Shield shell drilling test device under high-water-pressure water-permeable environment and construction method of shield shell drilling test device

Abstract

The invention belongs to the technical field of shield tunnel engineering, and particularly relates to a shield shell drilling test device in a high-water-pressure permeable environment, which comprises a test box body, one side of the test box body is an arc-shaped plate, the thickness of the arc-shaped plate is equal to that of a shield shell, and springs are arranged on the non-arc-shaped plate side and a bottom plate of the test box body. One end of the spring is fixedly connected with the inner wall of the test box body, the other end of the spring is fixedly connected with the movable steel plate, a test soil body is arranged in the test box body, a steel plate is arranged on the test soil body, a compressed air bag is arranged on the steel plate, and a detachable cover plate is arranged at the top of the test box body. The test device is pressurized by gas, so that the dependence on a servo hydraulic device is eliminated, and the test can be conveniently carried out on a construction site. The device can simulate shield shell drilling construction, grouting construction and freezing construction under different stratum conditions and different water pressure conditions, the pressure generated by grouting at the shield shell is monitored in the grouting process through a simulation test, and the stability of the shield shell is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of shield tunnel engineering, and in particular relates to a shield shell drilling test device in a high water pressure and strong water permeability environment. Background Art

[0002] At present, the construction trend of large-diameter shield tunnels in China is from single soft soil layer to complex soil layer, from large diameter to super-large diameter, from medium water pressure to high water pressure and super-high water pressure, from medium-intensity earthquake zone to high-intensity earthquake zone, from single-mode shield to multi-mode shield, from single construction method to combination of multiple construction methods, from traditional construction management to digital management, and from short-distance excavation to long-distance and ultra-long-distance excavation. When the shield tunnel under the sea is connected, it is necessary to use the grouting-freezing combined reinforcement method to establish a stable and waterproof construction space in the high-water pressure and high-permeability sandy soil layer. When the freezing method is used for construction, it is necessary to set up grouting pipes and freezing pipes 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 to lead out the grouting pipes and freezing pipes from the freezing holes. At the same time, how to monitor the pressure of the grouting on the shield shell generated during the grouting process, and how to monitor the frost heave 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, since the diffusion of slurry during the grouting process is random due to the unevenness of the stratum, it is also very important to intuitively evaluate the grouting effect. During the freezing process, the range of the frozen body formed during active freezing can only be indirectly reflected by the temperature of the temperature measuring tube in actual construction, and it is not possible to achieve an intuitive evaluation. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a shield drilling test device under high water pressure and strong water permeability environment, which adopts gas pressurization, gets rid of the dependence on servo hydraulic devices, and is convenient for conducting tests on the construction site. The device can simulate the shield drilling construction, grouting construction, and freezing construction under different formation conditions and different water pressure conditions, which can not only provide data parameter support for the development of actual projects, but also train operators.

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

[0005] The present invention provides a shield shell drilling test device under high water pressure and strong water permeability environment, comprising a test box body, one side of the test box body is an arc-shaped plate, the thickness of the arc-shaped plate is equal to the thickness of the shield shell, the non-arc-shaped plate side and the bottom plate of the test box body are both provided with springs, 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, a test soil body is installed in the test box 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 plate is provided on the top of the test box body.

[0006] Among them, the size of the curved 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 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 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 K is the measured stratum horizontal bed coefficient in the geological survey report, v D is the measured stratum horizontal bed coefficient 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, and λ is the coefficient of difference in the spacing between the springs in two directions.

[0016] Preferably, a pressure sensor is buried under the steel plate, and the pressure of the compressed airbag is adjusted by the difference between the numerical value of the pressure sensor and a predetermined value.

[0017] 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:

[0018] P3>P2>P1

[0019]

[0020] P3≥K a ×P1

[0021] 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.

[0022] Furthermore, firstly, the pressure regulator of the gas storage tank is used to set P2 = P1, and the initial value of the pressure in the airbag is set to the calculated pressure value P1. After pressurization, the pressure P of the soil pressure box under the steel plate is measured. c The pressure value is used to adjust the pressure value in the airbag.

[0023] 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.

