A test platform and comprehensive evaluation method for the soil and water load during the tunneling of a shield machine

Abstract

The present invention discloses a test platform and a comprehensive evaluation method for the excavation water and soil load of a shield machine, belonging to the technical field of shield tunnel engineering. The test platform is used for testing the performance of a water and soil pressure sensing and monitoring device, and the water and soil pressure sensing and monitoring device has a four-way joint. The comprehensive evaluation and monitoring method for the excavation water and soil load of the shield machine includes: determining an adaptive calculation method for the water and soil pressure of various strata, and constructing a shield water and soil pressure evaluation and monitoring early warning system; installing the water and soil pressure sensing and monitoring device that has passed the test on the shield machine, judging that the adaptive calculation method is feasible, and forming a corresponding comprehensive evaluation and perception method for the water and soil pressure. The comprehensive evaluation and actual measurement method for the excavation water and soil load of the shield machine of the present invention comprehensively applies the associated methods of theoretical correction, experimental testing, on-site monitoring, and system early warning, and improves the accuracy of the evaluation of the water and soil pressure of different strata.

Description

Technical Field

[0001] The invention belongs to the technical field of shield tunnel engineering. Specifically, it relates to a test platform and comprehensive evaluation method for the water and soil load during the tunneling of a shield machine. Background Art

[0002] Underwater shield tunnels have become the preferred transportation method for crossing rivers, lakes and seas because the construction process does not affect shipping traffic and the construction is not affected by seasons, climate, etc. However, with the increasingly complex construction environment, underwater shield tunnels show the characteristics of "extra-long distance, extra-large diameter, extra-high water pressure, and complex geology". Especially for extra-large diameter shield tunnels, the shield machine bears high external water pressure and large changes in tunnel section pressure difference, which have an important impact on the pressure resistance design of the shield machine, the tail seal, the setting of the cutting head pressure, the selection of grouting parameters, and the safety of entering the cabin under pressure. Therefore, it is urgent to carry out a comprehensive evaluation of the water and soil pressure during the tunneling of the shield machine and sense the state of the water and soil pressure through actual measurement methods to guide the safe construction of underwater and large-diameter shield tunnels. However, it is found that the existing technology has at least the following deficiencies in the use process:

[0003] The existing evaluation of the water and soil pressure of shield tunnels mainly uses the Rankine earth pressure as the calculation basis, which is not suitable for various strata such as clay, sand, soft upper and hard lower, and pebble soil; at present, few shield machines are equipped with sensing devices on the shield body for monitoring the external water and soil pressure, and there is also a lack of actual measurement methods for the water and soil pressure during the shield construction process; for the identification of the water and soil pressure of the shield machine, there is a lack of a comprehensive evaluation method of water and soil pressure that combines theory and actual measurement at the current stage. Summary of the Invention

[0004] In view of the problems in the related art, the invention provides a test platform and comprehensive evaluation method for the water and soil load during the tunneling of a shield machine to overcome the above technical problems existing in the existing related technology.

[0005] For this purpose, the specific technical solution adopted by the invention is as follows: A test platform for the water and soil load during the tunneling of a shield machine, which is used for the performance test of a water and soil pressure sensing and monitoring device, and the water and soil pressure sensing and monitoring device has a four-way joint; the test platform includes:

[0006] A platform body for accommodating the water and soil pressure sensing and monitoring device;

[0007] A pressure chamber installed on the platform body; the pressure chamber includes: an annular cavity wall, a lower end cover, a middle end cover and an upper end cover that are sequentially connected to the annular cavity wall from bottom to top; wherein, the middle end cover divides the pressure chamber into an upper pressure chamber and a lower pressure chamber;

[0008] A pressure head arranged on the upper surface of the upper end cover;

[0009] A number of osmometers and a number of pressure sensors are arranged on the inner wall surface of the lower pressure chamber as required.

