Method and system for calculating stability of upright rock slope under action of seismic force

Abstract

The invention belongs to the technical field of slope stability analysis, discloses a method and a system for calculating the stability of a vertical rock slope under the action of seismic force, combines kinematics analysis and energy conservation principles, and aims to solve the limitation that rock compression strength cannot be considered in stability analysis in a traditional method. The method comprises the following steps: firstly, constructing a simplified mechanical model of the upright rock slope and a corresponding kinematic mechanism; then, respectively calculating external force work power or internal energy dissipation rate corresponding to gravity, earthquake force, water pressure, and compressive strength and tensile strength of the rock mass; and finally, assuming a series of dumping rotation centers, solving an energy balance equation containing safety coefficients at different rotation centers, and taking the minimum safety coefficient solution as the slope safety coefficient. According to the method, the influence of rock compression strength as stability is considered, the limitation of rigid body hypothesis in a traditional method is broken through, and a more reasonable safety coefficient solution is provided.

Description

Technical Field

[0001] The present invention belongs to the field of geotechnical engineering technology, and in particular relates to a method and system for calculating the stability of a vertical rock slope under the action of earthquake force. Background Art

[0002] Vertical rock slopes formed by natural or artificial excavation are prone to collapse and instability during earthquakes. The stability of slope collapse is mainly characterized by the safety factor. Therefore, existing technologies mainly evaluate stability by calculating the slope safety factor. Currently, the rigid body limit equilibrium method is usually used to calculate the slope safety factor. However, in actual calculation practice, this stability evaluation is not applicable to the stability calculation of vertical rock slopes under earthquake forces. The reasons are: This method adopts the rigid body assumption that the rock mass can only rotate around a point on the slope surface when it collapses. In fact, the strength of the rock mass of a vertical rock slope under the action of seismic force is limited. When it collapses, the toe of the rock mass will inevitably undergo compression failure, resulting in the center of rotation being inside the rock mass rather than on the slope surface. At this time, the rigid body assumption will lead to an overly conservative or even erroneous slope safety factor, which in turn leads to overly conservative or erroneous results in the stability evaluation of the vertical rock slope.

[0003] Therefore, there is an urgent need for a calculation method for the toppling stability of vertical rock slopes that can take into account the compression failure of the rock toe, so as to obtain the safety factor of vertical rock slopes suitable for seismic forces. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for calculating the stability of vertical rock slopes under seismic forces that can obtain a safety factor of the vertical rock slopes suitable for the seismic forces, in response to the problem pointed out in the background technology that the calculation of the slope safety factor is too conservative or erroneous in the current calculation of the stability of vertical rock slopes under seismic forces.

[0005] In order to solve the technical problem, the technical solution of the present invention is: A method for calculating the stability of a vertical rock slope under earthquake force, the method comprising: A. Obtain the geometric dimensions and physical and mechanical parameters of the vertical rock slope and construct a simplified mechanical model of the vertical rock slope; B. Construct a rectangular coordinate system with the tilting rotation center as the origin, establish the corresponding kinematic mechanism based on the rigid-plastic assumption, and calculate the velocity distribution of each area of the model based on the constructed kinematic mechanism; C. Based on the constructed kinematic mechanism, the external work power acting on the rock mass and the internal energy dissipation rate caused by rock mass failure are calculated respectively; D. Assuming a series of toppling rotation centers, a nonlinear equation for the safety factor FoS is established based on the strength reduction method and energy balance principle, and solved using the Newton-Raphson method. The smallest FoS is taken as the slope safety factor.

[0006] The tipping rotation center in the above step B refers to the instantaneous geometric center point around which the rock mass rotates when the rock slope topples and fails, that is, the instantaneous center of velocity. In the mechanical model of this application, this point is located inside the rock mass and is the dividing point between the crushing zone (plastic zone) and the rigid zone. Its position is controlled by the width of the crushing zone. It can be seen that in step D, after assuming a series of crushing zone widths, a nonlinear equation for the safety factor FoS is established based on the strength reduction method and the energy balance principle, and solved by the Newton-Raphson method. The smallest FoS is taken as the slope safety factor. This breaks through the limitations of the traditional rigid body model and can more realistically reflect the composite failure mechanism of the rock mass under earthquake action. The kinematic mechanism in the above step B specifically includes two parts: the rock crushing zone in front of the rotation center, and the rest is the rigid area. The assumption of a series of tipping rotation centers in the above step D is to assume different rock crushing zone widths.

[0007] As a further preferred embodiment of the present invention, the geometric dimensions of the vertical rock slope in step A include: slope height, slope width, rock crushing zone width, trailing edge crack depth, and groundwater level height in the crack; The physical and mechanical parameters of the vertical rock slope described in step A include: rock mass, groundwater density in fractures, rock mass internal friction angle, rock mass cohesion, rock mass tensile strength, horizontal seismic force coefficient, vertical seismic force coefficient, and tilting rotation angular velocity.

