A geotechnical coupling performance testing device and method for non-uniform loading of soil body

Abstract

The application belongs to the technical field of geotechnical performance testing, and discloses a geotechnical coupling performance testing device and method for soil non-uniform loading, which comprises a pressure control assembly, a sensing optical fiber, an optical fiber adjusting assembly and a gluing assembly. The back of the pressure control assembly is provided with the gluing assembly. The outer wall of the gluing assembly is provided with a pressure transmission pipeline. The inner wall of the pressure transmission pipeline is provided with a plurality of pressure boosters. The inside of the pressure transmission pipeline is placed with a filled soil sample. The inside of the filled soil sample is placed with the sensing optical fiber. The outside of the pressure transmission pipeline is placed with an optical fiber pulling assembly. The top of the optical fiber pulling assembly is provided with an optical fiber holder. The gluing method in the multiple small amount mode can ensure that the glue on the surface of the sensing optical fiber is uniformly distributed, so as to prevent the optical fiber from being bent due to uneven distribution of the glue. The device can effectively improve the accuracy of detection.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical performance testing technology, specifically relating to a geotechnical coupling performance testing device and method for soil under non-uniform loading. Background Technology

[0002] Soil-rock coupling refers to the simultaneous action of multiple physical fields, such as groundwater, geostress, and temperature, on soil and rock masses in natural underground environments. These fields interact and influence each other, forming a complex coupled system. This coupling not only affects the physical and mechanical properties of soil and rock masses but also significantly impacts their stability and safety. Research on soil-rock coupling is crucial for understanding and predicting complex phenomena in geotechnical engineering. In-depth research into the behavior of soil and rock masses under the combined influence of multiple physical fields can reveal the mechanisms of their deformation and failure characteristics, providing a scientific basis for engineering design and construction. Simultaneously, research on soil-rock coupling also helps improve the prediction, forecasting, and disaster prevention and mitigation capabilities for geological disasters, ensuring the safety of people's lives and property. Optical fibers, with their advantages of long-term tracking, full distribution, and anti-interference, are currently widely used in monitoring soil and rock deformation in mining subsidence, foundation pit slope deformation, and road settlement. Common methods for constructing optical fibers include deployment inside the soil and rock mass and on its surface. Regardless of the method, the optical fiber and the soil and rock mass are considered as a whole, and the observations from the optical fiber reflect the deformation of the soil and rock mass. During monitoring, the fiber optic observation holes are not only affected by construction but also susceptible to natural factors such as precipitation, drought, and groundwater fluctuations. Furthermore, the complex deformation patterns and physical properties of the soil itself lead to a relatively complex strain transfer relationship between the sensing fiber and the soil. Therefore, ensuring the efficiency of strain transfer between the sensing fiber and the soil is a prerequisite for using fiber optic sensors to monitor soil deformation.

[0003] In existing technologies, it is usually necessary to insert and fix the sensing fiber inside the soil or rock mass to ensure the accuracy of the detection. When inserting the sensing fiber, glue is usually applied to fix the fiber inside the soil or rock mass. However, during the glue application process, due to the application method and the influence of the glue's own weight, the glue may be unevenly distributed in the sensing fiber. This can cause the sensing fiber to bend inside the soil or rock mass after the glue solidifies, thus affecting the detection results and accuracy. In addition, the strain transfer efficiency between the sensing fiber and the soil or rock mass is related to the physical and mechanical properties of both, as well as the mechanical properties of the interface. Among these, the shear strength of the interface has the greatest influence. Considering the accuracy and economy of the research, the current common method is to build an indoor similar material model and conduct pull-out tests to explore the relationship between the type of sensing fiber, the confining pressure of the soil or rock mass, the water content and density of the soil or rock mass, and the strain transfer efficiency. However, existing pull-out test equipment can only test the changes in strain transfer efficiency under uniform load and fixed water content conditions, which differs significantly from actual working conditions. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a grouting assembly and grouting machine with multiple grouting ports, thereby solving the problem of uneven glue application in existing technologies.

[0005] The objective of this invention can be achieved through the following technical solution: a soil-rock coupling performance testing device under non-uniform soil loading, comprising a pressure control component, a sensing optical fiber, an optical fiber adjustment component, and an adhesive application component.

[0006] A glue-applying assembly is installed on the back of the pressure control assembly. A pressure transmission pipe is installed on the outer wall of the glue-applying assembly. Multiple pressurizers are installed on the inner wall of the pressure transmission pipe. A filling soil sample is placed inside the pressure transmission pipe. A sensing optical fiber is placed inside the filling soil sample. An optical fiber pulling assembly is placed on the outside of the pressure transmission pipe. An optical fiber holder is installed on the top of the optical fiber pulling assembly. An optical fiber adjustment assembly is placed on the outside of the optical fiber holder. A data processing device is installed on the top of the optical fiber adjustment assembly. A total station is placed on the front of the pressure transmission pipe. Reflective markings are affixed to the outer wall of the pressure transmission pipe.

