A method for testing the bonding performance between shotcrete and surrounding rock in high ground temperature tunnels

Abstract

The present invention provides a method for testing the bonding performance of shotcrete and surrounding rock in high-temperature tunnels, comprising collecting data such as temperature and humidity at the high-temperature tunnel site, and collecting rocks from the tunnel construction site for preparing indoor test specimens; preparing the rocks into rock specimens; preparing a curing test chamber, and placing the rock specimens in the curing test chamber for curing after shotcrete is shotcreted; preparing standard cylindrical specimens for shear testing; and conducting a shear test to test the bonding performance of shotcrete and surrounding rock, taking into account the high-temperature service environment. The present invention takes into account the surface morphology of the actual surrounding rock after blasting in a high-temperature tunnel, the actual one-way heating temperature gradient environment of shotcrete during the curing period, and the high-temperature environment of long-term service. It can highly restore the actual morphological characteristics and service environment of the bonding surface between the shotcrete and surrounding rock at the engineering site, and the test results can greatly reflect the bonding performance of the interface between the shotcrete and surrounding rock in a real high-temperature tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnels and underground engineering, and in particular to a method for testing the bonding performance between shotcrete and surrounding rock in high ground temperature tunnels. Background Art

[0002] With the deepening of projects such as the "Western Development" initiative, a large number of major infrastructure projects, including railways, highways, water conservancy and hydropower projects, and inter-basin water diversion projects, have been implemented in western China. Construction is gradually extending to areas with complex topography and geology. Long, deep tunnels (holes) traversing areas of intense plate tectonic activity are becoming increasingly common, along with the increasing number of high-geothermal tunnels. According to the "Technical Guidelines for Railway Tunnel Construction," tunnel temperatures exceeding 28°C (14.3°F) can affect the safety of the tunnel structure and the health of construction workers. These tunnels are considered high-geothermal tunnels.

[0003] Mountain tunnels constructed by the mining method require spraying concrete after tunnel excavation to control the stress release and deformation of the surrounding rock, improve structural safety and facilitate construction. Sprayed concrete is in direct contact with the surrounding rock, and the bonding performance of the concrete-rock interface is the key to whether the support structure can function properly. Although domestic and foreign engineering practices and research have shown that high ground temperature will affect the mechanical properties of both the surrounding rock and concrete. For example, the impact of high temperature on the surrounding rock mainly has two aspects: one is the additional thermal stress effect caused by temperature change. Under high temperature conditions, for every 1°C change in temperature, 0.4~0.5MPa of thermal stress will appear in the rock, which can easily cause tensile fracture of the surrounding rock in the tensile stress zone; the other is the change in rock physical, mechanical properties and microstructure caused by temperature. The impact of high temperature on concrete is mainly manifested in the following aspects: (1) Water evaporates continuously, resulting in insufficient or even stopped cement hydration, and causing high concentration of hydration products; (2) High temperature will form high temperature stress, causing concrete to crack; (3) High temperature accelerates the early hydration reaction, forming a dense protective layer on the surface of cement particles to prevent water from entering, thereby affecting the later strength development of concrete. More importantly, as porous media, both rock and concrete exhibit heterogeneous, discontinuous, and nonlinear mechanical properties. The surrounding rock surface is at high temperatures, and the temperature gradient at the interface between shotcrete and surrounding rock makes it more susceptible to thermal damage during curing. This thermal damage inevitably has a significant impact on the long-term performance of the primary support structure.

[0004] At present, domestic and foreign scholars have mainly focused on the research on the bond tensile strength and shear properties of the concrete-rock interface under room temperature conditions. There is little research on the bonding properties of the shotcrete-rock interface under the influence of high temperature. Based on the measured environmental parameters and shotcrete temperature data in the tunnel, Wang Nianming et al. carried out a study on the changes in the mechanical properties of the interface caused by high temperature and variable temperature conditions. During the sample preparation process, they adopted a shotcrete-rock sample curing method of gradually cooling from high temperature to room temperature, and then cut it into cubic samples and carried out mechanical property tests at room temperature. After the shotcrete is sprayed onto the rock, it contacts the high-temperature rock on one side and the air in the tunnel on the other side. There is a temperature difference between the surrounding rock and the cave. The above research was cured under the same temperature environment and did not take into account the key factor of the influence of the temperature gradient on both sides on the bonding surface. At the same time, in the later service process, the environment in which the bonding surface is located is also a high-temperature environment, which is bound to have a great impact on its service performance. The above research also did not consider this key factor. Summary of the Invention

[0005] The present invention provides a method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel, comprising the following steps:

[0006] Step 1: Collect data on the post-blasting surrounding rock surface temperature, the air temperature after shotcreting in the tunnel body, the concrete curing humidity, and the post-blasting surrounding rock 3D point cloud data at the high-temperature tunnel site. Rock with a wheelbase greater than 30 cm at the tunnel construction site is also collected for indoor test specimen preparation.