[0008] As a further preferred embodiment of the present invention, the rock crushing zone of the simplified mechanical model in step B is an isosceles triangle area, the velocity of vertex A on the bottom side of the triangular plastic zone is perpendicular to the side OA, and point O in the side OA is the vertex angle of the isosceles triangle area. The size of the triangular plastic zone is determined according to the following method: Plastic compression failure of rock mass must satisfy the Mohr-Coulomb yield criterion and the associated flow law. The Mohr-Coulomb yield criterion of rock mass is: , Formula 1; In the formula and The maximum and minimum principal stresses, and are the friction angle and cohesion in the rock mass, The Law of Associative Flow states that: , Formula 2; In the formula and The maximum and minimum principal strain rates are respectively. Since the velocity of vertex A on the bottom edge of the triangular plastic zone is perpendicular to the edge OA, the geometric similarity relationship is: , Formula 3; In the formula is the width of the rock crushing zone, i.e. the length of the height of the base of the isosceles triangle; is the height of the rock crushing zone, that is, the length of the base of the isosceles triangle. Substituting the associated flow law into the above formula, we can obtain: , Formula 4; From this, the shape of the rock crushing zone can be determined, which is determined only by the internal friction angle of the rock mass and has nothing to do with the dimension b.

[0009] As a further preferred embodiment of the present invention, the velocity distribution of each region of the model in step B specifically includes: Horizontal velocity of the center of the dumped rock mass , where is the angular velocity of rock mass tipping, and the geometric parameters , H is the slope height; Vertical velocity of the center of the dumped rock mass ; Horizontal velocity of the trailing edge of the dumped rock mass ; Vertical velocity at the bottom of the dumped rock mass .

[0010] As a further preferred embodiment of the present invention, the external work power acting on the rock mass in step C includes the external work power of gravity, seismic force and water pressure, which are specifically as follows: The power of gravity , where the gravity of the dumped rock mass , is the weight of the rock mass, and B is the width of the dumped rock mass; The power of earthquake force , where the horizontal and vertical seismic forces are , , and are the horizontal and vertical seismic force coefficients, respectively; Water pressure power , where water pressure , is the fracture groundwater density, geometric parameters and , and are the fracture length and fracture groundwater height, respectively; The internal energy dissipation rate generated by the rock mass failure described in step C includes the internal energy dissipation rate of rock mass compression failure and rock mass tension failure, which are specifically as follows: Rock mass compression failure occurs in the rock mass crushing zone in the isosceles triangle area, and its energy dissipation rate is: , Formula 5; A is the rock crushing area. Substituting formula 1 and formula 2 into formula 5, it can be further simplified to: , Formula 6; The tensile failure of the rock mass occurs in the non-penetrating crack area at the bottom and rear edge of the dumped rock mass, and its energy dissipation rate is: + , Formula 7; is the tensile strength of rock mass.

[0011] As a further preferred embodiment of the present invention, the nonlinear equation for the safety factor FoS in step D is specifically: , Formula 8; When calculating FoS, the rock mass parameters after strength reduction need to be brought in, as follows: ; ; .

[0012] A system for use in any one of the above calculation methods, comprising: Equipment for obtaining geometric dimensions and physical and mechanical parameters of vertical rock slopes; A simplified mechanical model construction module for constructing a simplified mechanical model using the obtained geometric dimensions and physical and mechanical parameters of the vertical rock slope; Kinematic mechanism and slope safety factor calculation module established based on rigid-plastic assumption.

[0013] The established kinematic mechanism is used to simplify the mechanical model to calculate the velocity distribution in each area of the simplified mechanical model, the external work power acting on the rock mass, and the internal energy dissipation rate caused by rock mass failure. The operation process of the slope safety factor calculation module is as follows: assuming a series of toppling rotation centers, based on the strength reduction method and energy balance principle, a nonlinear equation for the safety factor FoS is established. Combined with the previously obtained data, it is solved using the Newton-Raphson method, and the smallest FoS is taken as the slope safety factor.

[0014] As a further preferred embodiment of the present invention, the equipment for obtaining the geometric dimensions and physical and mechanical parameters of a vertical rock slope includes a slope height measuring device, a slope width measuring device, a rock crushing zone width measuring device, a trailing edge crack depth measuring device, and a groundwater level height measuring device in the crack; a rock mass weight measuring device, a crack groundwater weight measuring device, a rock mass friction angle measuring device, a rock mass cohesion measuring device, a rock mass tensile strength measuring device, a horizontal seismic force coefficient measuring device, a vertical seismic force coefficient measuring device, and a tipping rotation angular velocity measuring device. The rock mass cohesion measuring device is a direct shear instrument, and the box walls of the upper shear box and the lower shear box of the direct shear instrument include a fixed wall and a lateral shear expansion adaption wall. The fixed wall is arranged perpendicular to the shear direction, and the lateral shear expansion adaption wall is arranged parallel to the shear direction. The lateral shear expansion adapting wall comprises a fixed plate, a spring connecting structure and a shear expansion adapting inner plate, wherein both ends of the fixed plate are fixedly connected to the fixed wall, the spring connecting structure is evenly arranged in the middle of the fixed plate, the shear expansion adapting inner plate is arranged on the inner side of the fixed plate, the outer end surface of the shear expansion adapting inner plate is fixedly connected to the spring connecting structure, the spring connecting structure comprises a threaded rod, an elastic force control push plate and a spring, the threaded rod is vertically penetrated through the middle of the fixed plate and is threadedly connected to the fixed plate, the elastic control push plate is arranged on the inner side of the fixed plate, the outer end surface of the elastic control push plate is rotatably connected to the inner end of the threaded rod, and the inner end surface of the elastic control push plate is fixedly connected to the spring, the outer end surface of the elastic control push plate is also provided with two guide grooves, and the position of the inner end surface of the fixed plate facing the guide groove is provided with a guide short column adapted to the guide groove.