[0007] The adhesive application assembly includes a housing installed at one end of a pressure transmission pipeline. The inner wall of the housing is provided with a connecting pipe, and the outer wall of the connecting pipe has multiple grooves. An adhesive applicator is installed through the inner wall of the grooves. An electric telescopic rod is installed on the inner wall of the adhesive applicator. An extrusion plate is installed at one end of the electric telescopic rod, and an arc-shaped adhesive application plate is installed at one end of the adhesive applicator. A replenishment pipe is connected to the outer wall of the adhesive applicator.

[0008] In some disclosures, a first motor is installed on the inner wall of the housing, and a chain is installed on the output end of the first motor via a sprocket. A rubber wheel is installed on the inner wall of the housing, and the rubber wheel is connected to the first motor via a sprocket and chain drive.

[0009] In some disclosures, a buffer spring is installed on the inner wall of the connecting pipe, an arc-shaped fixing plate is installed at one end of the buffer spring, drying plates are alternately installed on the inner wall of the connecting pipe, heating wires are installed on the inner wall of the drying plates, a motor is installed on the outer wall of the connecting pipe, and a drive gear is installed on the outer wall of the motor.

[0010] In some disclosures, a turntable is mounted on the outer wall of the connecting pipe via a ball bearing. A gear groove is formed on the outer wall of the turntable near the motor, and the gear groove meshes with a drive gear. A circular fixing ring is mounted on the outer wall of the other side of the turntable. A clamping rod is mounted on the outer wall of the fixing ring, and an adhesive applicator is mounted on the outer wall of the clamping rod.

[0011] In some disclosures, the inner wall of the housing is equipped with a storage cavity, the outer wall of the storage cavity is equipped with a delivery pump, the input end of the delivery pump extends into the interior of the storage cavity, the output end of the delivery pump is equipped with a replenisher, the bottom of the replenisher is provided with a fixing groove, the inner wall of the fixing groove is through which a moving rod is installed, the outer wall of the moving rod is surrounded by a return spring, the inner wall of the replenisher is equipped with multiple guide wheels, and the moving rod is connected to the output end of the delivery pump.

[0012] In some disclosures, the testing method of the testing device is as follows;

[0013] Step 1: First, determine the test sampling points based on existing geological and hydrological data, and conduct borehole sampling at the designated locations. To obtain representative physical and mechanical properties of the soil, conduct soil mechanics tests to acquire several key parameters of the soil, including: average water content, average density (g / cm3), average initial void ratio, average compression coefficient, and average compression modulus, denoted as w, ρ, e, a, and E respectively. Based on the collected soil parameter information, select coarse sand (particle size range of 0.5-2mm), medium sand (particle size range of 0.25-0.5mm), fine sand (particle size range of 0.075-0.25mm), and clay (particle size less than 0.005mm) to prepare test materials. Based on the prepared test materials, prepare soil and rock tests with diameters of 50mm and 100mm to verify whether their mechanical parameters are consistent with those of the field samples.

[0014] Step 2: Place the soil sample inside the pressurized water injection chamber. Drill a hole at the center of the soil sample and lay the distributed optical fiber inside the soil sample. After the laying is completed, inject a certain amount of glue into the drilled hole. After standing for a period of time, fix the position of the optical fiber with the fixing devices at both ends of the pressurized water injection chamber.

[0015] Step 3: Connect the fiber optic end to the clamping device, and adjust the height of the base to ensure that the centerline of the soil sample is level with the clamping device.

[0016] In some published studies, step four, the coupling between the optical fiber and the soil, is closely related to the confining pressure. For ease of analysis, the following assumptions are made:

[0017] The interfacial tension between the optical fiber and the soil satisfies static equilibrium.

[0018] F t =F g

[0019] The interfacial friction between the optical fiber and the soil is uniformly distributed on the surface of the optical fiber.

[0020] F t =πDLt

[0021] The horizontal stress on the optical fiber is equal to the circumferential self-weight of the soil.

[0022] F h =K0γL

[0023] In the above formula, F t F is the interfacial force between the optical fiber and the soil. g F is the axial tensile force on the optical fiber. h denoted as γ, where γ is the vertical stress on the optical fiber, D is the outer diameter of the optical fiber, L is the length of the optical fiber embedded in the soil, t is the shear strength at the optical fiber-soil interface, K0 is the static vertical pressure coefficient, and γ is the unit weight of the soil layer.

[0024] Where K0 is calculated using the following formula:

[0025] K0=λK a +(1-λ)K b

[0026] K a =1-sinσ

[0027]

[0028] In the above formula, K a K represents the coefficient of static vertical pressure of sand. b σ represents the static vertical pressure coefficient of clay, I represents the effective internal friction angle of sand, λ represents the plasticity index of clay, and λ represents the proportion of sand in the soil layer.

