Shield tunnel segment structure temperature and pressure loading test device and test method thereof

Abstract

The invention discloses a shield tunnel segment structure temperature and pressure loading test device and method. The shield tunnel segment structure temperature and pressure loading test device comprises a fixed support fixedly connected with a segment, a temperature and pressure loading system for loading water pressure and applying different temperatures to the segment, a displacement monitoring assembly for monitoring the displacement amount of the segment, a transverse loading system, a vertical loading system and a sealing gasket, wherein the transverse loading system and the vertical loading system are used for applying loads to the segment; the fixed support is connected with the transverse loading system; the temperature and pressure loading system comprises a cold and heat source and a plurality of test boxes with openings in the bottom surfaces, and the bottom surfaces of the test boxes are attached to the surfaces of the duct pieces through sealing strips; a water inlet of the test box is connected with a water pump through a pipeline and a water inlet valve, and a water outlet of the test box is connected with a water outlet valve through a pipeline; the cold and hot pipelines in the test box are connected with cold and hot sources, and the cold and hot sources comprise a cold source and a heat source. The shield tunnel duct piece and duct piece joint mechanical property testing device can be used for testing the bending resistance, the shearing resistance, the anti-seepage performance and the like of shield tunnel duct pieces and duct piece joints and testing the mechanical property of the duct pieces and the duct piece joints in the freezing, thawing, active heat preservation and freezing and thawing cycle states.

Description

Technical Field

[0001] The invention relates to the technical field of segment testing equipment, and in particular to a shield tunnel segment structure temperature and pressure loading testing device and a testing method thereof. Background Art

[0002] As an efficient, convenient and environmentally friendly public transportation mode, subway plays an important role in alleviating urban traffic pressure. However, in some areas with complex geological conditions, traditional subway tunnel construction methods face many challenges. Artificial freezing method came into being in this context. Under some unfavorable geological conditions such as soft soil and quicksand, as well as in areas with high groundwater levels, conventional construction methods are difficult to ensure the stability and safety of tunnels. Artificial freezing method freezes the water in the soil into ice, turning the soil into a hard frozen body, thereby providing a stable support environment for the excavation of underground projects such as subway tunnels or connecting passages. In some occasions that require high-precision construction, such as the connection between subway stations and tunnels, artificial freezing method can play its unique advantages to ensure construction quality.

[0003] During the freezing construction process of underground projects such as subway tunnels or communication passages, the water in the soil freezes into ice, and the volume expands to produce frost heave force, which acts on the shield segments, easily causing deformations such as bending and twisting of the segments, affecting the shape and dimensional accuracy of the tunnel. Uneven frost heave force may also cause local stress concentration in the segments, increasing the risk of segment cracking. During the freezing construction process, the rapid change in temperature will cause thermal stress inside the shield segments. When the surface temperature of the segment drops rapidly, a temperature gradient will form between the inside and the surface of the segment, resulting in tensile stress. This thermal stress may cause cracks in the segments, reducing the strength and durability of the segments. Temperature changes will also affect the mechanical properties of the segment materials. For example, the strength and elastic modulus of concrete will change at low temperatures, and the yield strength and elongation of steel bars will also be affected. These changes in material properties will further affect the overall mechanical properties of the shield segments.

[0004] In the early stage of freezing construction, the ambient temperature around the segments drops rapidly, and the strength of concrete in a low temperature environment will be improved to a certain extent. However, as the freezing time increases, cracks and damage may occur in the segments under the action of frost heave force, resulting in reduced strength. Especially at the junction of the segments and the frozen soil, the frost heave force is concentrated, which can easily cause cracking and damage to the segments. At present, no relevant experimental research has been carried out on the influence of freezing construction on the structural mechanical properties of shield segments. After the freezing construction is completed, as the soil thaws, the ambient temperature around the segments gradually increases. At this time, the strength of the concrete will gradually return to normal levels. However, if the segments have been severely damaged during the freezing process, the strength of the segments may not be fully restored after thawing, and may even continue to decline. There is no relevant test to verify the changes in the mechanical properties of the segments under the freezing-thawing action of the soil. In addition, during long-term use, due to the influence of factors such as groundwater erosion and freeze-thaw cycles, the strength of the segments will gradually decrease, and the segment joints are prone to misalignment and displacement, increasing the risk of water leakage. Especially after freezing, forced thawing is carried out to control the melting and settlement of frozen soil, or repeated freezing construction leads to freeze-thaw cycles. The impact on the structural performance of the shield segments has not been explained by experiments. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a temperature and pressure loading test device and a test method for a shield tunnel segment structure, which solves the problem in the prior art that the mechanism affecting the mechanical properties of reinforced concrete segments or segment joints under the action of frost heave, frozen soil thawing and freeze-thaw cycles of the shield tunnel segment structure under freezing construction is still insufficient.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] In a first aspect, a temperature and pressure loading test device for a shield tunnel segment structure is provided, which includes a fixed support fixedly connected to the segment, a temperature and pressure loading system for applying water pressure and different temperatures to the segment, a displacement monitoring component for monitoring the displacement of the segment, a lateral loading system and a vertical loading system for applying loads to the segment, and a sealing pad for waterproofing the segment joints; the fixed support is connected to the lateral loading system;

[0008] The temperature and pressure loading system includes a cold and hot source and several test boxes with bottom openings, the bottom of at least one test box is bonded to the surface of the pipe segment through a sealing strip; the water inlet of the test box is connected to the water pump through a pipeline and a water inlet valve, and the water outlet of the test box is connected to the water outlet valve through a pipeline; the cold and hot pipelines inside the test box are connected to the cold and hot sources, and the cold and hot sources include a cold source and a heat source;

[0009] The lateral loading system, the vertical loading system, the water inlet valve, the water outlet valve and the water pump are all electrically connected to the control console.