[0010] In a further embodiment, the test platform further includes:

[0011] A pressure pump, connected to the four-way joint of the soil and water pressure sensing and monitoring device;

[0012] A water tank, which provides water pressure to the lower pressure chamber through a water delivery channel for simulating the formation;

[0013] A pressure servo control unit, which uses an axial pressure loading channel to connect to the indenter to control the axial expansion and contraction of the indenter, generating an axial pressure on the upper end cover; the pressure servo control unit is also connected to the upper pressure chamber through a delivery pipeline for filling the medium in the upper pressure chamber.

[0014] In a further embodiment, the test method of the test platform includes the following steps:

[0015] Step 101: Install and connect the first joint in the four-way joint of the soil and water pressure sensing and monitoring device in the internal thread hole of the lower end cover, and connect the second joint to the pressure pump for scouring and silting test;

[0016] Step 102: Use formation materials to simulate the formation material environment of shield tunneling in the lower pressure chamber, and connect the connected water tank to the lower pressure chamber through a water delivery channel to provide the groundwater seepage required for simulating the soil and water pressure environment;

[0017] Step 103: Connect the pressure servo control unit to the indenter using the axial pressure loading channel, and control the axial expansion and contraction of the indenter to generate an axial pressure on the upper end cover; at the same time, fill the medium into the upper pressure chamber through the delivery pipeline;

[0018] Step 104: Based on the formation overall environment simulated in Steps 101 to 103, record the actual values acting on the formation overall environment through the pressure sensors and osmometers P 实际 : actual total pressure value P 总-实际 and actual water pressure value P 水-实际 , and use the following formula to evaluate the actual soil pressure value acting on the formation overall environment P 土-实际 , to achieve the independent simulation of the actual soil pressure value P 土-实际 and actual water pressure value P 水-实际 :

[0019] P 总-实际 = P 水-实际+ P 土-实际 ;

[0020] Step 105: Obtain the monitoring values of the soil and water pressure sensing monitoring device P 监测 , and the monitoring values P 监测 include: the total pressure monitoring value P 总-监测 , the water pressure monitoring value P 水-监测 , and the soil pressure monitoring value P 土-监测 , where P 土-监测 = P 总-监测 - P 水-监测 ;

[0021] Step 106: Determine whether the soil and water pressure sensing monitoring device is qualified according to the actual value P 实际 and the monitoring value P 监测 .

[0022] A comprehensive evaluation method for the soil and water load during the tunneling of a shield machine, based on a soil and water pressure sensing monitoring device that has passed the test, includes the following steps:

[0023] Step 1: Determine the adaptability calculation method for the soil and water pressure of various strata, and obtain the theoretical soil and water pressure value P 理论 ; Construct a shield soil and water pressure evaluation and monitoring warning system according to the geological parameters of various strata;

[0024] Step 2: Use the test platform to test the performance indicators of the soil and water pressure sensing monitoring device; the test platform is as described above;

[0025] Step 3: Install the soil and water pressure sensing monitoring device that has passed the test in step 2 on the shield machine, and use the soil and water pressure sensing monitoring device to sense the measured soil and water pressure value P 实测 from the outside world. If the measured soil and water pressure value P 实测 and the theoretical soil and water pressure value P 理论 meet the preset relationship, it means that the adaptability calculation method is feasible, and a corresponding comprehensive evaluation and perception method for soil and water pressure is formed; if not, the adaptability calculation method needs to be further corrected. The preset relationship is as follows:

[0026] , is a preset threshold value.

[0027] In a further embodiment, the acquisition process of the adaptive calculation method is as follows:

[0028] Based on the classical soil and water pressure calculation theory, considering the formation characteristics, tunnel burial depth and formation permeability respectively, analyze the applicable scope of each classical soil and water pressure calculation theory, and perform theoretical correction on the formation with poor adaptability to the classical soil and water pressure calculation theory to obtain the corrected calculation method;

[0029] The correction basis of the theoretical correction comes from the model test and data simulation results.

