Controlled earth pressure setting system

Abstract

The present invention provides a pressure recovery device that can accurately and easily control the pressure inside a chamber, which is necessary when performing a decompression test. [Solution] The pressure recovery device 8 (8A) of this embodiment is a pressure recovery device 8 that recovers pressure in the chamber 16 of a shield tunneling 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. The 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, and the support plate 83 is adapted to be retracted into the inside of the machine from a reference position that forms the same plane as the bulkhead 3 by driving the jack 82 to extend or retract.

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 an earth pressure shield, the controlled earth pressure of muddy soil pressure inside the chamber is set within the following range. (Passive earth pressure + water pressure) > Muddy earth 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 since high mud pressure in the chamber leads to increased cutter torque and jack thrust, resulting in inefficiencies in construction, it is desirable to set the controlled earth pressure low within the range where the stability of the face is ensured. 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-mentioned 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. Meanwhile, 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] Conventional methods for controlling mud pressure inside the chamber of earth pressure shield tunneling include the following two methods 1) and 2). 1) A method of calculating active earth pressure, passive earth pressure, static earth pressure, etc. using a formula for calculating earth pressure from 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 of the mud soil pressure in 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] JP 2012-233372 A [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: A preliminary soil survey is usually carried out by boring, and is 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. In addition, since the calculation formula for earth pressure is a theoretical one based only on a simplified two-dimensional balance of forces, it is not necessarily possible to accurately calculate the earth pressure on the shield face ground in an actual three-dimensional state.

[0009] · Management method 2) Issues: The mud pressure at stop measured when the shield is stopped is thought to reflect the earth pressure acting on the face relatively accurately if the shield itself is not moving and the cutter head does not have a face plate, but if these conditions are not maintained, the mud pressure at stop 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 the controlled earth pressure of a shield tunneling machine, which sets the controlled earth pressure by directly measuring the relationship between the mud earth pressure in the chamber and the displacement near the face, rather than setting the controlled earth pressure based on assumptions or estimates. In this controlled earth pressure setting system, it is necessary to carry out a decompression test to reduce the mud earth pressure in the chamber in order to obtain the deformation characteristics based on the pressure change in the chamber of the target ground.

[0011] Conventionally, in order to change the pressure in the chamber, a method of controlling the amount of soil discharged by adjusting the rotation of the screw conveyor has been used. However, there is a problem that it is difficult to accurately control the pressure in the chamber when controlling the amount of soil discharged by the screw conveyor. In other words, since the pressure in the chamber when the shield is stopped drops significantly even with a small amount of soil discharged, it was necessary to control the discharge of a small amount of soil in order to control the pressure accurately. Therefore, the inventors developed a pressure control device that can accurately and easily control the pressure in the chamber, which is necessary for carrying out a decompression test. However, when a decompression test is carried out and a moderate displacement of the face or a loosening of the ground is confirmed, or in an emergency (the usual means for restoring pressure is to extend the shield jack, but for example, when the reaction force is not uniform during segment assembly, etc., the jack cannot be freely operated), a technology for quickly restoring the pressure in the chamber is required.

[0012] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a pressure recovery device capable of quickly recovering the pressure inside a chamber. [Means for solving the problem]

[0013] The first form 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 for recovering pressure in a chamber of a shield machine, and includes a recovery storage tank for recovering and storing at least a portion of the mud discharged from the chamber by the soil discharge device, and a pressure pump for pumping the mud from the recovery storage tank into the chamber. In addition, it is also preferable to further include a volume change mechanism for changing the volume in 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 a chamber of a shield tunneling machine, and includes a mud storage tank for storing mud at a predetermined location outside the tunnel or inside the machine, and a pump for pumping the mud from the mud storage tank into the chamber. In addition, it is preferable to further include a volume change mechanism for changing the volume of the chamber by moving at least a portion of the mud to the outside and inside of the chamber.