[0015] Slope height measuring device, slope width measuring device, rock crushing zone width measuring device, trailing edge crack depth measuring device, crack groundwater level height measuring device; rock mass weight measuring device, crack groundwater weight measuring device, rock mass friction angle measuring device, rock mass tensile strength measuring device, horizontal seismic force coefficient measuring device, vertical seismic force coefficient measuring device and tilting rotation angular velocity measuring device are all commonly used equipment, belonging to the prior art and will not be repeated here. For example, the slope height and width measuring device can be a three-dimensional laser scanner, but the structure of the direct shear instrument is adjusted in this scheme. The direct shear instrument in the prior art is a commonly used This device is used for in-situ testing of the shear strength parameters (cohesion cc, internal friction angle ϕ) of rock / soil. However, the shear box of existing direct shear instruments is generally rigid. Therefore, when testing with air, it will restrict the lateral deformation of the rock mass, resulting in a "boundary effect". The rock mass cannot expand freely, which will cause the measured ϕ value to be too high. Therefore, in order to make the final result more accurate, this solution replaces the existing rigid shear box with a flexible shear box with a shear expansion-adaptive inner plate. This allows lateral expansion and effectively reduces the boundary effect. The position of the elastic control push plate can be adjusted by rotating the threaded rod, thereby adjusting the support force of the shear expansion-adaptive inner plate, which has better adaptability.

[0016] As a further preference of the present invention, the outer surface of the shear expansion adapting inner plate is provided with a simple support force recording short column, the surface of the simple support force recording short column is provided with a force scale, the simple support force recording short column is arranged perpendicular to the outer surface of the shear expansion adapting inner plate, the position of the fixed plate facing the simple support force recording short column is provided with an observation through hole adapted to the simple support force recording short column, the simple support force recording short column is passed through the observation through hole, the horizontal projection size of the upper shear box and the lower shear box of the direct shear instrument are both greater than 60cm×60cm, and the technology used to obtain the sample when testing large samples containing natural through-structure surfaces is frozen coring combined with CT digital reconstruction, and the specific steps of the frozen coring include a pre-freezing stage: drilling to the target After reaching the depth, liquid nitrogen is injected to freeze the area with a radius of 1m around the borehole; core drilling: a thin-walled double-tube drill with a diameter greater than 200mm is used, and the inner tube is lined with polytetrafluoroethylene coating to reduce friction; synchronous freezing: liquid nitrogen vapor is continuously injected during drilling to maintain low temperature; core extraction: the core is transported to the laboratory in a vacuum insulated container cooled by liquid nitrogen, and the temperature must be kept below -30℃ throughout the transportation; the core is kept in a low-temperature environment of -20℃ and placed in the shear box of the direct shear instrument. Before the test, it is thawed at a uniform speed to the natural moisture content. The CT digital reconstruction specifically performs a microfocus CT scan on the core sample with a resolution of ≤10μm during the scan, and digitally reconstructs the topology of the structural surface. When the obtained sample is tested with the above-mentioned direct shear instrument, low-viscosity epoxy resin needs to be injected into the sample to fill the microcracks before shearing.

[0017] The depth of the spring support can be clearly known by the simple support force recording short column, and the support force can be intuitively known by the scale set on it. The scale is a force scale converted from the support depth. There are some problems when using a direct shear instrument to obtain rock cohesion data, mainly including: the sample size is too small, and only the complete rock block may be cut, overestimating the overall strength; the natural structural surface is easily damaged during sample preparation; the above defects will cause the obtained data to be too far away from the actual data, and the large gap will affect the subsequent calculations. In order to reduce this error, the existing direct shear instrument is improved in this application. The horizontal projection dimensions of the upper shear box and the lower shear box of the direct shear instrument are both greater than 60cm×60cm, retaining the structural surface, avoiding the problem of the sample size being too small, and when coring, that is, when obtaining the sample, a special technology is used, which is a combination of liquid nitrogen freezing coring technology. and CT digital reconstruction technology provide high-fidelity parameters for the stability analysis of rigid-plastic slopes. Liquid nitrogen cryocoring technology uses liquid nitrogen (-196℃) to instantly freeze the pore water / fracture water in the rock mass, forming an "ice cementation" effect and temporarily enhancing the shear strength of the structural surface. After the core is frozen with liquid nitrogen, it is wrapped with a film to reduce unloading disturbance and keep the core in a low-temperature environment of -20℃ and placed in the shear box. It is slowly thawed to the natural moisture content before the test to avoid water migration during the melting process that changes the properties of the filling. CT digital reconstruction technology is to reproduce the real mechanical behavior of the structural surface in the numerical model. Finally, low-viscosity epoxy resin is injected into the specimen to fill microcracks before shearing, which can deal with the damage problem of the structural surface. Therefore, the improved direct shear apparatus can specifically make up for its defects such as specimen size limitations, stress distortion, and structural surface damage, effectively improving the accuracy of rock cohesion obtained by the direct shear apparatus.

