Controlled earth pressure setting system

Abstract

To provide a pressure recovery device that can accurately and easily control pressure inside a chamber required for carrying out a decompression test.SOLUTION: A pressure recovery device 8 (8A) of this embodiment is a pressure recovery device 8 that recovers pressure inside a chamber 16 of a shield tunneling machine, and comprises a volume change mechanism that changes volume inside the chamber by moving at least a portion thereof to the outside and inside of the chamber 16. The volume change mechanism comprises a recess 81 formed in a partition wall 3, a jack 82 installed in the recess 81, and a support plate 83 attached to the front side of the jack 82. The support plate 83 is designed to be retracted into the inside of the machine from a reference position that forms the same plane as the partition wall 3 by driving the jack 82 to extend or retract.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure recovery device in a chamber used in a shield tunneling machine. [Background technology]

[0002] Traditionally, managing the mud pressure inside the chamber of an earth pressure shield has been essential for maintaining the stability of the face while allowing the shield to excavate without causing deformation or subsidence of the surrounding ground, and proper management can suppress displacement of the surrounding ground.

[0003] In earth pressure shields, the controlled earth pressure of muddy soil pressure inside the chamber is set within the following range. (Passive earth pressure + water pressure) > Mud pressure in chamber (controlled earth pressure) > (Active earth pressure + water pressure)

[0004] If the mud pressure in the chamber is kept within the above range, the stability of the face is theoretically ensured, but as higher mud pressure in the chamber leads to increased cutter torque and jack thrust, resulting in inefficient construction, it is desirable to set the controlled earth pressure low within the range that ensures stability of the face. Therefore, it is common to set the lower limit to a value obtained by adding α to (active earth pressure + water pressure), and the upper limit to a value that further takes into account the range of construction fluctuations in addition to the above lower limit (active earth pressure + water pressure + α), or to (static earth pressure + water pressure).

[0005] Note that passive earth pressure, active earth pressure, and earth pressure at rest refer to the effective earth pressure transmitted between soil particles and do not include pore water pressure. On the other hand, muddy earth pressure in the chamber refers to the total earth pressure considering the soil particles and pore water in the chamber as a whole, and includes pore water pressure.

[0006] There are two methods for managing the mud pressure inside the chamber in conventional earth pressure shields: method 1) and method 2) shown below. 1) A method of calculating active earth pressure, passive earth pressure, static earth pressure, etc. using an earth pressure calculation formula based on the soil constants (φ, C, γ, etc.) of the target ground estimated by a prior soil survey, the groundwater level, and the overburden load, and then setting and managing upper and lower limits for the mud earth pressure inside the chamber based on these values ​​(see, for example, Patent Document 1). 2) A method of setting the controlled earth pressure based on the muddy earth pressure in the chamber measured when the shield is stopped (see, for example, Non-Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-233372 [Non-Patent Document 1] "Guidelines for Safe and Secure Construction of Shield Tunnels," Shield Tunnel Construction Technology Review Committee, December 2021, p. 19 Summary of the Invention [Problem to be solved by the invention]

[0008] ·Management method 1) Issues: Preliminary soil surveys are usually carried out by boring, and are often carried out at intervals of about 200 m along the length of the line. Therefore, if the soil conditions change between survey points, it may not be possible to calculate the appropriate control earth pressure. Furthermore, because the calculation formula for earth pressure is theoretical and based only on a simplified two-dimensional balance of forces, it does not necessarily accurately calculate the earth pressure on the shield face ground in an actual three-dimensional state.

[0009] ·Management method 2) Issues: The stopped mud pressure measured when the shield is stopped is thought to reflect the earth pressure acting on the face relatively accurately if the shield itself does not move and the cutter head does not have a face plate, but if these conditions are not maintained, the stopped mud pressure does not necessarily represent the static earth pressure of the ground or the active earth pressure plus water pressure.

[0010] Therefore, the inventors have developed a system for setting controlled earth pressure for shield tunneling machines that sets controlled earth pressure by directly measuring the relationship between mud pressure in the chamber and displacement near the face, rather than setting controlled earth pressure based on assumptions or estimates.This controlled earth pressure setting system requires a decompression test to reduce mud pressure in the chamber in order to determine the deformation characteristics of the target ground based on pressure changes in the chamber.

[0011] Conventionally, chamber pressure has been controlled by adjusting the rotation of a screw conveyor to control the amount of soil discharged. However, controlling the amount of soil discharged using a screw conveyor poses a challenge: it is difficult to accurately control the pressure in the chamber. Because the pressure in the chamber drops significantly even with a small amount of soil discharged when the shield is stopped, precise control of the amount of soil discharged is required. Therefore, the inventors developed a pressure control device that can accurately and easily control the pressure in the chamber, which is necessary for conducting depressurization tests. However, when a depressurization test is conducted and moderate displacement of the face or loosening of the ground is confirmed, or in an emergency (where extending the shield jack is the usual method of restoring pressure, but there are cases where the jack cannot be freely operated due to uneven reaction force, such as during segment assembly), a technique for quickly restoring the pressure in the chamber is required.

[0012] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a pressure recovery device that can quickly recover the pressure inside a chamber. [Means for solving the problem]

[0013] The first type of pressure recovery device is a pressure recovery device that recovers pressure within a chamber of a shield tunneling machine, and is equipped with a volume change mechanism that changes the volume within the chamber by moving at least a portion of it outside and inside the chamber.