[0010] The beneficial effects of the present invention are as follows: based on this device, in addition to realizing basic segment mechanical property tests such as bending resistance and shear resistance, it can also simulate the misalignment and opening of reinforced concrete segment joints under different freezing temperatures and freeze-thaw cycles during actual freezing construction, as well as the joint anti-seepage performance test against external water pressure, providing a theoretical basis for the construction of freezing shield tunnels and joint waterproofing design.

[0011] Furthermore, the test box includes a mounting groove and a side plate whose bottom shape matches the arc surface of the pipe segment, and the side plate is detachably connected to the mounting groove on the side of the test box; a fixing belt is hinged on the side of the test box, and the fixing belt is sleeved on the outer surface of the pipe segment;

[0012] The test box is provided with a temperature sensor for monitoring the temperature of the medium in the test box and a display screen for displaying the temperature.

[0013] The side panels can be removed and replaced to match the curvature of the current segment, ensuring the fit between the test box and the segment surface and increasing sealing reliability.

[0014] Furthermore, a plurality of slide grooves are arranged in parallel inside the test box, and a partition is detachably connected in the slide groove to divide the inside of the test box into a plurality of cavities;

[0015] The hot and cold pipes are U-shaped, and both ends of the hot and cold pipes are connected to the hot and cold sources. A hot and cold pipe is set in each cavity. The partition is easy to disassemble and replace to adapt to pipe segments with different curvatures, and can also be disassembled and not used. The test box is divided into multiple cavities and multiple hot and cold pipes are set to facilitate the study of the mechanical properties of the pipe segment structure at different temperatures and directions and the anti-permeability performance of the pipe segment joints.

[0016] Furthermore, the present invention also includes a self-balancing frame, which includes a base, a counterweight beam, and a plurality of guide columns arranged horizontally and vertically, wherein the outer surface of the guide column is provided with a thread, and a limiter bolted to the guide column is sleeved on the guide column;

[0017] The vertical guide column is fixedly connected to the counterweight beam; the base is mounted on the upper surface of the counterweight beam and is slidably connected to the counterweight beam; the fixed support is fixed to the upper surface of the base, and a force transmission beam is vertically fixed on the base.

[0018] Furthermore, the vertical loading system includes a driving box 1, which is connected to the loading beam through a hydraulic rod; a plurality of sliders 1 are fixedly connected to the side of the driving box 1, each slider 1 is sleeved on the outside of the vertical guide column, and both ends of each slider 1 are limited by limit members;

[0019] The lateral loading system includes a drive box 2, which is mounted on the upper surface of the counterweight beam; the drive box 2 is connected to the force transmission beam through a hydraulic rod; a plurality of sliders 2 are fixedly connected to the side of the drive box 2, each slider 2 is sleeved on the outside of the lateral guide column, and both ends of each slider 2 are limited by limit members; the drive box 1 and the drive box 2 are both electrically connected to the control console.

[0020] The beneficial effect of the above technical solution is that the fixed support can be made to move horizontally and linearly along the counterweight beam, so as to fine-tune the fixed position of the pipe segment. The driving box 1 drives the hydraulic rod to drive the loading beam to load the vertical load on the surface of the pipe segment; similarly, the driving box 2 can drive the force transmission beam by driving the hydraulic rod to load the lateral load on the pipe segment.

[0021] Furthermore, the present invention also includes two pressure-equalizing components which are symmetrically fixed to the upper surface of the pipe segment when in use; the bottom surface of the loading beam is an arc-shaped surface; the pressure-equalizing component includes a rectangular pressure beam, and an anti-skid groove is provided on the upper surface of the pressure beam along the length direction, and a hemispherical component which contacts the loading beam when loading is fixedly connected to the center of the anti-skid groove.

[0022] The beneficial effects of the above technical solution are: the pressure equalizing component facilitates the determination of the specific loading position on the surface of the pipe segment, thereby positioning the pipe segment by matching the loading beam with the pressure equalizing component, and the hemispherical component can also make the distribution of the loading force on the pipe segment more uniform.

[0023] Furthermore, the fixed support includes a fixing portion and an adjusting portion rotatably connected via a rotating shaft, and the top end of the adjusting portion is fixedly connected to two symmetrically arranged support pads; a gap is left between the two support pads;

[0024] A plurality of connection grooves are evenly provided on one side of the support pad close to the gap, and connection blocks are detachably connected in some of the connection grooves, and the thickness of the connection blocks is less than the depth of the connection grooves; threaded holes are provided on the connection blocks; the connection blocks of the two support pads are overlapped, and the bolts of the pipe segments simultaneously pass through the two overlapping connection blocks and are bolted to the two threaded holes at the same time;

[0025] The connecting block is in a straight plate shape or an "L" plate shape.

[0026] The beneficial effects of the above technical solution are as follows: the support angle of the support pad can be adjusted by rotating the adjustment part to adapt to segments with different curvatures, so as to keep the segment horizontal and make it as parallel as possible to the contact surface of the segment. After adjusting to a preset angle, the adjustment part and the fixing part can be fixed by fasteners. The connection block and the connection groove are provided to facilitate the adaptation of segments with different bolt spacings.

[0027] Furthermore, the support pad includes a flat cover and a rectangular box with an open end; the cover is fixedly connected to a plurality of springs arranged in a uniform array, and a nut is fixedly connected to the free end of the spring;

[0028] The bottom plate of the rectangular box body is provided with through holes arranged in a uniform array; the cover body is movably connected to the open end of the rectangular box body, and bolts pass through the through holes of the bottom plate and are bolted to nuts; a buffer pad made of flexible material is fixedly connected to the surface where the cover body contacts the pipe segment.

[0029] The beneficial effects of the above technical solution are as follows: the support pad can ensure the fit between the cross section of the pipe segment and the fixed support, increase the contact area with the fixed support, and alleviate the stress concentration at the fixed support.