[0018] As a further preference of the present invention, when obtaining the internal friction angle data of the rock mass, a data collaborative verification method is adopted. The data for collaborative verification include data obtained from laboratory triaxial tests, data obtained from in-situ direct shear tests, and data inferred from structural surface scanning JRC. After comparing the above data, if the deviation is greater than 15%, the average value is not adopted. If the deviation is less than 15%, further Bayesian optimization is performed to obtain data with a comprehensive error within ±5°. The rock mass tensile strength measuring device is a fracturing instrument.

[0019] In the slope stability evaluation based on the rigid-plastic hypothesis, the accuracy of rock cohesion must be coordinated with the accuracy of internal friction angle to achieve the best effect. The two together constitute the core parameters of the Mohr-Coulomb strength criterion, and their coordinated accuracy directly affects the reliability of the safety factor and the failure mechanism. Therefore, in addition to improving the accuracy of obtaining rock cohesion data, it is also necessary to improve the accuracy of obtaining internal friction angle data. In this scheme, a triple verification of triaxial test + in-situ direct shear + structural surface morphology analysis is applied to control the comprehensive error of the internal friction angle to ±5°. In order to further improve the accuracy in the above process, constant humidity control is required during the test to avoid the influence of moisture, so that it can better cooperate and synergize with the obtained rock cohesion data, making the final result more accurate. The fracturing instrument here can be a system of GCTS company, model SlimholeHF-100.

[0020] Compared with the prior art, the advantages of the present invention are: Starting from the rigid-plastic assumption and based on the energy balance principle, this paper proposes a method for calculating the stability of vertical rock slopes under earthquake action that can take into account the compression failure of the rock toe. Compared with the rigid body assumption, the rigid-plastic assumption can better reflect the actual failure state of the rock mass when it collapses. Therefore, compared with the rigid body limit equilibrium method, the stability analysis results obtained by this method are more reasonable and have important guiding significance for practical engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a technical roadmap for an energy method for calculating the stability of vertical rock slopes under earthquake action according to the present invention; Figure 2 It is a simplified mechanical model of vertical rock slope; Figure 3 The kinematic mechanism of the vertical rock slope; Figure 4 is the geometric size of the toe rock crushing zone; Figure 5 The calculation results of safety factor for different widths of crushing zone; Figure 6 It is a structural diagram of the upper shear box or the lower shear box of the direct shear apparatus; Figure 7 for Figure 6 Enlarged schematic diagram at X.

[0022] 1-fixed wall, 2-lateral shear expansion adapting wall, 21-fixed plate, 22-spring connection structure, 221-threaded rod, 222-elastic force control push plate, 223-spring, 23-shear expansion adapting inner plate, 231-simple support force recording short column, 3-guide groove, 4-guide short column. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is described below in conjunction with examples: It should be noted that the structures, proportions, sizes, etc. shown in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0024] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0025] Example 1: Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 As shown, taking a vertical rock slope as an example, the slope height H is 15m, the dumped rock mass width B is 2m. The rock mass weight γ is 28kN / m³, the rock mass cohesion c=1MPa, and the internal friction angle φ =35°, tensile strength =0MPa. There is a vertical tensile crack at the rear edge of the dumped rock mass, with a length of H c It is 8.5m, containing fissure water, and the water level height is H w is 2m, water density γ w It is 10kN / m³. It may collapse under the action of an earthquake. The horizontal earthquake acceleration coefficient used in the calculation is , vertical seismic acceleration coefficient .

