the second valve is opened, and return the return material from the second valve to confirm that the inside has been pressurized and filled at a predetermined pressure. It becomes possible. That is, the return device of the present invention can confirm both the concentration of the fluid and the pressurization state of the fluid, and is suitable for use in work requiring confirmation of both of these characteristics.
Further, according to the return device of the present invention, when the flow path is clogged, the clogging can be removed by manually opening and closing the first valve and pumping, and the load on the material pump can be reduced.
Furthermore, according to the present invention, the fluid contact surface of the piston rod is rounded, so that the gap between the inlet passage portion and the outlet passage portion does not open at once, and the return material is returned little by little. Without this, it is possible to detect the discharge of the return material while maintaining the injection pressure substantially at the set pressure P2 to complete the injection, thereby enhancing the fixing effect.

  Also, if a lock bolt is constructed by assembling a return device at the mouth end of the hollow bolt of the present invention, when injecting the fixing material, the material is returned from the first valve, the concentration of the return material is judged, and the return Close the first valve after the material has reached the proper concentration, pressurize the flow path until the second valve is open, and stop the injection when the second valve opens and the return material returns As a result, the fixing material can be injected so that the borehole and the spring water from the vicinity of the borehole are suppressed and the concentration in the hole is appropriate. In addition, it is possible to fill a material of an appropriate quality while reducing the load applied to the material pressure pump as much as possible.

-Rock bolt construction device Fig. 1 is an overall configuration diagram of a rock bolt construction device when the return device of the present invention is applied to rock bolt construction, and after a driller (bore hole) 22 already formed in a natural ground 21 is packed with a packer. The state where the injection type lock bolt 23 is installed is shown.
A post-injection type lock bolt 23 with a packer includes a hollow bolt 23a installed in a bore hole 22 and a water-permeable cloth bag-like packer 23b attached to the mouth of the hollow bolt 23a to close the hole. , A packer injection hose 23c for injecting the packer 23b under pressure and expanding in the radial direction, and a fixing material injection hose 23d for injecting a fixing material such as a grout material into the hole.
A cement grout material is injected into the packer 23b. When cement grout material is injected, the water-permeable packer 23b oozes out only the moisture inside, and the inside of the packer is filled in a hardened state, and the expanded packer adheres to the hole wall of the borehole. Then temporarily seal the borehole.

  The hollow bolt 23a is a hollow irregularly shaped screw node hollow rebar with a special screw formed on the outside as shown in FIG. 2 (A), and increases the adhesion force with the grout material by using the irregularly shaped screw node. Can do. In addition to the above components, the lock bolt 23 has a washer 23e and a special nut 23d for pressing the lock bolt against the ground as shown in FIGS. 2 (B) and 2 (C). . The washer 23e is provided with a bolt insertion hole H1, a fixing material injection hose insertion hole H2, and a packer injection hose insertion hole H3. The special nut 23d includes a cylindrical screw portion 23d-1 and a head portion 23d-2 in which screws to be screwed with the screw portion of the hollow bolt 23a are provided. The cylindrical screw portion 23d-1 is provided with a plastic cap CP for edge cutting. It is installed.

Returning to FIG. 1, a pressure gauge 31 for measuring the pressure in the exhaust / return side flow path is connected to the end of the hollow bolt 23 a on the mouth side, and a return device 32 is connected to the pressure gauge 31. As will be described in detail later, the return device 32 is opened at a predetermined pressure P2 (for example, 2 MPa: 2 megapascals) greater than the pressure P1 of the spring water in the borehole and a first valve (return valve) 41 that can be opened and closed freely. A second valve (release valve) 42 that connects to each of the first and second valves 41 and 42, and a branch pipe 43 that guides the return material flowing in from the hollow bolt 23a of the lock bolt to these valves. Yes. The pressure gauge 31 is for confirming that the release valve 42 is opened at the injection pressure P2, and is not necessarily required.
The outlet of the return valve 41 serves as a return port for the return material, and the return port is provided with a concentration measuring unit 33 for measuring the concentration of the return material. The well-known P funnel measurement can be employed for the measurement of the concentration of the return material. The release valve 42 is connected to a switching valve 34 that opens and closes the flow path to the release port. The switching valve 34 can be attached to and detached from the release valve 42 by screwing.