[0007] Step 2: Based on the three-dimensional point cloud data of the surrounding rock after blasting collected at the tunnel construction site, the rock is prepared into a rock sample that can reflect the surface roughness of the surrounding rock after the actual blasting;

[0008] Step 3: Prepare a curing test chamber that can reflect the actual one-way heating temperature gradient environment at the tunnel site, spray concrete onto the surface reflecting the roughness of the rock sample to form a concrete-rock sample, and place the concrete-rock sample in the curing test chamber for curing;

[0009] Step 4: Prepare the cured concrete-rock sample into a standard cylindrical sample with a diameter of 50 mm and a length of 100 mm for shear test;

[0010] Step 5: Shear test to test the bonding performance between shotcrete and surrounding rock considering high temperature service environment.

[0011] Optionally, the three-dimensional point cloud data of the surrounding rock after blasting in step 1 is obtained by collecting at least three typical sections using a three-dimensional laser scanner.

[0012] Optionally, the specific process of preparing the rock sample in step 2 is as follows:

[0013] S2.1. Cut the large rock samples collected on site into 30cm long pieces 30cm wide Plate-shaped rock specimen 8 cm high;

[0014] S2.2, importing the 3D point cloud data into a heavy-duty stone mold machine equipped with 3D engraving technology;

[0015] S2.3, in the plate-like rock specimen One of the wide planes is carved with a rough surface that matches the surface roughness of the surrounding rock on site;

[0016] S2.4. Use digital image processing technology to extract the grayscale image of the rough surface of the plate-like rock sample, and then use the fractal dimension of the image grayscale to quantitatively characterize the roughness of the object surface.

[0017] Optionally, the curing test box in step three includes a box body, a humidity control device, a cooling water pipe, a temperature sensing device, a humidity sensing device, a bottom heat conduction plate, a bottom heating water tank and a rubber insulation pad; the humidity control device is arranged on the box body, for adjusting the humidity in the box body; the cooling water pipe is arranged in the box body, for adjusting the temperature in the box body; the temperature sensing device and the humidity sensing device are both arranged on the inner wall of the box body, for real-time detection of the temperature and humidity in the box body; the bottom heat conduction plate is arranged at the bottom of the box body, and the bottom heating water tank is connected to the lower end surface of the bottom heat conduction plate, and the temperature in the bottom heating water tank is transmitted to the box body through the bottom heat conduction plate; the rubber insulation pad is arranged on the lower end surface of the bottom heating water tank, for achieving heat insulation of the bottom heating water tank.

[0018] Optionally, in step three, a concrete layer of 8 cm to 10 cm is sprayed on the rough surface of the plate-shaped rock sample to obtain a concrete-rock sample.

[0019] Optionally, in step three, the concrete-rock sample is placed in a curing test box with the rock surface facing downward and the sprayed concrete surface facing upward and cured for 28 to 30 days.

[0020] Optionally, the preparation process of the standard cylindrical specimen in step 4 is as follows:

[0021] S4.1. Drill a 50 mm diameter circular hole in the concrete-rock specimen with its central axis parallel to the concrete layer, and keep the concrete-rock bonding surface as close to the center of the hole as possible.

[0022] S4.2. Cut the drilled concrete-rock specimen into cylindrical specimens with a height of 100 mm;

[0023] S4.3. Remove a 5 mm thick rock structure from one end of the cylindrical specimen and a 5 mm thick concrete layer from the other end of the cylindrical specimen. Fill the removed portion of the cylindrical specimen with liquid silicone rubber.

[0024] S4.4. Leave the cylindrical specimen to stand for more than 48 hours until the liquid silicone rubber solidifies, and finally obtain a standard cylindrical specimen that meets the shear test accuracy requirements.