[0030] In a further embodiment, the shield soil and water pressure evaluation and monitoring and early warning system at least includes the following modules: soil and water pressure theoretical value evaluation module, shield body water pressure monitoring module, soil and water pressure value comparison module and shield body water pressure comparison module;

[0031] Among them, the soil and water pressure theoretical value evaluation module is configured to, for different formations encountered during the shield tunneling process, combine the adaptive calculation method and give the theoretical soil and water pressure values of the current tunneling ring, the front and rear two rings in tabular form P 理论 , and compare with the measured soil and water pressure values P 实测 to trigger level I-III early warning prompts;

[0032] The shield body water pressure monitoring module is configured to compare and analyze the theoretical soil and water pressure values obtained by various adaptive calculation methods P 理论 and the measured soil and water pressure values P 实测 and display them in the form of a bar chart;

[0033] The shield body water pressure monitoring module is configured to display the measuring point positions at the crown and haunch of different monitoring sections and the measured soil and water pressure values of real-time monitoring P 实测 ; the shield body water pressure comparison module is configured to display the measured soil and water pressure values of different ring numbers, different measuring points and different shield monitoring sections in real time in the form of a bar chart P 实测 .

[0034] In a further embodiment, the specific installation method of the soil and water pressure sensing and monitoring device on the shield machine is as follows:

[0035] Determine the monitoring section, and a predetermined number of Knifex holes are opened along the perimeter direction of the shield body around the monitoring section; the monitoring section at least includes: the front shield monitoring section, the middle shield monitoring section and the tail shield monitoring section;

[0036] The outer side of the Knitsoil hole is sequentially connected to a pressure pump and a water tank through a water delivery pipe, and the inner side is connected to a water and soil pressure sensing and monitoring device; among them, 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 the data acquisition of the simulated water and soil pressure.

[0037] In a further embodiment, the water and soil pressure comprehensive evaluation and perception method is used to guide the pressure resistance design of the shield, the setting of the cutting head pressure, the selection of grouting parameters, and the safety of entering the chamber under pressure.

[0038] In a further embodiment, the formations with poor adaptability to the classical water and soil pressure calculation theory at least include: deep-buried formations.

[0039] In a further embodiment, Knitsoil materials are injected into two adjacent groups of Knitsoil holes before and after the monitoring section to form a sealing ring, ensuring an objective water and soil pressure environment in the excavation gap between the sealing rings during a long-term shield machine shutdown.

[0040] The beneficial effects of the present invention: The present invention first discloses a test platform applicable to a water and soil pressure sensing and monitoring device ( ZL 202310841659.9). The performance of the water and soil pressure sensing and monitoring device is tested before use through the test platform, and a qualified water and soil pressure sensing and monitoring device is selected to improve the accuracy of the comprehensive evaluation of the water and soil load during the shield machine tunneling.

[0041] Correspondingly, a test platform and a comprehensive evaluation method for the water and soil load during the shield machine tunneling of the present invention comprehensively apply the associated methods of theoretical correction, experimental testing, on-site monitoring, and system warning, improve the accuracy of the water and soil pressure evaluation in different formations, objectively monitor the true water and soil pressure value of the shield of the shield machine, effectively guide the pressure resistance design of the shield, the setting of the cutting head pressure, the selection of grouting parameters, and the safety of entering the chamber under pressure, and ensure the safe and efficient tunneling of the underwater shield tunnel. Description of the Drawings

[0042] Figure 1 It is a schematic diagram of the shield water and soil pressure test platform.

[0043] Figure 2 It is a schematic diagram of the relationship between the shield machine diameter and the water and soil pressure borne.

[0044] Figure 3 It is a general scheme diagram of the shield water and soil pressure comprehensive evaluation and perception method.

[0045] Figure 4 It is a schematic diagram of the shield water and soil pressure theoretical calculation and correction method.