[0026] The meanings of the symbols in the diagram and the calculation formula are as follows: , are the maximum principal stress and the minimum principal stress respectively; , is the friction angle and cohesion in the rock mass; is the tensile strength of rock mass; is the slope safety factor; is the velocity of vertex A on the bottom edge of the triangular plastic zone; b is the width of the rock crushing zone; h is the height of the rock crushing zone; , are the maximum principal strain rate and the minimum principal strain rate respectively; H is the height of the slope; B is the width of the slope rock mass; , , All are geometric parameters; is the angular velocity of the rock mass falling; is the horizontal velocity of the center of the dumped rock mass; is the vertical velocity of the center of the dumped rock mass; is the horizontal velocity of the trailing edge of the dumped rock mass; is the vertical velocity at the bottom of the dumped rock mass; is the gravity of the dumped rock mass; is the rock mass; is the power of gravity; , are the horizontal seismic force coefficient and the vertical seismic force coefficient respectively; , are horizontal earthquake force and vertical earthquake force respectively; It is the groundwater weight; is the crack length; is the height of groundwater in the fracture; is water pressure; is the power of water pressure; is the energy dissipation rate of rock crushing; is the energy dissipation rate of rock mass tension; , are the friction angle and cohesion of the rock mass after strength reduction; is the tensile strength of rock mass after strength reduction.

[0027] The proposed energy method is used to calculate the safety factor of the slope under earthquake action. First, a series of rock mass crushing zone widths b are assumed. Based on the strength reduction method and energy balance principle, a nonlinear equation for the safety factor FoS is established and solved using the Newton-Raphson method. Figure 5 The calculation results of safety factor for different rock crushing zone widths b are shown. The results show that the safety factor increases first and then decreases with the increase of the crushing zone width b. When b=0.18m, the minimum FoS safety factor is 0.9774. This means that in the horizontal earthquake acceleration coefficient If the calculation is based on the rigid body assumption, that is, b = 0m, then FoS approaches positive infinity, which will lead to the wrong conclusion that the slope is stable.

[0028] Specific embodiment 2: A system for any of the above calculation methods, comprising: Equipment for obtaining geometric dimensions and physical and mechanical parameters of vertical rock slopes; A simplified mechanical model construction module for constructing a simplified mechanical model using the obtained geometric dimensions and physical and mechanical parameters of the vertical rock slope; Kinematic mechanism and slope safety factor calculation module established based on rigid-plastic assumption.

[0029] The established kinematic mechanism is used to simplify the mechanical model to calculate the velocity distribution in each area of the simplified mechanical model, the external work power acting on the rock mass, and the internal energy dissipation rate caused by rock mass failure. The operation process of the slope safety factor calculation module is as follows: assuming a series of toppling rotation centers, based on the strength reduction method and energy balance principle, a nonlinear equation for the safety factor FoS is established. Combined with the previously obtained data, it is solved using the Newton-Raphson method, and the smallest FoS is taken as the slope safety factor.

[0030] Specific embodiment 3: Figure 6-7 As shown, this embodiment further illustrates the equipment for obtaining the geometric dimensions and physical and mechanical parameters of a vertical rock slope on the basis of specific embodiment 2. The equipment for obtaining the geometric dimensions and physical and mechanical parameters of a vertical rock slope includes a slope height measuring device, a slope width measuring device, a rock crushing zone width measuring device, a rear edge crack depth measuring device, and a groundwater level height measuring device in the crack; a rock mass weight measuring device, a crack groundwater weight measuring device, a rock mass friction angle measuring device, a rock mass cohesion measuring device, a rock mass tensile strength measuring device, a horizontal seismic force coefficient measuring device, a vertical seismic force coefficient measuring device, and a tipping rotation angular velocity measuring device. The rock mass cohesion measuring device is a direct shear instrument. The box walls of the upper shear box and the lower shear box of the direct shear instrument include a fixed wall 1 and a lateral shear expansion adaption wall 2. The fixed wall 1 is arranged perpendicular to the shear direction, and the lateral shear expansion adaption wall 2 is arranged parallel to the shear direction. It includes a fixed plate 21, a spring connection structure 22 and a shear expansion adapting inner plate 23. The two ends of the fixed plate 21 are fixedly connected to the fixed wall 1. The spring connection structure 22 is evenly arranged in the middle of the fixed plate 21. The shear expansion adapting inner plate 23 is arranged on the inner side of the fixed plate 21. The outer end surface of the shear expansion adapting inner plate 23 is fixedly connected to the spring connection structure 22. The spring connection structure 22 includes a threaded rod 221, an elastic force control push plate 222 and a spring 223. The threaded rod 221 It is vertically penetrated through the middle of the fixed plate 21 and is threadedly connected to the fixed plate 21. The elastic force control push plate 222 is arranged on the inner side of the fixed plate 21. The outer end surface of the elastic force control push plate 222 is rotatably connected to the inner end of the threaded rod 221. The inner end surface of the elastic force control push plate 222 is fixedly connected to the spring 223. The outer end surface of the elastic force control push plate 222 is also provided with two guide grooves 3. The position of the inner end surface of the fixed plate 21 facing the guide groove 3 is provided with a guide short column 4 adapted to the guide groove 3.

[0031] In the prior art, a direct shear apparatus is a commonly used device for in-situ testing of the shear strength parameters (cohesion cc, internal friction angle ϕ) of rock / soil. However, the shear box of the existing direct shear apparatus is generally a rigid shear box. Therefore, when testing with air, the lateral deformation of the rock mass will be restricted, resulting in a "boundary effect". The inability of the rock mass to dilate freely will cause the measured ϕ value to be too high. Therefore, in order to make the final result more accurate, in this solution, the existing rigid shear box is replaced with a flexible shear box with a dilatancy-adaptive inner plate, which allows lateral dilatation and effectively reduces the boundary effect. The position of the elastic control push plate can be adjusted by rotating the threaded rod, thereby adjusting the support force of the dilatancy-adaptive inner plate, which has better adaptability.