[0024] Preferably, an automatic pressure relief valve is provided on the upper part of the test box, and when the pressure exceeds the maximum water pressure in the shield tunnel docking range, the test box automatically releases the pressure.

[0025] The present invention provides a coring test method for a shield shell drilling test device under a high water pressure and strong water permeability environment, comprising the following steps:

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

[0027] Step 2: Place a steel plate on top of the test soil, close the cover plate, and compress the airbag to apply pressure;

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

[0029] Step 4: The orifice pipe chamfer is fully welded to the arc plate side of the test box;

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

[0031] 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;

[0032] 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.

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

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

[0035] Step 2: After drilling to the designated location, start grouting operation;

[0036] Step 3: Real-time monitoring of the arc plate position pressure data during the grouting process. The arc plate position sensor monitoring value P 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;

[0037] Step 4: Carry out grouting tests at different positions and pressures to test the pressure on the shield caused by different grouting pressures;

[0038] 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.

[0039] The present invention also provides a method for simulating the freezing process of a shield drilling test device under a high water pressure and strong water permeability environment, comprising the following steps:

[0040] Step 1: Assemble the test device, apply pressure, and place temperature measurement sensors;

[0041] Step 2: Add a thermal insulation layer to the non-curved plate side of the test box;

[0042] Step 3: Carry out freezing test using the test soil after grouting;

[0043] Step 4: Seal the freezing pipe pores;

[0044] Step 5: Start the freezing pipe drilling machine and drill the freezing pipe into the formation;

[0045] Step 6: Stop freezing immediately after completing the active freezing according to the designed freezing period;

[0046] 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;

[0047] 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.

[0048] This technical solution can provide a more effective research solution for the research of shield underground butt joint construction technology. Specifically, compared with the existing technology, it has the following advantages:

[0049] In order to solve the above problems, the present invention provides a shield drilling test device under high water pressure and strong water permeability environment, which adopts gas pressurization, gets rid of the dependence on servo hydraulic devices, and is convenient for conducting tests on the construction site. The device can simulate the shield 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 can be monitored during the grouting process, and the pressure generated by different grouting points and different grouting pressures on the shield can be judged, thereby providing grouting pressure control parameters to ensure the stability of the shield, which can not only provide data parameter support for the development of actual projects, but also train operators. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0051] Figure 2 This is a schematic diagram of the test box assembly of the present invention;

[0052] Figure 3 It is a schematic diagram of drilling holes in the test box of the present invention;

[0053] Figure 4 This is a schematic diagram of measuring, positioning and setting out the test box of the present invention;

[0054] Figure 5 It is a schematic diagram of a test box grouting test of the present invention;

[0055] Figure 6 It is a schematic diagram of the freezing simulation of the test box of the present invention. DETAILED DESCRIPTION

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

[0057] First of all, the size of the shield machine is large. A shield machine has a diameter of more than 16m, a length of more than 15m, and a weight of more than 5,000 tons. It is impossible to use a whole shield machine for simulation testing. However, if a scaled test is adopted, the simulation effect of the actual working conditions will be greatly reduced. Although the scaled test can simulate possible rules, it cannot simulate the actual construction process. Therefore, a suitable local range is selected for testing, and in order to verify the actual working conditions of an 8cm thick shield shell obliquely drilling in a limited space, the thickness of the simulated shield shell to be selected is also 8cm, and the curvature and rib structure of the simulated shield shell must be consistent with the actual construction conditions.

[0058] Even if we get a steel plate that can simulate the actual shield shell of a shield machine, it is more difficult to set the shield shell steel plate to the actual working conditions of the shield machine in the stratum. It is necessary not only to simulate the soil pressure and water pressure in the stratum, but also to reflect the boundary conditions of the soil there. It is unrealistic to bury the test shield in the stratum under actual working conditions. In the laboratory, servo pressurization equipment is often used to simulate and control the pressure environment and boundary conditions of the test soil, but the size that can be simulated in the laboratory is very limited, and it is impossible to simulate the full-scale working conditions. Secondly, there are not many laboratories with servo pressurization equipment. It is necessary to make an appointment and queue to carry out the test, which is not friendly to the actual project with a tight schedule. Therefore, it is necessary to develop equipment that can carry out simulation tests on site, which can not only simulate the soil and water environment of the actual project, but also be easy to manufacture and assemble, and is suitable for on-site tests in engineering projects.

