Test platform and comprehensive evaluation method for tunneling water and soil load of shield tunneling machine

Abstract

The invention discloses a shield tunneling machine tunneling water and soil load test platform and a comprehensive evaluation method, and belongs to the technical field of shield tunneling engineering. The test platform is used for testing the performance of the water and soil pressure sensing and monitoring device, and the water and soil pressure sensing and monitoring device is provided with a four-way connector. The comprehensive evaluation and monitoring method for the tunneling water-soil load of the shield tunneling machine comprises the following steps: determining an adaptive calculation method for water-soil pressure of various stratums, and constructing a shield water-soil pressure evaluation and monitoring early warning system; and installing the water and soil pressure sensing and monitoring device which is tested to be qualified on the shield tunneling machine, judging that the adaptability calculation method is feasible, and forming a corresponding water and soil pressure comprehensive evaluation and sensing method. According to the comprehensive evaluation and actual measurement method for the tunneling water-soil load of the shield tunneling machine, association methods of theoretical correction, experimental testing, field monitoring and system early warning are comprehensively applied, and the accuracy of evaluation of water-soil pressure of different stratums is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of shield tunnel engineering, and in particular relates to a test platform and a comprehensive evaluation method for water and soil loads of shield machine excavation. Background Art

[0002] Underwater shield tunnels have become the preferred mode of transportation across rivers, lakes and seas because the construction process does not affect shipping traffic and the construction is not affected by seasons, climate, etc. However, as the construction environment becomes increasingly complex, underwater shield tunnels have the characteristics of "ultra-long distance, ultra-large diameter, ultra-high water pressure, and complex geology". Especially for ultra-large diameter shield tunnels, the shield machine is subject to high external water pressure and large changes in tunnel section pressure difference, which have an important impact on the shield machine's pressure resistance design, shield tail sealing, incision pressure setting, grouting parameter selection, and safety of entering the cabin under pressure. Therefore, it is urgent to carry out a comprehensive assessment of the water and soil pressure during the shield machine excavation process, and to perceive the water and soil pressure status through actual measurement methods to guide the safe construction of underwater and large-diameter shield tunnels. However, in the process of use, it was found that the existing technology has at least the following deficiencies: The existing shield tunnel water and soil pressure assessment mainly uses Rankine earth pressure as the calculation basis, which is not very applicable to various strata such as clay, sand, soft upper and hard lower, and pebble soil. At present, few shield machines are equipped with sensors on the shield body to monitor external water and soil pressure, and there is also a lack of actual measurement methods for water and soil pressure during shield construction. For the identification of water and soil pressure of shield machines, there is currently a lack of comprehensive water and soil pressure assessment methods that combine theory and actual measurement. Summary of the invention

[0003] In view of the problems in the related technology, the present invention proposes a testing platform and a comprehensive evaluation method for water and soil loads of shield machine excavation to overcome the above-mentioned technical problems existing in the existing related technology.

[0004] To this end, the specific technical solution adopted by the present invention is as follows: a test platform for water and soil loads of shield machine excavation, used for performance testing of a water and soil pressure sensing and monitoring device, wherein the water and soil pressure sensing and monitoring device has a four-way joint; the test platform comprises: The platform body is used to accommodate the water and soil pressure sensing and monitoring device; A pressure chamber is installed on the platform body; the pressure chamber comprises: an annular cavity wall, a lower end cover, a middle end cover and an upper end cover connected to the annular cavity wall in sequence from bottom to top; wherein the middle end cover divides the pressure chamber into an upper pressure chamber and a lower pressure chamber; A pressure head, arranged on the upper surface of the upper end cover; A plurality of osmometers and a plurality of pressure sensors are arranged on the inner wall surface of the lower pressure chamber as required.

[0005] In a further embodiment, the test platform further comprises: A pressure pump connected to the four-way connector of the water and soil pressure sensing and monitoring device; A water tank, which provides water pressure to the downward pressure chamber through a water delivery channel to simulate the formation; The pressure servo control unit uses the axial pressure loading channel to connect the pressure head to control the axial expansion and contraction of the pressure head, thereby generating axial pressure on the upper end cover; the pressure servo control unit is simultaneously connected to the upper pressure chamber through a conveying pipeline, and is used to fill the medium in the upper pressure chamber.