[0032] Specific embodiment 4: This embodiment further explains the direct shear instrument based on specific embodiment 3. The outer surface of the shear expansion adapting inner plate 23 is provided with a simple support force recording short column 231. The surface of the simple support force recording short column 231 is provided with a force scale. The simple support force recording short column 231 is arranged perpendicular to the outer surface of the shear expansion adapting inner plate 23. The position of the fixed plate 21 facing the simple support force recording short column 231 is provided with an observation through hole adapted to the simple support force recording short column 231. The simple support force recording short column 231 is passed through the observation through hole. The horizontal projection dimensions of the upper shear box and the lower shear box of the direct shear instrument are both greater than 60cm×60cm. The technology used to obtain the sample when testing large samples containing natural through-structure surfaces is frozen coring combined with CT digital gravity. The specific steps of the frozen coring include a pre-freezing stage: after drilling to the target depth, liquid nitrogen is injected to freeze the area within a radius of 1m around the drill hole; coring drilling: a thin-walled double-tube drill with a diameter greater than 200mm is used, and the inner tube is lined with a polytetrafluoroethylene coating to reduce friction; synchronous freezing: liquid nitrogen vapor is continuously injected during drilling to maintain the low temperature; core extraction: the core is transported to the laboratory in a vacuum insulated container cooled by liquid nitrogen, and the temperature must be maintained below -30°C throughout the transportation process; the core is kept in a low-temperature environment of -20°C and placed in the shear box of the direct shear instrument, and is thawed at a uniform rate to the natural moisture content before the test. The CT digital reconstruction specifically performs a microfocus CT scan on the coring sample with a resolution of ≤10μm during the scan, and digitally reconstructs the topology of the structural surface. When the obtained sample is tested using the above-mentioned direct shear instrument, low-viscosity epoxy resin must be injected into the sample to fill microcracks before shearing.

[0033] The depth of the spring support can be clearly known by the simple support force recording short column, and the support force can be intuitively known by the scale set on it. The scale is a force scale converted from the support depth. There are some problems when using a direct shear instrument to obtain rock cohesion data, mainly including: the sample size is too small, and only the complete rock block may be cut, overestimating the overall strength; the natural structural surface is easily damaged during sample preparation; the above defects will cause the obtained data to be too far away from the actual data, and the large gap will affect the subsequent calculations. In order to reduce this error, the existing direct shear instrument is improved in this application. The horizontal projection dimensions of the upper shear box and the lower shear box of the direct shear instrument are both greater than 60cm×60cm, retaining the structural surface, avoiding the problem of the sample size being too small, and when coring, that is, when obtaining the sample, a special technology is used, which is a combination of liquid nitrogen freezing coring technology. and CT digital reconstruction technology provide high-fidelity parameters for the stability analysis of rigid-plastic slopes. Liquid nitrogen cryocoring technology uses liquid nitrogen (-196℃) to instantly freeze the pore water / fracture water in the rock mass, forming an "ice cementation" effect and temporarily enhancing the shear strength of the structural surface. After the core is frozen with liquid nitrogen, it is wrapped with a film to reduce unloading disturbance and keep the core in a low-temperature environment of -20℃ and placed in the shear box. It is slowly thawed to the natural moisture content before the test to avoid water migration during the melting process that changes the properties of the filling. CT digital reconstruction technology is to reproduce the real mechanical behavior of the structural surface in the numerical model. Finally, low-viscosity epoxy resin is injected into the specimen to fill microcracks before shearing, which can deal with the damage problem of the structural surface. Therefore, the improved direct shear apparatus can specifically make up for its defects such as specimen size limitations, stress distortion, and structural surface damage, effectively improving the accuracy of rock cohesion obtained by the direct shear apparatus.

[0034] Specific embodiment 5: This embodiment further explains the steps of obtaining rock mass internal friction angle data and the device for obtaining rock mass tensile strength data on the basis of specific embodiment 3. When obtaining rock mass internal friction angle data, a data collaborative verification method is adopted. The data for collaborative verification include data obtained from laboratory triaxial tests, data obtained from in-situ direct shear tests, and data calculated by structural surface scanning JRC. After comparing the above data, if the deviation is greater than 15%, the average value is not adopted. If the deviation is less than 15%, further Bayesian optimization is performed to obtain data with a comprehensive error within ±5°. The rock mass tensile strength measuring device is a fracturing instrument.

