A shield shell drilling test device and its construction method under a high water pressure and highly permeable environment

Abstract

The present invention belongs to the technical field of shield tunnel engineering, and specifically relates to a shield shell drilling test device under a high water pressure and permeable environment. It includes a test box body. One side of the test box body is an arc-shaped plate, and the thickness of the arc-shaped plate is equal to that of the shield shell. Springs are provided on the non-arc-shaped plate side and the bottom plate of the test box body. One end of the spring is fixedly connected to the inner wall of the test box body, and the other end of the spring is fixedly connected to a movable steel plate. The test soil body is contained in the test box body. A steel plate is placed on the upper part of the test soil body, and a compression airbag is placed on the steel plate. A detachable cover plate is provided at the top of the test box body. The test device uses gas pressurization, getting rid of the dependence on the servo hydraulic device and facilitating the implementation of tests at the construction site. This device can simulate shield shell drilling construction, grouting construction, and freezing construction under different stratum conditions and different water pressure conditions. By means of simulation tests, the pressure generated by grouting at the shield shell can be monitored during the grouting process to ensure the stability of the shield shell.

Description

Technical Field

[0001] The present invention belongs to the technical field of shield tunnel engineering, and particularly relates to a shield shell drilling test device under a high water pressure and highly permeable environment. Background Art

[0002] At present, the construction trend of large-diameter shield tunnels in China is from single soft soil strata to complex strata, from large diameter to super-large diameter, from medium water pressure to high water pressure and ultra-high water pressure, from medium-intensity seismic areas to high-intensity seismic areas, from single-mode shields to multi-mode shields, from single construction method to combined multi-construction methods, from traditional construction management to digital management, and from short-distance tunneling to long-distance and ultra-long-distance tunneling. When docking shield tunnels under the sea, the grouting-freezing combined reinforcement method is required to establish a stable and water-proof construction space in high water pressure and highly permeable sandy soil strata. During the freezing method construction, grouting pipes and freezing pipes need to be drilled from the inside of the shield machine to the outside. The key is to safely drill freezing holes on the shield shell of the shield machine, and the grouting pipes and freezing pipes can be led out from the freezing holes. At the same time, how to monitor the pressure of the grouting on the shield shell during the grouting process and how to monitor the frost heaving force generated at the shield shell position during the freezing process are important factors related to the stability of the shield shell of the shield machine. At the same time, due to the randomness of the slurry diffusion during the grouting process caused by the inhomogeneity of the strata, how to intuitively evaluate the grouting effect is also very important. During the freezing process, the range of the frozen body formed during the active freezing can only be indirectly reflected by the temperature of the temperature measuring pipe in actual construction and cannot achieve intuitive evaluation. Summary of the Invention

[0003] To solve the above problems, the present invention provides a shield shell drilling test device under a high water pressure and highly permeable environment, which uses gas pressurization, gets rid of the dependence on the servo hydraulic device, and is convenient for carrying out tests on the construction site. The device can simulate shield shell drilling construction, grouting construction, and freezing construction under different stratum conditions and different water pressure conditions, and can not only provide data parameter support for the actual project, but also train the operators.

[0004] The technical solution of the present invention is as follows:

[0005] The present invention provides a shield shell drilling test device under a high water pressure and highly permeable environment, including a test box body. One side of the test box body is an arc-shaped plate, and the thickness of the arc-shaped plate is equal to the thickness of the shield shell. Springs are provided on the non-arc-shaped plate side and the bottom plate of the test box body. One end of the spring is fixedly connected to the inner wall of the test box body, and the other end of the spring is fixedly connected to a movable steel plate. The test soil body is contained in the test box body. A steel plate is placed on the upper part of the test soil body, and a compression airbag is placed on the steel plate. A detachable cover plate is provided on the top of the test box body.

[0006] Wherein, the size of the arc-shaped plate satisfies the following formula to ensure:

[0007] H = l 环向 × p

[0008] L = l 纵向 × q

[0009] Among them, H represents the circumferential length of the arc-shaped plate, L represents the longitudinal length of the arc-shaped plate, l 环向 represents the circumferential spacing of orifice pipe installation, l 纵向 represents the longitudinal spacing of orifice pipe installation, p represents the circumferential number of orifice pipes, and q represents the longitudinal number of orifice pipes.

[0010] Furthermore, the spring parameters satisfy the following constraints:

[0011] k h = K h × D h1 × L v1

[0012] k v = K v × D h2 × L v2

[0013] |D h1 - L v1 | ≤ λ × min{D h1 , L v1}

[0014] |D h2 - L v2 | ≤ λ × min{D h2 , L v2}

[0015] Among them, k h is the horizontal spring stiffness coefficient, k v is the vertical spring stiffness coefficient, K h is the measured formation horizontal subgrade coefficient in the geological exploration report, K v is the measured formation horizontal subgrade coefficient in the geological exploration report, D h1 is the vertical distance between the upper and lower horizontal springs, L v1 is the horizontal distance between the left and right horizontal springs, D h2 is the front and back distance between the vertical springs, L v2 is the left and right distance between the vertical springs, and λ is the difference coefficient of the spring spacing in two directions.

