How to install underground displacement meters

Abstract

To improve the detection accuracy of subgrade displacement with an underground displacement gauge.SOLUTION: An underground displacement gauge installation method for installing a linear underground displacement gauge 10 within an underground hole 20 formed in a subgrade 1 includes an injection step for injecting grout 50 between an outer peripheral surface 30c of a pipe material 30 arranged in the underground hole 20 and an internal surface of the underground hole 20, and an insertion step for inserting the underground displacement gauge 10 into the pipe material 30.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for installing a linear underground displacement meter in the ground. [Background technology]

[0002] When constructing a tunnel or an underground cavity, a linear underground displacement meter may be installed in the ground and used to detect the condition of the ground around the tunnel or underground cavity. Patent Documents 1 and 2 disclose methods of installing a linear underground displacement meter in the ground that can measure the displacement of the ground.

[0003] In the methods disclosed in Patent Documents 1 and 2, an underground displacement meter is inserted into a pipe material installed in an underground hole. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-208991 [Patent Document 2] JP 2020-41994 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described in Patent Documents 1 and 2, when a pipe is simply installed in an underground hole, a gap is formed between the inner wall surface of the underground hole and the outer circumferential surface of the pipe. When a gap is formed between the ground and the underground displacement meter in this way, it becomes difficult for the ground displacement to be transmitted to the underground displacement meter, and as a result, it becomes difficult for the underground displacement meter to accurately detect the ground displacement.

[0006] An object of the present invention is to improve the accuracy of detecting ground displacement using an underground displacement meter. [Means for solving the problem]

[0007] The present invention provides a method for installing a linear underground displacement meter in an underground hole formed in the ground, comprising the steps of: a drilling step of drilling the ground hole with a tubular rod member having a drilling rod attached to its tip; and a placement step of inserting the tubular member into the rod member and removing the rod member from the ground hole to place the tubular member in the ground hole; The method includes an injection step of injecting a filler material between the outer peripheral surface of a tubular member placed in the ground hole and the inner wall surface of the ground hole, and an insertion step of inserting the underground displacement meter into the tubular member. Effect of the Invention

[0009] According to the present invention, it is possible to improve the accuracy of detecting ground displacement using an underground displacement meter. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing an underground displacement meter installed in a hole by a method for installing an underground displacement meter according to an embodiment of the present invention. FIG. [Diagram 2] 1A to 1C are diagrams showing a method for installing an underground displacement meter according to an embodiment of the present invention in chronological order. [Diagram 3] 3 is a diagram showing a time series of the installation method of the underground displacement meter according to the embodiment of the present invention, following FIG. 2. [Figure 4] 4 is a diagram showing the installation method of the underground displacement meter according to the embodiment of the present invention in chronological order, following FIG. 3. [Diagram 5] FIG. 5 is an enlarged view showing a portion A in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, a method for installing an underground displacement meter according to an embodiment of the present invention will be described with reference to the drawings.

[0012] 1 to 5, a process of installing an underground displacement meter in an underground hole formed in the ground by the underground displacement meter installation method according to an embodiment of the present invention and members used in the underground displacement meter installation method will be described. Here, a case where the underground displacement meter is used as a displacement measuring instrument that measures the displacement of the ground immediately above the underground space associated with construction work to construct an underground space such as a tunnel in the ground will be described.

[0013] For example, when constructing an underground space such as a tunnel in the ground using a shield machine, it is important to understand the displacement of the ground directly above the shield machine in order to prevent the ground from subsiding or rising. For this reason, as shown in Figure 1, an underground displacement meter 10 capable of detecting displacement of the ground may be installed directly above the planned path 3 of a shield machine 4 that will construct a tunnel T in the ground 1.

[0014] The underground hole 20 into which the underground displacement meter 10 is inserted is drilled in advance approximately parallel to the planned path 3 of the shield machine 4 so as to have a curved section that bends in the same direction as the planned path 3 in the horizontal and vertical directions from the shaft 2 from which the shield machine 4 starts. As the underground displacement meter 10 to be inserted into the underground hole 20, for example, an optical fiber cable is used.