[0014] The second form of pressure recovery device is a pressure recovery device that recovers pressure in a chamber of a shield machine, and includes a recovery storage tank that recovers and stores at least a portion of the mud discharged from the chamber by the soil discharge device, and a pressure pump that pressure-feeds the mud from the recovery storage tank into the chamber. In addition, it is preferable to further include a volume change mechanism that changes the volume within the chamber by moving at least a portion of the mud to the outside and inside of the chamber.

[0015] The third form of pressure recovery device is a pressure recovery device for recovering pressure in the chamber of a shield tunneling machine, and comprises a mud storage tank for storing mud produced outside the tunnel or at a predetermined location inside the machine, and a pressure pump for pumping the mud from the mud storage tank into the chamber. In addition, it is preferable to further comprise a volume change mechanism for changing the volume inside the chamber by moving at least a portion of it outside and inside the chamber.

[0016] In addition, the controlled earth pressure setting system for a shield tunneling machine of the present invention comprises a pressure gauge that measures the mud pressure in the chamber, the above-mentioned pressure recovery device, a displacement measuring means that measures the displacement of the face, an analysis unit that analyzes the deformation characteristics of the ground based on the measured mud pressure and the measured displacement of the face, and a setting unit that sets the controlled earth pressure based on the analyzed deformation characteristics. [Effects of the Invention]

[0017] The pressure recovery device of the first form of the present invention is a pressure recovery device for recovering pressure in a chamber of a shield tunneling machine, and is equipped with a volume change mechanism that changes the volume of the chamber by moving at least a portion of it to the outside and inside of the chamber. With this configuration, the pressure in the chamber can be quickly recovered.

[0018] The pressure recovery device of the second embodiment of the present invention is a pressure recovery device for recovering pressure in the chamber of a shield tunneling machine, and includes a recovery storage tank and a pressure transfer pump. With this configuration, the pressure in the chamber can be quickly recovered.

[0019] The third embodiment of the pressure recovery device of the present invention is a pressure recovery device for recovering pressure in the chamber of a shield tunneling machine, and includes a mud storage tank and a pressure pump. With this configuration, the pressure in the chamber can be quickly recovered.

[0020] The system for setting the controlled earth pressure in a shield tunneling machine of the present invention comprises a pressure gauge that measures the mud pressure in the chamber, the above-mentioned pressure recovery device, a displacement measurement means that measures the displacement of the tunnel face, an analysis unit that analyzes the deformation characteristics of the ground based on the measured mud pressure and the measured displacement of the tunnel face, and a setting unit that sets the controlled earth pressure based on the analyzed deformation characteristics.With this configuration, the controlled earth pressure can be set by directly measuring the relationship between the mud pressure in the chamber and the displacement of the tunnel face, rather than setting the controlled earth pressure based on assumptions or estimates. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a cross-sectional view illustrating the internal structure of a shield tunneling machine. [Figure 2] FIG. 2 is a cross-sectional view illustrating the configuration of the detection jig and the measurement sensor. [Figure 3] An explanatory diagram of the on-board measurement method for measuring face displacement. (a) is an explanatory diagram during excavation, (b) is an explanatory diagram of inserting the detection jig, and (c) is an explanatory diagram during displacement measurement. [Figure 4] An explanatory diagram of a pre-installed face displacement measurement method. (a) is a cross-sectional view, and (b) is a longitudinal cross-sectional view. [Figure 5] FIG. 1 is a front view illustrating the arrangement of a support plate type pressure recovery device of the first embodiment. [Figure 6]1A and 1B are cross-sectional views illustrating the configuration of a pressure recovery device of a support plate type according to a first embodiment, in which (a) shows the state before retraction and (b) shows the state after retraction. [Figure 7] 1A and 1B are cross-sectional views illustrating the configuration of a slide stirring blade type pressure recovery device according to a modified example of the first embodiment, in which (a) shows the state before retraction and (b) shows the state after retraction. [Figure 8] FIG. 10 is an explanatory diagram illustrating the configuration of a return-type pressure recovery device of a second embodiment. [Figure 9] FIG. 10 is an explanatory diagram illustrating the configuration of a pressure recovery device for a new mud production method of the third embodiment. [Figure 10] 10 is a flowchart illustrating the procedure of a system for setting controlled earth pressure. [Figure 11] 1 is a graph showing the relationship between mud pressure and horizontal displacement in a depressurization test. [Figure 12] FIG. 1 is an explanatory diagram illustrating the concept of an FEM model. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the components described in the following embodiments are merely examples and are not intended to limit the technical scope of the present invention to those alone. Note that, although the following description will be given using an earth pressure shield 1 as an example, the present invention can also be applied to other types of shield tunneling machines. [Example]

[0023] (Shield tunneling machine configuration) Fig. 1 is a longitudinal side view showing an embodiment of the present invention. As shown in Fig. 1, the earth pressure shield 1 as a shield tunneling machine of this embodiment is equipped with a skin plate (shield main body cylinder) 2, a partition wall 3, a cutter head 5, a cutter rotation shaft 10, a cutter drive unit 12, a chamber 16, an earth removal device 17, a shield propulsion jack 18, a mud material supply pipe 21, a pressure gauge 22, a water pressure gauge 23, and a control unit 40 including an analysis unit 41 and a setting unit 42 arranged inside an operation room or the like.

[0024] The cutter head 5 has cutter spokes 51, a plurality of cutter bits 52, ... provided on the front surface of the cutter spokes 51, a fishtail bit 53 provided in the center of the front surface of the cutter spokes 51, and a plurality of stirring blades 54, ... provided on the back surface of the cutter spokes 51. The cutter head 5 is attached integrally to the cutter rotation shaft 10.