[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 and the constraints around the stratum in the test device. Grouting tests are often carried out in fixed boxes or in situ to explore the general laws of grouting. It is difficult to simulate the soil pressure and water pressure of the stratum at the location and the constraints of the infinite soil on the test soil on the side in a fixed box. The immovable boundary of the box constrains the horizontal and vertical displacements of the test soil, resulting in the test results not being able to represent the actual soil layer laws. The advantage of in-situ tests is that they can restore the actual soil layer and its location, but the disadvantage is that the grouting effect can only be fed back through limited measuring points and core sampling tests, and the grouting effect cannot be revealed intuitively. More importantly, it is impossible to simulate the magnitude of the pressure generated by grouting on the shield.

[0060] We can only draw on the experience of the freezing method construction of the shield tunnel communication channel, weld an orifice pipe on the shield shell, connect a ball valve to the orifice pipe, and drill a hole to connect a sealing box behind the ball valve.

[0061] However, compared with the traditional process, due to the high hardness of the shield shell and the long length of oblique coring, the single coring drilling time is long, the wear on the sealing system and the drill bit is large, and the drilling on the shield shell of the shield machine is more difficult. It is still unknown whether the traditional drilling process can be applied to the drilling construction on the shield shell under high water pressure and strong water permeability environment.

[0062] Therefore, it is necessary to establish a test device to establish a method for drilling holes on the shield under high water pressure and strong water permeability. High water pressure refers to water pressure higher than 0.5MPa, and strong water permeability refers to the formation permeability coefficient higher than 10 - 2 cm / s.

[0063] The present invention will be further described below in conjunction with the accompanying drawings and implementation examples.

[0064] Example 1

[0065] In this embodiment, the present invention designs a test device, such as Figure 1 and Figure 2 As shown, it is suitable for simulation tests of drilling construction on the shield under high water pressure and strong water permeability environment.

[0066] Since the shield machine is a circular structure with a diameter of more than 14 meters, it is expensive to take a full-size shield for simulation test. The model can be reduced in the actual design process. The experimental device uses part of the shield section to carry out the test. According to the actual diameter of the shield machine, one-tenth of the shield shell range is used, and a steel plate (80mm thick) with the same thickness as the shield shell is used to form an arc shape as the test shield shell. The test box has a rectangular structure as a whole, one side of which is a curved panel made at a ratio of 1:1 to the waist of the shield body to simulate the thickness of the shield shell of 80mm, and the thickness of the other plates is 50mm; the outer side of the box is reinforced with square hollow steel pipes, and reinforced supports are set except for one side of the curved panel. The box arc plate is made of Q355B low-alloy high-strength steel, and the rest is Q355B material.

[0067] The height, width and longitudinal length of the box must meet the dimensions required for process testing and the layout of internal components and parts. They can be adjusted according to the actual project dimensions to be simulated, but the pressure resistance safety of the box must meet the requirements.

[0068] The steel plate welding meets the water pressure sealing test of the box body. The top cover of the box body is a removable top cover, which is sealed with a rubber plate and tightened with bolts. It is convenient for soil filling, springs, steel plates and earth pressure boxes to be buried. More importantly, after grouting and freezing, it can be opened as a whole and excavated in layers to directly reflect the grouting and freezing effects. After the box body is processed, the guardrail area is reinforced with KW200 steel.

[0069] The size range of the box can provide space for shield drilling, grouting, and freezing. The radius of the shield is R. The curved surface of the 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 annular p (3≤p≤5) groups of orifice pipe installation space, and the annular spacing of orifice pipe installation is l 环向 , should not be less than 1m;

[0071] Provides longitudinal installation space for q (2≤q≤5) orifice pipes, and the longitudinal spacing of orifice pipes is l 纵向 , should not be less than 1.3m;

[0072] The orifice pipes are arranged in a plum blossom shape. Combined with the above two actual requirements, the following restrictions are imposed on the size of the arc surface:

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

[0074] H=l 环向 ×p

[0075] The longitudinal length of the curved plate is L, in m:

[0076] L = l 纵向 ×q

[0077] Therefore, changing the size can not only meet the needs of simulation tests, but also reduce the scale of simulation tests, and reduce the difficulty of manufacturing, assembling and testing the test equipment. Using a local 1:1 size or a size close to 1:1 to simulate the actual project can more realistically reflect the test rules; the main purpose of this test is not only to reflect the test rules, but more importantly, it can provide a platform for the selection and verification of construction processes that have not been used, 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 underground environments can provide a platform for simulated pressure testing for similar projects.