[0016] Preferably, earth pressure cells are buried under the steel plate, and the pressure of the compression airbag is adjusted according to the difference between the value of the earth pressure cell and the predetermined value.

[0017] The compression airbag is supplied with gas by an air storage tank. The pressure in the compression airbag is P2, and the pressure in the air storage tank is P3. The following formula needs to be satisfied:

[0018] P3 > P2 > P1

[0019]

[0020] P3 ≥ K a × P1

[0021] Wherein, P1 is the effective soil pressure value of the overlying soil layer of the test soil layer, γ i is the unit weight of the i-th soil layer, h i is the thickness of the i-th soil layer, n is the number of soil layers above the test soil layer to be tested, K a is the pressure reserve coefficient.

[0022] Furthermore, first, through the pressure regulator of the gas storage tank, make P2 = P1, set the initial pressure value in the airbag to the calculated P1 pressure value, and adjust the pressure value in the airbag according to the measured soil pressure cell pressure P c under the steel plate after pressurization.

[0023] The subsequent pressure increment △P = (P1 - P c ) × P c / P1. If the difference between P c and P1 is less than 5%, then increase the airbag pressure step by step and fixed amount next time, with each pressure increase of 2 kPa and stabilization for 30 min. If P c is still lower than P1, continue to adjust.

[0024] Preferably, an automatic pressure relief valve is provided at the upper part of the test box body. When the pressure exceeds the maximum water pressure in the docking range of the shield tunnel, the test box body automatically relieves pressure.

[0025] The present invention provides a core sampling test method for a shield shell drilling test device in a high water pressure and highly permeable environment, including the following steps:

[0026] Step 1: Fill the test soil body in layers in the test box body and vibrate and compact it;

[0027] Step 2: Place a steel plate on the upper part of the test soil body, close the cover plate, and apply pressure by compressing the airbag;

[0028] Step 3: Measure and position the position and angle of the orifice pipe;

[0029] Step 4: Weld the inclined section of the orifice pipe to the arc plate side of the test box body in full;

[0030] Step 5: Adjust the position of the drill rig to be flush with the orifice pipe and align the drill rig;

[0031] Step 6: Fine-tune the angle of the drill pipe, drill the drill pipe into the orifice pipe, and repeatedly measure to ensure the coaxiality and concentricity of the drill pipe and the orifice pipe;

[0032] Step 7: Use the drill rig to drive the coring bit to cut the arc-shaped plate of the test box body. After the shell is completely cored, withdraw the drill bit to the position between the sealing box and the ball valve, close the ball valve, and remove the coring bit.

[0033] The present invention also provides a simulation test method for the grouting process of a shield shell drilling test device under a high water pressure and permeable environment, including the following steps:

[0034] Step 1: Start the grouting drill pipe rig and drill the grouting pipe into the formation.

[0035] Step 2: After drilling to the designated position, start the grouting operation.

[0036] Step 3: During the grouting process, monitor the pressure data at the position of the arc-shaped plate in real time. During the grouting process, the monitored value P of the earth pressure cell at the position of the arc-shaped plate 注监 , the maximum pressure P that the arc-shaped plate can withstand max , and satisfy P 注监 ≤P max , so as to determine the maximum grouting pressure that can be set, as well as the maximum grouting pressure that can be set at different positions, and ensure the safety of the shield shell during the grouting process.

[0037] Step 4: Conduct grouting tests at different pressures at different positions to test the pressure generated on the shield shell by different grouting pressures.

[0038] Step 5: After completing the grouting test, wait for 14 days, relieve the pressure in the box body, disassemble the top cover of the test box body, excavate the test soil layer by layer, and record and analyze the grouting diffusion situation.

[0039] The present invention also provides a simulation method for the freezing process of a shield shell drilling test device under a high water pressure and permeable environment, including the following steps:

[0040] Step 1: Assemble the test device, apply pressure, and arrange temperature sensors.

[0041] Step 2: Add a thermal insulation layer to the non-arc-shaped plate side of the test box body.

[0042] Step 3: Conduct a freezing test using the grouted test soil.

[0043] Step 4: Seal the pores of the freezing pipe.

[0044] Step 5: Start the freezing pipe rig and drill the freezing pipe into the formation.

[0045] Step 6: According to the designed freezing period, immediately stop freezing after the active freezing is completed.

[0046] Step 7: Collect temperature sensor and earth pressure data during the active freezing process, analyze the development range and development speed of the frozen body, and analyze the pressure generated on the shield shell during the formation of the frozen body.

[0047] Step 8: After stopping the freezing, immediately open the top cover of the test box body, excavate in layers quickly, and observe and analyze the freezing range.