[0006] In a further embodiment, the testing method of the testing platform comprises the following steps: Step 101, installing and connecting the first joint of the four-way joint of the water and soil pressure sensing and monitoring device into the inner screw hole of the lower end cover, and connecting the second joint to the pressure pump for siltation flushing test; Step 102: using stratum materials to simulate the stratum material environment of shield tunneling in the lower pressure chamber, connecting the connected water tank with the lower pressure chamber through a water delivery channel to provide groundwater seepage required for simulating the water and soil pressure environment; Step 103, using the axial pressure loading channel to connect the pressure servo control unit to the pressure head, controlling the axial expansion and contraction of the pressure head to generate axial pressure on the upper end cover; and at the same time, filling the medium into the upward pressure chamber through the delivery pipeline; Step 104: Based on the simulation of steps 101 to 103, the overall environment of the formation is obtained, and the actual value acting on the overall environment of the formation is recorded by the pressure sensor and the osmometer. P 实际 : Actual total pressure value P 总-实际 and actual water pressure value P 水-实际 , the following formula is used to evaluate the actual earth pressure acting on the overall environment of the formation P 土-实际 , to achieve the actual earth pressure value P 土-实际 and actual water pressure value P 水-实际 A standalone simulation of: P 总-实际 = P 水-实际 + P 土-实际 ; Step 105: Obtain monitoring values ​​of the water and soil pressure sensing monitoring device P 监测 , the monitoring value P 监测 Includes: Total pressure monitoring value P 总-监测 , water pressure monitoring value P水-监测 and earth pressure monitoring values P 土-监测 ,in, P 土-监测 = P 总-监测 - P 水-监测 ; Step 106: According to the actual value P 实际 and monitoring values P 监测 Determine whether the soil and water pressure sensing monitoring device is qualified.

[0007] A comprehensive evaluation method for water and soil loads of shield machine excavation, based on a water and soil pressure sensing and monitoring device that has passed the test, comprises the following steps: Step 1: Determine the adaptive calculation method for water and soil pressure of various strata, and use the adaptive calculation method to obtain the theoretical water and soil pressure value P 理论 ; Construct shield water and soil pressure assessment and monitoring early warning system based on the geological parameters of various strata; Step 2: Use a test platform to test various performance indicators of the water and soil pressure sensing and monitoring device; the test platform is as described above; Step 3: Install the soil and water pressure sensor monitoring device that has passed the test in step 2 on the shield machine, and use the soil and water pressure sensor monitoring device to sense the actual soil and water pressure value outside. P 实测 If the measured water and soil pressure value P 实测 Theoretical soil and water pressure P 理论 If the pre-set relationship is satisfied, it means that the adaptive calculation method is feasible and forms a corresponding comprehensive assessment and perception method of water and soil pressure; if it is not satisfied, the adaptive calculation method needs to be further revised. The pre-set relationship is as follows: , is a pre-set threshold.

[0008] In a further embodiment, the acquisition process of the adaptability calculation method is as follows: Based on the classical water and soil pressure calculation theory, the applicable scope of each classical water and soil pressure calculation theory is analyzed by considering the stratum characteristics, tunnel burial depth and stratum permeability respectively. The corrected calculation method is obtained by theoretically correcting the stratum to which the classical water and soil pressure calculation theory is not well adapted. The basis for the theoretical correction is derived from model tests and data simulation results.

[0009] In a further embodiment, the shield water and soil pressure assessment and monitoring and early warning system comprises at least the following modules: a water and soil pressure theoretical value assessment module, a shield water pressure monitoring module, a water and soil pressure value comparison module and a shield water pressure comparison module; The water and soil pressure theoretical value evaluation module is configured to provide the theoretical water and soil pressure values ​​of the current excavation ring and the two rings before and after in a tabular form according to the different strata encountered during the shield tunneling process, combined with an adaptive calculation method. P 理论 , and compared with the measured water and soil pressure values P 实测 Triggering level I-III warning prompts; The shield water pressure monitoring module is configured to convert the theoretical water and soil pressure values ​​obtained by various adaptive calculation methods into P 理论 and measured soil and water pressure values P 实测 Comparative analysis, presented in the form of a bar graph; The shield water pressure monitoring module is configured to display the measurement point locations at the arch top and arch waist of different monitoring sections and the measured water and soil pressure values ​​monitored in real time. P 实测 The shield water pressure comparison module is configured to display the measured water and soil pressure values ​​of different ring numbers, different measuring points, and different shield monitoring sections in real time in the form of a bar graph. P 实测 .