[0015] Since the optical fiber cable generates distortion in response to distortion in the ground or loosening of the ground, it is possible to measure distortion in the ground or loosening of the ground by measuring the distortion of the optical fiber cable.

[0016] Specifically, an optical fiber cable has a property of slightly scattering incident pulsed light backward, and by utilizing this property, it is possible to measure the strain at multiple positions in the optical fiber cable. Since the frequency of the scattered light depends on the strain of the optical fiber cable, the strain of the optical fiber cable can be measured by injecting pulsed light into the optical fiber cable and measuring the frequency of the scattered light. In addition, by measuring the time from when pulsed light is injected into the optical fiber cable until the scattered light generated within the optical fiber cable returns to the incident position, the position where the scattered light is generated, i.e., the position where the strain is generated in the optical fiber cable, can be measured.

[0017] Therefore, by inserting an optical fiber cable into the underground hole 20 drilled directly above the planned route 3 of the shield tunneling machine 4, the displacement of the ground caused by the tunneling of the shield tunneling machine 4 can be understood by measuring the strain generated in the optical fiber cable.

[0018] The underground displacement meter 10 is not limited to an optical fiber cable, and may be any type of displacement meter that can measure ground displacement. For example, it may be formed in a linear shape by connecting multiple detection units, each equipped with an acceleration sensor, pressure sensor, strain sensor, or tilt sensor, in the longitudinal direction.

[0019] In order to smoothly insert the underground displacement meter 10 such as an optical fiber cable into the underground hole 20, a pipe material (tubular member) 30 is placed in the underground hole 20 as shown in FIG.

[0020] However, when the pipe material 30 is simply installed in the ground hole 20, a gap is formed between the inner wall surface of the ground hole 20 and the outer circumferential surface of the pipe material 30. When a gap is formed between the ground 1 and the underground displacement meter 10 in this way, the displacement of the ground 1 is difficult to transmit to the underground displacement meter 10, and as a result, it becomes difficult for the underground displacement meter 10 to accurately detect the displacement of the ground 1.

[0021] In order to solve such problems, the underground displacement meter installation method according to this embodiment goes through the steps shown in Figures 2 to 4 to eliminate any gap between the inner wall surface of the underground hole 20 and the outer circumferential surface of the pipe material 30, thereby improving the detection accuracy of the displacement of the ground 1 by the underground displacement meter 10. Figures 2(a) to (c), 3(a) to (c), and 4(a) to (c) are diagrams showing the underground displacement meter installation method according to this embodiment in chronological order, and Figure 5 is an enlarged view of part A in Figure 4.

[0022] A method for installing the pipe material 30 and the underground displacement meter 10 in the underground hole 20 as shown in FIG. 1 will be described below with reference to FIGS.

[0023] First, as shown in FIG. 2(a), a drilling process is performed in which an underground hole 20 is drilled from the shaft 2 toward the ground 1 using a drilling rod assembly (rod member) 22 extending from a drilling machine (not shown) installed in the shaft 2.

[0024] The drilling rod assembly 22 is composed of a drilling rod 23 having a drilling bit at one end, and a plurality of relay rods 28 that transmit the rotational force and impact force generated by the drilling machine to the drilling rod 23. As the drilling machine, a drilling machine capable of curved construction is used.

[0025] The drilling rod 23 is a hollow tubular member, and the open end facing the drilling surface 20a of the ground hole 20 is blocked by a blocking member 24 formed with a water injection hole 24a penetrating therethrough. In addition, a pinch valve (shutoff valve) 25 capable of blocking the passage formed within the drilling rod 23 is provided on the inner peripheral surface of the drilling rod 23. The end face of the drilling rod 23 facing the drilling surface 20a may be formed perpendicular to the drilling direction, or may be formed at an angle to the drilling direction.