[0016] In addition, the controlled earth pressure setting system for the 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 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. Effect of the Invention

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

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

[0019] The third embodiment of the pressure recovery device of the present invention is a pressure recovery device for recovering the 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 restored.

[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 measuring 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. Because of 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 description of the drawings]

[0021] [Figure 1] FIG. 2 is a cross-sectional view illustrating the internal structure of a shield tunneling machine. [Diagram 2] 4 is a cross-sectional view illustrating the configuration of an exploration jig and a measurement sensor. FIG. [Diagram 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 the insertion of the detection tool, and (c) is an explanatory diagram during displacement measurement. [Figure 4] An explanatory diagram of the pre-installed face displacement measurement method, (a) being a horizontal cross-sectional view and (b) being a vertical cross-sectional view. [Diagram 5] FIG. 2 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 support plate type pressure recovery device of the 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 for explaining the configuration of a slide agitating blade type pressure recovery device of a modified example of the first embodiment, in which (a) is the state before retraction and (b) is the state after retraction. [Figure 8] FIG. 11 is an explanatory diagram illustrating the configuration of a return type pressure recovery device of a second embodiment. [Figure 9] FIG. 11 is an explanatory diagram illustrating the configuration of a pressure recovery device of the 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. 2 is an explanatory diagram for explaining the concept of an FEM model. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an embodiment 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. In the following, an earth pressure shield 1 will be described as an example, but the present invention can also be applied to other types of shield tunneling machines. EXAMPLES

[0023] (Shield tunneling machine configuration) Fig. 1 is a vertical cross-sectional side view showing an embodiment of the present invention. As shown in Fig. 1, an earth pressure shield 1 as a shield tunneling machine of this embodiment includes a skin plate (shield body cylinder) 2, a bulkhead 3, a cutter head 5, a cutter rotating shaft 10, a cutter driving 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 rotating shaft 10 is rotatably supported by a bearing 11 provided in the partition 3 and a bearing provided at the rear of a gear box 13 described below. The cutter rotating shaft 10 is connected to a cutter driving unit 12. The cutter driving unit 12 has a gear box 13 installed on the rear side of the partition 3, a rotational drive source 14 connected to the gear box 13, and a reduction gear (arranged in the gear box 13; not shown) interposed between the output shaft of the rotational drive source 14 and the cutter rotating shaft 10.

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

[0027] Furthermore, an erector 15 for assembling the 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 portion of the skin plate 2.

[0028] The earth pressure shield 1 as the shield tunneling machine of this embodiment further comprises displacement measurement means 6, 7 that measure the displacement of the tunnel face or the vicinity of the tunnel face. Here, first, the on-board measurement type displacement measurement means 6 that measures the displacement of the tunnel face from inside the machine will be described with reference to Figures 2 and 3, and then the pre-installation type displacement measurement means 7, in which an instrument is installed in advance from the ground, will be described with reference to Figure 4.

[0029] As shown in Figure 2, the on-board displacement measuring means 6 is composed of a rod-shaped detection jig 61 having a sufficient length to penetrate the bulkhead 3 and allow its tip 61a to reach the face F, a hydraulic chuck 63 which grasps / releases the detection jig 61 and moves / releases the detection jig 61 as the jacks 62, 62 extend and retract, a detection unit 64 which is attached integrally to the end of the detection jig 61, a guide 65 which supports the sliding movement of the detection unit 64, a displacement sensor 66 which measures the amount of 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 hydraulic chuck 63 grips the exploration jig 61, the exploration jig 61 retreats when the jacks 62, 62 extend, and the exploration jig 61 advances when the jacks 62 retract. When the hydraulic chuck 63 is released, the exploration jig 61 is free. Therefore, in the released state (the exploration jig 61 can move freely), if the tip 61a of the exploration jig 61 is in contact with the face F, the exploration jig 61 moves (in the tunnel longitudinal direction) in accordance with the displacement of the face F. As described later, in the present invention, the mud pressure in the chamber 16 is reduced, causing the face F to protrude slightly, and the exploration jig 61 moves in the tunnel longitudinal direction toward the tunnel mouth.