[0078] The test box is reinforced with ribs to ensure that the internal pressure bearing capacity of the test box is not less than the maximum water pressure in the shield tunnel docking range. It can withstand an internal pressure of 1.0MPa to meet the pressure test requirements of deep buried tunnels. At the same time, for safety reasons, an automatic pressure relief valve is installed on the upper part of the box. When the pressure exceeds 1.0MPa, the test box can automatically release the pressure to ensure the safety of the test.

[0079] The soil body is made of springs and steel plates on four sides to simulate the contact relationship between the test soil body and the surrounding infinite soil body. In order to more realistically simulate the deformation constraint of the surrounding soil body on the test soil body, the spring stiffness is equivalently converted according to the base bed coefficient of the actual geological survey report. If the stratum where the shield is located is a composite multi-layer stratum, the spring and steel plate can be converted layer by layer. The conversion relationship is:

[0080] The horizontal spring stiffness satisfies:

[0081] k h =K h ×D h1 ×L v1

[0082] Vertical spring rate:

[0083] k v =K v ×D h2 ×L v2

[0084] In order to facilitate quick testing on site, the spring spacing can be adjusted based on the given stiffness springs that are easily available at the project site. That is, the horizontal spring spacing must meet the following requirements:

[0085] D h1 ×L v1 =k h / K h The vertical spring arrangement spacing meets the following requirements:

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

[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, unit (kN / m); k v is the vertical spring stiffness coefficient, unit (kN / m); λ is the difference coefficient of the spacing between the two directions of the spring, ranging from 0 to 0.2, K h It is the measured stratum horizontal bed coefficient in the geological survey report, unit (kN / m 3 );K v It is the measured stratum horizontal bed coefficient in the geological survey report, unit (kN / m 3 );D h1 is the upper and lower distance of the horizontal spring, in m; L v1 D is the left and right distance of the horizontal spring, in m;h2 is the front-to-back distance of the vertical spring, in m; L v2 is the left-right distance of the vertical spring, in 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, the spring can move evenly and freely to impose lateral constraints on the test soil.

[0091] The upper part of the test soil is pressurized with vertical pressure in the form of airbags and steel plates. The thickness of the steel plate is 10mm, which has sufficient rigidity to remain flat during the airbag pressurization process to ensure the uniformity of the airbag pressurization. Although the airbag pressurization is different from the servo pressurization in terms of accuracy, by burying a pressure sensor under the steel plate and adjusting the airbag pressure through the numerical feedback of the pressure sensor, the required pressurization value can also be accurately simulated.

[0092] The pressure of the earth pressure sensor simulates the earth pressure at the location of the shield machine. The earth pressure is the effective stress and is calculated as follows:

[0093]

[0094] Where: P1 is the effective earth pressure value of the overburden on the test soil layer, unit is kpa; γ i is the weight of the i-th layer of soil, the floating 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 to P2, and the pressure in the gas tank is P3. According to the gas pressure loss in the test, P3>P2>P1 must be satisfied, and in order to ensure sufficient pressure reserve in the gas tank, 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, set P2=P1, and set the initial value of the pressure in the airbag to the calculated P1 pressure value. Since the pressure loss caused by airbags of different specifications is different, it is difficult to quantitatively estimate in advance, so it is necessary to measure the pressure P of the soil pressure box under the steel plate after pressurization. c The pressure value is adjusted by the pressure value in the airbag. The subsequent pressure value increment △P=(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 the calculated value of P1, continue to adjust until it is equal to the calculated value P1. The earth pressure boxes are arranged in 2 rows, with a horizontal row spacing of 2m and a vertical spacing of 2m. A total of 14 earth pressure boxes are arranged at the bottom of the steel plate. The measured earth pressure box pressure P under the steel plate cTake the average value of the 14 pressure boxes, but the range R is required to be less than 10% of the average value, where the range is the maximum value minus the minimum value among the 14 pressure boxes. Otherwise, it means that the steel plate or airbag is not placed flat and needs to be re-placed.