[0029] To measure the coupling between the optical fiber and the soil during the pull-out process, the optical fiber-soil coupling coefficient is defined as α;

[0030]

[0031] In the above formula, x represents the distance from the left end point on the central axis of the pressurized water injection chamber. Assuming the length of the pressurized water injection chamber is L, then 0 ≤ x ≤ L. ε(x) represents the fiber optic observation value at the corresponding position, m0 is the deformation value of the clamping device segment, 0 ≤ α ≤ 1. The closer α is to 1, the better the coupling between the fiber optic cable and the soil.

[0032] In some publicly available methods, step five involves activating the hydraulic system after a period of stillness, applying an initial confining pressure of F0, and then calculating the axial force F of the fiber clamping device segment. z To verify the validity of the results from the verification device, F0 is used as the independent variable. z If a linear regression analysis is performed on the dependent variable and the R² of the regression equation is greater than 0.95, then the observation results are considered valid.

[0033] F z =EAε

[0034] In the above formula, E represents the average elastic modulus of the optical fiber, A is the cross-sectional area of ​​the optical fiber, and ε represents the strain of the optical fiber in the clamping device segment.

[0035] Step Six: Determine the pressure F(x) exerted by the soil layer at different depths at different locations within the pressurized water injection chamber, based on the depth of the target stratum. h The intelligent pressurization device is activated, and the force applied above the pressurized water injection chamber is denoted as F(x). 上 The force applied below the pressurized water injection chamber is F(x). 下 , where x is the distance from the left end point on the central axis of the pressurized water injection chamber. Assuming the length of the pressurized water injection chamber is L, then 0≤x≤L;

[0036] At this point, we have F(x). h -F0=F(x) 上 +F(x) 下

[0037] After applying pressure, the axial force F of the optical fiber in the clamping device section is calculated. z The coupling coefficient α was used to verify the validity of the experimental results and to explore the changes in fiber-soil coupling at different depths.

[0038] In some publications, in step seven, because the rock strata will move horizontally during the mining process, and the sensing fiber is poorly sensitive to horizontal movement, during the loading process in step seven, F(x)... c The displacement will inevitably be curvilinear, and the pressurized water injection chamber will experience vertical axis movement. Therefore, the vertical displacement of the pressurized water injection chamber will be observed using a total station and a total station reflector. For ease of analysis, we assume a point (x) on the sensing fiber. i y iMeanwhile, it is assumed that the optical fiber material is homogeneous, continuous, and linearly elastic; the interface geometry will not deform under stress; and the two ends of the infinitesimal element are simply supported. The force on the optical fiber here is shown in the figure, and the calculation formula is:

[0039]

[0040] In the above formula Indicates the deflection of the soil. denoted by fiber optic observation, R represents the outer radius of the pressurized water injection chamber, and a and b are integration coefficients, which were determined in this experiment by the observations at both ends of the pressurized water injection chamber.

[0041] In some published documents, during step eight and step seven of the loading process, the lateral displacement of the pressurized water injection chamber is observed using a total station, assuming point (x) i y i The deflection value of Y) q Let Y q As the independent variable, If a linear regression analysis is performed on the dependent variable and the R² of the regression equation is greater than 0.95, then the fiber-soil coupling is considered to be high.

[0042] The explanations of the nouns, conjunctions, or adjectives used in the above technical solutions are as follows:

[0043] A fixed connection refers to a connection in which parts or components are fixed in place and there is no relative movement between them;

[0044] A rotating connection is a connection between parts that allows the parts to rotate relative to each other.

[0045] Threaded connections are a type of detachable fixed connection with advantages such as simple structure, reliable connection, and convenient assembly and disassembly. They are widely used in mechanical engineering and connection structure fields.

[0046] A sliding connection is a connection between parts that allows the parts to slide against each other.

[0047] The beneficial effects of this invention are:

[0048] 1. This invention uses a multiple-batch, small-volume adhesive application method to ensure uniform distribution of adhesive on the surface of the sensing optical fiber, thereby preventing uneven adhesive distribution from causing the optical fiber to bend. This device can effectively improve the accuracy of detection.

[0049] 2. This invention is applicable to various mining conditions. The device can control the lateral pressure at different locations, facilitating the study of the variation patterns of the mechanical properties of the fiber-soil interface under different geological conditions, depths, and mining progress, and exploring the coupling relationship between the two. This invention utilizes distributed fiber optic stress measurement to achieve full-section soil measurement, resulting in low cost and strong resistance to external interference. The invention's structure offers high measurement accuracy and ease of operation, showing promising application prospects in mine safety and soil movement monitoring. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the total station and reflective indicator structure according to an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of the turntable structure according to an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram of the side sectional structure of the box according to an embodiment of the present invention;

[0055] Figure 5 This is a schematic diagram of the supplementary device structure according to an embodiment of the present invention;

[0056] Figure 6 This is a schematic diagram of the connecting pipe section in an embodiment of the present invention.