[0026] The relay rod 28 is a hollow tubular member having the same inner and outer diameters as the hole-drilling rod 23, and both ends thereof are configured to be connectable to the hole-drilling rod 23 or other relay rods 28. The cylindrical portion of the relay rod 28 has a communication hole (not shown) formed along the axial direction through which compressed air or nitrogen gas can flow when the pinch valve 25 is closed.

[0027] When compressed air is supplied through a flow hole formed in the relay rod 28, the pinch valve 25 provided in the drilling rod 23 operates in such a way that the pressure acting on the valve body formed of an elastic material increases, displacing the valve body radially inward and closing the passage in the drilling rod 23. On the other hand, when the supply of compressed air is stopped and the flow hole formed in the relay rod 28 is open to the atmosphere, the restoring force causes the valve body to displace radially outward, thereby opening the passage in the drilling rod 23.

[0028] 2(a), when drilling an underground hole 20 with a drilling rod 23 attached to the tip of a drilling rod assembly 22, pressurized water is supplied to the drilling surface 20a through the inside of the drilling rod assembly 22 and the water injection hole 24a of the blocking member 24. Soil and sand produced by drilling are discharged to the outside of the underground hole 20 together with the pressurized water through the gap between the inner wall surface of the underground hole 20 and the outer peripheral surface 22b of the drilling rod assembly 22.

[0029] Then, the drilling process using the drilling rod 23 and the extension of the relay rod 28 are repeated until the length of the underground hole 20 reaches a preset length, as shown in FIG. 2(b), and the drilling process is completed.

[0030] The drilling rod assembly 22 is inserted into the underground hole 20 via a water stop box (not shown) provided in the underground wall 5 of the shaft 2 (for example, a water stop box welded to an H-shaped steel embedded as a core material in the soil cement underground wall 5). This prevents soil and sand generated by drilling from leaking into the shaft 2.

[0031] Once the drilling process is completed, a drilling rod opening process is then performed in which the blocking member 24 attached to the drilling rod 23 is removed and the tip of the drilling rod 23 is opened.

[0032] In this process, first, as shown in Figure 2 (c), the drilling rod assembly 22 is pulled out a predetermined length from the ground hole 20 to create a space between the drilling rod 23 and the drilling surface 20a, and an opening jig 27 having a shape capable of sealing the water injection hole 24a formed in the blocking member 24 is inserted into the drilling rod assembly 22.

[0033] Then, with the water injection hole 24a sealed by the opening jig 27, pressurized water having a higher pressure than that during drilling is supplied into the drilling rod assembly 22, and the pressure within the drilling rod assembly 22 is increased.

[0034] Due to the increased pressure within the drilling rod assembly 22 in this manner, the blocking member 24 is pressed together with the opening jig 27, and as shown in FIG. 3(a), it is pulled out from the end of the drilling rod 23 toward the space on the drilling surface 20a side.

[0035] This opens the tip of drilling rod 23, i.e., an opening through which pipe material 30 can be inserted is provided in drilling rod 23, completing the drilling rod opening process. In order to increase the pressure inside drilling rod assembly 22, compressed air may be supplied instead of pressurized water.

[0036] If the tip of the drilling rod 23 is left open, groundwater, etc. will flow into the drilling rod assembly 22. For this reason, as shown in Fig. 3(b), the pinch valve 25 is closed after the drilling rod opening process is completed.

[0037] Next, with the passage in the drilling rod 23 closed by the pinch valve 25, a pipe material (tubular member) 30 is inserted into the drilling rod assembly 22, as shown in FIG. 3(b).

[0038] The pipe material 30 is a hollow tubular member made of a biodegradable plastic that is decomposed into water and carbon dioxide by microorganisms in the soil over time, and the tip side that is inserted into the drilling rod assembly 22 is a closed end 30a. The pipe material 30 may be made of a resin such as polyvinyl chloride.