[0035] In the slope stability evaluation based on the rigid-plastic hypothesis, the accuracy of rock cohesion must be coordinated with the accuracy of internal friction angle to achieve the best effect. The two together constitute the core parameters of the Mohr-Coulomb strength criterion, and their coordinated accuracy directly affects the reliability of the safety factor and the failure mechanism. Therefore, in addition to improving the accuracy of obtaining rock cohesion data, it is also necessary to improve the accuracy of obtaining internal friction angle data. In this scheme, a triple verification of triaxial test + in-situ direct shear + structural surface morphology analysis is applied to control the comprehensive error of the internal friction angle to ±5°. In order to further improve the accuracy in the above process, constant humidity control is required during the test to avoid the influence of moisture, so that it can better cooperate and synergize with the obtained rock cohesion data, making the final result more accurate. The fracturing instrument here can be a system of GCTS company, model SlimholeHF-100.

[0036] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0037] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0038] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0039] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0040] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

[0041] Many other changes and modifications can be made without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A method for calculating the stability of a vertical rock slope under earthquake force, characterized in that: The method comprises: A. Obtain the geometric dimensions and physical and mechanical parameters of the vertical rock slope and construct a simplified mechanical model of the vertical rock slope; B. Construct a rectangular coordinate system with the tilting rotation center as the origin, establish the corresponding kinematic mechanism based on the rigid-plastic assumption, and calculate the velocity distribution of each area of the model based on the constructed kinematic mechanism; C. Based on the constructed kinematic mechanism, the external work power acting on the rock mass and the internal energy dissipation rate caused by rock mass failure are calculated respectively; D. Assuming a series of toppling rotation centers, a nonlinear equation for the safety factor FoS is established based on the strength reduction method and energy balance principle, and solved using the Newton-Raphson method. The smallest FoS is taken as the slope safety factor.

2. The method for calculating the stability of a vertical rock slope under earthquake force according to claim 1, characterized in that: The geometric dimensions of the vertical rock slope described in step A include: slope height, slope width, rock crushing zone width, trailing edge crack depth, and groundwater level in the crack; The physical and mechanical parameters of the vertical rock slope described in step A include: rock mass, groundwater density in fractures, rock mass internal friction angle, rock mass cohesion, rock mass tensile strength, horizontal seismic force coefficient, vertical seismic force coefficient, and tilting rotation angular velocity.

3. The method for calculating the stability of a vertical rock slope under earthquake force according to claim 1, characterized in that: The rock crushing zone of the simplified mechanical model in step B is an isosceles triangle. The velocity of vertex A on the base of the triangular plastic zone is perpendicular to side OA. Point O on side OA is the vertex angle of the isosceles triangle. The size of the triangular plastic zone is determined according to the following method: Plastic compression failure of rock mass must satisfy the Mohr-Coulomb yield criterion and the associated flow law. The Mohr-Coulomb yield criterion of rock mass is: , Formula 1; In the formula and The maximum and minimum principal stresses, and are the friction angle and cohesion in the rock mass, The Law of Associative Flow states that: , Formula 2; In the formula and The maximum and minimum principal strain rates are respectively. Since the velocity of vertex A on the bottom edge of the triangular plastic zone is perpendicular to the edge OA, according to the geometric similarity relationship, we have: , Formula 3; In the formula is the width of the rock crushing zone, i.e. the length of the height of the base of the isosceles triangle; is the height of the rock crushing zone, that is, the length of the base of the isosceles triangle. Substituting the associated flow law into the above formula, we can obtain: , Formula 4; From this, the shape of the rock crushing zone can be determined, which is determined only by the internal friction angle of the rock mass and has nothing to do with the dimension b.

4. The method for calculating the stability of a vertical rock slope under earthquake force according to claim 1, characterized in that: The velocity distribution of each area of the model in step B specifically includes: Horizontal velocity of the center of the dumped rock mass , where is the angular velocity of rock mass tipping, and the geometric parameters , H is the slope height; Vertical velocity of the center of the dumped rock mass ; Horizontal velocity of the trailing edge of the dumped rock mass ; Vertical velocity at the bottom of the dumped rock mass .

5. The method for calculating the stability of a vertical rock slope under earthquake force according to claim 3, characterized in that: The external work power acting on the rock mass in step C includes the external work power of gravity, seismic force and water pressure, which are specifically as follows: The power of gravity , where the gravity of the dumped rock mass , is the weight of the rock mass, and B is the width of the dumped rock mass; The power of earthquake force , where the horizontal and vertical seismic forces are , , and are the horizontal and vertical seismic force coefficients, respectively; Water pressure power , where water pressure , is the fracture groundwater density, geometric parameters and , and are the fracture length and fracture groundwater height, respectively; The internal energy dissipation rate generated by the rock mass failure described in step C includes the internal energy dissipation rate of rock mass compression failure and rock mass tension failure, which are specifically as follows: Rock mass compression failure occurs in the rock mass crushing zone in the isosceles triangle area, and its energy dissipation rate is: , Formula 5; A is the rock crushing area. Substituting formula 1 and formula 2 into formula 5, it can be further simplified to: , Formula 6; The tensile failure of the rock mass occurs in the non-penetrating crack area at the bottom and rear edge of the dumped rock mass, and its energy dissipation rate is: + , Formula 7; is the tensile strength of rock mass.