[0057] In the diagram: 1. Pressure control component; 2. Pressure transmission pipeline; 3. Pressurizer; 4. Soil sample filling; 5. Sensor fiber optic; 6. Fiber optic pulling component; 7. Fiber optic clamp; 8. Fiber optic adjustment component; 9. Data processing device; 10. Total station; 11. Reflective indicator; 12. Glue application component; 120. Box; 13. Connecting pipe; 14. First motor; 15. Chain; 16. Rubber wheel; 17. Storage chamber; 18. Delivery pump; 19. Supplementer; 20. Fixing groove; 21. Moving rod; 22. Return spring; 23. Guide wheel; 25. Buffer spring; 26. Fixing plate; 27. Drying plate; 28. Heating wire; 29. ​​Motor; 30. Drive gear; 31. Turntable; 32. Fixing ring; 33. Clamping rod; 34. Glue applicator; 35. Electric telescopic rod; 36. Extrusion plate; 37. Glue application plate; 38. Supplement pipe. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Please see Figure 1 , Figure 3 and Figure 6 A soil-rock coupling performance testing device under non-uniform soil loading includes a pressure control component 1, a sensing optical fiber 5, an optical fiber adjustment component 8, and an adhesive application component 12. The adhesive application component 12 is mounted on the back of the pressure control component 1. A pressure transmission pipe 2 is mounted on the outer wall of the adhesive application component 12. Multiple pressure injectors 3 are mounted on the inner wall of the pressure transmission pipe 2. A soil sample 4 is placed inside the pressure transmission pipe 2, and the sensing optical fiber 5 is placed inside the soil sample 4. An optical fiber pulling component 6 is placed on the outside of the pressure transmission pipe 2. An optical fiber holder 7 is mounted on the top of the optical fiber pulling component 6, and an optical fiber adjustment component is placed on the outside of the optical fiber holder 7. The top of the fiber optic adjustment assembly 8 is equipped with a data processing device 9. A total station 10 is placed on the front of the pressure transmission pipeline 2. Reflective markers 11 are affixed to the outer wall of the pressure transmission pipeline 2. The glue application assembly 12 includes a box 120 installed at one end of the pressure transmission pipeline 2. A connecting pipe 13 is provided on the inner wall of the box 120. Multiple grooves are opened on the outer wall of the connecting pipe 13. A glue applicator 34 is installed through the inner wall of the grooves. An electric telescopic rod 35 is installed on the inner wall of the glue applicator 34. An extrusion plate 36 is installed at one end of the electric telescopic rod 35. An arc-shaped glue application plate 37 is installed at one end of the glue applicator 34. A replenishment pipe 38 is connected to the outer wall of the glue applicator 34.

[0060] Specifically, during the application of adhesive, the adhesive enters the interior of the adhesive applicator 34 through the replenishment tube 38. Then, the electric telescopic rod 35 extends and drives the extrusion plate 36 to move. The extrusion plate 36 squeezes the adhesive, causing it to be discharged through the coating plate 37. The coating plate 37 applies the adhesive to the outer surface of the sensing optical fiber 5, thus realizing the adhesive application function.

[0061] Please see Figure 6 The inner wall of the housing 120 is equipped with a first motor 14, and the output end of the first motor 14 is equipped with a chain 15 through a sprocket. The inner wall of the housing 120 is equipped with a rubber wheel 16, and the rubber wheel 16 is connected to the first motor 14 through the sprocket and chain 15.

[0062] Specifically, the sensing optical fiber 5 is sent into the interior of the housing 120. Then, the first motor 14 rotates, driving the chain 15 to rotate, which in turn drives the rubber wheel 16 to rotate. The rubber wheel 16 drives the sensing optical fiber 5 forward by rotating, thereby delivering the sensing optical fiber 5 into the interior of the filling soil sample 4.

[0063] Please see Figure 5 and Figure 6 A buffer spring 25 is installed on the inner wall of the connecting pipe 13. An arc-shaped fixing plate 26 is installed at one end of the buffer spring 25. Drying plates 27 are installed alternately on the inner wall of the connecting pipe 13. Heating wires 28 are installed on the inner wall of the drying plates 27. A motor 29 is installed on the outer wall of the connecting pipe 13. A drive gear 30 is installed on the outer wall of the motor 29.

[0064] Specifically, when the sensing fiber 5 moves to the fixing plate 26, the fixing plate 26 scrapes off the excess glue on the sensing fiber 5, so that the glue applied to the surface of the sensing fiber 5 can be uniform. After the glue is applied, the heating wire 28 works to dissipate heat, and the drying plate 27 performs preliminary drying and shaping of the glue, so that the outermost layer of glue solidifies into a thin film, preventing the sensing fiber 5 from being scraped off during the movement of the filling soil sample 4, which would cause uneven application.