[0025] The cutter rotation shaft 10 is rotatably supported by a bearing 11 provided in the partition wall 3 and a bearing provided at the rear of a gear box 13 (described later). The cutter rotation shaft 10 is connected to a cutter drive unit 12. The cutter drive unit 12 has a gear box 13 installed on the rear side of the partition wall 3, a rotary drive source 14 connected to the gear box 13, and a reduction gear (disposed within the gear box 13; not shown) interposed between the output shaft of the rotary drive source 14 and the cutter rotation shaft 10.

[0026] The chamber 16 is formed by a space surrounded by the hood portion 2a of the skin plate 2, the partition wall 3, and the working face F. A screw conveyor, for example, is used as the earth removal device 17. The mud intake port of the earth removal device 17 is open and installed so as to face the chamber 16.

[0027] Furthermore, an erector 15 for assembling segments 90 is installed in the tail portion 2b of the skin plate 2. Furthermore, a plurality of shield propulsion jacks 18 are installed at required intervals in the circumferential direction inside the skin plate 2. In addition, a tail seal 19 is provided at the rear end of the skin plate 2.

[0028] The earth pressure shield 1 as a shield tunneling machine of this embodiment is further equipped with displacement measurement means 6, 7 that measure the displacement of the tunnel face or the area around the tunnel face. Here, we will first use Figures 2 and 3 to explain the on-board displacement measurement means 6 that measures the displacement of the tunnel face from inside the machine, and then use Figure 4 to explain the pre-installed displacement measurement means 7, in which an instrument is installed from the ground in advance.

[0029] As shown in Figure 2, the on-board displacement measurement means 6 is composed of a rod-shaped detection jig 61 that is long enough to penetrate the bulkhead 3 and allow its tip 61a to reach the working face F, a hydraulic chuck 63 that grasps and releases the detection jig 61, thereby moving and releasing the detection jig 61 as the jacks 62, 62 extend and retract, a detection unit 64 that is attached integrally to the end of the detection jig 61, a guide 65 that supports the sliding movement of the detection unit 64, a displacement sensor 66 that measures the displacement of the detection jig 61 by measuring the distance from the detection unit 64, a water stop device 67 for the detection jig 61, and water stop valves 68, 68.

[0030] Therefore, when the detecting jig 61 is gripped by the hydraulic chuck 63, the detecting jig 61 moves backward when the jacks 62, 62 extend, and moves forward when the jack 62 retracts. When the hydraulic chuck 63 is released, the detecting jig 61 is in a free state. Therefore, in the released state (the detecting jig 61 can move freely), if the tip 61a of the detecting jig 61 is in contact with the face F, the detecting jig 61 moves (in the longitudinal direction of the tunnel) in accordance with the displacement of the face F. As will be described later, in the present invention, the mud pressure in the chamber 16 is reduced, causing the face F to protrude slightly, and the detecting jig 61 moves in the longitudinal direction of the tunnel toward the tunnel entrance.

[0031] Next, the operating procedure of the displacement measuring means 6 having the detecting jig 61 and the displacement sensor 66 in the decompression test of this embodiment will be described with reference to FIG. 2 and FIGS. 3(a) to 3(c). 1. During shield tunneling, the exploration jig 61 is retracted to the partition wall 3 position (Fig. 3(a)). 2. After the shield stops, the hydraulic chuck 63 grips the detection jig 61 and slides it until the tip 61a contacts the face F (see FIG. 3(b)). The jack 62 is retracted. 3. When the tip 61a of the detection jig 61 is pressed against the face F, the hydraulic chuck 63 is released. 4. The soil removal means is operated slowly to gradually reduce the mud pressure in the chamber 16. 5. When the face F is displaced due to the pressure reduction, the displacement pushes the detection jig 61 into the shield (see FIG. 3(c)). 6. A measuring device (detection unit 64, displacement sensor 66) is attached inside the shield of the detection jig 61. The amount of displacement is measured by the displacement sensor 66 through the detection unit 64. 7. The measurement value is sent from the displacement sensor 66 to the PC. At the same time, the pressure gauge 22 installed on the partition wall 3 measures the mud pressure inside the chamber 16. 8. Using the above procedure, the relationship between the mud pressure in chamber 16 and the face F displacement is determined. 9. The decompression test is stopped when all or part of the transition region (including the yield point) in the face displacement becomes clear. 10. For example, the soil discharge means is reversed to return the mud and increase the mud pressure in the chamber 16 to the initial state. 11. The detecting jig 61 is gripped by the hydraulic chuck 63 and pulled back by operating the jack 62, and the detecting jig 61 is retracted to the partition wall 3 position (FIG. 3(a)). The jack 62 is extended.

[0032] Of the components of the on-board displacement measurement means 6 described above, the component for measuring displacement can be replaced with pre-installed multi-stage inclinometers (or layer-by-layer settlement meters) 71-74, 75-78 that are installed in advance from the ground. That is, the pre-installed displacement measurement means 7 has a plurality of multi-stage inclinometers 71-74, 75-78 installed at a predetermined depth from the ground surface, as shown in Figure 4. The installation locations preferably include, for example, in addition to the vicinity of the face at the planned tunnel excavation position, positions directly above it and positions shifted to the left and right (and directly above them).

[0033] In other words, it is possible to measure ground displacement by installing multi-stage inclinometers 71-74 and layer-by-layer settlement meters in advance from the ground within the cross section where the shield is scheduled to pass, temporarily halting shield excavation just before the measuring device, and conducting a decompression test. These multi-stage inclinometers 71-74 are preferably buried at specified intervals in the area where the shield is scheduled to pass. In this case, it is preferable to bury them at intervals narrower than the conventional boring interval (200 (m)).