[0025] Optionally, the specific process of the shear test for the bonding performance of shotcrete and surrounding rock considering the high temperature service environment in step 5 is as follows:

[0026] S5.1. Place the standard cylindrical specimen in a triaxial pressure chamber. After sealing, apply confining pressure to the chamber at a constant rate of 2 MPa / min until the confining pressure reaches the preset value.

[0027] S5.2. After the confining pressure stabilizes, heat to the preset temperature at a heating rate of 5°C / min;

[0028] S5.3. After the temperature of the pressure chamber stabilizes, perform shear displacement loading at an axial compression rate of 0.02 mm / min until the standard cylindrical specimen fails. Automatically record the stress-strain curve during the shearing process.

[0029] S5.4. By conducting triaxial compression tests at different temperatures and confining pressures on standard cylindrical specimens under different temperature curing conditions, the ultimate stress circles of shear specimens at different temperatures and confining pressures were drawn, and the strength envelopes were plotted. The shear strength parameters of the bonding surface at different temperatures were obtained by fitting using the Mohr-Coulomb strength criterion. c and friction angle Finally, the cohesion of the bonding surface under different temperature curing conditions was obtained. c and friction angle The relationship curve of the heating temperature in the thermal-mechanical coupling test is used to evaluate the bonding performance of the interface between the shotcrete and the surrounding rock in the high ground temperature tunnel.

[0030] Optionally, the preset values ​​of the confining pressure in S5.1 are set to 0 MPa, 20 MPa, 40 MPa, and 60 MPa respectively;

[0031] The temperature preset value in S5.2 can be set to 30°C, 50°C, or 70°C;

[0032] In S5.4, triaxial compression tests were conducted on standard cylindrical specimens under different temperature curing conditions at different temperatures and confining pressures, and shear specimens at different temperatures of T = 30 ° C, 50 ° C, and 70 ° C were made. =The ultimate stress circle under confining pressure of 0 MPa, 20 MPa, 40 MPa, and 60 MPa, and the strength envelope are drawn.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention takes into account the surface morphology of the actual surrounding rock after blasting in a high-geotemperature tunnel, the actual one-way heating temperature gradient environment of shotcrete on site during the curing period, and the high-temperature environment of long-term service. It can restore the actual morphological characteristics and service environment of the bonding surface between shotcrete and surrounding rock at the engineering site to a very high degree. The test results can reflect the bonding performance of the interface between shotcrete and surrounding rock in a real high-geotemperature tunnel to the greatest extent.

[0035] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 1 is a flow chart of a method for testing the bonding performance of shotcrete and surrounding rock in a high ground temperature tunnel according to an embodiment of the present invention;

[0038] Figure 2 It is a schematic diagram of a plate-like rock specimen;

[0039] Figure 3 It is a schematic diagram of the structure of the curing test chamber;

[0040] Figure 4 is a schematic diagram of the concrete-rock specimen;

[0041] Figure 5 This is a schematic diagram of a typical shear standard cylindrical specimen;

[0042] Figure 6 This is a schematic diagram of the calculation process of the shear strength parameters of standard cylindrical specimens;

[0043] Figure 7 This is a schematic diagram of the relationship between the shear strength parameters of standard cylindrical specimens and loading temperature.

[0044] in:

[0045] 1. Humidity control device, 2. Cooling water pipe, 3. Temperature sensing device, 4. Humidity sensing device, 5. Bottom heat conduction plate, 6. Bottom heating water tank, 7. Rubber insulation pad. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned purposes, features and advantages of the present invention more clear and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be noted that the drawings of the present invention are all simplified and non-precisely scaled, and are only used to conveniently and clearly assist in explaining the implementation of the present invention; the "numbers" mentioned in the present invention are not limited to the specific quantities in the examples in the accompanying drawings; the directions or positional relationships indicated by "front", "middle", "back", "left", "right", "up", "down", "top", "bottom", "middle", etc. mentioned in the present invention are based on the directions or positional relationships shown in the drawings of the present invention, and do not indicate or imply that the devices or components referred to must have a specific direction, nor can they be understood as limitations on the present invention. Example

[0047] See also Figure 1 As shown, the present invention provides a method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel, comprising the following steps:

[0048] Step 1: Collect post-blasting surrounding rock surface temperature, post-concrete air temperature, concrete curing humidity, and post-blasting surrounding rock 3D point cloud data at the high-temperature tunnel site. Rock with a wheelbase greater than 30 cm at the tunnel construction site is also collected for indoor test specimen preparation. Preferably, the post-blasting surrounding rock 3D point cloud data is obtained by using a 3D laser scanner to collect data from at least three representative cross-sections.