[0065] Please see Figure 3 , Figure 4 and Figure 5 The outer wall of the connecting pipe 13 is equipped with a turntable 31 via a ball bearing. A gear groove is provided on the outer wall of the turntable 31 near the motor 29. The gear groove meshes with the drive gear 30. A circular fixing ring 32 is installed on the outer wall of the other side of the turntable 31. A clamping rod 33 is installed on the outer wall of the fixing ring 32. An adhesive applicator 34 is installed on the outer wall of the clamping rod 33.

[0066] Specifically, the rotation of motor 29 drives the drive gear 30 to rotate, the drive gear 30 drives the turntable 31 to rotate, the turntable 31 rotates and drives the clamping rod 33 to rotate, the clamping rod 33 drives the glue applicator 34 to rotate, at this time the glue applicator 34 drives the glue applicator plate 37 to rotate around the outer wall of the sensing optical fiber 5, and while rotating, the glue is applied to the surface of the sensing optical fiber 5.

[0067] It should be noted that multiple glue applicators 34 can be placed, and each application should be done in small amounts multiple times to prevent excessive glue from dripping or unevenly spreading on the sensing optical fiber 5. After each application, the glue is slightly dried and shaped using a drying plate 27 to further ensure the uniformity of the glue. By applying the glue in the above manner, the glue content on the surface of the sensing optical fiber 5 is the same when it enters the filling soil sample 4, preventing the optical fiber from bending due to uneven glue application.

[0068] Please see Figure 3and Figure 6 The inner wall of the housing 120 is equipped with a storage cavity 17, and the outer wall of the storage cavity 17 is equipped with a delivery pump 18. The input end of the delivery pump 18 extends into the interior of the storage cavity 17, and the output end of the delivery pump 18 is equipped with a supplementer 19. The bottom of the supplementer 19 is provided with a fixing groove 20, and a moving rod 21 is installed through the inner wall of the fixing groove 20. A return spring 22 is installed around the outer wall of the moving rod 21. Multiple guide wheels 23 are installed on the inner wall of the supplementer 19, and the moving rod 21 is connected to the output end of the delivery pump 18.

[0069] Specifically, the delivery pump 18 extracts the glue from the storage chamber 17. At this time, the replenishment tube 38 is located in the replenisher 19. The replenishment tube 38 squeezes the moving rod 21, and the moving rod 21 retracts, causing the return spring 22 to extend. At this time, the cable pulls the output end of the delivery pump 18 down through the guide wheel 23, so that the output end of the delivery pump 18 is connected to the replenishment tube 38. The delivery pump 18 works to deliver the glue through the pipe to the inside of the glue applicator 34, realizing the function of replenishing glue.

[0070] Please see Figure 1 and Figure 2 The testing method of the testing device is as follows;

[0071] Step 1: First, determine the test sampling points based on existing geological and hydrological data, and conduct borehole sampling at the designated locations. To obtain representative physical and mechanical properties of the soil, conduct soil mechanics tests to acquire several key parameters of the soil, including: average water content, average density (g / cm3), average initial void ratio, average compression coefficient, and average compression modulus, denoted as w, ρ, e, a, and E respectively. Based on the collected soil parameter information, select coarse sand (particle size range of 0.5-2mm), medium sand (particle size range of 0.25-0.5mm), fine sand (particle size range of 0.075-0.25mm), and clay (particle size less than 0.005mm) to prepare test materials. Based on the prepared test materials, prepare soil and rock tests with diameters of 50mm and 100mm to verify whether their mechanical parameters are consistent with those of the field samples.

[0072] Step 2: Place the soil sample inside the pressurized water injection chamber. Drill a hole at the center of the soil sample and lay the distributed optical fiber inside the soil sample. After the laying is completed, inject a certain amount of glue into the drilled hole. After standing for a period of time, fix the position of the optical fiber with the fixing devices at both ends of the pressurized water injection chamber.

[0073] Step 3: Connect the fiber optic end to the clamping device, and adjust the height of the base to ensure that the centerline of the soil sample is level with the clamping device.

[0074] In some published studies, step four, the coupling between the optical fiber and the soil, is closely related to the confining pressure. For ease of analysis, the following assumptions are made:

[0075] The interfacial tension between the optical fiber and the soil satisfies static equilibrium.

[0076] F t =F g

[0077] The interfacial friction between the optical fiber and the soil is uniformly distributed on the surface of the optical fiber.

[0078] F t =πDLt

[0079] The horizontal stress on the optical fiber is equal to the circumferential self-weight of the soil.

[0080] F h =K0γL

[0081] In the above formula, F t F is the interfacial force between the optical fiber and the soil. g F is the axial tensile force on the optical fiber. h denoted as γ, where γ is the vertical stress on the optical fiber, D is the outer diameter of the optical fiber, L is the length of the optical fiber embedded in the soil, t is the shear strength at the optical fiber-soil interface, K0 is the static vertical pressure coefficient, and γ is the unit weight of the soil layer.