[0010] In a further embodiment, the specific installation method of the water and soil pressure sensing monitoring device installed on the shield machine is as follows: Determine the monitoring section, and open a predetermined number of mud-reducing effect holes along the monitoring section around the peripheral direction of the shield body; the monitoring section at least includes: a front shield monitoring section, a middle shield monitoring section and a rear shield monitoring section; The outer side of the mud-reducing hole is connected to a pressure pump and a water tank in sequence through a water pipe, and the inner side is connected to a water and soil pressure sensing and monitoring device; wherein the data of the water and soil pressure sensing and monitoring device is connected to a data transceiver through a data transmission line to realize data collection of simulated water and soil pressure.

[0011] In a further embodiment, the comprehensive water and soil pressure assessment and perception method is used to guide the shield's pressure resistance design, incision pressure setting, grouting parameter selection, and pressurized entry safety.

[0012] In a further embodiment, the strata that are not well adapted to the classical water and soil pressure calculation theory include at least: deeply buried strata.

[0013] In a further embodiment, mud-removing material is injected into two adjacent groups of mud-removing holes before and after the monitoring section to form a sealing ring, which ensures that the excavation gap between the sealing rings is in an objective water and soil pressure environment during a long period of shield shutdown.

[0014] Beneficial effects of the invention: The invention first discloses a test platform suitable for a water and soil pressure sensing monitoring device ( ZL 202310841659.9), the water and soil pressure sensing and monitoring device is tested for performance before use through the test platform, and qualified water and soil pressure sensing and monitoring devices are selected to improve the accuracy of the comprehensive assessment of water and soil loads during shield machine excavation.

[0015] Correspondingly, a test platform and comprehensive evaluation method for water and soil loads of shield machine excavation of the present invention comprehensively applies the associated methods of theoretical correction, experimental testing, on-site monitoring, and system early warning, which improves the accuracy of water and soil pressure evaluation in different strata, objectively monitors the actual water and soil pressure values ​​of the shield machine, effectively guides the shield pressure resistance design, incision pressure setting, grouting parameter selection, and pressurized entry safety, and ensures safe and efficient excavation of underwater shield tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the shield water and soil pressure test platform.

[0017] Figure 2 This is a schematic diagram of the relationship between the diameter of the shield machine and the water and soil pressure it bears.

[0018] Figure 3 It is the overall scheme diagram of the comprehensive assessment and perception method of water and soil pressure of shield tunneling.

[0019] Figure 4 It is a schematic diagram of the theoretical calculation and correction method of water and soil pressure of shield.

[0020] Figure 5 It is a schematic diagram of the shield tunneling soil and water pressure assessment and monitoring early warning system.

[0021] Figure 6 This is a schematic diagram of the shield tunneling water and soil pressure simulation test.

[0022] Figure 7 It is a schematic diagram of the shield tunneling soil and water pressure field testing method.

[0023] Figure 8 It is a stratigraphic model for numerical simulation.

[0024] Fig. 9 It is a schematic diagram of the correction calculation method for deeply buried sandy soil strata.

[0025] Figures 1 to 7The labels in the figure are: test platform 1, water and soil pressure sensing monitoring device 2, pressure pump 3, water tank 4, pressure servo control unit 5, computer control system 6, mud-killing effect hole 7, shield water and soil pressure assessment and monitoring early warning system 8, cutter head 9, pressure head 11, upper end cover 12, annular cavity wall 13, middle end cover 14, piezometer 15, lower end cover 16, upper pressure chamber 17, lower pressure chamber 18, pressure sensor 19, water pipe 21, water tank 22, data transmission line 23, data transceiver 24, cloud platform 25, server 26, water transmission channel 41, axial pressure loading channel 51, transmission pipeline 52, shield body 91, sealing ring 92, mud 93, excavation gap 94, monitoring section 95. DETAILED DESCRIPTION

[0026] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments. They can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. By referring to these contents, ordinary technicians in this field should be able to understand other possible implementation methods and advantages of the present invention.

[0027] Example 1 According to an embodiment of the present invention, a test platform 1 is provided for testing the performance indicators of a water and soil pressure sensing and monitoring device 2. It is worth mentioning that the water and soil pressure sensing and monitoring device 2 described in this embodiment is ZL The water and soil pressure monitoring device in the water and soil pressure monitoring system disclosed in 202310841659.9 includes: a plurality of grouting holes radially distributed on the shield shell; at least one set of water pressure monitoring devices and total pressure sensors 19, which are detachably installed in the corresponding grouting holes; the water pressure monitoring devices and total pressure sensors 19 are used to monitor the water pressure at the corresponding positions p w and total pressure p Then, the earth pressure p s Calculated by the following formula: p s = p - p w Therefore, the performance indicators of the water and soil pressure sensing and monitoring device 2 at least include: sensitivity, anti-clogging, flushability, sealing reliability, etc.