[0030] In a second aspect, a test method for a shield segment test device is provided, comprising the following steps:

[0031] S1. Connect the pipe segment to the fixed support and use the lateral loading system to pressurize the pipe segment and control the pressure;

[0032] S2, fix the pressure equalizing assembly at the preset loading position on the surface of the segment, apply pressure using the vertical loading system, and perform pressure stabilization control after reaching the preset load;

[0033] S3. When the segment is in a stable state, fix the test box on the segment through the waterproof sealing strip, and turn on the displacement monitoring component to record the joint misalignment and opening amount of the segment at each stage in real time;

[0034] S4, open the water inlet valve to apply water pressure, open the water outlet valve to exhaust air, and close the water outlet valve after water flows out of the water outlet valve;

[0035] S5. Increase the water pressure by 0.1 MPa. Each time the water pressure increases by 0.1 MPa, close the water inlet valve and keep the pressure steady for at least 10 minutes. Continue the operation until leakage occurs at the joint of the pipe segment. Close the water inlet valve and record the water pressure value at this time as the water pressure that can be tolerated under normal temperature and load conditions.

[0036] S6. Remove the water pressure, introduce normal pressure water into the test box, connect the hot and cold pipes with the cold source according to the test plan, control the water in the test box to cool down and freeze, and keep the frozen state according to the preset time, and record the temperature change every five minutes during the cooling process;

[0037] S7, after freezing, record the misalignment and opening amount of the pipe segment joints at this time; repeat the step of applying water pressure in S5, record the water pressure gauge reading when leakage occurs, and compare it with the water pressure value recorded in S5;

[0038] S8. When leakage occurs, close the water inlet valve and adjust the water pressure back to normal pressure; connect the hot and cold pipes with the heat source, control the temperature rise of the water in the test box, and record the temperature changes of the test box.

[0039] Furthermore, step S1 further includes the following steps:

[0040] S1-1, stick the sealing gasket into the sealing groove of the pipe segment;

[0041] S1-2, use a crane to place the segment on a fixed support with a support pad, and when the segment is level, bolt it to the fixed support;

[0042] S1-3, applying thrust to the segments through the transverse loading system, and fixing the two segments together when the two segments are in contact;

[0043] S1-4. Continue to use the lateral loading system to apply thrust to simulate the segment axial force in actual engineering, where the segment axial force is calculated based on the axial pressure ratio λ = N / (f c *b*h) to control,

[0044] Where: f c is the design value of concrete axial compressive strength, b is the width of the segment, h is the thickness of the segment, and N is the applied axial force;

[0045] S1-5. After reaching the set pressure, the lateral loading system is controlled by the console to stabilize the pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the warm and compressive loading device for the shield tunnel segment structure;

[0047] Figure 2 for Figure 1 Schematic diagram of the self-balancing framework;

[0048] Figure 3 for Figure 1 Schematic diagram of the test box;

[0049] Figure 4 It is a schematic diagram of the connection relationship between the test box and the segment structure;

[0050] Figure 5 for Figure 1 Schematic diagram of the middle base and fixed support;

[0051] Figure 6 It is a schematic diagram of the connection relationship between the fixed support and the pipe segment;

[0052] Figure 7 Schematic diagram of the internal structure of the support pad;

[0053] Figure 8 It is a schematic diagram of the connection between two support pads and segment bolts;

[0054] Fig. 9 Schematic diagram of the pressure equalizing component.

[0055] Among them, 100, self-balancing frame; 110, base; 111, force transmission beam; 120, fixed support; 121, fixing part; 122, adjustment part; 123, gap; 130, counterweight beam; 140, guide column; 150, limiter; 160, support pad; 161, spring; 162, buffer pad; 163, bottom plate; 164, bolt; 165, cover; 166, connecting groove; 167, connecting block; 200, vertical loading system; 201, drive box 1; 202, slider 1 ; 203, loading beam; 204, hydraulic rod; 210, lateral loading system; 211, drive box two; 212, slider two; 300, pressure equalizing assembly; 310, pressure beam; 320, anti-slip groove; 330, hemispherical component; 400, pipe segment; 510, test box; 511, water inlet; 512, water outlet; 513, hot and cold pipelines; 514, side panel; 515, mounting groove; 516, slide; 517, partition; 550, hot and cold source; 560, fixing belt; 600, control console. DETAILED DESCRIPTION

[0056] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0057] like Figure 1 As shown, the shield segment test device and method of this scheme include a fixed support 120 fixedly connected to the segment 400, a temperature and pressure loading system for applying water pressure and different temperatures to the segment 400, a displacement monitoring component for monitoring the displacement of the segment 400, a lateral loading system 210 and a vertical loading system 200 for applying loads to the segment 400, and a sealing pad for waterproofing the joints of the segment 400; the fixed support 120 is connected to the lateral loading system 210. During implementation, the two segments 400 are fixedly connected, and the two segments 400 together form an arch structure.

[0058] The temperature and pressure loading system includes a cold and hot source 550 and a plurality of test boxes 510 with bottom openings. The bottom of at least one test box 510 is bonded to the surface of the pipe segment 400 via a sealing strip. The water inlet 511 of the test box 510 is connected to a water pump via a pipeline and a water inlet valve, and the water outlet 512 of the test box 510 is connected to a water outlet valve via a pipeline. The cold and hot pipelines 513 inside the test box 510 are connected to the cold and hot source 550. The cold and hot source 550 includes a cold source and a hot source.

[0059] The lateral loading system 210 , the vertical loading system 200 , the water inlet valve, the water outlet valve and the water pump are all electrically connected to the control console 600 .