[0095] The test soil body is in direct contact with the shield body, which is consistent with the actual working conditions. An earth pressure box is buried at the shield shell position to test the pressure on the shield shell during grouting and freezing.

[0096] The drilling, grouting and freezing test side is an arc surface, and the curvature is consistent with the curvature of the actual shield machine shell, which can simulate the actual construction working environment and improve the authenticity of the test simulation.

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

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

[0099] The top cover of the test chamber is detachable as a whole, which is convenient for the installation of test soil and measuring components. More importantly, after the grouting and freezing tests are completed, the soil can be easily dug up in layers to visually measure the grouting and freezing effects.

[0100] The thickness of the test box is 80mm, simulating the actual thickness of the shield shell. Oblique holes are drilled on the shield shell of this thickness, with a drilling length of more than 800mm. Construction is carried out under high permeability and high water pressure. The difficulty of drilling and preventing water leakage is extremely high. The test device can conduct a real-time simulation test of the construction process.

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

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

[0103] Example 2

[0104] The present invention also provides a simulation construction step and method for the coring process of 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 spring and steel plate in the test box.

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

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

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

[0110] (5) Measurement and setting out: Figure 3 and Figure 4 As shown, first, on the artificial rear-view surface BD at the rear of the test box, use the total station to determine the azimuth axis position DE, and determine the intersection point A of the orifice tube and the test box (shield) according to the circumferential and longitudinal dimensions marked on the design drawings. By measuring the angle between AC and the azimuth axis DE, the angular direction of the orifice tube is made consistent with the design angle, and the rear-view point position C is determined. The line connecting AC is used as the azimuth line for positioning, and the position of point A is clearly marked with paint. In this way, the measurement and positioning of the orifice tube position and angle are completed.

[0111] (6) Orifice pipe welding: Orifice pipe pre-processing → Orifice pipe temporary fixation → Re-measurement and positioning → Orifice pipe full welding and fixation.

[0112] Pre-processing: Use Ф146×10mm seamless steel pipe, and process the chamfered 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 positioning: Re-position as described in 3.1.1 to ensure the coaxiality of the positioning line AC and the axis of the orifice pipe. Full welding fixation: The chamfered surface of the orifice pipe is fully welded to the side of the arc plate of the test box, and then reinforced with reinforcing ribs.

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

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

[0115] Pressure test 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, pressurized to 1 / 3 of the test pressure, maintained for 10 minutes, and observe whether the pressure gauge and pipeline have any abnormalities. After stabilizing the pressure 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 sealing device are leaking.

[0117] Sealing test standard:

[0118] Check the sealing performance of flanges, threaded joints and other connection parts, and there must be no leakage. Open and close the valve to check whether the valve sealing performance is good.

[0119] Abnormal situation inspection:

[0120] Under the test pressure, check whether the pipeline has deformation, leakage, etc. During the pressurization process, the pressure should be increased gradually and slowly. After reaching the test pressure, it should be maintained for more than 5 minutes, and the pressure gauge and pipeline should be observed for abnormal phenomena.

[0121] (8) Lifting platform installation:

[0122] Four φ89×5 steel pipes (or drill pipes) are used as columns, and the base is made of 100 square pipes. Four lifting ears are welded with 2cm thick steel plates under the top frame, and each lifting ear is hung with a 2T hand chain hoist for lifting the lifting platform. A φ89×5 crossbeam is set in the middle of the lifting platform, and the crossbeam is equipped with 4 lifting ears for lifting the drill pipe materials on the platform.

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

[0124] Transport the core sampling equipment such as the drilling rig to the drilling platform, and install the fixed drilling rig on the platform. Adjust the lifting platform to adjust the position of the drilling rig to be flush with the orifice pipe, and align the drilling rig.