[0028] Correspondingly, the test platform of this embodiment is as follows: Figure 1As shown, it includes: a platform body for accommodating the water and soil pressure sensing and monitoring device 2, wherein a pressure chamber is installed on the upper surface of the platform body. Further, the pressure chamber includes: an annular cavity wall 13, a lower end cover 16, a middle end cover 14 and an upper end cover 12 connected to the annular cavity wall 13 from bottom to top, and the middle end cover 14 divides the pressure chamber into an upper pressure chamber 17 and a lower pressure chamber 18. In order to simulate axial pressure, a pressure head 11 is arranged on the upper surface of the upper end cover 12, and the pressure head 11 uses the axial pressure loading channel 51 and the pressure servo control unit 5 to control the axial expansion and contraction of the pressure head 11 to generate axial pressure on the upper end cover 12. Further, the pressure servo control unit 5 is connected to the upper pressure chamber 17 through a conveying pipe 52, and is used to fill the medium in the lower pressure chamber 18, and the conveying pipe 52 can be used to convey oil or gas.

[0029] In order to obtain the monitoring value in the corresponding chamber, a plurality of osmometers 15 and pressure sensors 19 are arranged on the inner wall surface of the lower pressure chamber 18 as required. In other words, the readings of the pressure sensor 19 and the osmometer 15 are the monitoring values.

[0030] In order to better simulate the real excavation environment, the test platform also includes: a pressure pump 3 connected to the four-way joint of the water and soil pressure sensing and monitoring device 2. The pressure pump 3 is added to complete the siltation and flushing test of the water and soil pressure sensing and monitoring device 2.

[0031] The lower pressure chamber 18 is connected to the water tank 4 through a water pipe 21, and the water flow rate is increased to provide groundwater seepage required for simulating the water and soil pressure environment.

[0032] Based on the above description of the test platform, this embodiment also discloses a test method for the test platform of water and soil load of shield machine excavation, including the following steps: Step 101, install and connect the first joint of the four-way joint of the water and soil pressure sensing and monitoring device 2 to the inner screw hole of the lower end cover 16, and connect the second joint to the pressure pump 3 for siltation flushing test; Step 102: Use stratum materials to simulate the stratum material environment of shield tunneling in the lower pressure chamber 18, connect the connected water tank 4 with the lower pressure chamber 18 through the water delivery channel 41, and provide groundwater seepage required for simulating the water and soil pressure environment. The stratum materials used in this embodiment can be sand, gravel, clay and the like, and correspondingly, the stratum material environment includes: sandy soil stratum, clay stratum, pebble soil stratum, composite stratum and the like.

[0033] Step 103, the pressure servo control unit 5 is connected to the pressure head 11 through the axial pressure loading channel 51, and the pressure head 11 is controlled to axially expand and contract to generate axial pressure on the upper end cover 12; at the same time, the medium is filled into the upper pressure chamber 17 through the delivery pipeline 52. The delivery pipeline 52 in this embodiment is specifically an oil / gas delivery pipeline, so the filled medium can be hydraulic oil or compressed air.

[0034] Step 104: Based on the simulation of steps 101 to 103, the overall environment of the formation is obtained, and the actual value acting on the overall environment of the formation is recorded by the pressure sensor 19 and the osmometer 15. P 实际 : Actual total pressure value P 总-实际 and actual water pressure value P 水-实际 , the following formula is used to evaluate the actual earth pressure acting on the overall environment of the formation P 土-实际 , to achieve the actual earth pressure value P 土-实际 and actual water pressure value P 水-实际 A standalone simulation of: P 总-实际 = P 水-实际 + P 土-实际 ; Step 105: Obtain the monitoring value of the water and soil pressure sensing monitoring device 2 P 监测 , the monitoring value P 监测 Includes: Total pressure monitoring value P 总-监测 , water pressure monitoring value P 水-监测 and earth pressure monitoring values P 土-监测 ,in, P 土-监测 = P 总-监测 - P 水-监测 ; Step 106: The actual value P 实际 and monitoring values P 监测 Recorded in the computer control system 6, and based on the actual value P 实际 and monitoring values P 监测 Determine whether the water and soil pressure sensing monitoring device 2 is qualified.