[0049] Step 2: Preparation of rock samples with different surface roughness indoors: Based on the 3D point cloud data of the surrounding rock after blasting collected at the tunnel construction site, rock samples are prepared to reflect the actual surface roughness of the surrounding rock after blasting (e.g. Figure 2 shown).

[0050] Specifically, the specific process of processing the rock sample is as follows:

[0051] 1) Cut the large rock samples collected on site into 30cm long pieces 30cm wide Plate-shaped rock specimen 8 cm high;

[0052] 2) Import the 3D point cloud data into a heavy-duty stone mold machine with 3D engraving technology;

[0053] 3) In plate-like rock samples, One of the wide planes is carved with a rough surface that matches the surface roughness of the surrounding rock on site;

[0054] 4) Digital image processing technology is used to extract the grayscale image of the rough surface of the plate-like rock sample, and then the fractal dimension of the image grayscale is used to quantitatively characterize the roughness of the object surface.

[0055] Step 3: Prepare a curing test chamber that can reflect the actual one-way heating temperature gradient environment at the tunnel site. The curing humidity is determined based on the on-site curing humidity and is constant. Spray concrete onto the rough surface of the rock sample to form a concrete-rock sample. Place the concrete-rock sample in the curing test chamber for high-temperature gradient curing.

[0056] Specifically, such as Figure 3 As shown, the curing test box includes a box body, a humidity control device 1, a cooling water pipe 2, a temperature sensing device 3, a humidity sensing device 4, a bottom heat conduction plate 5, a bottom heating water tank 6 and a rubber insulation pad 7; the humidity control device 1 is arranged on the box body, for adjusting the humidity in the box body; the cooling water pipe 2 is arranged in the box body, for adjusting the temperature in the box body; the temperature sensing device 3 and the humidity sensing device 4 are both arranged on the inner side wall of the box body, for real-time detection of the temperature and humidity in the box body; the bottom heat conduction plate 5 is arranged at the bottom of the box body, and the bottom heating water tank 6 is connected to the lower end surface of the bottom heat conduction plate 5, and the temperature in the bottom heating water tank 6 is transmitted to the box body through the bottom heat conduction plate 5; the rubber insulation pad 7 is arranged on the lower end surface of the bottom heating water tank 6, for achieving heat insulation of the bottom heating water tank 6. The bottom heating water tank 6 transfers heat to the box body through the bottom heat conduction plate 5. The temperature sensing device 3 detects the temperature inside the box body in real time and feeds back to the control system. The control system compares the data sensed by the temperature sensing device 3 with the rated temperature data inside the box body. When the temperature inside the box body exceeds the rated temperature data inside the box body, the cooling control system drives the coolant (the coolant is preferably set to water) into the cooling water pipe 2 to cool the temperature inside the box body; when the temperature sensing device 3 detects that the temperature inside the box body is equal to or less than the rated temperature data inside the box body, the cooling control system is shut down to stop delivering the coolant.

[0057] Specifically, the concrete-rock specimens were placed in a curing test chamber with the rock side facing downward and cured for 28 days.

[0058] Specifically, when curing the concrete-rock specimens, it is necessary to keep the temperature of the bottom heat conducting plate 5 in the curing test box the same as the temperature of the tunnel face, the temperature inside the box the same as the temperature of the tunnel body, and the humidity inside the box constant. According to several different sets of tunnel face temperatures and tunnel body temperatures measured on site, several sets of concrete-rock specimens under different temperature difference curing conditions (such as Figure 4 shown).

[0059] Step 4: Prepare the cured concrete-rock sample into a standard cylindrical sample with a diameter of 50 mm and a length of 100 mm for shear test (such as Figure 5Specifically, the central axis of the standard cylindrical specimen is parallel to the bonding surface between concrete and rock.

[0060] Specifically, the preparation process of the standard cylindrical specimen is as follows:

[0061] 1) Drill a circular hole with a diameter of 50 mm on the concrete-rock specimen, with its central axis parallel to the concrete layer, and keep the bonding surface between the concrete and the rock in the middle of the circular hole as much as possible;

[0062] 2) Cut the drilled concrete-rock specimen into cylindrical specimens with a height of 100 mm;

[0063] 3) Remove a 5mm thick rock structure from one end of the cylindrical specimen and a 5mm thick concrete layer from the other end; and fill the removed portion of the cylindrical specimen with liquid silicone rubber.