[0048] This technical solution can provide a more effective research solution for the research on the shield tunneling in-situ docking construction technology. Specifically, compared with the existing technology, it has the following advantages:

[0049] To solve the above problems, the present invention provides a shield shell drilling test device under a high water pressure and highly permeable environment. By using gas pressurization, it gets rid of the dependence on the servo hydraulic device and is convenient for conducting tests at the construction site. This device can simulate shield shell drilling construction, grouting construction, and freezing construction under different formation conditions and different water pressure conditions. Through simulation tests, the pressure generated by grouting at the shield shell can be monitored during the grouting process, and the magnitudes of the pressures exerted on the shield shell by different grouting points and different grouting pressures can be judged, so as to provide grouting pressure control parameters to ensure the stability of the shield shell. It can not only provide data parameter support for the actual project, but also train the operators. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic three-dimensional diagram of the test box body designed for the present invention;

[0051] Figure 2 Schematic assembly diagram of the test box body of the present invention;

[0052] Figure 3 Schematic drilling diagram of the test box body of the present invention;

[0053] Figure 4 Schematic measurement positioning and lofting diagram of the test box body of the present invention;

[0054] Figure 5 Schematic grouting test diagram of the test box body of the present invention;

[0055] Figure 6 Schematic freezing simulation diagram of the test box body of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0056] The difficulty of the model test is how to restore the actual working conditions as much as possible. Under the working conditions of the reinforcement of the super-large diameter shield docking section under the high water pressure and highly permeable formation conditions, there are many difficulties.

[0057] First, the shield machine is large in size. The diameter of a shield machine exceeds 16 m, the length exceeds 15 m, and the weight exceeds 5,000 tons. It is impossible to use a whole shield machine for simulation tests. However, if a scale-down test is adopted, the simulation effect of the actual working conditions will be greatly reduced. Although the scale-down test can simulate possible laws, it cannot simulate the actual construction technology. Therefore, it is necessary to select a suitable local range for testing. And to verify the actual working conditions of the 8-cm-thick shield shell with oblique drilling in a limited space, the simulated shield shell thickness to be selected is also 8 cm, and the bending arc and rib structure of the simulated shield shell should be consistent with the actual construction conditions.

[0058] Even if the steel plate that can simulate the actual shield shell of the shield machine is obtained, it is more difficult to set the shield shell steel plate to the working conditions of the actual shield machine in the stratum. It is necessary to not only simulate the earth pressure and water pressure of the stratum where it is located, but also reflect the boundary conditions of the soil mass at that location. It is unrealistic to bury the test shield shell in the stratum under actual working conditions. In the laboratory, a servo-pressure device is often used to simulate and control the pressure environment and boundary conditions of the test soil mass. However, the size that can be simulated in the laboratory is very limited, and the full-scale working conditions cannot be simulated. Secondly, there are not many laboratories equipped with servo-pressure devices. To carry out tests, reservations and queuing are required, which is not friendly to actual projects with tight construction periods. Therefore, it is necessary to develop equipment that can carry out simulation tests on the construction site, which can not only simulate the soil and water environment of the actual project, but also be easily fabricated and assembled, and is suitable for carrying out tests on the project site.

[0059] It is difficult to simulate the actual situation on site for grouting tests. The main reason is that it is difficult to restore the consolidation characteristics of the stratum soil mass and the surrounding constraints of the stratum in the test device. Usually, grouting tests are carried out in a fixed box or in situ to explore the general laws of grouting. It is difficult to simultaneously simulate the earth pressure, water pressure at the location of the stratum and the constraint of the infinite soil mass on the side of the test soil mass in the fixed box. The fixed boundary of the box restricts the horizontal and vertical displacements of the test soil mass, resulting in the test results not being able to represent the laws of the actual soil layer. The advantage of the in-situ test is that it can restore the actual soil layer and its location, but the disadvantage is that it can only reflect the grouting effect through limited measuring points and core sampling tests, and cannot intuitively reveal the grouting effect. More importantly, it cannot simulate the magnitude of the pressure generated by grouting on the shield shell.

[0060] Only the experience during the construction of the freezing method for the connection passage of the shield tunnel can be used for reference, that is, the drilling process of welding an orifice pipe on the shield shell, connecting a ball valve to the orifice pipe, and connecting a sealing box behind the ball valve.

[0061] However, compared with this traditional process, due to the high hardness of the shield shell and the long length of the inclined core sampling, the single-core drilling time is long, the wear on the sealing system and the drill bit is large, and it is more difficult to drill on the shield shell of the shield machine. Whether the traditional drilling process can be applied to the drilling construction on the shield shell in a high water pressure and strong water permeability environment is still unknown.

[0062] Therefore, it is necessary to establish a test device and, through experiments, establish a method suitable for drilling construction on the shield shell in a high water pressure and strong water permeability environment. High water pressure means that the water pressure is higher than 0.5 MPa, and strong water permeability means that the formation permeability coefficient is higher than 10 - 2 cm / s.

[0063] The following further describes the present utility model in conjunction with the attached drawings and embodiments.

[0064] Embodiment 1

[0065] In this embodiment, the present invention designs a test device, as shown in Figure 1 and Figure 2 , which is applicable to the simulation test of drilling construction on the shield shell in a high water pressure and strong water permeability environment.