[0034] (First form of pressure recovery device) Next, the configuration and operation of the pressure recovery device 8 of the first embodiment will be described using Figures 5, 6(a), and 6(b). As shown in Figures 5, 6(a), and 6(b), the pressure recovery device 8 is equipped with a volume change mechanism that increases the volume of the chamber 16 by moving a portion of it outside the chamber 16 (i.e., toward the inside of the aircraft), and decreases the volume of the chamber 16 by moving it inside the chamber 16 (i.e., toward the outside of the aircraft). This volume change mechanism comprises a recess 81 formed in the bulkhead 3, a jack 82 installed in the recess 81, and a support plate 83 attached to the front side of the jack 82; by extending or contracting the jack 82, the support plate 83 is retracted toward the inside of the aircraft from a reference position that is flush with the bulkhead 3.

[0035] Specifically, the recess 81 is a cylindrical case with a bottom, and has a jack 82 and a bearing plate 83 inside. The jack 82 is composed of a cylinder portion 82a and a rod portion 82b. The cylinder portion 82a of the jack 82 is fixed to the back side of the recess 81, and the rod portion 82b moves back and forth (reciprocating) on ​​the front side of the recess 81. The bearing plate 83 is attached to the front side (face side) of the rod portion 82b. This bearing plate 83 is configured to be flush with the bulkhead 3 when the jack 82 is extended.

[0036] During shield tunneling, as shown in Figure 6(a), the bearing plate 83 of the pressure recovery device 8 is positioned so that it is flush with the bulkhead 3. On the other hand, when a depressurization test is performed after the shield has stopped, the bearing plate 83 is moved rearward (from the reference position toward the inside of the machine) by retracting the jack 82, as shown in Figure 6(b). This action draws the mud in the chamber 16 into the recess (case) 81 of the pressure recovery device 8. As a result, the pressure in the chamber 16 decreases.

[0037] Conversely, the pressure recovery device 8 in the first form can push the bearing plate 82 forward (from the inside of the aircraft toward the reference position) by extending the jack 82. This action pushes the mud trapped in the recess (case) 81 of the pressure recovery device 8 into the chamber 16. As a result, the pressure in the chamber 16 increases. This makes it possible to quickly restore the pressure in the chamber 16 when conducting a decompression test or in an emergency.

[0038] In this way, the amount of mud taken in is controlled by extending or retracting the jacks 82, allowing for minute control. The amount of mud taken in can be increased or decreased by expanding or contracting the cross-sectional area of ​​the pressure recovery device 8. The amount of mud taken in can also be adjusted by increasing or decreasing the number of pressure recovery devices 8. After that, when the decompression test is completed, the jacks 82 of the pressure recovery device 8 are extended to push the bearing plate 83 back to its initial position (reference position), and the pressure inside the chamber 16 is restored.

[0039] (Pressure recovery device according to a modification of the first embodiment) Next, the configuration and operation of a pressure recovery device 8A, a modified version of the first embodiment, will be described with reference to Figures 7(a) and (b). As shown in Figures 7(a) and (b), the pressure recovery device 8A is equipped with a volume change mechanism that changes (increases) the volume within the chamber 16 by moving a portion of it outside the chamber 16. This volume change mechanism is equipped with an agitating blade 84 that protrudes into the chamber 16 from the partition wall 3, and a jack 85 attached to the back side of the agitating blade 84. By driving the jack 85 to extend or retract, the agitating blade 84 is retracted into the interior of the device from a reference position where it protrudes a predetermined amount from the partition wall 3.

[0040] Specifically, the agitator 84 is formed in a cylindrical shape and passes through an opening 3a provided in the partition wall 3, protruding a predetermined amount into the chamber 16. A jack 85 is attached to the rear end (mouth side) of the agitator 84. The jack 85 is composed of a cylinder portion 85a and a rod portion 85b, with the cylinder portion 85a fixed to the skin plate 2 side via a bracket 86, and the agitator 84 attached to the rod portion 85b. Therefore, by retracting the jack 85, the agitator 84 is retracted a predetermined amount into the interior of the machine, and therefore the agitator 84 can be called a sliding agitator 84.

[0041] During shield tunneling, as shown in Figure 7(a), the (sliding) stirring blade 84 penetrates the partition wall 3 and protrudes into the chamber 16 (reference position). On the other hand, when a depressurization test is performed after the shield has stopped, as shown in Figure 7(b), the (sliding) stirring blade 84 is pulled out of the chamber 16 by operating the jack 85, thereby increasing the actual air volume within the chamber 16 and reducing the pressure within the chamber 16. In this way, minute changes in air volume can be controlled by operating the jack 85, allowing for accurate pressure management.

[0042] Conversely, the pressure recovery device 8A of the modified first embodiment can push the agitating blade 84 forward (from the inside of the machine toward the reference position) by extending the jack 85. That is, as shown in Figures 7(b) to 7(a), by operating the jack 85 to push (slide) the agitating blade 84 into the chamber 16, the actual air volume in the chamber 16 is reduced and the pressure in the chamber 16 is increased. This makes it possible to quickly recover the pressure in the chamber 16 when a decompression test is performed or in an emergency.

[0043] The amount of change in the air volume within the chamber 16 can be increased or decreased by expanding or contracting the cross-sectional area of ​​the (sliding) agitator blade 84 of the pressure recovery device 8A. The amount of change in air volume can also be adjusted by increasing or decreasing the number of pressure recovery devices 8A. After the pressure reduction test is completed, the pressure within the chamber 16 can be restored by pushing the (sliding) agitator blade 84 back to its original position. In this example, the volume change is achieved using the agitator blade (84), but the present invention is also applicable to any part that does not necessarily have the function of the agitator blade (84) and that protrudes into and out of the chamber 16.