[0039] As described above, the tip of the drilling rod 23 is in an open state due to the removal of the blocking member 24, so that it is possible to insert the pipe material 30 into the drilling rod assembly 22 beyond the tip of the drilling rod 23 into the ground 1, as shown in Fig. 3(c). When inserting the pipe material 30 in this manner, the pinch valve 25 is switched from a closed state to an open state.

[0040] Next, as shown in Figure 4(a), a process is performed in which the drilling rod assembly 22 is removed from the ground hole 20, thereby leaving the pipe material 30 inserted into the drilling rod assembly 22 in the ground hole 20, i.e., a placement process is performed in which the pipe material 30 is placed in the ground hole 20 through the drilling rod assembly 22.

[0041] 3(c) and 4(a), there is a risk that groundwater or the like may leak into the shaft 2 through the gap between the inner peripheral surface 22a of the drilling rod assembly 22 and the outer peripheral surface 30c of the pipe material 30. For this reason, before the pinch valve 25 is switched from the closed state to the open state, pressurized water is supplied between the inner peripheral surface 22a of the drilling rod assembly 22 and the outer peripheral surface 30c of the pipe material 30. In addition, a water stop box provided on the underground wall 5 of the shaft 2 stops the groundwater from leaking into the shaft 2.

[0042] When the boring rod assembly 22 is pulled out from the ground hole 20 in this manner, a gap is generated between the outer circumferential surface of the pipe material 30 left in the ground hole 20 and the inner wall surface of the ground hole 20. In the next step, an injection step is carried out in which grout (filler material) 50 such as cement bentonite is injected into this gap.

[0043] In the injection step, first, a filling hose 40 through which grout (filling material) 50 flows is inserted into the pipe material 30, as shown in FIG. 4(b).

[0044] The filling hose 40 is a flexible hose, and the tip side inserted into the pipe material 30 is a closed end 40a. In addition, as shown in Figures 4(b) and 5, the tip side of the filling hose 40 is provided with a plurality of discharge ports 41 formed by penetrating in the radial direction along the circumferential direction, and a pair of packer portions (sealing portions) 42 are provided on either side of the discharge ports 41 in the axial direction.

[0045] The packer portion 42 is structured to expand in an annular shape radially outward when compressed air is supplied through an air hose (not shown) provided along the filling hose 40 .

[0046] When the filling hose 40 of the above configuration is inserted into the pipe material 30 and the blocked end 40a of the filling hose 40 abuts or is close to the blocked end 30a of the pipe material 30, compressed air is supplied to the pair of packer sections 42.

[0047] The pair of packer portions 42 expand radially outward, thereby fixing the filling hose 40 to the pipe material 30.

[0048] As shown in Figures 4(b) and 5, the pipe material 30 has an injection hole 31 formed in a position opposite to the discharge port 41 provided in the filling hose 40, which connects the inside and outside of the pipe material 30.

[0049] As a result, the grout 50 flowing inside the filling hose 40 and discharged from the discharge port 41 passes between a pair of packer sections 42, as shown by arrows in Figures 4(b) and 5, and is injected between the outer surface 30c of the pipe material 30 and the inner wall surface of the underground hole 20 through the injection hole 31.

[0050] In this manner, the pair of packer portions 42 define a part of the flow passage through which the grout 50 flows from the discharge port 41 toward the injection hole 31. In other words, the pair of packer portions 42 function as a sealing portion that prevents the grout 50 discharged from the discharge port 41 from flowing into the gap between the inner peripheral surface 30b of the pipe material 30 and the outer peripheral surface 40c of the filling hose 40.

[0051] If the injection hole 31 formed in the pipe material 30 is always open, groundwater or the like will flow into the pipe material 30 through the injection hole 31 when placing the pipe material 30 in the ground hole 20 or after the pipe material 30 has been placed in the ground hole 20, making it impossible to insert the filling hose 40 into the pipe material 30. For this reason, the injection hole 31 is provided with a check valve 32 that only allows flow from the inside to the outside of the pipe material 30, as shown in Fig. 5.