A hand mixer 35 is provided on the grout material injection side, and a grout material as a fixing material is kneaded and fed into a mixing pressure pump 36 (the hand mixer 35 is adapted to the mixing capacity of the mixing pressure pump). Can be omitted). The mixing pressure feed pump 36 mixes the introduced grout material and injects it into the bore hole from the fixing material injection hose 23d. A pressure sensor 37 is disposed in the output side grout material passage of the mixing pressure feed pump 36, and the mixing pressure feed pump 36 stops the pressure feed of the grout material when the injection pressure on the injection side becomes larger than a set value. The fixing material injection hose 23d is provided with a valve 38 for controlling the passage of the grout material.
As described above, the mixing pressure feed pump 36 is connected to the fixing material injection hose 23d of the lock bolt 23 via the pressure sensor 37, and the return device 32 and the switching valve 34 are provided on the exhaust / return side of the lock bolt. Is open at the return port and release port connected.
FIG. 3 is an enlarged view of the mouth portion of the lock bolt, and the same parts as those in FIG. One end of the pressure gauge 31 is connected to the end of the hollow bolt 23 a, and the other end of the pressure gauge 31 is connected to the first end 43 a of the T-shaped branch pipe 43 of the return device 32. A return valve 41 is connected to the second end 43b of the branch pipe 43, and the respective parts are connected to each other by screwing. The release valve 42 to which the switching valve 34 is assembled has a T-shaped shape as a whole, the fluid inlet side is connected to the third end 43c of the branch pipe 43 by a lever type pressure-resistant joint 44, and the fluid outlet side is switched by a screw. It is connected to the valve 34. The packer injection hose 23c is provided with a valve 39 for controlling the passage of the grout material.

Release valve Fig. 4 is a sectional view of the release valve assembly, (A) shows the closed state of the flow path, (B) shows the open state of the flow path, Fig. 5 is an exploded view of the release valve, and Fig. 6 shows the release state. It is operation | movement principle explanatory drawing of a valve | bulb.
The release valve 42 includes a piston cylinder 51, a spring 52, a spring pressing member 53, a piston rod 54, and a connecting portion 55 as shown in FIG. The piston cylinder 51 has a cylindrical inlet passage portion 51a with a thread TH1 cut therein, a cylindrical cylinder portion 51b that communicates linearly with the inlet passage portion, and an outlet passage portion 51c that communicates perpendicularly with the cylindrical cylinder portion. is doing. A spring 52, a spring pressing member 53, and a piston rod 54 with an O-ring 54a are fitted into the cylindrical cylinder portion 51b. A connecting portion 55 is attached to the inlet passage portion 51a of the piston cylinder 51 by screwing with a screw TH1 formed therein, and at the time of attachment, one end of the connecting portion 55 abuts on the piston rod 54 and springs. Thus, a predetermined spring force is applied to the piston rod 54 from the spring.
Normally, as shown in FIG. 4 (A), the piston rod 54 blocks the entrance passage 51a and the exit passage 51c while the spring 52 is pressed. However, when the return material arrives as shown in FIG. 4B and a predetermined injection pressure P2 that overcomes the spring force of the spring is applied, the piston rod 54 moves in the direction in which the spring 52 is compressed (to the right). As a result, the flow path between the inlet passage 51a and the outlet passage 51c is opened, and the return material can move in the direction of the release port. A screw TH2 is formed on the outer periphery of the distal end of the outlet passage 51c, and the switching valve 34 can be attached and detached by screwing.

  The connecting portion 55 has a cylindrical hollow portion 55a formed therein, and a screw TH3 is formed on the outer peripheral portion of the hollow portion on the cylinder side. With this screw TH3, the connecting portion 55 is screwed into a screw TH1 formed inside the inlet passage portion 51a of the piston cylinder 51 so that it can be attached to the piston cylinder 51. One end abuts against the piston rod 54 and presses the spring 52, whereby a predetermined spring force acts on the piston rod 54 from the spring. Further, a screw TH4 is formed on the outer peripheral portion of the hollow portion 55a of the connection portion 55 on the branch pipe side, and is screwed with a screw formed on the lever type pressure joint 44, so that the lever type pressure joint 44 is connected to the connection portion 55. It can be installed. The screws TH3 and TH4 are separated by a circumferential projection 55b, and an O-ring 55c is fitted into the non-threaded portion of the tip of the screw TH3.