[0064] 4) Let the cylindrical specimen stand for more than 48 hours to allow the liquid silicone rubber to solidify, and finally obtain a standard cylindrical specimen that meets the shear test accuracy requirements.

[0065] Step 5: Shear test to test the bonding performance between shotcrete and surrounding rock considering high temperature service environment.

[0066] For details, see Figure 6 and Figure 7 As shown in the figure, the shear test of the bonding performance between shotcrete and surrounding rock is carried out. The test equipment is preferably an MTS815 triaxial press with real-time temperature loading function, which can simulate the high temperature environment of shotcrete in high ground temperature tunnels during operation. The specific steps of the test are as follows:

[0067] ① Place the standard cylindrical specimen in the triaxial pressure chamber. After sealing, apply confining pressure to the chamber at a constant rate of 2 MPa / min until the confining pressure reaches the preset value. The preset confining pressure value can be set to 0 MPa, 20 MPa, 40 MPa, and 60 MPa.

[0068] ② After the confining pressure stabilizes, heat to the preset temperature at a heating rate of 5°C / min. The preset temperature values ​​are set to 30°C, 50°C, and 70°C respectively;

[0069] ③ After the temperature of the pressure chamber stabilizes, shear displacement loading is performed at an axial compression loading rate of 0.02 mm / min until the standard cylindrical specimen is destroyed. The stress-strain curve is automatically recorded during the shearing process.

[0070] ④, by carrying out triaxial compression tests at different temperatures and confining pressures on standard cylindrical specimens under different temperature curing conditions, shear specimens at different temperatures (T=30℃, 50℃, 70℃) were made under different confining pressures ( =0MPa, 20MPa, 40MPa, 60MPa), draw the strength envelope, and use the Mohr-Coulomb strength criterion ( ) to obtain the shear strength parameters of the bonding surface at different temperatures by fitting c and friction angle Finally, the cohesion of the bonding surface under different temperature curing conditions was obtained. c and friction angle The relationship curve of heating temperature in the thermal-mechanical coupling test is used to evaluate the bonding performance of the interface between shotcrete and surrounding rock in high-temperature tunnels, providing a theoretical basis for the optimization design of lining materials and structures of high-temperature tunnels.

[0071] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for testing the bonding performance between shotcrete and surrounding rock in high ground temperature tunnels, characterized in that: The following steps are involved: Step 1: Collect data on the post-blasting surrounding rock surface temperature, the air temperature after shotcreting in the tunnel body, the concrete curing humidity, and the post-blasting surrounding rock 3D point cloud data at the high-temperature tunnel site. Rock with a wheelbase greater than 30 cm at the tunnel construction site is also collected for indoor test specimen preparation. Step 2: Based on the three-dimensional point cloud data of the surrounding rock after blasting collected at the tunnel construction site, the rock is prepared into a rock sample that can reflect the surface roughness of the surrounding rock after the actual blasting; Step 3: Prepare a curing test chamber that can reflect the actual one-way heating temperature gradient environment at the tunnel site, spray concrete onto the surface reflecting the roughness of the rock sample to form a concrete-rock sample, and place the concrete-rock sample in the curing test chamber for curing; Step 4: Prepare the cured concrete-rock sample into a standard cylindrical sample with a diameter of 50 mm and a length of 100 mm for shear test; Step 5: Shear test of the bonding performance between shotcrete and surrounding rock considering high temperature service environment; In the step 1, the three-dimensional point cloud data of the surrounding rock after blasting is obtained by collecting at least three typical sections using a three-dimensional laser scanner; The specific process of preparing the rock sample in step 2 is as follows: S2.

1. Cut the large rock samples collected on site into 30cm long pieces 30cm wide Plate-shaped rock specimen 8 cm high; S2.2, importing the 3D point cloud data into a heavy-duty stone mold machine equipped with 3D engraving technology; S2.3, in plate-like rock specimens One of the wide planes is carved with a rough surface that matches the surface roughness of the surrounding rock on site; S2.

4. Use digital image processing technology to extract the grayscale image of the rough surface of the plate-like rock sample, and then use the fractal dimension of the image grayscale to quantitatively characterize the roughness of the object surface.