[0052] The check valve 32 is a plate-shaped member having a sealing portion 32a at one end that is capable of sealing the injection hole 31, and a fixed portion 32b at the other end that is fixed to the outer peripheral surface 30c of the pipe material 30, and is attached to the pipe material 30 so as to block flow from the outside to the inside of the pipe material 30 while allowing flow from the inside to the outside of the pipe material 30.

[0053] By providing the check valve 32 that functions in this manner, the injection hole 31 is opened only while the grout 50 is being discharged from the discharge port 41 of the filling hose 40. The check valve 32 is not limited to the above type, and may be of any type as long as it is capable of allowing flow in only one direction in the injection hole 31.

[0054] The grout 50 injected between the outer peripheral surface 30c of the pipe material 30 and the inner wall surface of the ground hole 20 through the injection hole 31 of the pipe material 30 gradually fills the gap between the pipe material 30 and the ground hole 20 from the tip side of the ground hole 20, and eventually reaches the open end of the ground hole 20 on the shaft 2 side. When it is confirmed that the grout 50 has reached the shaft 2 side, the pressure-feeding of the grout 50 through the filling hose 40 is stopped.

[0055] Then, after the supply of compressed air to the packer portion 42 is stopped, the filling hose 40 is pulled out from inside the pipe material 30. In this manner, the filling hose 40 is pulled out from inside the pipe material 30, and the injection process is completed in a state where the inside of the pipe material 30 is hollow.

[0056] After the injection step is completed, an insertion step is performed in which the linear underground displacement meter 10 is inserted into the pipe material 30 .

[0057] Since the inside of the pipe material 30 is hollow when the injection process is completed, as shown in Fig. 4(c), it is possible to easily insert the linear underground displacement meter 10 into the pipe material 30. In particular, since the inside of the pipe material 30 is relatively smooth, the underground displacement meter 10 can be easily inserted even if the underground hole 20 is twisted.

[0058] As described above, through each of the above steps, the gap between the inner wall surface of the ground hole 20 and the outer circumferential surface of the pipe material 30 is filled with grout 50, i.e., there is no gap between the inner wall surface of the ground hole 20 and the outer circumferential surface of the pipe material 30, and the underground displacement meter 10 is installed in the pipe material 30 arranged in the ground hole 20. After inserting the underground displacement meter 10 such as an optical fiber cable into the pipe material 30, the underground displacement meter 10 may be fixed in the pipe material 30 by, for example, filling the pipe material 30 with a low-strength filling material (grout material).

[0059] According to the above embodiment, the following effects are achieved.

[0060] According to the underground displacement meter installation method of this embodiment, the pipe material 30 into which the linear underground displacement meter 10 is inserted is placed in the underground hole 20 via the grout 50. By filling the space between the inner wall surface of the underground hole 20 and the outer peripheral surface 30c of the pipe material 30 with the grout 50 in this manner, the displacement of the ground 1 is easily transmitted to the underground displacement meter 10 via the grout 50 and the pipe material 30. As a result, the underground displacement meter 10 can accurately detect the displacement of the ground 1.

[0061] Furthermore, according to the underground displacement meter installation method of this embodiment, the underground displacement meter 10 can be easily installed in the underground hole 20 by simply inserting the underground displacement meter 10 into the pipe material 30. Furthermore, if the underground displacement meter 10 is not fixed in the pipe material 30 via a filling material or the like, it is possible to reuse the underground displacement meter 10 in another location by removing it from the pipe material 30 after detection of the displacement of the ground 1 is completed.

[0062] According to the underground displacement meter installation method of this embodiment, the pipe material 30 is placed in the underground hole 20 through the drilling rod assembly 22. By placing the pipe material 30 in the underground hole 20 through the drilling rod assembly 22, which has a relatively smooth interior, rather than directly inserting the pipe material 30 into the underground hole 20 with its excavation surface exposed, it is possible to prevent the pipe material 30 from coming into contact with the ground 1 during installation and being damaged. Furthermore, the pipe material 30 can be easily placed even over a relatively long distance. In particular, the pipe material 30 can be easily placed even if the underground hole 20 has many curved sections.