[0031] Next, the operation procedure of the displacement measuring means 6 having the detection jig 61 and the displacement sensor 66 in the decompression test of this embodiment will be described with reference to FIG. 2 and FIGS. 1. During shield tunneling, the exploration jig 61 is retracted to the partition wall 3 position (Figure 3(a)). 2. After the shield stops, the detection jig 61 is gripped by the hydraulic chuck 63 and slid to a position where 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. Operate the soil removal means at a slow speed to gradually reduce the soil pressure in the chamber 16. 5. When the face F is displaced due to the reduction in pressure, 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 mud pressure in the chamber 16 is measured by the pressure gauge 22 installed in the bulkhead 3. 8. Using the above procedure, the relationship between the mud pressure in chamber 16 and the face F displacement is determined. 9. The depressurization test is stopped when all or part of the transition region in the face displacement (including the yield point) becomes clear. 10. For example, the soil discharge means is reversed to return the soil to the chamber 16, thereby increasing the soil pressure to the initial state. 11. The detection jig 61 is gripped by the hydraulic chuck 63 and pulled back by operating the jack 62, and the detection 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 measuring means 6 described above, the components for measuring displacement can be replaced with pre-installed multi-stage inclinometers (or layer-by-layer settlement gauges) 71-74, 75-78 that are installed in advance from the ground. That is, the pre-installed displacement measuring means 7 is configured such that a plurality of multi-stage inclinometers 71-74, 75-78 are installed at a predetermined depth position from the ground surface, as shown in Fig. 4. The installation positions preferably include, for example, in addition to the vicinity of the face at the planned position for tunnel excavation, positions directly above it and positions shifted to the left and right (and directly above it).

[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 in the cross section where the shield is scheduled to pass, temporarily halting shield tunneling just before the measuring device, and conducting a decompression test. These multi-stage inclinometers 71-74 are preferably buried at a specified interval in the area where the shield is scheduled to pass. In this case, it is preferable to bury them at an interval 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 with reference to Figures 5, 6(a) and 6(b). As shown in Figures 5, 6(a) and 6(b), the pressure recovery device 8 is provided with a volume change mechanism that increases the volume inside the chamber 16 by moving a part of it to the outside of the chamber 16 (i.e., the inside of the aircraft), and decreases the volume inside the chamber 16 by moving it to the inside of the chamber 16 (i.e., the outside of the aircraft). This volume change mechanism is provided with 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, and this support plate 83 is adapted to be drawn in from a reference position that forms the same plane as the bulkhead 3 to the inside of the aircraft by driving the jack 82 to extend or retract.

[0035] Specifically, the recess 81 is a cylindrical case with a bottom, and has a jack 82 and a support 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 support plate 83 is attached to the front side (face side) of the rod portion 82b. This support plate 83 forms the same plane as the bulkhead 3 when the jack 82 is extended.

[0036] During shield tunneling, as shown in Fig. 6(a), the bearing plate 83 of the pressure recovery device 8 is positioned so as to be flush with the bulkhead 3. On the other hand, when a depressurization test is performed after the shield is stopped, as shown in Fig. 6(b), the bearing plate 83 is moved rearward (from the reference position toward the inside of the machine) by retracting the jack 82. 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 aircraft interior 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 performing 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. Thereafter, when the decompression test is completed, the jacks 82 of the pressure recovery devices 8 are extended to push the support plate 83 back to the initial position (reference position), thereby restoring the pressure inside the chamber 16.

[0039] (Pressure recovery device according to a modification of the first embodiment) Next, the configuration and operation of a pressure recovery device 8A of a modified example 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 inside the chamber 16 by moving a part of it to the outside of the chamber 16. This volume change mechanism is equipped with an agitator blade 84 that protrudes from the partition wall 3 into the chamber 16, and a jack 85 attached to the back side of the agitator blade 84, and the agitator blade 84 is retracted from a reference position protruding a predetermined amount from the partition wall 3 to the inside of the machine by driving the jack 85 to extend or retract.