[0035] The qualified earth pressure sensor monitoring device is finally determined by the above method. If the actual value P 实际 and monitoring values P 监测 If the difference is within the allowable error range and the change trend is consistent, it is qualified.

[0036] Example 2 Combination Figure 2 As shown, in this embodiment, the underwater shield tunnel is subjected to the water and soil pressure of the excavated strata during the construction process. h The increase in the diameter of the tunnel excavation will also cause the increase in water and soil pressure. Φ 1 > Φ 2 > Φ 3 The external water and soil pressure on the shield machine is expressed as ( P w1 + P s1 )>( P w2 + P s2 )>( P w3 + P s3 ), and the larger the diameter of the shield machine, the greater the difference in water and soil pressure at the top and bottom of the tunnel section. Φ 1 is the diameter of tunnel one, Φ 2 is the diameter of tunnel 2, Φ 3 is the diameter of tunnel three. Correspondingly, P w1 and P s1 are the water pressure and earth pressure of the tunnel. P w2 and P s2 They are the water pressure and earth pressure of Tunnel 2. P w3 and P s3 They are the water pressure and earth pressure borne by Tunnel 3.

[0037] like Figure 3 As shown, the shield machine excavation water and soil load comprehensive evaluation and monitoring method of this embodiment includes the following steps: Step 1: Determine the adaptive calculation method for water and soil pressure of various strata, and use the adaptive calculation method to obtain the theoretical water and soil pressure value P 理论 ; Construct shield water and soil pressure assessment and monitoring early warning system based on the geological parameters of various strata8; Step 2: Use a test platform to test various performance indicators of the water and soil pressure sensing and monitoring device 2; the test platform is as described in Example 1; Step 3: Install the soil and water pressure sensor monitoring device 2 that has passed the test in step 2 on the shield machine, and use the soil and water pressure sensor monitoring device 2 to sense the actual soil and water pressure value outside. P 实测 If the measured water and soil pressure value P 实测 Theoretical soil and water pressure P 理论 If the preset relationship is satisfied, it means that the adaptive calculation method is feasible, and a corresponding comprehensive assessment and perception method of water and soil pressure is formed; if it is not satisfied, the adaptive calculation method needs to be further revised.

[0038] The pre-set relationship is as follows: , is a preset threshold value. The value of is 10.

[0039] Combination Figure 4 , the acquisition process of the adaptability calculation method is as follows: Based on the classical water and soil pressure calculation theory, the stratum characteristics, tunnel burial depth and stratum permeability are considered respectively, and the applicable scope of each classical water and soil pressure calculation theory is analyzed: the stratum to which the classical water and soil pressure calculation theory is not highly adaptable is theoretically corrected to obtain an adaptive calculation method; the correction basis of the theoretical correction comes from model tests and data simulation results.

[0040] It is worth mentioning that the classical water and soil pressure calculation theories mentioned in this embodiment at least include: Rankine earth pressure theory, Terzaghi earth pressure theory, Protzsprung arch theory, wedge calculation model and multi-truncated cone model, etc. Figure 4It can be seen that the stratum characteristics are further represented by sandy strata, clay strata, rock strata, upper soft and lower hard strata, etc. The tunnel burial depth includes deep buried strata and shallow buried strata. The stratum permeability is mainly reflected in the water and soil calculation and the water and soil separate calculation. In other words, not every stratum is suitable for the classical water and soil pressure calculation theory. For example, for deep buried strata, the classical water and soil pressure calculation theory needs to be revised to meet the applicability. To further illustrate, the Rankine earth pressure theory is applicable to shallow buried strata, the Terzaghi earth pressure theory is applicable to shallow buried sand, the Protz arch theory is applicable to rock strata, the wedge calculation model is applicable to shallow buried sand, etc. Therefore, the adaptive calculation method in this embodiment includes the classical water and soil pressure calculation theory and the revised calculation method.

[0041] In another embodiment, Figure 5 The shield soil and water pressure assessment and monitoring early warning system 8 shown is a functional summary and demonstration of the comprehensive assessment and monitoring method of soil and water load during shield machine excavation, and is further represented as including a soil and water pressure theoretical value assessment module, a shield body water pressure monitoring module, a soil and water pressure value comparison module and a shield body water pressure comparison module.