[0060] The vertical loading system 200 can apply vertical load to the pipe segment 400 to detect its bending resistance, and the transverse loading system 210 can apply transverse load to the pipe segment 400, and cooperate with the vertical loading system 200 to detect its shear resistance. In addition, vertical load and transverse load can be applied to the pipe segment 400 at the same time, and the pipe segment 400 can be frozen or actively kept warm at different temperatures through the test box 510, so as to test the waterproof performance of the joint of the pipe segment 400 against the external water pressure under the superposition of load and temperature. The displacement monitoring component can preferably be a DIC digital speckle three-dimensional full-field displacement measurement system. Under the premise of ensuring non-contact full-field measurement, DIC can collect and calculate the displacement and deformation of the pipe segment in real time, and the results can be clearly seen on the computer. The test box 510 can be installed at the joint of the pipe segment 400, or multiple test boxes can be installed around the pipe segment 400, but the water seepage test only passes water pressure into the test box 510 at the joint of the pipe segment 400.

[0061] Based on this device, in addition to realizing basic bending, shear and other tests of full-scale segment 400, it can also simulate the misalignment and opening of shield segment 400 during actual freezing construction, as well as the joint anti-seepage performance test under the combined action of temperature load and resistance to external water pressure, providing a theoretical basis for the construction of shield tunnels under the freezing method and the waterproof design of joints.

[0062] refer to Figure 3 The test box 510 includes a mounting groove 515 and a side plate 514 whose bottom shape matches the arc surface of the pipe segment 400. The side plate 514 is detachably connected to the mounting groove 515 on the side of the test box 510. A fixing belt 560 is hinged on the side of the test box 510. The fixing belt 560 is sleeved on the outer surface of the pipe segment 400. The fixing belt 560 is used to fix the test box 510 on the pipe segment 400. The connection structure can be referred to Figure 4 There are several bolt holes on the fixing belt 560. The bottom plate and the top plate of the fixing belt 560 are bolted to the side plates of the fixing belt 560. The fixing height of the bottom plate of the fixing belt 560 can be adjusted according to different bolt holes to adapt to pipe segments 400 of different thicknesses. The top plate and the side plates are detachable to facilitate the installation of the test box 510 when vertical load is loaded.

[0063] The test box 510 is provided with a temperature sensor for monitoring the temperature of the medium in the test box 510 and a display screen for displaying the temperature.

[0064] The side panel 514 can be removed and replaced. When testing pipe segments 400 of different sizes or models, the side panel 514 can be replaced with a panel that matches the curvature of the current pipe segment 400 to ensure the fit between the test box 510 and the surface of the pipe segment 400 and increase the sealing reliability.

[0065] Specifically, a plurality of slide grooves 516 are arranged in parallel inside the test box 510, and a partition 517 is detachably connected in the slide groove 516 to divide the inside of the test box 510 into a plurality of cavities;

[0066] The hot and cold pipeline 513 is U-shaped, and both ends of the hot and cold pipeline 513 are connected to the hot and cold sources 550 . A hot and cold pipeline 513 is disposed in each cavity.

[0067] The partition 517 can be easily disassembled and replaced with plates of different heights to adapt to the pipe segments 400 of different curvatures, and can also be disassembled and not used. The test box 510 is divided into multiple cavities and multiple cold and hot pipes 513 are set. When the cold and hot sources 550 are connected to different cold and hot pipes 513, the freezing direction in the test box 510 is changed, so as to study the effects of freezing in different directions on the pipe segments 400.

[0068] The present invention also includes a self-balancing frame 100, referring to Figure 2 The self-balancing frame 100 includes a base 110, a counterweight beam 130 and a plurality of guide posts 140 arranged horizontally and vertically. The outer surface of the guide posts 140 is provided with threads, and the guide posts 140 are sleeved with a stopper 150 bolted to the guide posts 140;

[0069] The vertical guide column 140 is fixedly connected to the counterweight beam 130 ; the base 110 is mounted on the upper surface of the counterweight beam 130 and is slidably connected to the counterweight beam 130 ; the fixed support 120 is fixed to the upper surface of the base 110 , and a force transmission beam 111 is vertically fixed on the base 110 .

[0070] The vertical loading system 200 includes a drive box 201, which is connected to the loading beam 203 through a hydraulic rod 204; a plurality of sliders 202 are fixedly connected to the side of the drive box 201, each slider 202 is sleeved on the outside of the vertical guide column 140, and both ends of each slider 202 are limited by a limit piece 150; preferably, there are four sliders 202, each of which is located at the corners of the rectangular drive box 201.

[0071] The lateral loading system 210 includes a drive box 211, which is mounted on the upper surface of the counterweight beam 130; the drive box 211 is connected to the force transmission beam 111 through a hydraulic rod 204; a plurality of sliders 212 are fixedly connected to the side of the drive box 211, each slider 212 is sleeved on the outside of the lateral guide column 140, and both ends of each slider 212 are limited by a limit piece 150; the drive box 1 201 and the drive box 211 are both electrically connected to the console 600.

[0072] The counterweight beam 130 is fixed on the ground, the base 110 and the second drive box 211 are mounted on the counterweight beam 130, and the self-balancing frame 100 has a deadweight of tens of tons, which ensures the stability of the structure itself. The hydraulic rod 204 can provide a maximum load of 5000 kN. The counterweight beam 130 and the base 110 can be slidably connected through a track or a slideway, or a small ball is set between the counterweight beam 130 and the base 110 to reduce friction and increase the convenience of applying lateral loads. Since the weight of the second drive box 211 is very large, a jack can be used to move it along the guide column 140 when it needs to be moved.

[0073] When the limit piece 150 is bolted to the guide column 140, the position of the drive box 1 201 and the drive box 2 211 can be fixed. After the limit piece 150 is loosened, the drive box 1 201 and the drive box 2 211 can slide along the guide column 140 through the slider 1 202 or the slider 2 212, so that the fixed support 120 can make a horizontal linear motion along the counterweight beam 130, thereby fine-tuning the fixed position of the pipe segment 400.