2. The method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel according to claim 1 is characterized in that: The curing test box in step 3 includes a box body, a humidity control device (1), a cooling water pipe (2), a temperature sensing device (3), a humidity sensing device (4), a bottom heat conducting plate (5), a bottom heating water tank (6) and a rubber heat insulating pad (7); The humidity control device (1) is arranged on the box body and is used to adjust the humidity inside the box body; The cooling water pipe (2) is arranged in the box body and is used to adjust the temperature in the box body; The temperature sensing device (3) and the humidity sensing device (4) are both arranged on the inner wall of the box body, and are used to detect the temperature and humidity inside the box body in real time; The bottom heat conducting plate (5) is arranged at the bottom of the box body, and the lower end surface of the bottom heat conducting plate (5) is connected to a bottom heating water tank (6), and the temperature in the bottom heating water tank (6) is transmitted to the box body through the bottom heat conducting plate (5); The rubber heat-insulating pad (7) is arranged on the lower end surface of the bottom heating water tank (6) and is used to achieve heat insulation for the bottom heating water tank (6).

3. The method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel according to claim 1 is characterized in that: In the step 3, a concrete layer of 8 cm to 10 cm is sprayed on the rough surface of the plate-shaped rock sample to obtain a concrete-rock sample.

4. The method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel according to claim 3 is characterized in that: In the step 3, the concrete-rock sample is placed in a curing test box with the rock surface facing downward and the sprayed concrete surface facing upward and cured for 28 to 30 days.

5. The method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel according to claim 4 is characterized in that: The preparation process of the standard cylindrical specimen in step 4 is as follows: S4.

1. Drill a 50 mm diameter circular hole in the concrete-rock specimen with its central axis parallel to the concrete layer, and keep the concrete-rock bonding surface as close to the center of the hole as possible. S4.

2. Cut the drilled concrete-rock specimen into cylindrical specimens with a height of 100 mm; S4.

3. Remove a 5 mm thick rock structure from one end of the cylindrical specimen and a 5 mm thick concrete layer from the other end of the cylindrical specimen. Fill the removed portion of the cylindrical specimen with liquid silicone rubber. S4.

4. Leave the cylindrical specimen to stand for more than 48 hours until the liquid silicone rubber solidifies, and finally obtain a standard cylindrical specimen that meets the shear test accuracy requirements.

6. The method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel according to claim 5, characterized in that: The specific process of the shear test for the bonding performance of shotcrete and surrounding rock considering the high temperature service environment in step 5 is as follows: S5.

1. Place the standard cylindrical specimen in a triaxial pressure chamber. After sealing, apply confining pressure to the chamber at a constant rate of 2 MPa / min until the confining pressure reaches the preset value. S5.

2. After the confining pressure stabilizes, heat to the preset temperature at a heating rate of 5°C / min; S5.

3. After the temperature of the pressure chamber stabilizes, perform shear displacement loading at an axial compression rate of 0.02 mm / min until the standard cylindrical specimen fails. Automatically record the stress-strain curve during the shearing process. S5.

4. By conducting triaxial compression tests at different temperatures and confining pressures on standard cylindrical specimens under different temperature curing conditions, the ultimate stress circles of shear specimens at different temperatures and confining pressures were drawn, and the strength envelopes were plotted. The shear strength parameters of the bonding surface at different temperatures were obtained by fitting using the Mohr-Coulomb strength criterion. c and friction angle Finally, the cohesion of the bonding surface under different temperature curing conditions was obtained. c and friction angle The relationship curve of the heating temperature in the thermal-mechanical coupling test is used to evaluate the bonding performance of the interface between the shotcrete and the surrounding rock in the high ground temperature tunnel.

7. The method for testing the bonding performance between shotcrete and surrounding rock in a high ground temperature tunnel according to claim 6, characterized in that: The preset values ​​of confining pressure in S5.1 are set to 0 MPa, 20 MPa, 40 MPa, and 60 MPa respectively; The temperature preset value in S5.2 can be set to 30°C, 50°C, or 70°C; In S5.4, triaxial compression tests were conducted on standard cylindrical specimens under different temperature curing conditions at different temperatures and confining pressures, and shear specimens at different temperatures of T = 30 ° C, 50 ° C, and 70 ° C were made. =The ultimate stress circle under confining pressure of 0 MPa, 20 MPa, 40 MPa, and 60 MPa, and the strength envelope are drawn.

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