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

[0041] During shield tunneling, as shown in Fig. 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 decompression test is performed after the shield is stopped, as shown in Fig. 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 in the chamber 16 and decreasing the pressure in the chamber 16. In this way, minute changes in the air volume can be controlled by operating the jack 85, allowing 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 Figs. 7(b) to 7(a), the (sliding) agitating blade 84 is pushed into the chamber 16 by operating the jack 85, thereby reducing the actual air space in the chamber 16 and increasing the pressure in the chamber 16. 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 inside the chamber 16 can be increased or decreased by expanding or contracting the cross-sectional area of ​​the (sliding) agitator 84 of the pressure recovery device 8A. The amount of change in the air volume can also be adjusted by increasing or decreasing the number of pressure recovery devices 8A. After the reduction pressure test is completed, the pressure inside the chamber 16 can be restored by pushing the (sliding) agitator 84 back to its original position. Note that in this embodiment, the volume change is caused by using the agitator (84), but the present invention can be applied to any part that does not necessarily have the function of the agitator (84) as long as it is a part that protrudes into and out of the chamber 16.

[0044] (Second embodiment of 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 Fig. 8. As shown in Fig. 8, the pressure recovery device 8B is equipped with a volume change mechanism that increases the volume inside the chamber 16 by moving a part of it to the outside of the chamber 16 (i.e., the inside of the machine), and decreases the volume inside the chamber 16 by moving it to the inside of the chamber 16 (i.e., the outside of the machine).

[0045] This volume change mechanism includes a recess 81 formed in the partition 3, a jack 82 installed in the recess 81, and a support plate 83 attached to the front side of the jack 82, and this support plate 83 is adapted to be retracted from a reference position that forms the same plane as the partition 3 to the inside of the machine by driving the jack 82 to extend or retract. Note that the volume change mechanism may be configured using a stirring blade 84 and a jack 85 as shown in FIG. 7.

[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, in addition to 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 then, for example, after the completion of a decompression test, it is returned into the chamber 16 by a pressure pump 31 (such as a positive displacement rotary pump) to restore the pressure inside the chamber 16. It can of course also be used to restore pressure in an emergency. The position where the mud is returned into the chamber 16 is not limited to the bottom as shown in the figure, and may be installed anywhere. The volume change mechanism and pressure transport method can be used independently, or both may be used together.

[0048] Furthermore, the recovery storage tank 30 is further provided with a mixing mechanism 32 for injecting a muddy soil material, such as bentonite or clay, and mixing the mud stored in the recovery storage tank 30 with the injected muddy soil material. By injecting and mixing a separate muddy soil material into the mud to be returned in this way, it is possible to change the material into one that is easier to return. Here, the case where a muddy soil material is mixed into the recovery storage tank 30 has been described, but this is not limiting, and the present invention can be established whether or not a muddy soil material is injected.

[0049] (Third form of new mud making method pressure recovery device) Next, the configuration and operation of the pressure recovery device 8C of the third embodiment of the new mud making method will be described with reference to 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 part of it to the outside of the chamber 16 (i.e., the inside of the machine), and decreases the volume inside the chamber 16 by moving it to the inside of the chamber 16 (i.e., the outside of the machine).

[0050] This volume change mechanism includes a recess 81 formed in the partition 3, a jack 82 installed in the recess 81, and a support plate 83 attached to the front side of the jack 82, and this support plate 83 is adapted to be retracted from a reference position that forms the same plane as the partition 3 to the inside of the machine by driving the jack 82 to extend or retract. Note that the volume change mechanism may be configured using a stirring blade 84 and a jack 85 as shown in FIG. 7.