[0082] Where K0 is calculated using the following formula:

[0083] K0=λK a +(1-λ)K b

[0084] K a =1-sinσ

[0085]

[0086] In the above formula, K a K represents the coefficient of static vertical pressure of sand. b σ represents the static vertical pressure coefficient of clay, I represents the effective internal friction angle of sand, λ represents the plasticity index of clay, and λ represents the proportion of sand in the soil layer.

[0087] To measure the coupling between the optical fiber and the soil during the pull-out process, the optical fiber-soil coupling coefficient is defined as α;

[0088]

[0089] In the above formula, x represents the distance from the left end point on the central axis of the pressurized water injection chamber. Assuming the length of the pressurized water injection chamber is L, then 0≤x≤L, ε(x) represents the fiber optic observation value at the corresponding position, m0 is the deformation value of the clamping device section, 0≤α≤1, and the closer α is to 1, the better the coupling between the fiber optic and the soil.

[0090] In some publicly available methods, step five involves activating the hydraulic system after a period of stillness, applying an initial confining pressure of F0, and then calculating the axial force F of the fiber clamping device segment. z To verify the validity of the results from the verification device, F0 is used as the independent variable. z If a linear regression analysis is performed on the dependent variable and the R² of the regression equation is greater than 0.95, then the observation results are considered valid.

[0091] F z =EAε

[0092] In the above formula, E represents the average elastic modulus of the optical fiber, A is the cross-sectional area of ​​the optical fiber, and ε represents the strain of the optical fiber in the clamping device segment.

[0093] Step Six: Determine the pressure F(x) exerted by the soil layer at different depths at different locations within the pressurized water injection chamber, based on the depth of the target stratum. h The intelligent pressurization device is activated, and the force applied above the pressurized water injection chamber is denoted as F(x). 上 The force applied below the pressurized water injection chamber is F(x). 下 , where x is the distance from the left end point on the central axis of the pressurized water injection chamber. Assuming the length of the pressurized water injection chamber is L, then 0≤x≤L;

[0094] At this point, we have F(x). h -F0=F(x) 上 +F(x) 下

[0095] After applying pressure, the axial force F of the optical fiber in the clamping device section is calculated. z The coupling coefficient α was used to verify the validity of the experimental results and to explore the changes in fiber-soil coupling at different depths.

[0096] In some publications, in step seven, because the rock strata will move horizontally during the mining process, and the sensing fiber is poorly sensitive to horizontal movement, during the loading process in step seven, F(x)... c The displacement will inevitably be curvilinear, and the pressurized water injection chamber will experience vertical axis movement. Therefore, the vertical displacement of the pressurized water injection chamber will be observed using a total station and a total station reflector. For ease of analysis, we assume a point (x) on the sensing fiber. i y i Meanwhile, it is assumed that the optical fiber material is homogeneous, continuous, and linearly elastic; the interface geometry will not deform under stress; and the two ends of the infinitesimal element are simply supported. The force on the optical fiber here is shown in the figure, and the calculation formula is:

[0097]

[0098] In the above formula Indicates the deflection of the soil. denoted by fiber optic observation, R represents the outer radius of the pressurized water injection chamber, and a and b are integration coefficients, which were determined in this experiment by the observations at both ends of the pressurized water injection chamber.

[0099] In some published documents, during step eight and step seven of the loading process, the lateral displacement of the pressurized water injection chamber is observed using a total station, assuming point (x) i y i The deflection value of Y) q Let Y q As the independent variable, If a linear regression analysis is performed on the dependent variable and the R² of the regression equation is greater than 0.95, then the fiber-soil coupling is considered to be high.

[0100] Working principle: The pressurizer in this device mainly includes an intelligent pressurization and water injection module, a main device module, an optical fiber pulling module, an optical fiber demodulation module, and an auxiliary observation module. The intelligent pressurization and water injection module includes an intelligent pressurization device, a hydraulic device, a pressurization circuit, a pressurization probe, and water injection pipes. The pressurization control device consists of a hydraulic pump, a water injection pump, and a control device. The hydraulic pump is used to pressurize the main device, the water injection pump is used to inject water into the main device, and the control device is used to regulate the hydraulic pump and the water injection pump to apply different levels of pressure and inject different amounts of water at different locations on the main device. The hydraulic device is used to provide a uniform and stable initial pressure to simulate the undisturbed confining pressure of the rock strata.

[0101] The main module of the device consists of a pressurized water injection chamber and an optical fiber fixing device. The pressurized water injection chamber is used to house the optical fiber and fill the soil sample; the optical fiber fixing device is used to fix the optical fiber at the central position of the pressurized water injection chamber.

[0102] The fiber optic pulling module consists of a fiber optic clamping device and a pulling device. The fiber optic clamping device is used to connect the fiber optic cable to the pulling device; the pulling device is used to apply a certain degree of tension to the sensing fiber optic cable.