The lever type pressure-resistant joint 44 includes an insertion portion 44a into which the third end portion 43c of the branch pipe 43 is inserted, a nut portion 44b in which a screw that engages with the screw portion TH4 of the connection portion 55 is formed, and a plurality of opening / closing operations. A lever 44c is provided. When the lever type pressure-resistant joint 44 is attached to the connection part 55 of the release valve 42 by the nut part 44b and the lever 44c is opened, the third end part 43c of the branch pipe 43 abuts against the abutting part 44d from the insertion part 44a. Until the lever 44c is closed, the branch pipe 43 is connected to the connection portion 55 of the release valve.
As shown in FIG. 6A, in the normal state, the piston rod 54 of the release valve 42 has a spring 52 in a direction that blocks the flow path between the inlet passage 51a and the outlet passage 51c (leftward in the figure). Spring force F1 is working. Further, the injection pressure F2 acts on the piston rod 54 in a direction (rightward in the drawing) in which the flow path between the inlet passage 51a and the outlet passage 51c is opened by injection of the fixing material. Accordingly, the injection pressure of the fixing material into the bore hole increases, and at the injection pressure P2 where F2> F1, the piston rod 54 moves to the right as shown in FIG. 6B, and the inlet passage 51a The flow path between the outlet passage portions 51c is opened, the return material flows in the direction of the release port, and is discharged from the release port.

-Rock bolt construction method Fig. 7 shows the construction flow of rock bolts. It is assumed that the return device 32 is already connected to the exhaust / return side of the hollow bolt 23a, and that the switching valve 34 is also attached to the release valve 42.
First, a bore hole 22 is drilled in the natural ground 21 (FIG. 1) (step 100), and a post-injection type lock bolt 23 with a packer is inserted and set therein (step 101).
Next, in order to insert and expand the cement grout material in the packer 23b, the pressure sensor (not shown) is set to a pressure P1 (based on the spring pressure P1) suitable for the packer set (step 102), Packer injection is performed by a pressure pump (not shown) through the packer injection hose 23c (step 103).
When cement-type grout material is injected, the water-permeable packer 23b exudes only the moisture inside, and the inside of the packer is filled in a hardened state, and the expanded packer adheres to the hole wall of the bore hole 22. Seal the borehole temporarily. At this time, the injection pressure becomes P1, and the injection of the cement grout material from the pressure pump is completed. Note that the mixing pressure feed pump 36 and the pressure sensor 37 can also be used as the pressure feed pump and pressure sensor for the packer.

With step 103 completed, the pressure sensor 35 is set to a pressure P3 higher than the spring water pressure P1 (step 104). Note that when the injection pressure becomes higher than a set pressure P3 (for example, 6 MPa (megapascal)), the mixing pressure feed pump 34 stops the pressure feeding of the fixing material in order to stop the load of the machine within the limit.
Next, grout injection from the packer to the back side of the hole is started (step 105). The target of the injection pressure is a predetermined pressure P2 that is larger than P1 and smaller than P3. For example, P2 = 2 MPa (megapascal). Note that at the initial stage of injection, the return valve 41 and the switching valve 34 are opened (step 106, confirmation of return valve opening).
When the grout material is injected into the borehole from the fixing material injection hose 23d, the air or water that has been in the borehole until then passes from the tip opening of the lock bolt through the hollow portion to the return valve 41 of the return device 32. Then, it is discharged from the return valve (step 107).

When the return of the return material is confirmed, the concentration of the return material is detected by the concentration detection unit 33 provided at the return port, and it is determined whether or not the return material has an appropriate concentration (step 108). When spring water dilutes the grout material in the borehole, the dilute grout material is initially discharged as the return material, and the concentration of the return material is not appropriate. If the concentration is not appropriate, the process returns to step 105 to further inject the grout material under pressure.
When the return material reaches an appropriate concentration, the return valve 41 is closed (step 109), and the grout material injection is continued. Since the return valve 41 is closed, the pressure on the exhaust / return side rises and the grouting material is pressurized and injected (step 110). When the injection pressure on the exhaust / return side reaches the set pressure P2, the piston rod 54 moves to the right (see FIG. 4), and the return material is discharged from the release port via the release valve 42 and the switching valve 34 (step). 111 “YES”). If the return material is drained from the release port and the “grouting material concentration OK?” In the next step 112 is “YES”, the switching valve 34 is closed. Thereafter, when the pumping from the mixing pump 36 is continued, the injection pressure on the injection side becomes equal to or higher than the set pressure P3, and the mixing pump 36 automatically stops the feeding of the fixing material. This completes the fixing material injection process. However, if the discharged return material concentration is “NO”, the process returns to step 110 to continue the pressure injection, confirm that the grout material has reached an appropriate concentration, close the switching valve 34, and complete the injection. Migrate to
If the grout material is not discharged from the release port even though the return valve 41 is closed (“NO” in step 111), the return valve 41 is manually opened and closed with the release valve 42 closed. The operation (pumping) is repeated (steps 113 and 114), and after confirming that the grout material has an appropriate concentration, the return valve 41 is closed (step 109) until the return material is discharged from the release valve 42. Repeat the pressure injection (step 110). As a result, it is possible to perform grouting with an appropriate quality without imposing a load on the pump.