[0125] (10) Drill rod angle adjustment

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

[0127] (11) Drilling and coring

[0128] Use a drilling rig to drive a Φ96mm diamond core drill bit to cut the 80mm curved plate side of the test box. After the shell is unblocked, the drill bit is withdrawn to between the sealing box and the DN125 ball valve, the DN125 ball valve is closed, and the core drill bit is removed.

[0129] Example 3

[0130] 1) The present invention also provides a test device based on the present invention. Figure 5 As shown in the figure, the grouting process simulation test method is as follows:

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

[0132] 2) Install the grouting drill rod to the rear end of the ball valve to seal the drilled hole;

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

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

[0135] 5) Real-time monitoring of the shield shell position soil pressure box pressure data during grouting, and the arc plate position sensor monitoring value P during grouting 注监 , the maximum pressure P that the curved plate can withstand max , satisfying P 注监 ≤P max , in order 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; the number of single-row arrangements is consistent with the single-hole grouting points, and the earth pressure box is arranged on the projection line of the grouting pipe or freezing pipe to the shield shell.

[0136] 6) Carry out grouting tests at different positions and pressures to test the pressure on the shield caused by different grouting pressures;

[0137] 7) After completing the grouting test, wait for 14 days, release the pressure in the test chamber, remove the top cover of the test chamber, excavate the test soil in layers, and record and analyze the grouting diffusion.

[0138] 8) The grouting test is completed.

[0139] Example 4

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

[0141] 1) Assemble the test device, apply pressure, and arrange the temperature measurement sensors in 4 rows on each section, with a row spacing of 1m and a measurement point spacing of 0.3m. Arrange 3 measurement sections longitudinally.

[0142] 2) The freezing pipe should be at least 1m away from the soil boundary to avoid freezing the water at the spring position during the freezing process, which would affect the deformation boundary of the soil.

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

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

[0145] 5) Remove the sealing box at the rear end of the ball valve, connect the freezing pipe and drill into the sealing box;

[0146] 6) Install the freezing pipe to the rear end of the ball valve and seal the pores of the freezing pipe with a sealing 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 design freezing period, after completing the active freezing, stop freezing immediately;

[0150] 10) Collect data from temperature sensors and soil pressure boxes during active freezing, analyze the development range and speed of the frozen body, and analyze the pressure on the shield during the formation of the frozen body;

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

[0152] 12) The freezing test is completed.

[0153] The present invention can monitor the pressure generated by grouting at the shield shell during the grouting process through simulation tests, and judge the pressure generated by different grouting points and different grouting pressures on the shield shell, thereby providing grouting pressure control parameters to ensure the stability of the shield shell. After the grouting test is completed, the top cover is opened, and the soil in the box is layered and sampled and analyzed to clarify the diffusion range of the slurry and determine the changes in soil parameters after grouting. Through the freezing simulation test, the size of the frost heave force acting on the shield shell during the freezing process can be measured to judge the impact of freezing on the stability of the shield shell. After the grouting test is completed, the top cover is opened, the unfrozen soil is excavated, the size and range of the frozen body can be measured, and the freezing effect can be intuitively judged.

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

Claims

1. A shield drilling test device under high water pressure and strong water permeability environment, characterized by: The test box comprises a test box body, one side of which is an arc-shaped plate, the thickness of which is equal to the thickness of the shield shell, the non-arc-shaped plate side and the bottom plate of the test box body are both provided with springs, 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 the movable steel plate, the test box body is filled with a test soil body, a steel plate is placed on the top 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 body.

2. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 1, characterized in that: 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 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.

3. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 1, characterized in that: 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 stratum horizontal bed coefficient 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, and λ is the coefficient of difference in the spacing between the springs in two directions.

4. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 1, characterized in that: A pressure sensor is buried under the steel plate, and the pressure of the compressed air bag is adjusted according to the difference between the numerical value of the pressure sensor and the preset value.

5. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 4, 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.

6. The shield shell drilling test device under high water pressure and strong water permeability environment according to claim 5, 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.

7. 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.

8. 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.

9. A grouting process simulation test method for a shield shell 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 arc plate position pressure data during the grouting process. The arc plate position sensor monitoring value P 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.

10. 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 measurement 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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