[0074] The driving box 1 201 drives the hydraulic rod 204 to drive the loading beam 230 to load a vertical load on the surface of the pipe segment 400 ; similarly, the driving box 211 can drive the force transmission beam 111 by driving the hydraulic rod 204 to load a lateral load on the pipe segment 400 .

[0075] The existing shield tunnel segment 400 loading devices are mostly fixed jack devices, which results in a relatively fixed loading position. When the segment 400 and the support system are offset in a certain horizontal plane in three-dimensional space, the force applied by the loading will be unevenly distributed, which can easily affect the accuracy of the test results. This is because the segment 400 is usually a symmetrical arch. If the loading device is not directly above the segment 400, one side of the segment 400 will be subjected to a greater force, while the other side will be subjected to a smaller force or no force. Since the segment 400 is generally heavy, it is difficult to fine-tune the position of the segment 400. Therefore, the force applied by the loading device is often different from the predetermined position. How to deal with these deviations is also an urgent problem to be solved by the existing segment 400 loading device. The cooperation between the self-balancing frame 100 and the lateral loading system 210 in this embodiment can also achieve fine-tuning of the position of the segment 400, ensuring that the applied load is as consistent as possible with the predetermined position, and minimizing or avoiding loading deviations.

[0076] Preferably, the bottom surface of the loading beam 203 is an arc-shaped surface to ensure that the loading beam 203 does not contact the test box 510 during loading. In this embodiment, two pressure equalizing assemblies 300 are also included, and the two pressure equalizing assemblies 300 are symmetrically arranged on the upper surface of the pipe segment 400. Fig. 9The pressure equalizing assembly 300 includes a rectangular compression beam 310, and an anti-skid groove 320 is opened on the upper surface of the compression beam 310 along the length direction. A hemispherical component 330 that contacts the loading beam 203 when loaded is fixedly connected to the center of the anti-skid groove 320.

[0077] The pressure equalizing assembly 300 facilitates the determination of the specific loading position on the surface of the segment 400, thereby positioning the segment 400 by matching the loading beam 203 with the pressure equalizing assembly 300, and solving the problem of uneven force caused by the position deviation of the segment 400 caused by installation. The hemispherical component 330 can also make the distribution of the loading force on the segment 400 more uniform. The point force of the hemispherical component 330 transfers the load evenly and reasonably to the lower segment 400. In order to prevent the loading beam 203 from slipping after contacting the spherical surface, an anti-skid groove 320 is also provided on its surface.

[0078] refer to Figure 5 and Figure 6 The fixed support 120 includes a fixing portion 121 and an adjusting portion 122 which are rotatably connected via a rotating shaft. The top of the adjusting portion 122 is fixedly connected to two symmetrically arranged support pads 160 ; a gap 123 is left between the two support pads 160 .

[0079] refer to Figure 6 A plurality of connection grooves 166 are evenly formed on one side of the support pad 160 near the gap 123, and a connection block 167 is detachably connected to some of the connection grooves 166. The thickness of the connection block 167 is less than the depth of the connection groove 166. Specifically, the depth of the connection groove 166 should be slightly deeper than the sum of the thicknesses of the two connection blocks 167. Threaded holes are formed on the connection blocks 167; the connection blocks 167 of the two support pads 160 are overlapped, and the bolts of the pipe segment 400 pass through the two overlapping connection blocks 167 at the same time and are bolted to the two threaded holes at the same time; the connection block 167 can be in a straight plate shape or an "L" plate shape.

[0080] In the bending and shearing loading tests of the shield tunnel segment 400, the boundary conditions of the segment 400 are complex and diverse, depending on different working conditions and design standards, which puts forward requirements for the test device to meet the diversity of loading objects, especially the support that affects the stability of the overall loading device. The rotating adjustment part 122 can adjust the support angle of the support pad 160 to adapt to the segments 400 of different curvatures, so as to keep the segment 400 horizontal. After adjusting to the preset angle, the adjustment part 122 and the fixing part 121 can be fixed by fasteners.

[0081] Since the segments 400 are generally fixedly connected to the supports by bolts, and the bolt spacing of segments 400 of different sizes is different, in most cases, the same type of supports can only be used for the same size of segments 400 for testing. When testing segments 400 of different sizes and different working conditions, it is often necessary to replace new supports and repeat the installation of the supports. If the supports are not replaced, it is very easy to cause stress concentration and damage to the segment 400 supports due to mismatched support sizes, thereby affecting the accuracy and safety of the test results.

[0082] Considering the above problems, the inventors set up the above connection structure. The spacing and width of the connection grooves 166 can be set according to actual conditions. In one embodiment of the present invention, the spacing can be set to 40mm and the width can be set to 20mm. Figure 8 According to the bolt positions of the pipe segment 400, the two connecting blocks 167 are fixedly installed in the corresponding connecting grooves 166 respectively. It is necessary to ensure that the hole positions corresponding to the pipe segment bolts correspond to the hole positions of the connecting blocks 167. After ensuring that there is no error, tighten the bolts to fix the pipe segment 400 on the fixed support 120.

[0083] The connection block 167 and the connection groove 166 can be connected by coating a high-viscosity adhesive such as a bolt fastener that can adhere to metal on the side of the connection block 167, and pressing the connection block 167 into the connection groove 166 to ensure that the two are connected with each other with interference fit. When the connection block 167 needs to be removed, it can be pulled out with pliers to facilitate the replacement of the straight plate shape and the "L" plate shape.