Another Embodiment of Release Valve FIG. 8 shows another embodiment of a release valve, and the same reference numerals are given to the same parts as those of the release valve of FIG. The release valve of FIG. 8 differs from the release valve of FIG. 4 in that the end surface 54b of the piston rod 54 is rounded instead of flat, for example, spherical, and the spherical end surface 54b of the piston rod 54 is in contact with the connecting portion 55. This is because the part is notched partially on the outlet passage 51c side, while the other part (the upper part in the figure) is formed to be in close contact. By rounding the surface of the piston rod 54 that receives pressure from the return material in this way, the gap between the inlet passage 51a and the outlet passage 51c does not open at once, and the return material is returned little by little. Without lowering, it is possible to detect the discharge of the return material while maintaining the injection pressure substantially at the set pressure P2, thereby completing the injection, and the fixing effect can be enhanced. On the other hand, it is possible to prevent the return material from clogging between the members, resulting in malfunction of the piston rod 54, so that the release valve can withstand repeated use, or normally as a fixing material. It is also possible to use mortar using sand, which is a material that tends to clog.
In the above, the return device is used for confirming the return of the return material during the construction of the lock bolt. However, the return device of the present invention is not limited to this case, and it is necessary to confirm both the predetermined pressure and the appropriate concentration. In this case, it can be adopted as appropriate.

1 is an overall configuration diagram of a rock bolt construction device that realizes the rock bolt construction method of the present invention. It is explanatory drawing of a lock bolt. It is an enlarged view of the mouth part of a lock bolt. It is an assembly sectional view of a release valve. It is an exploded view of a release valve. It is operation | movement principle explanatory drawing of a release valve. It is a construction flow of rock bolts. It is another assembly sectional view of a release valve. It is support construction explanatory drawing in tunnel construction. It is a block diagram of the conventional post-injection type rock bolt with a packer. It is explanatory drawing of the conventional problem in case the spring water pressure in a borehole is high.

Explanation of symbols

21 Ground 22 Drilling hole
23 Post-injection lock bolt with packer 23a Hollow bolt 23b Packer 23c Packer injection hose 23d Fixing material injection hose 32 Return device 33 Concentration measuring unit 34 Switching valve 36 Mixing pressure feed pump 37 Pressure sensor 41 Return valve 42 Release valve 43 Branch pipe

Claims (4)

A first valve that can be freely opened and closed;
A second valve that opens at a predetermined fluid pressure;
A branch pipe that connects to each of the first and second valves and guides fluid to these valves;
A return device comprising: The second valve has a cylinder portion having an inlet passage at one end and an outlet passage in the middle;
A spring disposed on the opposite side of the inlet passage in the cylinder portion;
A piston rod that normally closes the flow path between the inlet passage and the outlet passage by the spring force of the spring and pushes the spring with the predetermined fluid pressure to open the flow path between the inlet passage and the outlet passage;
2. The return device according to claim 1, further comprising:   The return device according to claim 2, wherein the fluid contact portion of the piston rod is formed in a spherical shape. In the lock bolt that is installed in the hole and strengthens the ground,
A hollow body installed in the hole;
A packer attached to the mouth of the main body and closing the hole;
An injection portion for injecting a fixing material into the hole;
A return device connected to the hollow body in communication with the hole partitioned by the packer;
The return device comprises:
A first valve that can be freely opened and closed;
A second valve that opens at a predetermined injection pressure;
A branch pipe connected to the hollow main body and leading the return material flowing in from the hollow main body to each of the first and second valves;
A lock bolt characterized by comprising:

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