[0066] Since the shield machine is a circular ring structure with a diameter of more than 14 meters, it is costly to take a whole full-scale shield for simulation tests. In the actual design process, the model can be reduced. The experimental device uses a partial cross-section of the shield and, according to the actual diameter of the shield machine, adopts one-tenth of the shield shell range and circles it into an arc with a steel plate (80 mm thick) with the same thickness as the shield shell as the test shield shell. The test box body is overall a rectangular structure, and one of its side surfaces is an arc-shaped panel made according to a 1:1 ratio of the shield body waist to simulate a shield shell thickness of 80 mm, and the thickness of the remaining plates is 50 mm; the outer side surface of the box body is reinforced with square hollow steel pipes, and strengthening supports are arranged on all sides except the arc-shaped panel side. The material of the arc-shaped plate of the box body is Q355B low-alloy high-strength steel, and the rest is Q355B material.

[0067] The height, width, and longitudinal length of the box body need to meet the dimensions required for the process test and the layout of internal components and components, and can be adjusted according to the actual engineering dimensions to be simulated, but it is necessary to ensure that the pressure resistance safety of the box body meets the requirements.

[0068] The steel plate welding meets the water pressure sealing test of the box body. The upper top cover of the box body is a detachable top cover, sealed with a rubber plate and tightened with bolts. This is convenient for filling the soil body, burying the springs, steel plates, and earth pressure cells, and more importantly, it can be opened as a whole and excavated layer by layer after grouting and freezing to visually reflect the grouting and freezing effects. After the box body is processed, the box body in the guardrail area is reinforced with KW200 steel.

[0069] The box body size range can provide the construction space for shield shell drilling, grouting, and freezing. The radius of the shield is R. The arc surface of this platform is the test surface with a thickness of 80 mm. Therefore, the following two points need to be considered during the design process:

[0070] It can provide the installation space for p (3 ≤ p ≤ 5) groups of orifice pipes in the circumferential direction, and the circumferential spacing for orifice pipe installation is l 环向 , and it should not be less than 1 m;

[0071] It can provide the installation space for q (2 ≤ q ≤ 5) orifice pipes in the longitudinal direction, and the longitudinal spacing for orifice pipe installation is l 纵向 , and it should not be less than 1.3 m;

[0072] The orifice pipes are arranged in a plum blossom pattern. Combining the above two actual requirements, the following limit design is carried out for the arc surface size:

[0073] The circumferential length of the arc plate is H, unit: m:

[0074] H = l 环向 × p

[0075] The longitudinal length of the arc plate is L, unit: m:

[0076] L = l 纵向 × q

[0077] Therefore, this size can not only meet the needs of the simulation test, but also reduce the scale of the simulation test, and reduce the manufacturing, assembly and test difficulties of the test device. Using a local 1:1 size or a size close to 1:1 to simulate the actual project can more truly reflect the test law; the main purpose of this test is not only to reflect the test law, but more importantly, it can provide a platform for the selection and verification of construction technologies that have not been used before, verify their applicability, and optimize their operability. At the same time, the operating skills of the operators can be trained and even assessed. Therefore, this test equipment and its principle of simulating the underground environment can provide a simulation test platform for similar projects.

[0078] The test box body is strengthened by adding ribs to ensure that the internal pressure bearing capacity of the test box body is not lower than the maximum water pressure in the shield tunnel docking range. It can withstand an internal pressure of 1.0 MPa, meeting the pressure test requirements of deep-buried tunnels. At the same time, for safety considerations, an automatic pressure relief valve is set on the upper part of the box body. When the pressure exceeds 1.0 MPa, the test box body can achieve automatic pressure relief to ensure the test safety.

[0079] The soil body adopts a form of springs plus steel plates on all four sides to simulate the contact relationship between the test soil body and the surrounding infinite soil body. To more truly simulate the deformation constraint of the surrounding soil on the test soil body, the spring stiffness is equivalently converted according to the bedding coefficient in the measured geological exploration report. If the formation where the shield is located is a composite multi-layer formation, the springs and steel plates can be converted in layers. The conversion relationship is:

[0080] The horizontal spring stiffness satisfies:

[0081] k h = K h × D h1 × L v1

[0082] The vertical spring stiffness:

[0083] k v = K v × D h2 × L v2

[0084] For the convenience of rapid on-site tests at the construction site, it can be achieved by adjusting the vertical and horizontal distances of the springs according to the springs with established stiffness that can be conveniently purchased at the location of the engineering project. That is: The horizontal spring arrangement distance satisfies:

[0085] D h1 × L v1 = k h / K h The vertical spring arrangement distance satisfies:

[0086] D h2 × L v2 = k v / K v At the same time, the difference in the distances in the two directions of the spring arrangement should not be too large, and the distances in the two directions should satisfy:

[0087] |D h1 - L v1 | ≤ λ × min{D h1 , L v1}

[0088] |D h2 - L v2 | ≤ λ × min{D h2 , L v2}

[0089] Where: k h is the horizontal spring stiffness coefficient, with the unit (kN / m); k v is the vertical spring stiffness coefficient, with the unit (kN / m); λ is the coefficient of difference in the distances in the two directions of the spring, with a value range of 0 to 0.2, and K h is the measured horizontal subgrade coefficient of the formation in the geological exploration report, with the unit (kN / m 3 ); K v is the measured horizontal subgrade coefficient of the formation in the geological exploration report, with the unit (kN / m 3 ); D h1 is the vertical distance of the horizontal spring, with the unit m; L v1 is the horizontal distance of the horizontal spring, with the unit m; Dh2 is the front - rear distance of the vertical spring, unit: m; L v2 is the left - right distance of the vertical spring, unit: m.

[0090] One end of the spring is fixed to the inner wall of the test box, and the other end is fixed to the movable steel plate. Under the action of soil pressure, it can move evenly and freely, applying lateral restraint to the tested soil.

[0091] For the upper part of the tested soil, vertical pressure is applied in the form of an airbag plus a steel plate. The thickness of the steel plate is 10 mm, which has sufficient stiffness to remain flat during the airbag pressurization process, ensuring the uniformity of airbag pressurization. Although there are differences in accuracy between airbag pressurization and servo pressurization, by burying earth pressure cells under the steel plate and adjusting the airbag pressure according to the values of the earth pressure cells, the required pressurization value can also be accurately simulated.

[0092] The pressure of the earth pressure cell is the earth pressure at the position where the shield machine is located. The earth pressure is the effective stress and is calculated according to the following formula:

[0093]

[0094] Where: P1 is the value of the effective overburden soil pressure of the test soil layer, unit: kPa; γ i is the unit weight of the i - th layer of soil. The buoyant unit weight is taken below the water level. hi is the thickness of the i - th layer of soil, and n is the number of soil layers above the test layer. The pressure in the airbag is set as P2, and the pressure in the gas storage tank is P3. According to the gas pressure loss in the test, it is necessary to satisfy P3>P2>P1. And to ensure sufficient pressure reserve in the gas storage tank, it should satisfy P3≥K a ×P1, K a is the pressure reserve coefficient, which should not be less than 1.5. First, through the pressure regulator of the gas storage tank, make P2 = P1, and set the initial value of the airbag pressure as the calculated P1 pressure value. Since the pressure loss caused by airbags of different specifications is different and it is difficult to quantitatively estimate in advance, it is necessary to adjust the airbag pressure value according to the pressure P c measured by the earth pressure cell under the steel plate after pressurization. The subsequent pressure increment △P=(P1 - P c )×P c / P1. If the difference between P c and P1 is less than 5%, then the airbag pressure is increased step - by - step by a fixed amount next time. Each time the pressure is increased by 2 kPa and stabilized for 30 min. If P C is still lower than the calculated value of P1, continue to adjust until it equals the calculated value P1. The earth pressure cells are arranged in 2 rows, with a horizontal row spacing of 2 m and a vertical spacing of 2 m. A total of 14 earth pressure cells are arranged at the bottom of the steel plate. The pressure P cTake the average value of 14 pressure cells, but require that the range R is less than 10% of the average value, where the range is the maximum value minus the minimum value among the 14 pressure cells. Otherwise, it indicates that the steel plate or airbag is not placed flat and needs to be re-placed.

[0095] On the side where the test soil mass contacts the shield body, a direct contact method is adopted, which is consistent with the actual working conditions. Soil pressure cells are buried at the shield shell position to measure the pressure on the shield shell during the grouting and freezing processes.

[0096] The side for drilling, grouting, and freezing tests is an arc surface, and the radian is the same as that of the actual shield shell of the shield machine, which can simulate the actual construction working condition environment and improve the authenticity of the test simulation.

[0097] The simulation of the water pressure in the formation is carried out by means of air pressure pressurization, which can accurately control the magnitude of the groundwater pressure and is conducive to simulating the water pressure of the actual formation.

[0098] The air pressure of the pressurized airbag and the test box body is connected to the pressure tank through a voltage regulator. The gas storage capacity of the pressure tank is not less than 20m 3 , and the pressure is not less than 1.2 MPa to ensure the stability of the pressure supply.

[0099] The top cover of the test box body is integrally detachable. While facilitating the installation of the test soil mass and measuring components, more importantly, it can facilitate the layered excavation of the soil mass after the grouting and freezing tests to visually measure the grouting and freezing effects.

[0100] The thickness of the test box body is to simulate the actual shield shell thickness, which is 80 mm. Oblique holes are drilled on the shield shell with this thickness, and the drilling length exceeds 800 mm. And when constructing under high permeability and high water pressure, the difficulties of drilling and preventing water leakage are extremely high. This test device can conduct a live simulation test on this construction process.

[0101] Through this test device, the test simulation of the entire process of grouting and freezing reinforcement in the shield docking section is carried out, which can not only provide control parameters for the actual construction, but also train the operators to improve their operation proficiency.