[0042] For better understanding, the water and soil pressure theoretical value evaluation module in this embodiment is set to target different strata encountered during shield tunneling, combined with Figure 4 The adaptive calculation method shown in the figure gives the theoretical water and soil pressure values ​​of the current excavation ring and the two rings before and after in a table form. P 理论 , and compared with the measured water and soil pressure values P 实测 Trigger level I-III warning prompts.

[0043] The shield water pressure monitoring module is configured to combine various adaptive calculation methods (through Figure 4 It can be seen that there are many calculation methods) to obtain the theoretical water and soil pressure values P 理论 and measured soil and water pressure values P 实测 Comparative analysis is presented in the form of a bar graph.

[0044] The shield water pressure monitoring module is configured to display the measurement point locations of different monitoring sections 95 at the arch top and arch waist and the measured water and soil pressure values ​​monitored in real time. P 实测 .

[0045] The shield water pressure comparison module is configured to display the measured water and soil pressure values ​​of different ring numbers, different measuring points, and different shield monitoring sections 95 in real time in the form of a bar graph. P 实测 .

[0046] In order to better understand the shield machine excavation water and soil load comprehensive evaluation monitoring method of this embodiment, this embodiment also discloses a specific installation method of the water and soil pressure sensor monitoring device 2 installed on the shield machine, refer to Figure 6 Understand. The tested soil and water pressure sensing and monitoring device 2 is subjected to a soil and water pressure simulation test on a physical shield machine. The soil and water pressure simulation test refers to the process of the shield machine being remanufactured or assembled in a workshop, in which the pressure around the shield is artificially created to simulate the soil and water pressure environment, so as to realize the full process verification test of "sensing device-data transmission-system warning" for soil and water pressure perception. First, the specific installation method of the soil and water pressure sensing and monitoring device 2 on the shield machine is as follows: A monitoring section 95 is determined, and a predetermined number of mud-reducing holes 7 are opened along the monitoring section 95 in the peripheral direction around the shield body 91; the monitoring section 95 at least includes: a front shield monitoring section, a middle shield monitoring section and a rear shield monitoring section.

[0047] Among them, the outer side of the mud effect hole 7 is connected to the pressure pump 3 and the water tank 22 in sequence through the water pipe 21, and the inner side is connected to the water and soil pressure sensing and monitoring device 2; in addition, the water and soil pressure sensing and monitoring device 2 is connected to the data transceiver 24 through the data transmission line 23 to realize the data collection of simulated water and soil pressure.

[0048] Furthermore, the data transceiver 24 forwards the collected water and soil pressure monitoring data to the cloud platform 25 by wireless transmission, and stores it in the server 26. The shield water and soil pressure assessment and monitoring early warning system 8 realizes the interface display and early warning of simulated test water and soil pressure by reading the data of the server 26.

[0049] Combination Figure 7 In ( a ), which is a schematic diagram of the shield water and soil pressure field test method Figure 1 During the tunneling process of the shield machine, the mud 93 is usually used to apply the incision pressure to maintain the balance of the tunnel face in front of the cutterhead 9. Since the diameter of the cutterhead 9 is large and the diameter of the shield body 91 is smaller than the diameter of the cutterhead 9, there is usually a situation where the mud 93 flows forward and backward. Figure 7 In ( a ). That is, the excavation gap 94 is filled with mud 93 instead of the objective water and soil environment.

[0050] Combination Figure 6 and Figure 7 In ( b ), which is a schematic diagram of the shield water and soil pressure field test method Figure 2In order to reduce the impact of mud 93 disturbance on water and soil pressure monitoring during the shield machine excavation process, mud-reducing materials are injected into the two mud-reducing holes 7 before and after the monitoring section 95 to form a plugging ring 92 during the shield machine shutdown stage (such as shutdown for tool change, mud cake cleaning, and pressure cabin inspection). During the long-term shield shutdown process, the excavation gap 94 between the plugging rings 92 is guaranteed to be an objective water and soil pressure environment. At this time, the water and soil pressure measured by the water and soil pressure sensing and monitoring device 2 is the actual water and soil pressure value borne by the shield.

[0051] Taking deep buried strata as an example, the specific idea is to revise: according to the failure mode of tunnel excavation surface, which can be obtained from engineering site, model test or numerical simulation, an analytical model for calculating water and soil pressure in tunnel is established. Then, the water and soil pressure is solved by using limit equilibrium theory or limit analysis theory.