[0046] Figure 5 It is a schematic diagram of the shield water and soil pressure evaluation and monitoring warning system.

[0047] Figure 6 It is a schematic diagram of the shield soil and water pressure simulation test.

[0048] Figure 7 It is a schematic diagram of the on-site test method for shield soil and water pressure.

[0049] Figure 8 It is the stratum model of numerical simulation.

[0050] Figure 9 It is the schematic diagram of the principle of the correction calculation method for deep-buried sandy soil stratum.

[0051] Figures 1 to 7 The various markings in it are: test platform 1, soil and water pressure sensing and monitoring device 2, pressure pump 3, water tank 4, pressure servo control unit 5, computer control system 6, Knifework hole 7, shield soil and water pressure evaluation and monitoring early warning system 8, cutter head 9, pressure head 11, upper end cover 12, annular cavity wall 13, middle end cover 14, osmometer 15, lower end cover 16, upper pressure chamber 17, lower pressure chamber 18, pressure sensor 19, water delivery pipe 21, water tank 22, data transmission line 23, data transceiver 24, cloud platform 25, server 26, water delivery channel 41, axial pressure loading channel 51, delivery pipeline 52, shield body 91, sealing ring 92, slurry 93, excavation gap 94, monitoring section 95. Specific implementation manners

[0052] To further illustrate the embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be combined with the relevant descriptions in the specification to explain the operation principle of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention.

[0053] Embodiment 1

[0054] According to an embodiment of the present invention, a test platform 1 is provided for testing the performance indexes of the soil and water pressure sensing and monitoring device 2. It should be noted that the soil and water pressure sensing and monitoring device 2 described in this embodiment is ZL the soil and water pressure monitoring device in the soil and water pressure monitoring system disclosed in 202310841659.9, including: a plurality of grouting holes radially distributed on the shield shell; at least one set of water pressure monitoring devices and a total pressure sensor 19 detachably installed in the corresponding grouting holes; the water pressure monitoring devices and the total pressure sensor 19 are used to monitor the water pressure p w and the total pressure p ; then, the soil pressure p s is calculated by the following formula: ps = p - p w Therefore, the performance indicators of the soil and water pressure sensing and monitoring device 2 at least include: sensitivity, anti-silting, washability, sealing reliability, etc.

[0055] Correspondingly, the test platform of this embodiment is as Figure 1 shown, and includes: a platform body for accommodating the soil and water 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 that are sequentially 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 the axial pressure, a pressure head 11 is provided on the upper surface of the upper end cover 12, and the pressure head 11 uses an axial pressure loading channel 51 to communicate with the pressure servo control unit 5 to control the axial expansion and contraction of the pressure head 11 to generate an axial pressure on the upper end cover 12. Further, the pressure servo control unit 5 communicates with the upper pressure chamber 17 through a conveying pipeline 52 for filling a medium in the lower pressure chamber 18, and the conveying pipeline 52 can be used to convey oil or gas.

[0056] In order to obtain the monitoring values in the corresponding chamber, several piezometers 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 sensors 19 and the piezometers 15 are the monitoring values.

[0057] In order to better simulate the real tunneling environment, the test platform further includes: a pressure pump 3 connected to the four-way joint of the soil and water pressure sensing and monitoring device 2, and the addition of the pressure pump 3 is used to complete the silt flushing test on the soil and water pressure sensing and monitoring device 2.

[0058] The lower pressure chamber 18 is connected to a water tank 4 through a water pipe 21, and the added water flow is used to provide the groundwater seepage required for simulating the soil and water pressure environment.