[0063] According to the underground displacement meter installation method of this embodiment, the grout 50 is injected into the gap between the underground hole 20 and the pipe material 30 from inside the pipe material 30 through the injection hole 31 formed in the pipe material 30 into which the underground displacement meter 10 is inserted. In other words, in order to inject the grout 50 into the gap between the underground hole 20 and the pipe material 30, it is not necessary to lay a separate hose for injecting grout between the underground hole 20 and the pipe material 30. Therefore, the configuration for injecting the grout 50 is simplified, and the work of injecting the grout 50 is facilitated.

[0064] Furthermore, according to the underground displacement meter installation method of this embodiment, the pipe material 30 is made of a biodegradable material. Therefore, even if the detection of the displacement of the ground 1 is completed and the underground displacement meter 10 is pulled out of the pipe material 30, leaving the pipe material 30 in the ground 1, the pipe material 30 will be decomposed into water and carbon dioxide by microorganisms in the soil over time, and therefore there is no need to remove the pipe material 30. After the underground displacement meter 10 is pulled out of the pipe material 30, grout is injected into the pipe material 30.

[0065] The following modifications are also within the scope of the present invention.

[0066] In the above embodiment, the discharge port 41 is formed to open on the outer peripheral surface 40c of the filling hose 40. Alternatively, the discharge port 41 may be provided on the closed end 40a of the filling hose 40 or its periphery. In this case, one packer portion is provided on the outer peripheral surface 40c of the filling hose 40 to prevent the grout 50 discharged from the discharge port 41 from flowing into the gap between the inner peripheral surface 30b of the pipe material 30 and the outer peripheral surface 40c of the filling hose 40. In this case, the injection hole 31 of the pipe material 30 may be provided on the closed end 30a.

[0067] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0068] 1...ground 10. Underground displacement meter 20...underground hole 22....Drilling rod assembly (rod member) 23...Drilling rod 24...Blocking member 25 Pinch valve (Shut-off valve) 28....Relay rod 30... Pipe material (tubular member) 31...Injection hole 32 Check valve 40···Filling hose 41...Discharge port 42 Packer part (sealing part) 50 Grout (filler)

Claims

1. A method for installing a linear underground displacement meter in an underground hole formed in the ground, comprising the steps of: a drilling step of drilling the underground hole using a tubular rod member having a drilling rod attached to its tip; a placement step of placing the tubular member in the ground hole by inserting the tubular member into the rod member and extracting the rod member from the ground hole; an injection step of injecting a filler material between an outer peripheral surface of the tubular member disposed in the ground hole and an inner wall surface of the ground hole; and an insertion step of inserting the underground displacement meter into the tubular member. How to install underground displacement meters.

2. Before the tubular member is inserted into the rod member, a portion of the drilling rod is removed to form an opening in the drilling rod through which the tubular member can be inserted. The method for installing an underground displacement meter according to claim 1.

3. After the opening is formed in the drilling rod, a shutoff valve is closed to prevent fluid from entering the rod member through the opening. The method for installing an underground displacement meter according to claim 2.

4. In the injection step, a filling hose through which the filling material flows is inserted into the tubular member.

4. A method for installing an underground displacement meter according to claim 1.

5. the tubular member has an injection hole communicating between the inside and the outside of the tubular member, The filler is injected between the outer circumferential surface of the tubular member and the inner wall surface of the underground hole through the injection hole. The underground displacement meter installation method according to claim 4.

6. The filling hose has a discharge port for discharging the filling material, and a sealing portion for preventing the filling material discharged from the discharge port from flowing into a space between an inner peripheral surface of the tubular member and an outer peripheral surface of the filling hose, a part of a flow passage through which the filler flows from the discharge port to the injection hole is defined by the sealing portion; The underground displacement meter installation method according to claim 5.

7. The tubular member is formed of a biodegradable material.

7. A method for installing an underground displacement meter according to claim 1.

Images