[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 specified location inside the machine, and a pump 31 for pumping the mud from the mud storage tank 30A into the chamber 16. That is, the pressure recovery device 8C includes a device for supplying mud produced outside into the chamber 16 in addition to the volume change mechanism. In this way, by performing pressure recovery using mud suitable for pumping, rather than recovered mud, smoother pumping becomes possible, which contributes to quicker pressure recovery. Note that the third embodiment may also use pressure recovery using a volume change mechanism, as in the second embodiment.

[0052] (Control system configuration) In addition, the earth pressure shield 1 further includes a control unit 40. The control unit 40 is, for example, a general-purpose personal computer having a memory, a CPU, an SSD, and the like. The control unit 40 sets the managed earth pressure of the earth pressure shield 1 and controls the excavation. That is, during excavation, the earth pressure is changed by discharging the mud with the soil discharge device 17 (screw conveyor) while advancing the earth pressure shield 1 with the shield driving jack 18, and at the same time, the mud pressure is measured with the pressure gauge 22. Furthermore, the water pressure is measured with the water pressure gauge 23. It is of course possible that the functions of the analysis unit 41 and the setting unit 42 described later can be executed by 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 has a function as an analysis unit 41 that analyzes the deformation characteristics of the ground based on the measured mud pressure and the measured displacement (e.g. horizontal displacement) of the face, and a function as a setting unit 42 that sets the controlled earth pressure based on the analyzed deformation characteristics. The control unit 40 is connected to input means such as a keyboard and a mouse, as well as to receive 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. 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 the setting unit 42 will be described in the control flow described next.

[0054] The controlled earth pressure setting system S of the present invention is constituted by the above-mentioned pressure gauge 22, the above-mentioned pressure recovery device 8 (8A), the displacement measuring means 6 (7), and the control unit 40 including an analysis unit 41 and a 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 advanced according to this initial value of the controlled earth pressure (step S3). That is, in the initial stage after the shield starts advancing (before the decompression test is carried out), 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 the displacement of the ground.

[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 segment 90, the pressure recovery device 8 (8A) is pulled inward by a small amount to control the pressure highly accurately, and the mud in the chamber 16 is gradually discharged and reduced. During the reduction in pressure, the mud pressure is measured by the pressure gauge 22. At the same time, the water pressure is measured by the water pressure gauge 23. Furthermore, during the reduction in pressure, the displacement of the face F is directly measured by the displacement measuring means 6, 7 (step S5). Based on the measured mud pressure and face displacement (e.g. horizontal displacement), the deformation characteristics are grasped (step S6). That is, the mud pressure-face displacement is plotted on a graph to obtain the deformation characteristics. Once the deformation characteristics are grasped, 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, by this 3D-FEM model analysis, the effects on the surrounding ground and adjacent structures are predicted (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 a boring survey 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 judging whether the amount of ground surface subsidence, etc. is within 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, the mechanical constants are, for example, Young's modulus, Poisson's ratio, internal friction angle, and cohesion. A rational simulation of behavior can be performed by adopting an FEM model based on the ground characteristics obtained based on this on-site behavior. A rational simulation based on the above-mentioned on-site behavior makes it possible to predict the ground surface subsidence and the impact on adjacent structures in advance and more accurately, minimizing the impact on the surrounding area or setting the controlled earth pressure corresponding to the regulated values ​​for ground displacement, etc.

[0062] Analysis and settings (steps S13 to S14) On the other hand, if the deformation characteristics of the ground are grasped, the yield point earth pressure is obtained by analysis from the muddy earth pressure-displacement graph as shown in FIG. 11 (step S13). That is, the analysis unit 41 of the control unit 40 finds the point where the gradient suddenly increases, regards this point as the yield point, and obtains the active earth pressure. For example, an approximation line can be obtained from a plurality of plots in the elastic region by the least squares method, and an approximation line can be obtained from a plurality of plots in the plastic region by the least squares method, and the intersection of these can be regarded as the yield point. Alternatively, it can be estimated that the transition region has been entered by the appearance of consecutive plots that are significantly different from the moving average. Then, if a 3D-FEM model analysis is required due to the presence of buildings nearby, 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 it is set to the active earth pressure plus water pressure plus α (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 above lower limit and the construction fluctuation range. On the other hand, if a 3D-FEM model analysis is required ("Required" in step S14), the 3D-FEM model analysis is executed (step S9).