[0102] The structure of the test device is simple, which is suitable for the processing and assembly of test equipment at the construction site, improving the convenience of using the device.

[0103] Embodiment 2

[0104] The present invention also provides a simulated construction step and method for the coring process based on the test device of the present invention

[0105] Specifically, the coring process simulation test method includes the following steps:

[0106] (1) Assemble the test device and install the springs and steel plates in the test box body.

[0107] (2) Burying of earth pressure cells.

[0108] (3) The test soil is filled in layers and vibrated and compacted.

[0109] (4) Place the top steel plate and connect the airbag, seal the top cover plate, apply pressure, and start the test.

[0110] (5) Measurement and layout: As Figure 3 and Figure 4 shown, first, an artificial rear sight surface BD is made at the rear of the test box body. Use a total station to determine the position of the azimuth axis DE. According to the circumferential and longitudinal dimensions marked on the design drawing, determine the intersection position A of the orifice pipe and the test box body (shield shell). By measuring the angle between AC and the azimuth axis DE, make the angular direction of the orifice pipe consistent with the design angle, determine the position C of the rear sight point, use the connection line of AC as the azimuth line for positioning, and make an obvious mark on the position of point A with paint. In this way, the measurement and positioning of the position and angle of the orifice pipe are completed.

[0111] (6) Welding of orifice pipe: Preprocessing of orifice pipe → Temporary fixation of orifice pipe → Re-measurement and positioning → Full welding fixation of orifice pipe.

[0112] Preprocessing: Use a seamless steel pipe of Ф146×10mm and preprocess the inclined cutting surface in advance according to the drilling angle requirements. Temporary fixation: Temporarily fix the orifice pipe by spot welding according to the positioning. Re-measurement and positioning: Re-position according to the description in 3.1.1 to ensure the coaxiality of the positioning line AC and the axis line of the orifice pipe. Full welding fixation: The inclined cutting surface of the orifice pipe is fully welded to the side surface of the arc-shaped plate of the test box body, and then reinforced with stiffening ribs.

[0113] (7) Connect the ball valve and the seal box

[0114] Connect a DN125 ball valve and a seal box (with a length of not less than 500mm at the tail end of the orifice pipe. The length of the seal box of the traditional device is about 200mm, with insufficient wear resistance and sealing level. After testing, it is determined that a seal box length of not less than 500mm can meet the requirements of shield shell drilling). Use an air compressor to pressurize through the bypass valve of the orifice pipe and conduct a sealing pressure test on the orifice pipe. According to the requirements of the formation water and soil pressure, the designed sealing pressure resistance of the orifice pipe weld, sealing device, etc. should not be less than 0.8MPa.

[0115] Pressure inspection standard:

[0116] In the pressure test, the test pressure should be 1.5 times the working pressure of the orifice pipe system and shall not be less than 0.6MPa. The test should be carried out after the pre-test. Pressurize to 1 / 3 of the test pressure and maintain for 10 minutes to observe whether there are any abnormal phenomena on the pressure gauge and the pipeline. After stabilizing at the test pressure for 10 minutes, the pressure drop should not exceed 0.05MPa, and then reduce the pressure to the working pressure to check whether the orifice pipe and the sealing device leak.

[0117] Sealing inspection standard:

[0118] Check the sealing performance of the connection parts such as flanges and threaded joints, and there shall be no leakage. Perform opening and closing operations on the valves to check whether the valve sealing performance is good.

[0119] Abnormal situation inspection:

[0120] Under the test pressure, check whether there are phenomena such as deformation and leakage of the pipeline. During the pressurization process, the pressure should be gradually increased slowly. After reaching the test pressure, it should be maintained for more than 5 minutes, and observe whether there are any abnormal phenomena on the pressure gauge and the pipeline.

[0121] (8) Erection of the lifting platform:

[0122] Use 4 steel pipes (or drill pipes) of φ89×5 as columns, and the base is processed from 100 square pipes. Weld 4 lifting lugs under the top frame with 2 cm thick steel plates, and hang a 2T manual chain hoist on each lifting lug for the lifting of the lifting platform. Install a φ89×5 cross beam in the middle of the lifting platform, and set 4 lifting lugs on the cross beam for hoisting the drill pipe materials on the platform.

[0123] (9) Installation and fixation of the coring equipment:

[0124] Transport the coring equipment such as the drill rig to the drill rig platform, and install and fix the drill rig on the platform. Adjust the lifting platform to align the position of the drill rig with the orifice pipe, and perform drill rig alignment.

[0125] (10) Drill pipe angle adjustment

[0126] Fine-tune the drill pipe angle, drill the drill pipe into the orifice pipe, and repeatedly measure to ensure the coaxiality and concentricity of the drill pipe and the orifice pipe.

[0127] (11) Drilling and coring

[0128] Use the drill rig to drive the Φ96mm diamond coring bit to cut the arc-shaped plate side of the 80mm test box body. After the shell is drilled through, the bit is withdrawn to between the sealing box and the DN125 ball valve, close the DN125 ball valve, and remove the coring bit.