[0044] (Second form return type pressure recovery device) Next, the configuration and operation of the return-type pressure recovery device 8B of the second embodiment will be described with reference to Figure 8. As shown in Figure 8, the pressure recovery device 8B is equipped with a volume change mechanism that increases the volume inside the chamber 16 by moving a portion of it outside the chamber 16 (i.e., toward the inside of the machine), and decreases the volume inside the chamber 16 by moving a portion of it inside the chamber 16 (i.e., toward the outside of the machine).

[0045] This volume change mechanism comprises a recess 81 formed in the partition wall 3, a jack 82 installed in the recess 81, and a support plate 83 attached to the front side of the jack 82, and by driving the jack 82 to extend or retract, this support plate 83 is retracted into the inside of the machine from a reference position that is flush with the partition wall 3. Note that the volume change mechanism may also be configured using a stirring blade 84 and a jack 85 as shown in FIG.

[0046] The pressure recovery device 8B of the second embodiment is equipped with, in addition to the volume change mechanism, a recovery storage tank 30 that recovers and stores at least a portion of the mud discharged from the chamber 16 by the soil discharge device 17, and a pressure pump 31 that pressure-feeds the mud from the recovery storage tank 30 into the chamber 16. In other words, the pressure recovery device 8B is equipped with a device that returns the mud into the chamber 16, separate from the volume change mechanism.

[0047] The mud that has passed through the screw conveyor is transported outside the mine by, for example, a pressure pump (not shown). In this embodiment, a portion of the transported mud is collected and stored in a collection storage tank 30, and after the completion of a depressurization test, for example, it is returned to the chamber 16 by a pressure pump 31 (such as a positive displacement rotary pump) to restore the pressure inside the chamber 16. Of course, it can also be used to restore pressure in an emergency. Note that the location where the mud is returned to the chamber 16 is not limited to the bottom as shown, and it can be installed anywhere. Furthermore, the volume change mechanism and pressure transport method can be used independently, or both can be used together.

[0048] Furthermore, the recovery storage tank 30 is filled with a soil preparation material, such as bentonite or clay, and is further equipped with a stirring mechanism 32 that stirs the mud stored in the recovery storage tank 30 with the injected soil preparation material. By injecting and mixing a separate soil preparation material into the mud to be returned in this way, it is possible to change the material into one that is easier to return. Note that while the case where soil preparation material is mixed into the recovery storage tank 30 has been described here, this is not limited to this, and the present invention can be implemented whether or not soil preparation material is injected.

[0049] (Third type new mud production method pressure recovery device) Next, the configuration and operation of the pressure recovery device 8C of the third embodiment, a new mud-making method, will be explained using Figure 9. As shown in Figure 9, the pressure recovery device 8C is equipped with a volume change mechanism that increases the volume inside the chamber 16 by moving a portion of it outside the chamber 16 (i.e., inside the machine), and decreases the volume inside the chamber 16 by moving it inside the chamber 16 (i.e., outside the machine).

[0050] This volume change mechanism comprises a recess 81 formed in the partition wall 3, a jack 82 installed in the recess 81, and a support plate 83 attached to the front side of the jack 82, and by driving the jack 82 to extend or retract, this support plate 83 is retracted into the inside of the machine from a reference position that is flush with the partition wall 3. Note that the volume change mechanism may also be configured using a stirring blade 84 and a jack 85 as shown in FIG.

[0051] The pressure recovery device 8C of the third embodiment includes, in addition to the volume change mechanism, a mud storage tank 30A for storing mud produced outside the mine or at a designated location inside the machine, and a pump 31 for pumping the mud from the mud storage tank 30A into the chamber 16. In other words, the pressure recovery device 8C includes, in addition to the volume change mechanism, a device for supplying mud produced outside into the chamber 16. In this way, by using mud suitable for pumping, rather than recovered mud, for example, to perform pressure recovery, smoother pumping is possible and contributes to quicker pressure recovery. Note that, like the second embodiment, the third embodiment may also use pressure recovery using a volume change mechanism.

[0052] (Control system configuration) In addition, the earth pressure shield 1 further comprises a control unit 40. The control unit 40 is, for example, a general-purpose personal computer having a memory, a CPU, an SSD, etc. The control unit 40 sets the controlled earth pressure of the earth pressure shield 1 and controls the excavation. That is, during excavation, the earth pressure is changed by advancing the earth pressure shield 1 using the shield propulsion jack 18 while discharging mud using the soil discharge device 17 (screw conveyor), and at the same time, the mud pressure is measured using the pressure gauge 22. Furthermore, water pressure is measured using the water pressure gauge 23. It is of course possible to execute the functions of the analysis unit 41 and the setting unit 42, which will be described later, in a control unit (computing device; personal computer) separate from the control unit 40 that controls the excavation of the earth pressure shield 1. In this sense, the control unit can also be called a "computing unit."

[0053] The control unit 40 of this embodiment further functions as an analysis unit 41 that analyzes the deformation characteristics of the ground based on the measured mud pressure and the measured displacement of the excavation face (for example, horizontal displacement), and as a setting unit 42 that sets the controlled earth pressure based on the analyzed deformation characteristics. The control unit 40 receives input of the mud pressure value from the pressure gauge 22, the water pressure value from the water pressure gauge 23, and the input value (displacement) from the displacement sensor 66 via a communication cable 43, and is also connected to input means such as a keyboard and a mouse. Furthermore, the control unit 40 is connected to a monitor, a separate PC for excavation management, and the like as output means. The functions of the analysis unit 41 and setting unit 42 will be explained in the control flow described next.