[0084] When the hole positions of the segment bolts can correspond to the hole positions of the connecting block 167, the straight plate connecting block 167 is directly used. When the bolt hole positions do not correspond to the hole positions of the straight plate connecting block, the L-shaped plate connecting block 167 is used. The L-shaped connecting block 167 has three styles to choose from, which are 10mm, 20mm, and 30mm different from the original hole positions in the waist hole direction, covering the required range of different bolt hole positions, ensuring the fixation and safety of the bolt position, and also ensuring the adaptability of the waist hole to different bolt sizes.

[0085] refer to Figure 6 and Figure 7 The support pad 160 includes a flat cover 165 and a rectangular box body with an open end; a plurality of springs 161 in a uniform array are fixedly connected to the cover 165, and a nut is fixedly connected to the free end of the spring 161. The bottom plate 163 of the rectangular box body is provided with a uniform array of through holes; the cover 165 is movably connected to the open end of the rectangular box body, and the bolt 164 passes through the through hole of the bottom plate 163 and is bolted to the nut; a buffer pad 162 made of a flexible material is fixedly connected to the surface of the cover 165 in contact with the pipe segment 400.

[0086] During the bending and shear tests of the shield tunnel segment 400, stress concentration occurs at the support. This is due to the uneven stress distribution after the end face shape of the segment 400 and the external load distribution during the test loading process. The smaller the contact area between the segment 400 and the fixed support 120, the more likely it is to produce stress concentration. This phenomenon is particularly obvious when the support does not fit well with the segment 400 during installation.

[0087] In actual tests, the inventors realized that it is difficult to ensure that the end face of the pipe segment 400 is completely parallel to the supporting surface of the support, so it cannot fit well, thereby increasing the stress concentration at the support. When hanging the pipe segment 400, how to make fine adjustments at the fixed support 120 to make the end face of the pipe segment 400 fit better with the contact surface of the fixed support 120 and reduce the local stress concentration phenomenon is a problem that cannot be solved by the existing pipe segment 400 test device.

[0088] Based on the above considerations, the inventor designed a support pad 160 at the fixed support 120, and its installation steps and working principle are as follows: the pipe segment 400 is hoisted onto the fixed support 120 and placed on the buffer pad 162, ensuring that the cover body 165 is parallel to the end face of the pipe segment 400, and then a number of bolts 164 are respectively inserted into each spring 161, and bolted to the nut at the end of the spring 161, and the spring 161 is tightened at the same time to increase its load-bearing capacity. Since the cover plate 165 can flexibly adjust the rotation angle, it can also flexibly fit with the end face of any pipe segment 400, and at the same time it also has support stability, ensuring the support constraint force while solving the problem that the pipe segment 400 and the fixed support 120 are difficult to fit closely.

[0089] In summary, the device structure in the present invention has the following advantages and benefits compared with the prior art:

[0090] 1. The self-balancing frame 100 and the cooperation of the horizontal and vertical loading systems can realize the assembly and performance testing of the pipe segment 400, presenting the complex working state of the joint rubber sealing pad that conforms to the actual engineering state;

[0091] 2. Use the adjustable support pad 160 to achieve horizontal placement of the full-size segment 400, reducing stress concentration and the test error caused by it;

[0092] 3. Using the fixed support 120 to adapt to different sizes of segments 400 without affecting the connection stability;

[0093] 4. Using the temperature and pressure loading system to realize water pressure loading, freezing, melting and freeze-thaw cycles on the joints of the pipe segments 400, and realizing freezing, melting and freeze-thaw cycle conditions in different directions and at different rates through different cold and hot pipelines 513;

[0094] 5. Use the pressure equalizing assembly 300 to achieve uniform loading of external loads and avoid uneven loading caused by uneven lifting.

[0095] At present, the domestic joint anti-seepage test is mainly based on the aging performance test of the sealing rubber pad or the internal water pressure test. The internal water pressure test mainly tests the waterproof performance of the rubber sealing pad in the steel plate prefabricated groove in normal temperature water, which is different from the complex boundary conditions under the actual engineering state. In the actual freezing construction process, the opening and misalignment of the pipe segment 400 joint will be caused by factors such as structural longitudinal deformation, construction error, and gap between rings, which will affect the anti-seepage performance of the pipe segment joint. At the same time, the water pressure on the pipe segment 400 is mostly external water pressure, while the above test uses internal water pressure. In view of the fact that the influence of freezing temperatures in different directions and at different rates on the anti-seepage performance of the pipe segment 400 joints during freezing construction is still unclear, this test has strong practical significance.

[0096] The test device provided in the present invention can perform a variety of tests. Example tests and their test steps are as follows:

[0097] A. Freezing test

[0098] S1, the pipe segment 400 is fixedly connected to the fixed support 120, and the pipe segment 400 is pressurized and stabilized by using the lateral loading system 210;

[0099] S2, fixing the pressure equalizing assembly 300 at a preset loading position on the surface of the pipe segment 400, applying pressure using the vertical loading system 200, and performing pressure stabilization control after reaching a predetermined load;

[0100] S3. When the pipe segment 400 is in a stable state, the test box 510 is fixed to the pipe segment 400 through a waterproof sealing strip, and the displacement monitoring component is turned on to record the joint misalignment and opening amount of the pipe segment 400 at each stage in real time;

[0101] S4, open the water inlet valve to apply water pressure, open the water outlet valve to exhaust air, and close the water outlet valve after water flows out of the water outlet valve;

[0102] S5. Increase the water pressure by 0.1 MPa. Each time the water pressure increases by 0.1 MPa, close the water inlet valve and keep the pressure steady for at least 10 minutes. Continue the operation until leakage occurs at the joints of the pipe segments. Close the water inlet valve and record the water pressure value at this time as the water pressure that can be tolerated under normal temperature and load conditions.

[0103] S6, remove the water pressure, and introduce normal pressure water into the test box 510. According to the test plan, connect the hot and cold pipes 513 with the cold source, control the water in the test box 510 to cool down and freeze, and keep the frozen state according to the preset time. Record the temperature change every five minutes during the cooling process. This step can be used to study the effect of the freezing direction on the pipe segment 400 by connecting different hot and cold pipes 513.