[0129] Example 3

[0130] 1) The present invention also provides a simulation test method for the grouting process as shown in Figure 5 the test device based on the present invention:

[0131] Remove the sealing box at the back end of the ball valve and connect the grouting sealing box;

[0132] 2) Install the grouting drill pipe to the back end of the ball valve to seal the drilling pores;

[0133] 3) Open the ball valve, start the grouting drill pipe rig, and drill the grouting pipe into the formation;

[0134] 4) After drilling to the designated position, start the grouting operation;

[0135] 5) During the grouting process, monitor the pressure data of the soil pressure cells at the shield position in real time. During the grouting process, the monitored value P of the soil pressure cell at the position of the arc plate 注监 , the maximum pressure P that the arc plate can withstand max , satisfying P 注监 ≤P max , thereby determining the maximum grouting pressure that can be set, as well as the maximum grouting pressure that can be set at different positions, to ensure the safety of the shield of the shield machine during the grouting process; the number of single-row arrangements is the same as the single-hole grouting point positions, and the soil pressure cells are arranged on the projection line of the grouting pipe or freezing pipe towards the shield.

[0136] 6) Conduct grouting tests at different pressures at different positions to test the pressures generated on the shield by different grouting pressures;

[0137] 7) After completing the grouting test, wait for 14 days, relieve the pressure in the test box body, remove the top cover of the test box body, excavate the test soil layer by layer, and record and analyze the grouting diffusion situation.

[0138] 8) The grouting test is completed.

[0139] Example 4

[0140] The present invention also provides a simulation method for the freezing process based on the test device of the present invention, as Figure 6 shown:

[0141] 1) Assemble the test device, apply pressure, and arrange temperature sensors. Four rows are arranged in each cross-section, the row spacing is 1 m, the measuring point spacing is 0.3 m, and three measuring cross-sections are arranged longitudinally.

[0142] 2) The freezing pipe is not less than 1 m away from the soil boundary to avoid freezing the water body at the spring position during the freezing process and affecting the soil deformation boundary.

[0143] 3) Use 10 cm thick foam insulation cotton to wrap the outside of the test box body (except the shield side) for heat preservation.

[0144] 4) After another group of grouting is completed, carry out a freezing test using the grouted test soil;

[0145] 5) Remove the seal box at the rear end of the ball valve and connect the freezing pipe to the seal box;

[0146] 6) Install the freezing pipe to the rear end of the ball valve and seal the pores of the freezing pipe using the seal box;

[0147] 7) Open the ball valve, start the freezing pipe drilling rig, and drill the freezing pipe into the formation;

[0148] 8) After the freezing pipe is drilled to the designated position, connect the freezing pipeline, freezing equipment, etc., and start freezing;

[0149] 9) According to the designed freezing period, immediately stop freezing after the active freezing is completed;

[0150] 10) During the active freezing process, collect the data of the temperature sensors and earth pressure cells, analyze the development range and development speed of the frozen body, and analyze the pressure generated on the shield during the formation of the frozen body;

[0151] 11) After stopping freezing, immediately open the top cover of the test box body, quickly excavate in layers, and observe and analyze the freezing range.

[0152] 12) The freezing test is over.

[0153] Through the simulation test of the present invention, during the grouting process, the magnitude of the pressure generated by the grouting at the shield can be monitored, and the magnitudes of the pressures generated by different grouting points and different grouting pressures on the shield can be judged, so as to provide grouting pressure control parameters to ensure the stability of the shield. After the grouting test is over, open the top cover, take stratified samples of the soil in the box for analysis, clarify the slurry diffusion range, and determine the changes in the soil parameters after grouting. Through the freezing simulation test, the magnitude of the frost heaving force acting on the shield during the freezing process can be measured to judge the influence of freezing on the stability of the shield. After the grouting test is over, open the top cover and excavate the unfrozen soil to measure the size and range of the frozen body and visually judge the freezing effect.

[0154] The content of the present invention has been introduced in detail through the above preferred embodiments, but it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A shield drilling test device under high water pressure and strong water permeability environment, characterized by: It includes a test box, one side of the test box is an arc plate, the thickness of the arc plate is equal to the thickness of the shield shell, the non-arc plate side and the bottom plate of the test box are provided with springs, one end of the spring is fixedly connected to the inner wall of the test box, and the other end of the spring is fixedly connected to the movable steel plate, the test box is filled with a test soil body, a steel plate is placed on the upper part of the test soil body, a compressed air bag is placed on the steel plate, and a detachable cover is provided on the top of the test box; The spring parameters satisfy the following constraints: k h =K h ×D h1 ×L v1 k v =K v ×D h2 ×L v2 |D h1 -L v1 |≤λ×min{D h1 ,L v1 } |D h2 -L v2 |≤λ×min{D h2 ,L v2 } Among them, k h is the horizontal spring stiffness coefficient, k v is the vertical spring stiffness coefficient, K h K is the measured stratum horizontal bed coefficient in the geological survey report, v D is the measured horizontal bed coefficient of the stratum in the geological survey report. h1 is the upper and lower distance of the horizontal spring, L v1 is the left and right distance of the horizontal spring, D h2 is the vertical distance between the spring and the ground, L v2 is the left-right distance of the vertical spring, λ is the coefficient of difference in the spacing between the two directions of the spring; The size of the curved plate meets the following formula to ensure: H=l 环向 ×p L=l 纵向 ×q Among them, H represents the circumferential length of the arc plate, L represents the longitudinal length of the arc plate, and l 环向 Indicates the installation annular spacing of the orifice pipe, l 纵向 It indicates the longitudinal spacing of orifice pipe installation, p indicates the circumferential number of orifice pipes, and q indicates the longitudinal number of orifice pipes; An earth pressure box is buried under the steel plate, and the pressure of the compressed air bag is adjusted according to the difference between the value of the earth pressure box and the preset value.

2. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 1, characterized in that: The compressed air bag is supplied by the air tank. The pressure inside the compressed air bag is P2, and the pressure in the air tank is P3. The following formula needs to be satisfied: P3>P2>P1 P3≥K a ×P1 Among them, P1 is the effective earth pressure value of the overlying soil on the test soil layer, γ i is the density of the i-th layer of soil, h i is the thickness of the i-th soil layer, n is the number of soil layers above the test layer, K a is the pressure reserve factor.

3. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 2, characterized in that: First, through the pressure regulator of the gas tank, set P2 = P1, set the initial value of the pressure in the airbag to the calculated P1 pressure value, and measure the pressure P of the soil pressure box under the steel plate after pressurization. c The pressure value is used to adjust the pressure value in the airbag. The pressure increment △P applied subsequently is (P1-P c )×P c / P1, if P c If the difference with P1 is less than 5%, the airbag pressure will be increased step by step next time, with each pressure increase of 2kPa and stable for 30 minutes. c If it is still lower than P1, continue to adjust.

4. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 1, characterized in that: An automatic pressure relief valve is installed on the upper part of the test box. When the pressure exceeds the maximum water pressure in the shield tunnel docking range, the test box will automatically release the pressure.

5. Based on the core sampling test method of the shield shell drilling test device under high water pressure and strong water permeability environment described in claim 1, It is characterized in that The steps include: Step 1: Fill the test soil in layers in the test box and compact it by vibration; Step 2: Place a steel plate on top of the test soil, close the cover plate, and compress the airbag to apply pressure; Step 3: Measure and locate the position and angle of the orifice pipe; Step 4: The orifice pipe chamfer is fully welded to the arc plate side of the test box; Step 5: Adjust the drilling rig position to be flush with the orifice pipe and align the drilling rig; Step 6: Fine-tune the drill rod angle, drill the drill rod into the orifice pipe, and repeatedly measure to ensure the coaxiality and concentricity of the drill rod and the orifice pipe; Step 7: Use a drilling rig to drive the coring drill bit to cut the arc plate of the test box. After the shell is unblocked, the drill bit is withdrawn to between the sealing box and the ball valve, the ball valve is closed, and the coring drill bit is removed.

6. A grouting process simulation test method for a shield drilling test device under a high water pressure and strong water permeability environment according to claim 1, characterized in that: The steps include: Step 1: Start the grouting drill rig and drill the grouting pipe into the formation; Step 2: After drilling to the designated location, start grouting operation; Step 3: Real-time monitoring of the pressure data at the arc plate position during the grouting process. The monitoring value P of the soil pressure box at the arc plate position during the grouting process 注监 , the maximum pressure P that the curved plate can withstand max , and satisfy P 注监 ≤P max , so as to determine the maximum grouting pressure that can be set, as well as the maximum grouting pressure that can be set at different positions, to ensure the safety of the shield shell of the shield machine during the grouting process; Step 4: Carry out grouting tests at different positions and pressures to test the pressure on the shield caused by different grouting pressures; Step 5: After completing the grouting test, wait for 14 days, release the pressure in the box, remove the top cover of the test box, excavate the test soil in layers, and record and analyze the grouting diffusion.

7. A method for simulating the freezing process of a shield drilling test device under a high water pressure and strong water permeability environment according to claim 1, characterized in that: The steps include: Step 1: Assemble the test device, apply pressure, and place temperature sensors; Step 2: Add a thermal insulation layer to the non-curved plate side of the test box; Step 3: Carry out freezing test using the test soil after grouting; Step 4: Seal the freezing pipe pores; Step 5: Start the freezing pipe drilling machine and drill the freezing pipe into the formation; Step 6: Stop freezing immediately after completing the active freezing according to the designed freezing period; Step 7: Collect temperature sensor and soil pressure data during the active freezing process, analyze the development range and speed of the frozen body, and analyze the pressure on the shield during the formation of the frozen body; Step 8: After freezing stops, immediately open the top cover of the test chamber, quickly excavate in layers, and observe and analyze the freezing range.

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