[0059] Based on the above description of the test platform, this embodiment also discloses a test method for the test platform of the soil and water load during shield tunneling, including the following steps:

[0060] Step 101: Install and connect the first joint in the four-way joint of the soil and water pressure sensing and monitoring device 2 in the internal thread hole of the lower end cover 16, and connect the second joint to the pressure pump 3 for the silt flushing test;

[0061] Step 102: Simulate the stratum material environment during shield tunneling in the lower pressure chamber 18 using stratum materials. Connect the water tank 4 to the lower pressure chamber 18 through the water conveyance channel 41 to provide the groundwater seepage required for simulating the water and soil pressure environment. The stratum materials used in this embodiment may be materials such as sand, gravel, clay, etc. Correspondingly, the stratum material environment includes: sandy stratum, clay stratum, pebble stratum, composite stratum, etc.

[0062] Step 103: Connect the pressure servo control unit 5 to the indenter 11 through the axial compression loading channel 51 to control the axial expansion and contraction of the indenter 11 to generate an axial pressure on the upper end cover 12; at the same time, fill the upper pressure chamber 17 with a medium through the conveying pipeline 52. The conveying pipeline 52 in this embodiment is specifically an oil / gas conveying pipeline, so the filled medium may be hydraulic oil or compressed air.

[0063] Step 104: Based on the overall stratum environment simulated in Steps 101 to 103, record the actual values acting on the overall stratum environment through the pressure sensor 19 and the piezometer 15 P 实际 : actual total pressure value P 总-实际 and actual water pressure value P 水-实际 , and use the following formula to evaluate the actual soil pressure value acting on the overall stratum environment P 土-实际 , and realize the independent simulation of the actual soil pressure value P 土-实际 and actual water pressure value P 水-实际 :

[0064] P 总-实际 = P 水-实际 + P 土-实际 ;

[0065] Step 105: Obtain the monitoring values of the water and soil pressure sensing and monitoring device 2 P 监测 , and the monitoring values P 监测 include: total pressure monitoring value P 总-监测 , water pressure monitoring value P 水-监测 and soil pressure monitoring value P 土-监测 , where P 土-监测 = P 总-监测 - P 水-监测 ;

[0066] Step 106: Record the actual value P 实际 and the monitored value P 监测 into the computer control system 6, and determine whether the soil and water pressure sensing monitoring device 2 is qualified according to the actual value P 实际 and the monitored value P 监测 .

[0067] Finally determine the qualified earth pressure sensing monitoring device through the above method. If the difference between the actual value P 实际 and the monitored value P 监测 is within the allowable error range and the change trend is consistent, it is qualified.

[0068] Embodiment 2

[0069] As shown in combination with Figure 2 , in this embodiment, the underwater shield tunnel is subjected to the action of soil and water pressure of the excavated stratum during construction. On the one hand, as the tunnel burial depth h increases, the soil and water pressure borne by the shield machine becomes greater; on the other hand, the increase in the tunnel excavation diameter will also cause the growth of soil and water pressure. For example, when the tunnel diameter Φ 1 > Φ 2 > Φ 3 , the external soil and water pressure borne by the shield machine is expressed as ( P w1 + P s1 ) > ( P w2 + P s2 ) > ( P w3 + P s3 ), and the greater the diameter of the shield machine, the greater the difference in soil and water pressure at the crown and invert of the tunnel section. Among them, Φ 1 is the diameter of Tunnel 1, Φ 2 is the diameter of Tunnel 2, Φ 3 is the diameter of Tunnel 3. Correspondingly, P w1 and P s1 are the water pressure and soil pressure borne by Tunnel 1 respectively, P w2and P s2 are the water pressure and soil pressure borne by Tunnel 2 respectively, P w3 and P s3 are the water pressure and soil pressure borne by Tunnel 3 respectively.