[0052] The following takes the correction algorithm of deep buried sand strata as an example, uses numerical simulation method to establish the stratum model, and initial stress balance, and applies support pressure on the tunnel face. The support pressure value is the horizontal ground stress at the center of the tunnel face. Figure 8 As shown in the figure, considering the computational efficiency, a half model is used for simulation. The model is 3D wide and 8D long. It is excavated to 4D at one time. The model height is 6D+C (D is the tunnel radius and C is the tunnel depth). The boundary conditions of the model are: fixed bottom, constrained normal displacement around, and free top.

[0053] Based on the vertical formation model, the support pressure value is reduced, and the horizontal displacement of the center point of the tunnel face under the support pressure is recorded. When the support pressure is reduced to a certain value, the horizontal displacement of the center point of the tunnel face increases sharply, and the support pressure is regarded as the ultimate support water and soil pressure P.

[0054] Combination Fig. 9 , then the calculation method for the correction of the ultimate support soil and water pressure P is as follows: According to the calculation formula of soil and water pressure acting on the excavation surface: .

[0055] in, is the theoretical water and soil pressure value in this embodiment ， The calculation formula is: , , , represents the angle between the sliding surface and the horizontal plane, is the internal friction angle of soil. , It represents the soil bulk density, R is the equivalent radius of soil arch, represents the soil arch height correction factor, c It represents the cohesion of soil. is the mold resistance on the side of the wedge, , is the soil lateral pressure coefficient.

[0056] is the vertical average stress of the wedge: . is the equivalent side length: , is the tunnel diameter, is the width of the wedge, . is the dead weight of the soil: , It is the soil bulk density.

Claims

1. A test platform for water and soil loads of shield machine excavation, used for performance testing of water and soil pressure sensing and monitoring devices, wherein the water and soil pressure sensing and monitoring devices have a four-way joint; characterized in that: The test platform comprises: The platform body is used to accommodate the water and soil pressure sensing and monitoring device; A pressure chamber is installed on the platform body; the pressure chamber comprises: an annular cavity wall, a lower end cover, a middle end cover and an upper end cover connected to the annular cavity wall in sequence from bottom to top; wherein the middle end cover divides the pressure chamber into an upper pressure chamber and a lower pressure chamber; A pressure head, arranged on the upper surface of the upper end cover; A plurality of osmometers and a plurality of pressure sensors are arranged on the inner wall surface of the lower pressure chamber as required.

2. A test platform for water and soil loads of shield machine excavation according to claim 1, characterized in that: The test platform also includes: A pressure pump connected to the four-way connector of the water and soil pressure sensing and monitoring device; A water tank, which provides water pressure to the downward pressure chamber through a water delivery channel to simulate the formation; The pressure servo control unit uses the axial pressure loading channel to connect the pressure head to control the axial expansion and contraction of the pressure head, thereby generating axial pressure on the upper end cover; the pressure servo control unit is simultaneously connected to the upper pressure chamber through a conveying pipeline, and is used to fill the medium in the upper pressure chamber.

3. A test platform for water and soil loads of shield machine excavation according to claim 1, characterized in that: The testing method of the testing platform comprises the following steps: Step 101, installing and connecting the first joint of the four-way joint of the water and soil pressure sensing and monitoring device into the inner screw hole of the lower end cover, and connecting the second joint to the pressure pump for siltation flushing test; Step 102: using stratum materials to simulate the stratum material environment of shield tunneling in the lower pressure chamber, connecting the connected water tank with the lower pressure chamber through a water delivery channel to provide groundwater seepage required for simulating the water and soil pressure environment; Step 103, using the axial pressure loading channel to connect the pressure servo control unit to the pressure head, controlling the axial expansion and contraction of the pressure head to generate axial pressure on the upper end cover; and at the same time, filling the medium into the upward pressure chamber through the delivery pipeline; Step 104: Based on the simulation of steps 101 to 103, the overall environment of the formation is obtained, and the actual value acting on the overall environment of the formation is recorded by the pressure sensor and the osmometer. P 实际 : Actual total pressure value P 总-实际 and actual water pressure value P 水-实际 , the following formula is used to evaluate the actual earth pressure acting on the overall environment of the formation P 土-实际 , to achieve the actual earth pressure value P 土-实际 and actual water pressure value P 水-实际 A standalone simulation of: P 总-实际 = P 水-实际 + P 土-实际 ； Step 105: Obtain monitoring values ​​of the water and soil pressure sensing monitoring device P 监测 , the monitoring value P 监测 Includes: Total pressure monitoring value P 总-监测 , water pressure monitoring value P 水-监测 and earth pressure monitoring values P 土-监测 ,in, P 土-监测 = P 总-监测 - P 水-监测 ; Step 106: According to the actual value P 实际 and monitoring values P 监测 Determine whether the soil and water pressure sensing monitoring device is qualified.