[0104] S7, after freezing, record the joint misalignment and opening amount of the pipe segment 400 at this time; repeat the step of applying water pressure in S5, record the water pressure gauge reading when leakage occurs, and compare it with the water pressure value recorded in S5;

[0105] S8. When leakage occurs, close the water inlet valve and adjust the water pressure to normal pressure; connect the hot and cold pipes 513 with the heat source to increase the temperature of the water in the test box 510, and record the temperature change of the test box 510.

[0106] When implemented, the solution preferably S1 further comprises the following steps:

[0107] S1-1, pasting the sealing gasket into the sealing groove of the pipe segment 400;

[0108] S1-2, using a crane to place two segments 400 on two fixed supports 120 with support pads 160 respectively, and after ensuring that the segments 400 are level, bolt the segments 400 to the fixed supports 120;

[0109] S1-3, applying thrust to the pipe segment 400 through the transverse loading system 210, and fixing and connecting the two pipe segments 400 when the two pipe segments 400 are in contact;

[0110] S1-4, applying thrust again through the transverse loading system 210 to simulate the segment axial force in actual engineering, wherein the segment axial force is calculated according to the axial pressure ratio λ = N / f c *b*h to control,

[0111] Where: f c is the design value of the concrete axial compressive strength, b is the width of the segment 400, h is the thickness of the segment 400, and N is the applied axial force;

[0112] S1-5. After reaching the set pressure, the console 600 controls the lateral loading system 210 to stabilize the pressure.

[0113] B. Active insulation test

[0114] S1-S5 are the same as S1-S5 in Experiment A, so they are not repeated here;

[0115] S6. Install a pressure sensor in the test box 510, open the water inlet and outlet valves, and close the outlet valve after water flows out of the outlet valve; select a hot and cold pipe 513 to connect to the cold source, and according to the test plan, select another hot and cold pipe 513 to connect to the heat source, so that the water in the test box 510 is heated on one side and cooled on the other side; record the values ​​of the pressure sensor and the temperature sensor every 10 minutes.

[0116] S7. After a certain period of time, repeat the step of applying water pressure in S5, record the water pressure gauge reading when leakage occurs, and compare it with the water pressure value recorded in S5.

[0117] In summary, the present invention is a device that can solve common problems in tunnel segment loading tests and can perform various tests on the segment 400. It can achieve: 1. Testing the bending, shearing, and impermeability performance of the segment 400; 2. Testing the impermeability performance of the segment 400 under load and freezing conditions; 3. Testing the active thermal insulation performance of the segment 400.

Claims

1. A shield tunnel segment structure temperature and pressure loading test device, characterized in that: The invention comprises a fixed support (120) fixedly connected to the pipe segment (400), a temperature and pressure loading system for applying water pressure and different temperatures to the pipe segment (400), a displacement monitoring component for monitoring the displacement of the pipe segment (400), a lateral loading system (210) and a vertical loading system (200) for applying load to the pipe segment (400), and a sealing pad for waterproofing the joint of the pipe segment (400); the fixed support (120) is connected to the lateral loading system (210); The temperature and pressure loading system comprises a cold and hot source (550) and a plurality of test boxes (510) with bottom openings, wherein the bottom surface of at least one of the test boxes (510) is bonded to the surface of the pipe segment (400) via a sealing strip; The water inlet (511) of the test box (510) is connected to a water pump via a pipeline and a water inlet valve, and the water outlet (512) of the test box (510) is connected to a water outlet valve via a pipeline; the cold and hot pipelines (513) inside the test box (510) are connected to the cold and hot sources (550), and the cold and hot sources (550) include a cold source and a hot source; The lateral loading system (210), the vertical loading system (200), the water inlet valve, the water outlet valve and the water pump are all electrically connected to the control console (600).

2. The shield tunnel segment structure temperature and pressure loading test device according to claim 1 is characterized by: The test box (510) comprises a mounting groove (515) and a side plate (514) whose bottom shape matches the arc surface of the pipe segment (400), and the side plate (514) is detachably connected to the mounting groove (515) on the side of the test box (510); a fixing belt (560) is hinged on the side of the test box (510), and the fixing belt (560) is sleeved on the outer surface of the pipe segment (400); The test box (510) is provided with a temperature sensor for monitoring the temperature of the medium in the test box (510), and a display screen for displaying the temperature.

3. The shield tunnel segment structure temperature and pressure loading test device according to claim 1 is characterized by: A plurality of slide grooves (516) are arranged in parallel inside the test box (510), and a partition (517) is detachably connected in the slide groove (516) to divide the inside of the test box (510) into a plurality of cavities; The hot and cold pipeline (513) is U-shaped, and both ends of the hot and cold pipeline (513) are connected to the hot and cold sources (550), and a hot and cold pipeline (513) is arranged in each cavity.

4. The shield tunnel segment structure temperature and pressure loading test device according to claim 1 is characterized by: Also included is a self-balancing frame (100), the self-balancing frame (100) comprising a base (110), a counterweight beam (130) and a plurality of guide columns (140) arranged transversely and vertically, the outer surface of the guide column (140) is provided with a thread, and the guide column (140) is sleeved with a stopper (150) bolted to the guide column (140); The vertical guide column (140) is fixedly connected to the counterweight beam (130); the base (110) is mounted on the upper surface of the counterweight beam (130) and is slidably connected to the counterweight beam (130); the fixed support (120) is fixed to the upper surface of the base (110), and a force transmission beam (111) is vertically fixed on the base (110).