[0070] As Figure 3 shown, the comprehensive evaluation and monitoring method for the water and soil load during the tunneling of the shield machine in this embodiment includes the following steps:

[0071] Step 1: Determine the adaptability calculation method for the water and soil pressure of various strata, and obtain the theoretical water and soil pressure value by using the adaptability calculation method P 理论 ; construct the shield water and soil pressure evaluation and monitoring warning system 8 according to the geological parameters of various strata;

[0072] Step 2: Test the performance indexes of the water and soil pressure sensing and monitoring device 2 by using the test platform; the test platform is as described in Embodiment 1;

[0073] Step 3: Install the water and soil pressure sensing and monitoring device 2 that has passed the test in Step 2 on the shield machine, and use the water and soil pressure sensing and monitoring device 2 to sense the measured water and soil pressure value of the outside world P 实测 , if the measured water and soil pressure value P 实测 and the theoretical water and soil pressure value P 理论 meet the pre-set relationship, it means that the adaptability calculation method is feasible, and a corresponding comprehensive evaluation and perception method for the water and soil pressure is formed; if not, the adaptability calculation method needs to be further corrected.

[0074] The pre-set relationship is as follows:

[0075] , is the pre-set threshold value, and in this embodiment takes the value of 10.

[0076] Combined with Figure 4 , the acquisition process of the adaptability calculation method is as follows:

[0077] Based on the classical water and soil pressure calculation theory, consider the formation characteristics, tunnel burial depth and formation permeability respectively, and analyze the applicable scope of each classical water and soil pressure calculation theory: perform theoretical correction on the formation with poor adaptability to the classical water and soil pressure calculation theory to obtain the adaptability calculation method; the correction basis of the theoretical correction comes from the model test and data simulation results.

[0078] It is worth mentioning that the classical earth and water pressure calculation theories mentioned in this embodiment at least include: Rankine earth pressure theory, Terzaghi earth pressure theory, Prandtl arch theory, wedge calculation model, multi-truncated cone model, and so on. Combining Figure 4 It can be seen that the formation characteristics are further expressed as sandy soil formation, clay formation, rock formation, soft upper and hard lower formation, and so on. The tunnel burial depth includes deep-buried formation and shallow-buried formation. The formation permeability is mainly reflected in the combined calculation of water and soil and the separate calculation of water and soil. In other words, not every formation is applicable to the classical earth and water pressure calculation theory. For example, for deep-buried formations, the classical earth and water pressure calculation theory needs to be modified to meet the applicability. Further examples are as follows: the Rankine earth pressure theory is applicable to shallow-buried formations, the Terzaghi earth pressure theory is applicable to shallow-buried sandy soils, the Prandtl arch theory is applicable to rock formations, the wedge calculation model is applicable to shallow-buried sandy soils, and so on. Therefore, the adaptability calculation method in this embodiment includes the classical earth and water pressure calculation theory and the modified calculation method.

[0079] In another embodiment, as Figure 5 shown, the shield earth and water pressure evaluation and monitoring and early warning system 8 is the functional extraction and display of the comprehensive evaluation and monitoring method of the earth and water load during shield tunneling, and is further expressed as including the earth and water pressure theoretical value evaluation module, the shield body water pressure monitoring module, the earth and water pressure value comparison module, and the shield body water pressure comparison module.

[0080] For better understanding, the earth and water pressure theoretical value evaluation module in this embodiment is set to, for different formations encountered during shield tunneling, combine Figure 4 the shown adaptability calculation method, and give the theoretical earth and water pressure values of the current tunneling ring, the front and rear two rings in tabular form P 理论 , and compare with the measured earth and water pressure values P 实测 to trigger level I-III early warning prompts.

[0081] The shield body water pressure monitoring module is set to compare and analyze the theoretical earth and water pressure values Figure 4 obtained by various adaptability calculation methods (it can be seen from P 理论 that there are multiple calculation methods) and the measured earth and water pressure values P 实测 and display them in the form of a histogram.

[0082] The shield body water pressure monitoring module is set to display the measuring point positions at the crown and the waist of the arch of different monitoring sections 95 and the measured earth and water pressure values monitored in real time P 实测 .