4. A comprehensive evaluation method for water and soil loads of shield machine excavation, based on a water and soil pressure sensing and monitoring device that has passed the test, characterized in that: The following steps are involved: Step 1: Determine the adaptive calculation method for water and soil pressure of various strata, and use the adaptive calculation method to obtain the theoretical water and soil pressure value P 理论 ; Construct shield water and soil pressure assessment and monitoring early warning system based on the geological parameters of various strata; Step 2: Use a test platform to test various performance indicators of the water and soil pressure sensing and monitoring device; the test platform is as described in any one of claims 1 to 2; Step 3: Install the soil and water pressure sensor monitoring device that has passed the test in step 2 on the shield machine, and use the soil and water pressure sensor monitoring device to sense the actual soil and water pressure value outside. P 实测 If the measured water and soil pressure value P 实测 Theoretical soil and water pressure P 理论 If the preset relationship is satisfied, it means that the adaptive calculation method is feasible, and a corresponding comprehensive assessment and perception method of water and soil pressure is formed; if it is not satisfied, the adaptive calculation method needs to be further revised; The preset relationship is as follows: , is a pre-set threshold.

5. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 4, characterized in that: The acquisition process of the adaptability calculation method is as follows: Based on the classical water and soil pressure calculation theory, the applicable scope of each classical water and soil pressure calculation theory is analyzed by considering the stratum characteristics, tunnel burial depth and stratum permeability respectively. The corrected calculation method is obtained by theoretically correcting the stratum to which the classical water and soil pressure calculation theory is not well adapted. The basis for the theoretical correction is derived from model tests and data simulation results.

6. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 4, characterized in that: The shield water and soil pressure assessment and monitoring early warning system includes at least the following modules: a water and soil pressure theoretical value assessment module, a shield water pressure monitoring module, a water and soil pressure value comparison module and a shield water pressure comparison module; The water and soil pressure theoretical value evaluation module is configured to provide the theoretical water and soil pressure values ​​of the current excavation ring and the two rings before and after in a tabular form according to the different strata encountered during the shield tunneling process, combined with an adaptive calculation method. P 理论 , and compared with the measured water and soil pressure values P 实测 Triggering level I-III warning prompts; The shield water pressure monitoring module is configured to convert the theoretical water and soil pressure values ​​obtained by various adaptive calculation methods into P 理论 and measured soil and water pressure values P 实测 Comparative analysis, presented in the form of a bar graph; The shield water pressure monitoring module is configured to display the measurement point locations at the arch top and arch waist of different monitoring sections and the measured water and soil pressure values ​​monitored in real time. P 实测 ; The shield water pressure comparison module is configured to display the measured water and soil pressure values ​​of different ring numbers, different measuring points, and different shield monitoring sections in real time in the form of a bar graph. P 实测 .

7. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 4, characterized in that: The specific installation method of the water and soil pressure sensor monitoring device on the shield machine is as follows: Determine the monitoring section, and open a predetermined number of mud-reducing effect holes along the monitoring section around the peripheral direction of the shield body; the monitoring section at least includes: a front shield monitoring section, a middle shield monitoring section and a rear shield monitoring section; The outer side of the mud-reducing hole is connected to a pressure pump and a water tank in sequence through a water pipe, and the inner side is connected to a water and soil pressure sensing and monitoring device; wherein the data of the water and soil pressure sensing and monitoring device is connected to a data transceiver through a data transmission line to realize data collection of simulated water and soil pressure.

8. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 4, characterized in that: The comprehensive water and soil pressure assessment and perception method is used to guide the shield's pressure resistance design, cut pressure setting, grouting parameter selection, and pressurized entry safety.

9. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 5, characterized in that: The strata that are not well adapted to the classical soil and water pressure calculation theory include at least: deeply buried strata.

10. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 7, characterized in that: Mud-repellent material is injected into two adjacent groups of mud-repellent holes before and after the monitoring section to form a sealing ring. During the long-term shield shutdown process, the excavation gap between the sealing rings is guaranteed to have an objective water and soil pressure environment.

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