5. The shield tunnel segment structure temperature and pressure loading test device according to claim 4 is characterized by: The vertical loading system (200) comprises a driving box (201) connected to a loading beam (203) via a hydraulic rod (204); a plurality of sliders (202) are fixedly connected to the side of the driving box (201); each of the sliders (202) is sleeved on the outside of a vertical guide column (140), and both ends of each slider (202) are limited by the limiting member (150); The transverse loading system (210) comprises a second drive box (211), which is mounted on the upper surface of the counterweight beam (130); the second drive box (211) is connected to the force transmission beam (111) via a hydraulic rod (204); a plurality of second slide blocks (212) are fixedly connected to the side of the second drive box (211), each of the second slide blocks (212) is sleeved on the outside of the transverse guide column (140), and both ends of each second slide block (212) are limited by a limit piece (150); the first drive box (201) and the second drive box (211) are both electrically connected to the control console (600).

6. The shield tunnel segment structure temperature and pressure loading test device according to claim 5 is characterized by: The invention also comprises two pressure-equalizing assemblies (300) which are symmetrically fixed to the upper surface of the pipe segment (400) when in use; the bottom surface of the loading beam (203) is an arc-shaped surface; the pressure-equalizing assembly (300) comprises a rectangular parallelepiped pressure beam (310), the upper surface of the pressure beam (310) is provided with an anti-skid groove (320) along the length direction, and the center of the anti-skid groove (320) is fixedly connected with a hemispherical component (330) which contacts the loading beam (203) when loading.

7. The shield tunnel segment structure temperature and pressure loading test device according to claim 1 is characterized by: The fixed support (120) comprises a fixed portion (121) and an adjusting portion (122) rotatably connected via a rotating shaft, and the top end of the adjusting portion (122) is fixedly connected to two symmetrically arranged support pads (160); a gap (123) is left between the two support pads (160); A plurality of connection grooves (166) are evenly formed on one side of the support pad (160) close to the gap (123); a connection block (167) is detachably connected to some of the connection grooves (166); the thickness of the connection block (167) is smaller than the depth of the connection groove (166); threaded holes are formed on the connection blocks (167); the connection blocks (167) of the two support pads (160) are overlapped and placed, and the bolts of the pipe segment (400) simultaneously pass through the two overlapping connection blocks (167) and are bolted to the two threaded holes at the same time; The connecting block (167) is in a straight plate shape or an "L" plate shape.

8. The shield tunnel segment structure temperature and pressure loading test device according to claim 7 is characterized by: The support pad (160) comprises a flat cover (165) and a rectangular box body with an opening at one end; a plurality of springs (161) arranged in a uniform array are fixedly connected to the cover (165), and a nut is fixedly connected to the free end of the spring (161); The bottom plate (163) of the rectangular box body is provided with through holes arranged in a uniform array; the cover body (165) is movably connected to the open end of the rectangular box body, and the bolts (164) pass through the through holes of the bottom plate (163) and are bolted to the nuts; a buffer pad (162) made of a flexible material is fixedly connected to the surface of the cover body (165) in contact with the pipe segment (400).

9. A test method for the shield tunnel segment structure temperature and pressure loading test device according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, the pipe segment (400) is fixedly connected to the fixed support (120), and the pipe segment (400) is pressurized and stabilized by using the transverse loading system (210); S2, fixing the pressure equalizing assembly (300) at a preset loading position on the surface of the pipe segment (400), applying pressure using the vertical loading system (200), and performing pressure stabilization control after reaching a predetermined load; S3. When the pipe segment (400) is in a stable state, the test box (510) is fixed to the pipe segment (400) through a waterproof sealing strip, and the displacement monitoring component is turned on to record the joint misalignment and opening amount of the pipe segment (400) at each stage in real time; S4, open the water inlet valve to apply water pressure, open the water outlet valve to exhaust air, and close the water outlet valve after water flows out of the water outlet valve; S5, increasing the water pressure by 0.1 MPa, closing the water inlet valve every time the water pressure increases by 0.1 MPa, and maintaining the pressure for at least 10 minutes, and continuing the operation until leakage occurs at the joint of the pipe segment (400), closing the water inlet valve, and recording the water pressure value at this time as the water pressure that can be tolerated under normal temperature and load conditions; S6, removing the water pressure, introducing normal pressure water into the test box (510), connecting the hot and cold pipes (513) with the cold source according to the test plan, controlling the water in the test box (510) to cool down and freeze, and keeping the frozen state according to the preset time, and recording the temperature change every five minutes during the cooling process; S7, after cooling to freezing, record the misalignment and opening amount of the pipe segment (400) or the pipe segment joint at this time; repeat the step of applying water pressure in S5, record the water pressure gauge reading when leakage occurs, and compare it with the water pressure value recorded in S5; S8. When leakage occurs, close the water inlet valve and adjust the water pressure to normal pressure; connect the cold and hot pipes (513) with the heat source, control the water temperature in the test box (510), and record the temperature change of the test box (510).

10. The test method according to claim 9, characterized in that: Step S1 further comprises: S1-1, pasting the sealing gasket into the sealing groove of the pipe segment (400); S1-2, using a crane to place the pipe segment (400) on a fixed support (120) with a support pad (160), and when the pipe segment (400) is horizontal, bolting the pipe segment (400) to the fixed support (120); S1-3, applying a thrust to the pipe segment (400) through the transverse loading system (210), and fixing and connecting the two pipe segments (400) when the two pipe segments (400) are in contact; S1-4. Continue to use the transverse loading system (210) to apply thrust to simulate the segment axial force in actual engineering, where the segment axial force is calculated based on the axial pressure ratio λ = N / (f c *b*h) to control, Where: f c is the design value of the axial compressive strength of concrete, b is the width of the segment (400), h is the thickness of the segment (400), and N is the applied axial force; S1-5. After reaching the set pressure, the control console (600) controls the lateral loading system (210) to stabilize the pressure.

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