[0083] The shield body water and soil pressure comparison module is configured to display in real time the measured water and soil pressure values of different ring numbers, different measuring points, and different shield monitoring sections 95 in the form of a bar chart. P 实测 。

[0084] To better understand the comprehensive evaluation and monitoring method of the water and soil load during the tunneling of the shield machine in this embodiment, this embodiment also discloses the specific installation method of the water and soil pressure sensing and monitoring device 2 installed on the shield machine. Refer to Figure 6 for understanding. The water and soil pressure sensing and monitoring device 2 that has passed the test is used for the water and soil pressure simulation test on the physical shield machine. The water and soil pressure simulation test refers to the process of remanufacturing or assembling in the workshop of the shield machine. By artificially creating the shield perimeter pressure to simulate the water and soil pressure environment, a full-process verification test of "sensing device - data transmission - system warning" for water and soil pressure perception is realized. First, the specific installation method of the water and soil pressure sensing and monitoring device 2 on the shield machine is as follows:

[0085] Determine the monitoring section 95. A predetermined number of Knifex holes 7 are opened along the perimeter direction of the shield body 91 around the monitoring section 95. The monitoring section 95 at least includes: the front shield monitoring section, the middle shield monitoring section, and the tail shield monitoring section.

[0086] Among them, the outside of the Knifex hole 7 is sequentially connected to a pressure pump 3 and a water tank 22 through a water delivery pipe 21, and the inside 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 a data transceiver 24 through a data transmission line 23 to realize the data acquisition of the simulated water and soil pressure.

[0087] Furthermore, the data transceiver 24 forwards the collected water and soil pressure monitoring data to the cloud platform 25 through wireless transmission and stores it in the server 26. The shield water and soil pressure evaluation and monitoring warning system 8 realizes the interface display and warning of the simulated test water and soil pressure by reading the data of the server 26.

[0088] Combined with Figure 7 in the ( a ), this figure shows the schematic of the on-site test method of the shield water and soil pressure. Figure 1 。During the tunneling process of the shield machine, the slurry 93 is usually used to apply the cutting pressure to maintain the face balance 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 that of the cutterhead 9, there is generally a situation of slurry 93 flowing back and forth, as shown in Figure 7 in the ( a ). That is, the excavation gap 94 is filled with the slurry 93 instead of the objective water and soil environment.

[0089] Combined with Figure 6 and Figure 7 in the ( b), which shows the schematic of the on-site test method for the shield's water and soil pressure Figure 2 . To reduce the impact of slurry 93 disturbance on water and soil pressure monitoring during the tunneling process of the shield machine, it is selected to inject the Knifefish material to form a sealing ring 92 through two Knifefish holes 7 before and after the monitoring section 95 during the shield machine's shutdown stage (such as changing tools during shutdown, cleaning the mud cake, and inspecting the pressure cabin). During the long-term shield shutdown process, an objective water and soil pressure environment is ensured within the excavation gap 94 between the sealing rings 92. At this time, the water and soil pressure measured by the water and soil pressure sensing and monitoring device 2 is the true water and soil pressure value borne by the shield circumference.

[0090] Taking the deep-buried stratum as an example, the specific idea of correction: According to the failure mode of the tunnel excavation face, which can be obtained from the engineering site, model test, or numerical simulation, establish an analytical model for calculating the tunnel's water and soil pressure. Then, use the limit equilibrium theory or the limit analysis theory to solve the water and soil pressure.

[0091] Taking the correction algorithm for the deep-buried sandy soil stratum as an example below, use the numerical simulation method to establish a stratum model and perform the initial stress balance. Apply the support pressure to the tunnel face, and this support pressure value is the horizontal ground stress at the center point of the tunnel face. As Figure 8 shown, considering the calculation efficiency, a half-model is used for simulation. The width of the model is 3D, the length is 8D, and it is excavated to 4D at one time. The height of the model is 6D + C (D is the tunnel radius, and C is the tunnel burial depth). The boundary conditions of the model are: fixed at the bottom, the normal displacements are constrained on the four sides, and free at the top.