[0103] The fiber optic demodulation module consists of a fiber optic demodulation device and a fiber optic data processing device. The fiber optic demodulation device is used to demodulate the frequency data of the sensing fiber into strain data, and the fiber optic data processing device is used to clean, reduce noise, calculate, and store the demodulated fiber optic data.

[0104] The auxiliary observation module consists of a total station and a total station reflector. The total station reflector is attached to the outer surface of the pressurized water injection chamber to assist the total station in monitoring the horizontal and vertical displacements on the outer surface and axis of the pressurized water injection chamber.

[0105] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0106] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A geotechnical coupling performance testing device for non-uniform loading of soil mass, characterized in that, It comprise pressure control component (1), sensing optical fiber (5), optical fiber adjusting component (8) and glue coating component (12); The back of the pressure control component (1) is provided with a glue coating component (12), the outer wall of the glue coating component (12) is provided with a pressure transmission pipeline (2), the inner wall of the pressure transmission pipeline (2) is provided with a plurality of pressure boosters (3), the inside of the pressure transmission pipeline (2) is placed with a filling soil sample (4), the inside of the filling soil sample (4) is placed with a sensing optical fiber (5), the outside of the pressure transmission pipeline (2) is placed with a fiber pulling component (6), the top of the fiber pulling component (6) is provided with a fiber holder (7), the outside of the fiber holder (7) is placed with an optical fiber adjusting component (8), the top of the optical fiber adjusting component (8) is provided with a data processing device (9), the front of the pressure transmission pipeline (2) is placed with a total station (10), and the outer wall of the pressure transmission pipeline (2) is pasted with a reflective mark (11). The glue coating component (12) comprises a box body (120) installed at one end of the pressure transmission pipeline (2), the inner wall of the box body (120) is provided with a connecting pipe (13), the outer wall of the connecting pipe (13) is provided with a plurality of grooves, the inner wall of the groove is provided with a glue coating device (34) penetratingly installed, the inner wall of the glue coating device (34) is provided with an electric telescopic rod (35), one end of the electric telescopic rod (35) is provided with an extrusion plate (36), one end of the glue coating device (34) is provided with an arc-shaped glue coating plate (37), and the outer wall of the glue coating device (34) is connected with a supplement pipe (38). The outer wall of the connecting pipe (13) is provided with a rotating disc (31) through a ball bearing, the outer wall of one side of the rotating disc (31) close to the motor (29) is provided with a gear groove, the gear groove is engaged with a driving gear (30), the other side of the outer wall of the rotating disc (31) is provided with a circular fixing ring (32), the outer wall of the fixing ring (32) is provided with a clamping rod (33), and the outer wall of the clamping rod (33) is provided with the glue coating device (34). 2.The soil body non-uniform loading geotechnical body coupling performance testing device according to claim 1, characterized in that, The inner wall of the box body (120) is provided with a first motor (14), the output end of the first motor (14) is provided with a chain (15) through a sprocket, the inner wall of the box body (120) is provided with a rubber wheel (16), and the rubber wheel (16) is in driving connection with the first motor (14) through the sprocket chain (15).

3. The geotechnical coupling performance testing device for non-uniform loading of soil mass according to claim 1, characterized in that, The inner wall of the connecting pipe (13) is provided with a buffer spring (25), one end of the buffer spring (25) is provided with an arc-shaped fixing plate (26), the inner wall of the connecting pipe (13) is provided with staggered drying plates (27), the inner wall of the drying plate (27) is provided with an electric heating wire (28), the outer wall of the connecting pipe (13) is provided with a motor (29), and the outer wall of the motor (29) is provided with a driving gear (30).

4. The geotechnical coupling performance testing device for non-uniform loading of soil mass according to claim 1, characterized in that, The inner wall of the box (120) is provided with a storage cavity (17), the outer wall of the storage cavity (17) is provided with a conveying pump (18), the input end of the conveying pump (18) extends into the inside of the storage cavity (17), the output end of the conveying pump (18) is provided with a replenisher (19), the bottom of the replenisher (19) is provided with a fixing groove (20), the inner wall of the fixing groove (20) is throughly provided with a moving rod (21), the outer wall of the moving rod (21) is surroundedly provided with a return spring (22), the inner wall of the replenisher (19) is provided with a plurality of guide wheels (23), and the moving rod (21) is connected with the output end of the conveying pump (18).