[0063] In this way, the observed digital values ​​(observed values) are compared with the digital values ​​(analytical values) obtained through analysis using a 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 progresses (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 the shield machine, and is provided 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 such a 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 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. The support plate 83 is retracted from a reference position that is flush with the bulkhead 3 to the inside of the machine and pushed from the inside of the machine to the reference position by driving the jack 82 to extend and retract. Therefore, the volume in the chamber 16 increases or decreases by an amount corresponding to the retraction amount of the support plate 83, and the pressure can be changed and controlled accurately and quickly. That is, when the support plate 83 is retracted into the recess 81, mud enters the recess 81, and the pressure in the chamber 16 decreases by that amount. Conversely, when the support plate 83 is pushed out from the recess 81 to the reference position, mud is pushed out from the recess 81, and the pressure in the chamber 16 increases by that amount.

[0067] (3) Furthermore, the volume change mechanism includes an impeller 84 protruding from the partition 3 into the chamber 16 and a jack 85 attached to the back side of the impeller 84. The impeller 84 is retracted from a reference position protruding from the partition 3 by a predetermined amount to the inside of the machine and pushed from the inside of the machine to the reference position by driving the jack 85 to extend and retract. Therefore, the volume in the chamber 16 increases or decreases by an amount corresponding to the retracted or pushed-out amount of the impeller 84, and the pressure can be changed and controlled accurately and quickly. That is, by retracting the impeller 84 into the inside of the machine, the volume in the chamber 16 increases by an amount corresponding to the retracted amount of the impeller 84, and the pressure decreases. Conversely, by pushing out the impeller 84, the volume in the chamber 16 decreases by an amount corresponding to the pushed-out amount of the impeller 84, and the pressure in the chamber 16 increases by that amount.

[0068] (4) In addition, a pressure recovery device 8B for recovering the pressure in the chamber of a shield tunneling machine of another type includes a volume change mechanism for changing the volume in the chamber 16 by moving at least a part of it to the outside and inside of the chamber 16, a recovery storage tank 30 for recovering and storing at least a part of the mud discharged from the chamber 16 by the soil discharge device 17, and a pressure pump 31 for pressure-feeding the mud from the recovery storage tank 30 into the chamber 16. With this configuration, the pressure in the chamber 16 can be accurately and quickly restored. Furthermore, since the mud in the chamber 16 is reused, unlike the case where only the mud-making material (additive) is injected alone, a material with properties similar to the mud in the chamber 16 is returned, thereby making it possible to restore a more stable face state.

[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 the muddy soil material in the recovery storage tank 30, thereby making it possible to change the material to one that is easier to return.

[0070] (6) A pressure recovery device 8C for recovering pressure in the chamber of a shield tunneling machine of yet another form comprises a volume change mechanism for changing the volume in the chamber 16 by moving at least a portion of it to the outside and inside of the chamber 16, a mud work storage tank 30A for storing mud work done at a specified location outside the tunnel or inside the machine, and a pressure pump 31 for pressure-feeding the mud from the mud work storage tank 30A into the chamber 16. With this configuration, the pressure in the chamber 16 can be recovered accurately and quickly. In this case, it is possible to supply mud with properties similar to those of the mud in the chamber 16, or mud with properties significantly different from those of the mud in the chamber 16.