[0092] Reduce the support pressure value based on the established stratum model and record the horizontal displacement of the center point of the tunnel face under the support pressure. When the support pressure is reduced to a certain value and the horizontal displacement of the center point of the tunnel face increases sharply, then this support pressure is regarded as the limit support water and soil pressure P.

[0093] Combined with Figure 9 , the corrected calculation method for the limit support water and soil pressure P is as follows: According to the calculation formula for the water and soil pressure acting on the excavation face: .

[0094] Among them, is the theoretical water and soil pressure value in this embodiment ， Its calculation formula is , , , represents the angle between the slip surface and the horizontal plane, is the internal friction angle of the soil. , represents the unit weight of the soil, R is the equivalent radius of the soil arch, represents the correction coefficient of the soil arch height, cRepresents the cohesion of the soil mass. is the frictional resistance on the side of the wedge, , is the coefficient of lateral earth pressure of the soil mass.

[0095] 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 self-weight of the soil mass: , is the unit weight of the soil mass.

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 which are sequentially connected to the annular cavity wall from bottom to top; wherein the middle end cover divides the pressure chamber into an upper pressure chamber and a lower pressure chamber, and the water and soil pressure sensing and monitoring device is installed on the lower end cover; A pressure head, arranged on the upper surface of the upper end cover; Several piezometers and pressure sensors are arranged on the inner wall of the lower pressure chamber as required; the actual value P acting on the overall environment of the formation is recorded by the pressure sensor and the piezometer. 实际 : Actual total pressure value P 总-实际 And the actual water pressure value P 水-实际 The actual earth pressure value P acting on the overall environment of the stratum is evaluated using the following formula: 土-实际 , to achieve the actual earth pressure value P 土-实际 And the actual water pressure value P 水-实际 Independent simulation of: P 总-实际 =P 水-实际 +P 土-实际 ; 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.

2. 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 P acting on the overall environment of the formation is recorded by the pressure sensor and the osmometer. 实际 : Actual total pressure value P 总-实际 And the actual water pressure value P 水-实际 The actual earth pressure value P acting on the overall environment of the stratum is evaluated using the following formula: 土-实际 , to achieve the actual earth pressure value P 土-实际 And the 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 P of the water and soil pressure sensor monitoring device 监测 , the monitoring value P 监测 Including: total pressure monitoring value P 总-监测 , water pressure monitoring value P 水-监测 And the earth pressure monitoring value P 土-监测 , where P 土-监测 =P 总-监测 -P 水-监测 ; Step 106: According to the actual value P 实际 and monitoring value P 监测 Determine whether the soil and water pressure sensing monitoring device is qualified.

3. 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 claim 1; 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 P of the outside world. 实测 , if the measured water and soil pressure value P 实测 and theoretical soil and water pressure value 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.

4. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 3, 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.

5. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 3, 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 ​​P 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 and in combination with an adaptive calculation method. 理论 , and compared with the measured water and soil pressure value 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 ​​P obtained by various adaptive calculation methods into 理论 and measured soil and water pressure value 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 ​​P of real-time monitoring. 实测 ; The shield water pressure comparison module is configured to display the measured water and soil pressure values ​​P of different ring numbers, different measuring points, and different shield monitoring sections in real time in the form of a bar graph. 实测 .

6. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 3, 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.

7. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 3, 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.

8. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 4, 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; the corresponding modified adaptive calculation method is as follows: According to the calculation formula of water and soil pressure acting on the excavation surface: ; Furthermore, The calculation formula is , , , represents the angle between the sliding surface and the horizontal plane, is the internal friction angle of soil, , represents the soil bulk density, R is the equivalent radius of the soil arch, represents the soil arch height correction coefficient, c represents the cohesion of the soil, is the mold resistance on the side of the wedge, , is the soil lateral pressure coefficient, is the vertical average stress of the wedge, and its calculation formula is: ; 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.

9. A comprehensive evaluation method for water and soil loads during shield machine excavation according to claim 8, 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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