5. The testing method of the geotechnical coupling performance testing device for non-uniform loading of soil body according to claim 1, characterized in that, The testing method of the rock-soil coupling performance testing device is as follows; Step one, first according to the existing geological and hydrological data to determine the test sampling point, and in the designated position drilling sampling, for obtaining representative soil physical and mechanical properties, soil mechanics test is carried out, and a plurality of key parameters of soil are obtained, including: average moisture content, average density , average initial void ratio, average compression coefficient and average compression modulus, sequentially recorded as , according to the collected soil parameter information, the test material is configured by selecting coarse sand with particle size range of 0.5-2mm, medium sand with particle size range of 0.25-0.5mm, fine sand with particle size range of 0.075-0.25mm and clay with particle size less than 0.005mm, based on the configured test material, the test material is made into geotechnical test with diameter of 50mm and 100mm, and whether the mechanical parameters are consistent with the on-site sampling is verified; Step two, place the soil sample in the pressurized water injection chamber, drill a hole in the center of the soil sample, lay the distributed optical fiber in the soil sample, after laying, inject a certain amount of glue into the hole, and then fix the position of the optical fiber through the fixing device at both ends of the pressurized water injection chamber after a period of static state; Step three, connect the optical fiber end with the clamping device, and adjust the height of the base to ensure that the central axis of the soil sample and the clamping device are horizontal.

6. The testing method of the geotechnical coupling performance testing device for non-uniformly loaded soil mass according to claim 5, characterized in that, Step four, the coupling between the optical fiber and the soil body is closely related to the confining pressure, in order to facilitate analysis, the following assumptions are made: The interface tension between the optical fiber and the soil body satisfies the static equilibrium: The interface friction between the optical fiber and the soil body is uniformly distributed on the surface of the optical fiber: The horizontal stress of the optical fiber is equal to the self-weight of the soil body in the circumferential direction: In the above equation is the interface force between the optical fiber and the soil, is the axial tension force on the optical fiber, is the vertical stress on the optical fiber, D is the outer diameter of the optical fiber, L is the length of the optical fiber embedded in the soil, and t is the shear strength of the optical fiber-soil interface, is the static vertical pressure coefficient, is the unit weight of the soil layer; wherein calculated by the following equation: In the above formulae denotes the static vertical pressure coefficient of sand, denotes the static vertical pressure coefficient of clay, denotes the effective internal friction angle of sand, I denotes the plasticity index of clay, denotes the proportion of sand in the soil layer; In order to measure the coupling between the optical fiber and the soil during the pulling process, the fiber-soil coupling coefficient is defined as ; In the above formula denotes the distance from the left end point on the axis of the pressurized water injection chamber, assuming that the length of the pressurized water injection chamber is L, then , denotes the optical fiber observation value at the corresponding position, is the deformation value of the clamping device section, , The closer to 1, the better the coupling of the optical fiber-rock-soil body.

7. The testing method of the geotechnical coupling performance testing device for non-uniformly loaded soil mass according to claim 5, characterized in that, Step 5: After a period of stillness, start the hydraulic device and apply the initial confining pressure sequentially. By calculating the axial force value of the optical fiber in the clamping device segment To verify the validity of the results from the verification device, As the independent variable, If a linear regression analysis is performed on the dependent variable and the R² of the regression equation is greater than 0.95, then the observation results are considered valid. In the above formula Eavg represents the average modulus of elasticity of the optical fiber, A represents the cross-sectional area of the optical fiber, εs represents the strain of the optical fiber clamped by the clamping device segment Step six, according to the depth of the target layer, the pressure of the soil layer at different depths in the pressurized water injection chamber is determined , the intelligent pressurizing device is started, the force applied above the pressurized water injection chamber is , the force applied below the pressurized water injection chamber is , wherein is the distance from the left end point on the axis of the pressurized water injection chamber, assuming the length of the pressurized water injection chamber is L, then ; At this time there are After applying pressure, the axial force value of the segment fiber of the clamping device is calculated and coupling coefficient , verify the effectiveness of the experimental results, and explore the changes in the coupling of optical fibers and rock-soil at different depths.

8. The testing method of the geotechnical coupling performance testing device for non-uniformly loaded soil mass according to claim 5, characterized in that, Step seven, due to the mining process, the rock strata will appear horizontal movement, and the sensing fiber is less sensitive to horizontal movement, in step seven loading process, It will be a curve distribution, and the vertical axis of the pressurized water injection chamber will move, therefore, by observing the vertical displacement of the pressurized water injection chamber by the total station and the total station reflector, in order to facilitate analysis, it is assumed that a point on the sensing fiber At the same time, it is assumed that the material of the optical fiber is uniform, continuous and linearly elastic; The interface geometry will not be deformed by force; The two ends of the micro-element are simply supported, and the stress calculation formula of the optical fiber at this point is: In the above formula represents the deflection of the soil body, represents the optical fiber observation value, R represents the outer radius of the pressurized water injection chamber, and b are integral coefficients, which are determined in this experiment by the observation values at both ends of the pressurized water injection chamber.

9. The testing method of the geotechnical coupling performance testing device for non-uniformly loaded soil mass according to claim 5, characterized in that, Step eight, during the loading process in step seven, the lateral displacement of the pressurized water injection chamber is observed by the total station, assuming that the deflection value of point is , and taking as the independent variable and as the dependent variable to perform linear regression analysis. If the of the regression equation is greater than 0.95, it is considered that the fiber-soil coupling is high at this time.

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