[0054] The control earth pressure setting system S of the present invention is made up of the above-mentioned pressure gauge 22, the above-mentioned pressure recovery device 8 (8A), the displacement measurement means 6 (7), and the control unit 40 including the analysis unit 41 and the setting unit 42. In addition, a water pressure gauge 23 is provided on the top end of the skin plate 2.

[0055] (action) Next, the flow of the controlled earth pressure setting system S of this embodiment will be described with reference to Figures 10 to 12. As shown in Figure 10, the flow of the controlled earth pressure setting system S is realized by executing the following steps S1 to S14.

[0056] Initial value processing (step S1) First, an initial value of the controlled earth pressure is set (Step S2) based on the initial calculated earth pressure set by a boring test or the like (Step S1). Then, the shield is excavated according to this initial value of the controlled earth pressure (Step S3). In other words, in the early stages after the shield starts excavating (before the decompression test is conducted), the controlled earth pressure is set based on the theoretical earth pressure calculated from the soil constants obtained from the preliminary soil survey. Alternatively, the mechanical constants of the ground obtained from the preliminary soil survey are given to the 3D-FEM model, and the controlled earth pressure is set from the relationship between the earth pressure and ground displacement.

[0057] Decompression test (steps S4 to S8) Next, while the shield machine is stopped, the mud pressure in the chamber is reduced (Step S4). That is, when excavation is stopped, such as when assembling the segments 90, the bearing plate 83 (or mixing blade 84) of the pressure recovery device 8 (8A) is retracted slightly toward the machine interior to precisely control the pressure, gradually discharging the mud from the chamber 16 and reducing the pressure. During the pressure reduction, the mud pressure is measured using the pressure gauge 22. At the same time, the water pressure is measured using the water pressure gauge 23. Furthermore, during the pressure reduction, the displacement of the face F is directly measured using the displacement measuring devices 6 and 7 (Step S5). The deformation characteristics are determined based on the measured mud pressure and face displacement (e.g., horizontal displacement) (Step S6). That is, the mud pressure-face displacement is plotted on a graph to determine the deformation characteristics. Once the deformation characteristics are determined, the mechanical constants of the ground are analyzed by back analysis (Step S7) (Step S8).

[0058] 3D-FEM model analysis (steps S9 to S12) Then, using the mechanical constants of the ground analyzed by the depressurization test, a 3D-FEM analysis is performed as shown in Fig. 12 (step S9). Then, this 3D-FEM model analysis predicts the impact on the surrounding ground and adjacent structures (step S10).

[0059] That is, once the deformation characteristics of the target ground are clarified by the depressurization test, the mechanical constants of the ground are calculated (step S8) by back analysis of a ground model based on the in-situ boundary conditions such as the ground structure assumed from boring surveys and the measured water pressure (step S7). Using the mechanical constants of the ground calculated in this way, a 3D-FEM analysis is performed (step S9) as shown in Fig. 12.

[0060] As a result of the analysis, the presence or absence of harmful effects is determined by determining whether the amount of ground surface subsidence, etc. is below the allowable displacement amount (step S11). If harmful effects are found ("Yes" in step S11), the controlled earth pressure is changed (step S12) and the analysis is redone (steps S9 to S11). On the other hand, if harmless ("No" in step S11), the process returns to step S2 and the controlled earth pressure setting system S is executed at the next position and time.

[0061] Here, mechanical constants include, for example, Young's modulus, Poisson's ratio, angle of internal friction, and cohesion. A rational simulation of behavior is possible by conducting a simulation using an FEM model based on the ground characteristics obtained from this on-site behavior. Such a rational simulation based on on-site behavior makes it possible to predict ground surface subsidence and the impact on adjacent structures in advance and more accurately, minimizing the impact on the surrounding area or setting controlled earth pressures that correspond to regulatory values ​​for ground displacement, etc.

[0062] Analysis and settings (steps S13 to S14) On the other hand, once the deformation characteristics of the ground are understood, the yield point earth pressure is calculated by analysis from a muddy earth pressure-displacement graph as shown in Figure 11 (step S13). That is, the analysis unit 41 of the control unit 40 determines the point where the gradient suddenly increases, regards this point as the yield point, and calculates the active earth pressure. For example, an approximation line can be calculated using the least squares method from multiple plots in the elastic region, and an approximation line can be calculated using the least squares method from multiple plots in the plastic region, and the intersection of these lines can be determined as the yield point. Alternatively, the appearance of consecutive plots that significantly deviate from the moving average can be used to infer that the ground has entered the transition region. If a 3D-FEM model analysis is required due to the presence of nearby buildings, etc. ("Required" in step S14), the impact on the surrounding ground and adjacent structures is predicted by the 3D-FEM analysis (step S10). If a 3D-FEM model analysis is not required ("Not Required" in step S14), the control earth pressure is reset based on the active earth pressure (step S2). Specifically, the controlled earth pressure in the chamber 16 during excavation must not fall below the active earth pressure plus water pressure, so the active earth pressure plus water pressure (0 to 20 kN / m 2 ) is set as the lower limit of the controlled earth pressure. On the other hand, the upper limit of the controlled earth pressure may be theoretically calculated using C and φ calculated back from the active earth pressure (yield point earth pressure), or may be set as a value that further takes into account the construction fluctuation range in addition to the above lower limit. On the other hand, if a 3D-FEM model analysis is required ("Required" in step S14), the 3D-FEM model analysis is performed (step S9).

[0063] In this way, the observed digital values ​​(observed values) are compared with the digital values ​​(analytical values) obtained from analysis using the model ground, and the model is constantly corrected to create a model ground that is consistent with changes in the ground as the shield face advances (the so-called "digital twin").