6. The method for calculating the stability of a vertical rock slope under earthquake force according to claim 1, characterized in that: The nonlinear equation for the safety factor FoS described in step D is specifically: , Formula 8; When calculating FoS, the rock mass parameters after strength reduction need to be brought in, as follows: ； ； 。 7. A system for the calculation method according to any one of claims 1 to 6, characterized in that: include: Equipment for obtaining geometric dimensions and physical and mechanical parameters of vertical rock slopes; A simplified mechanical model construction module for constructing a simplified mechanical model using the obtained geometric dimensions and physical and mechanical parameters of the vertical rock slope; Kinematic mechanism and slope safety factor calculation module established based on rigid-plastic assumption.

8. A system according to claim 7, characterized in that: The equipment for obtaining the geometric dimensions and physical and mechanical parameters of a vertical rock slope includes a slope height measuring device, a slope width measuring device, a rock crushing zone width measuring device, a rear edge crack depth measuring device, and a groundwater level height measuring device in the crack; a rock mass weight measuring device, a crack groundwater weight measuring device, a rock mass friction angle measuring device, a rock mass cohesion measuring device, a rock mass tensile strength measuring device, a horizontal seismic force coefficient measuring device, a vertical seismic force coefficient measuring device, and a tilting rotation angular velocity measuring device. The rock mass cohesion measuring device is a direct shear instrument, and the box walls of the upper shear box and the lower shear box of the direct shear instrument include a fixed wall and a lateral shear expansion adaption wall. The fixed wall is arranged perpendicular to the shear direction, and the lateral shear expansion adaption wall is arranged parallel to the shear direction. The adaptable wall includes a fixed plate, a spring connection structure and a shear expansion adaptable inner plate, wherein both ends of the fixed plate are fixedly connected to the fixed wall, the spring connection structure is evenly arranged in the middle of the fixed plate, the shear expansion adaptable inner plate is arranged on the inner side of the fixed plate, and the outer end surface of the shear expansion adaptable inner plate is fixedly connected to the spring connection structure, the spring connection structure includes a threaded rod, an elastic force control push plate and a spring, the threaded rod is vertically penetrated through the middle of the fixed plate and is threadedly connected to the fixed plate, the elastic control push plate is arranged on the inner side of the fixed plate, the outer end surface of the elastic control push plate is rotatably connected to the inner end of the threaded rod, and the inner end surface of the elastic control push plate is fixedly connected to the spring, and the outer end surface of the elastic control push plate is also provided with two guide grooves, and the position of the inner end surface of the fixed plate facing the guide groove is provided with a guide short column adapted to the guide groove.

9. A system according to claim 8, characterized in that: The outer surface of the shear expansion adapting inner plate is provided with a simple support force recording short column, the surface of the simple support force recording short column is provided with a force scale, the simple support force recording short column is arranged perpendicular to the outer surface of the shear expansion adapting inner plate, the position of the fixed plate facing the simple support force recording short column is provided with an observation through hole adapted to the simple support force recording short column, the simple support force recording short column is passed through the observation through hole, the horizontal projection size of the upper shear box and the lower shear box of the direct shear instrument are both greater than 60cm×60cm, the technology used to obtain the sample when testing large samples containing natural through-structure surfaces is frozen coring combined with CT digital reconstruction, the specific steps of the frozen coring include the pre-freezing stage: after drilling to the target depth, inject Liquid nitrogen is used to freeze the area within a radius of 1m around the borehole; for core drilling, a thin-walled double-tube drill with a diameter greater than 200mm is used, and the inner tube is lined with a polytetrafluoroethylene coating to reduce friction; synchronous freezing: liquid nitrogen vapor is continuously injected during drilling to maintain low temperature; core extraction: the core is transported to the laboratory in a vacuum insulated container cooled by liquid nitrogen, and the temperature must be maintained below -30°C throughout the transportation process; the core is kept in a low-temperature environment of -20°C and placed in the shear box of the direct shear apparatus, and thawed at a uniform rate to the natural moisture content before the test. The CT digital reconstruction specifically performs a microfocus CT scan on the core sample with a resolution of ≤10μm during the scan, and digitally reconstructs the topology of the structural surface. When the obtained sample is tested using the above-mentioned direct shear apparatus, low-viscosity epoxy resin must be injected into the sample to fill the microcracks before shearing.

10. A system according to claim 8, characterized in that: When obtaining the internal friction angle data of the rock mass, a data collaborative verification method is adopted. The data for collaborative verification include data obtained from laboratory triaxial tests, data obtained from in-situ direct shear tests, and data calculated by JRC from structural surface scanning. After comparing the above data, if the deviation is greater than 15%, the average value is not used. If the deviation is less than 15%, further Bayesian optimization is performed to obtain data with a comprehensive error within ±5°. The rock mass tensile strength measuring device is a fracturing instrument.

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