[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 earth pressure in the chamber 16, pressure recovery devices 8, 8A that change the mud earth 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 earth 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 earth 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 specified amount of mud into the machine, thereby reducing the mud pressure in chamber 16, and the active earth pressure can be found from the deformation of the ground by analysis unit 41. Therefore, when the shield machine is stopped excavating - for example, when the segments are being assembled - the pressure in chamber 16 is slightly reduced to slightly displace face F towards chamber 16, and the active earth pressure can be directly found 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 predicts the impact on the surrounding ground and / or structures using the updated FEM model. Therefore, although not completely in real time, by updating the FEM model at intervals that are close to real time updates and much shorter than conventional intervals, the characteristics of the ground can be made much closer to the actual characteristics. Therefore, prediction and impact assessment using the FEM model can be realized with extremely high accuracy.

[0074] Although an embodiment of the present invention has been described in detail above 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 bulkhead 3 to reach the face F, but this is not limited thereto, and the detection jig 61 does not have to penetrate the bulkhead 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 thereto, and for example, it may be attached 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 for example, the displacement at a position slightly recessed from the face (temporarily referred to as the vicinity of the face) may be used.

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

[0077] Furthermore, the pressure recovery devices 8, 8A of the embodiment and the 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 section 2b: Tail section 3: Bulkhead 5: Cutter head 6: Displacement measurement means 7: Displacement measurement means 10: Cutter rotation axis 11: Bearings 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: Mixing 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 tool 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 section 83: Support plate 8A: Pressure relief device 84: Agitator blade (slide agitator blade) 85: Jack 85a: Cylinder section 85b: Rod section 86: Bracket 3a: opening 90 :Segment S: Controlled earth pressure setting system F: Face

Claims

1. A system for setting controlled earth pressure in a shield tunneling machine, comprising: a pressure gauge for measuring the mud pressure in the chamber; A pressure recovery device for recovering pressure in a chamber of a shield machine, the pressure recovery device comprising: a volume change mechanism for changing the volume of the chamber by moving at least a portion of the volume change mechanism to the outside and inside of the chamber; a recovery storage tank for recovering and storing at least a portion of the mud discharged from the chamber by the soil discharge device; and a pressure pump for pressure-feeding the mud from the recovery storage tank into the chamber; A displacement measuring means for measuring a displacement of the face during the reduction in the mud pressure by moving a part of the volume change mechanism to the outside of the chamber; an analysis unit that analyzes deformation characteristics of the ground based on the measured mud pressure and the measured displacement of the tunnel face; A setting unit that sets an earth pressure control based on the analyzed deformation characteristics; A controlled earth pressure setting system comprising:

2. In the pressure recovery device, The recovery storage tank is filled with muddy soil material, The controlled earth pressure setting system according to claim 1, further comprising a mixing mechanism for mixing the mud and the muddy soil material in the recovery storage tank.

3. A system for setting controlled earth pressure in a shield tunneling machine, comprising: a pressure gauge for measuring the mud pressure in the chamber; A pressure recovery device for recovering pressure in a chamber of a shield tunneling machine, the pressure recovery device comprising: a volume change mechanism for changing the volume of the chamber by moving at least a portion of the volume change mechanism to the outside and inside of the chamber; a mud storage tank for storing mud generated outside the tunnel or at a specified location inside the machine; and a pressure pump for pumping the mud from the mud storage tank into the chamber; A displacement measuring means for measuring a displacement of the face during the reduction in the mud pressure by moving a part of the volume change mechanism to the outside of the chamber; an analysis unit that analyzes deformation characteristics of the ground based on the measured mud pressure and the measured displacement of the tunnel face; A setting unit that sets an earth pressure control based on the analyzed deformation characteristics; A controlled earth pressure setting system comprising:

4. A system for setting controlled earth pressure as described in any one of claims 1 to 3, wherein when the shield machine is stopped, the pressure recovery device reduces the mud pressure in the chamber, thereby allowing the analysis unit to determine the active earth pressure from the deformation of the ground.

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

5. The system for setting an administered earth pressure according to claim 4, further comprising a step of predicting an effect on the surrounding ground and / or structures using the updated FEM model.

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