[0064] (effect) Next, the effects of the pressure recovery device 8 (8A) and the controlled earth pressure setting system S of this embodiment will be listed and explained.

[0065] (1) As described above, the pressure recovery device 8 (8A) of this embodiment is a pressure recovery device 8 (8A) that recovers the pressure inside the chamber 16 of a shield machine, and is equipped with a volume change mechanism that changes the volume inside the chamber by moving at least a portion of it to the outside and inside of the chamber 16. By providing this volume change mechanism, it is possible to quickly recover the pressure control inside the chamber 16 that is necessary for carrying out a depressurization test.

[0066] (2) The volume change mechanism also includes a recess 81 formed in the bulkhead 3, a jack 82 installed in the recess 81, and a support plate 83 attached to the front side of the jack 82. By driving the jack 82 to extend or retract, the support plate 83 is retracted from a reference position that is flush with the bulkhead 3 toward the interior of the aircraft and pushed from the interior of the aircraft to the reference position. This increases or decreases the volume within the chamber 16 by an amount corresponding to the amount of retraction of the support plate 83, allowing the pressure to be accurately and quickly changed and controlled. That is, by retracting the support plate 83 into the recess 81, mud enters the recess 81, and the pressure within the chamber 16 decreases accordingly. Conversely, by pushing the support plate 83 out of the recess 81 to the reference position, mud is pushed out of the recess 81, and the pressure within the chamber 16 increases accordingly.

[0067] (3) Furthermore, the volume change mechanism includes an agitator 84 protruding from the partition wall 3 into the chamber 16 and a jack 85 attached to the back side of the agitator 84. By driving the jack 85 to extend or retract, the agitator 84 is retracted from a reference position protruding a predetermined amount from the partition wall 3 to the interior of the chamber 16, and is pushed from the interior of the chamber 16 to the reference position. This increases or decreases the volume within the chamber 16 by an amount corresponding to the amount of retraction or extrusion of the agitator 84, enabling accurate and rapid change and control of pressure. That is, by retracting the agitator 84 into the interior of the chamber 16, the volume within the chamber 16 increases by an amount corresponding to the amount of retraction of the agitator 84, and the pressure decreases. Conversely, by pushing the agitator 84 out, the volume within the chamber 16 decreases by an amount corresponding to the amount of extrusion of the agitator 84, and the pressure within the chamber 16 increases accordingly.

[0068] (4) Another type of pressure recovery device 8B for restoring pressure within the chamber of a shield tunneling machine includes a volume change mechanism that changes the volume within the chamber 16 by moving at least a portion of it to the outside and inside of the chamber 16, a recovery storage tank 30 that recovers and stores at least a portion of the mud discharged from the chamber 16 by the soil discharge device 17, and a pressure pump 31 that pressure-feeds the mud from the recovery storage tank 30 into the chamber 16. This configuration allows the pressure within the chamber 16 to be restored accurately and quickly. Furthermore, since the mud within the chamber 16 is reused, unlike when only mud-making material (additive) is injected alone, returning mud with properties similar to the mud within the chamber 16 allows for a more stable face condition to be restored.

[0069] (5) In this alternative embodiment, the recovery storage tank 30 is injected (added) with muddy soil material, and a mixing mechanism 31 is further provided to mix the mud and muddy soil material in the recovery storage tank 30, thereby making it possible to change the material into one that is easier to return.

[0070] (6) Another type of pressure recovery device 8C for restoring pressure in the chamber of a shield tunneling machine includes a volume change mechanism that changes the volume of the chamber 16 by moving at least a portion of it to the outside and inside of the chamber 16, a mud storage tank 30A that stores mud produced outside the tunnel or at a specified location inside the machine, and a pressure pump 31 that pumps the mud from the mud storage tank 30A into the chamber 16. This configuration allows the pressure in the chamber 16 to be restored accurately and quickly. In this case, it is possible to supply mud that is similar in properties to the mud in the chamber 16, or mud with significantly different properties.

[0071] (7) As described above, the controlled earth pressure setting system S of this embodiment is a controlled earth pressure setting system S for an earth pressure shield 1 as a shield tunneling machine, and includes a pressure gauge 22 that measures mud pressure in the chamber 16, pressure recovery devices 8, 8A that change the mud pressure in the chamber 16, displacement measurement means 6, 7 that measure the displacement of the face F, an analysis unit 41 that analyzes the deformation characteristics of the ground based on the measured mud pressure and the measured displacement of the face, and a setting unit 42 that sets the controlled earth pressure based on the analyzed deformation characteristics. Because of this configuration, the controlled earth pressure setting system S can set the controlled earth pressure by directly measuring the relationship between the mud pressure in the chamber and the displacement of the face, rather than setting the controlled earth pressure based on assumptions or estimates.

[0072] (8) Furthermore, when the shield machine is stopped, the pressure recovery devices 8, 8A draw a predetermined amount of mud into the machine, thereby reducing the mud pressure in chamber 16, and the analysis unit 41 can determine the active earth pressure from the deformation of the ground. Therefore, when the shield machine is stopped from excavating - for example, when the segments are being assembled - the pressure in chamber 16 is slightly reduced, causing face F to move slightly toward chamber 16, and the active earth pressure can be directly determined by analyzing the yield point from the transition region in the graph showing the relationship between mud pressure and face displacement.

[0073] (9) In addition, the analysis unit 41 estimates the mechanical constants of the ground by inverse analysis based on the analyzed deformation characteristics of the ground, updates the FEM model using the estimated mechanical constants of the ground, and uses the updated FEM model to predict the impact on the surrounding ground and / or structures. Therefore, although not completely in real time, by updating the FEM model at intervals that are close to real time and much shorter than conventional methods, the characteristics of the ground can be made much closer to the actual characteristics. As a result, predictions and impact assessments using the FEM model can be achieved with extremely high accuracy.

[0074] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes that do not deviate from the gist of the present invention are included in the present invention.

[0075] For example, in the embodiment, an example has been described in which the detection jig 61 penetrates the partition wall 3 and reaches the face F, but this is not limited to this, and the detection jig 61 does not have to penetrate the partition wall 3 as long as it is configured to be able to move forward and backward within the chamber 16. Also, in the embodiment, the water pressure gauge 23 is attached to the top end of the skin plate 2, but this is not limited to this, and it may be attached, for example, to another location on the skin plate 2 or to the cutter head 5, etc. Also, the measurement position for displacement measurement is not limited to the face F, and it may also be possible to use, for example, displacement at a position slightly recessed from the face (temporarily referred to as the vicinity of the face).

[0076] In addition, in the embodiment, the control flow is divided into processes according to whether 3D-FEM model analysis is required or not, but this is not limited to this, and it is of course possible to configure the system so that 3D-FEM model analysis is always performed.

[0077] Furthermore, the pressure recovery devices 8, 8A of the embodiment and modified examples are not limited to being attached at the positions shown in Figures 5 to 7. For example, as shown in Figures 5 to 7, they may be attached near the bottom of the partition wall 3, near the middle, or at the top. [Explanation of symbols]

[0078] 1: Earth pressure shield 2: Skin plate 2a: Hood part 2b: Tail section 3: Bulkhead 5: Cutter head 6: Displacement measurement means 7: Displacement measurement means 10: Cutter rotation axis 11: Bearing 12: Cutter drive unit 13: Gearbox 14: Rotation drive source 15: Erector 16: Chamber 17:Earth removal equipment 18: Shield propulsion jack 19: Tail seal 21:Soil supply piping 22: Pressure gauge 23: Water pressure gauge 30: Collection storage tank 30A: Mud storage tank 31: Pressure pump 32: Stirring mechanism 40: Control section 41:Analysis Department 42: Setting section 43: Communication cable 51: Cutter Spoke 52: Cutter bit 53: Fishtail bit 54: Mixing blade 61: Inspection jig 61a: Tip 62: Jack 63: Hydraulic chuck 64: Detection unit 65: Guide 66: Displacement sensor 67: Water stop device 68: Valve 71-78: Multi-stage inclinometer (or layer-by-layer settlement meter) 8, 8A-8C: Pressure recovery device 81: Recess 82: Jack 82a: Cylinder section 82b: Rod part 83: Support plate 8A: Pressure recovery device 84: Mixing blade (sliding mixing blade) 85: Jack 85a: Cylinder section 85b: Rod part 86: Bracket 3a: opening 90: Segment S: Controlled earth pressure setting system F: Face

Claims

1. A pressure recovery device for recovering pressure in a chamber of a shield tunneling machine, A pressure recovery device comprising a volume change mechanism, at least a portion of which is moved outside and inside the chamber to change the volume within the chamber.

2. A pressure recovery device as described in claim 1, wherein the volume change mechanism comprises a recess formed in the partition wall, a jack installed in the recess, and a support plate attached to the front side of the jack, and the support plate is adapted to be retracted from a reference position that is flush with the partition wall toward the inside of the aircraft by driving the jack to extend and retract, and to be pushed from the inside of the aircraft to the reference position.

3. A pressure recovery device as described in claim 1, wherein the volume change mechanism comprises an agitator blade protruding from the partition into the chamber and a jack attached to the back side of the agitator blade, and the agitator blade is adapted to be retracted into the inside of the machine from a reference position protruding a predetermined amount from the partition by driving the jack to extend and retract, and to be pushed out from the inside of the machine to the reference position.

4. A pressure recovery device for recovering pressure in a chamber of a shield tunneling machine, a recovery storage tank that recovers and stores at least a portion of the mud discharged from the chamber by the soil discharge device; a pressure pump that pumps mud from the collection reservoir into the chamber.

5. The recovery storage tank is filled with soil material, 5. The pressure recovery device according to claim 4, further comprising a stirring mechanism for stirring the mud and the mud-making material in the recovery storage tank.

6. A pressure recovery device for recovering pressure in a chamber of a shield tunneling machine, A mud storage tank for storing the mud produced at a designated location outside the mine or inside the machine; a pressure recovery device comprising: a pressure pump that pressure-feeds mud from the mud storage tank into the chamber.

7. A system for setting controlled earth pressure in a shield tunneling machine, a pressure gauge for measuring the mud pressure in the chamber; A pressure recovery device according to any one of claims 1 to 6; a displacement measuring means for measuring the displacement of the tunnel face; an analysis unit that analyzes the deformation characteristics of the ground based on the measured mud pressure and the measured displacement of the tunnel face; a setting unit that sets the controlled earth pressure based on the analyzed deformation characteristics; A controlled earth pressure setting system comprising:

8. A control earth pressure setting system as described in claim 7, wherein when the shield tunneling machine is stopped, the pressure recovery device reduces the mud pressure in the chamber, allowing the analysis unit to determine the active earth pressure from the deformation of the ground.

9. The analysis unit Based on the analyzed deformation characteristics of the ground, the mechanical constants of the ground are estimated by inverse analysis, and the FEM model is updated using the mechanical constants of the ground.

9. The system for setting controlled earth pressure according to claim 8, wherein the updated FEM model is used to predict the effects on the surrounding ground and / or structures.

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