Test method and apparatus for evolution of neighborhood stress field during fault instability

Abstract

A test method and apparatus for the evolution of a neighborhood stress field during fault instability. The test method comprises: step S1: manufacturing a substrate (101); S2, selecting a pre-configured surface (101a) of the substrate to fix a strain sensing member (102); step S3, fixing the substrate (101) to the position of a fault in an experimental model (103), and determining a coordinate position of the substrate (101) on the basis of an inclination angle of the fault; step S4, connecting the strain sensing member (102) to a strain gauge; step S5, applying in-situ triaxial stress to the experimental model (103), and applying disturbance to the experimental model (103) when the experimental model reaches equilibrium; and step S6, calculating a stress value on the basis of a strain component measured by the strain gauge, and capturing the dynamic evolution of a neighborhood stress field during fault plane instability caused by the disturbance.

Description

Method and device for testing the evolution of stress field in the neighborhood during fault instability Technical Field

[0001] The present application relates to the technical field of dynamic monitoring and analysis of rock fault stress fields in mining, petroleum, geology and civil engineering, and in particular to a testing method and device for the evolution of neighborhood stress fields when a fault becomes unstable. Background Art

[0002] The deep earth possesses a unique environment characterized by "three highs and one disturbance": high geostress, high geotemperature, high osmotic pressure, and even more severe engineering disturbances. Due to the evolution of crustal plates, fault structures are widely distributed at depth. This makes the development and utilization of deep space and resources more susceptible to geological disasters induced by mining disturbances, such as induced earthquakes and rock bursts. The dynamic evolution of the stress field state in the fault neighborhood is an important precursor to fault instability and the occurrence of induced disasters. Therefore, accurately capturing the evolution of the stress field on the fault during fracturing is a prerequisite for achieving geological disaster early warning.

[0003] However, the current conclusions and laws of experimental research on fault instability can no longer guide deep earth engineering.

[0004] Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a method and device for testing the evolution of the neighborhood stress field when a fault becomes unstable.

[0006] In order to achieve the above objectives, the technical solutions provided in the embodiments of the present application are as follows:

[0007] This application provides a method for testing the evolution of the stress field in the neighborhood when a fault fails, including:

[0008] Step S1: preparing a substrate;

[0009] Step S2: selecting a predetermined surface of the substrate to fix the strain detection element;

[0010] Step S3: fixing the substrate to the position of the fault plane in the experimental model, and determining the coordinate position of the substrate according to the inclination angle of the fault plane;

[0011] Step S4: connecting the strain detection member to the strain gauge;

[0012] Step S5: applying in-situ triaxial stress to the experimental model, and applying disturbance to the experimental model after the experimental model is balanced;

[0013] Step S6: Calculating stress values ​​according to the strain components measured by the strain gauges to capture the dynamic evolution of the neighborhood stress field when the fault plane is unstable due to disturbance.

[0014] In some possible embodiments, the strain detection component in step S2 includes a first strain gauge, a second strain gauge, and a third strain gauge;

[0015] The first strain gauge, the second strain gauge and the third strain gauge are sequentially arranged at a preset angle on a preset surface of the substrate;

[0016] The preset surface is arranged perpendicular to the fault plane.

[0017] In some possible embodiments, the substrate is a cubic structure, the preset angle is 45°, the first strain gauge is arranged on the preset surface along the Y direction, and the third strain gauge is arranged on the preset surface along the Z direction;

[0018] The step S5 of capturing the normal stress and shear stress when the fault plane is unstable specifically includes:

[0019] Obtain the linear strain in any direction of the preset surface

[0020] ε y =ε0;

[0021] ε z =ε 90 ;

[0022] Among them, ε y is the linear strain of the preset surface along the Y direction, ε z is the linear strain of the preset surface along the Z direction, γ xz is the shear strain of the preset surface, α is the angle between any direction of the preset surface and the Y direction, ε0 is the linear strain on the preset surface with an angle of 0° with the Y direction, and ε 90 The linear strain when the angle between the preset surface and the Y direction is 90°;

[0023] The shear strain γ of the preset surface xz =ε0+ε 90 -2ε 45 ;

[0024] The shear stress τ of the preset surface can be calculated by Hooke's law of shear xz =Gγ xz ;

[0025] Shear modulus of the matrix E is the elastic modulus of the substrate;

[0026] According to the shear reciprocity theorem, the shear stress τ on the fault plane can be obtained as zx =τ xz ;

[0027] According to Hooke's law of elasticity, the normal stress on the fault plane can be calculated as σ=Eε z =Eε 90 .

[0028] In some possible embodiments, fixing the substrate to the fault plane position in the experimental model in step S3 specifically includes:

[0029] fixing the matrix to the fault plate, and embedding the matrix into the experimental model by casting;

[0030] After the experimental model is demoulded, the fault plate is removed, and the gap between the matrix and the fault surface is filled with the same material as the experimental model. The material of the matrix is ​​the same as that of the implementation model.

[0031] In some possible embodiments, fixing the substrate to the experimental model in step S3 specifically includes: bonding a plurality of substrates to the fault plate through adhesive layers respectively;

[0032] The gap between the substrate and the fault plane is the gap between the substrate and the fault plane after the bonding layer is removed along with the fault plate.

[0033] In some possible embodiments, fixing the strain detection component in step S2 specifically includes:

[0034] The preset surface is cleaned, and the strain detection component is seamlessly attached and bonded to the preset surface.

[0035] In some possible embodiments, step S7 is further included between step S2 and step S3: providing a protective layer on the surface of the strain detection member and on the edge bonded to the preset surface.

[0036] In some possible embodiments, in step S4, the strain detection member is connected to the strain gauge via a lead wire, and the lead wire is led out from a side edge of the experimental model;

[0037] Before step S1, step S8 is also included: 3D printing a base mold, where the base mold is used to make the base.

[0038] The present application also provides a testing device for the evolution of the stress field in the neighborhood when a fault becomes unstable, comprising:

[0039] A testing device for analyzing the evolution of a neighborhood stress field during fault instability, for implementing any of the above-described testing methods, comprising:

[0040] An experimental model, wherein an inclined fault plane is provided in the experimental model;

[0041] A base body fixed at a fault plane position in the experimental model, wherein a strain detection member is fixed on a preset surface of the base body;

[0042] a strain gauge connected to the strain detection member;

[0043] A loading device is used to perform triaxial servo loading on the experimental model according to in-situ triaxial stress until a preset target load is reached, and when the experimental model is balanced, the loading device is also used to apply disturbance to the experimental model.

[0044] In some possible embodiments, the testing device further includes a protective layer, the strain detection member is bonded to the predetermined surface, and the protective layer covers the surface of the strain detection member and the edge bonded to the predetermined surface;

[0045] And / or, the strain detection member is connected to the strain gauge via a lead wire, and the lead wire is led out from a side edge of the experimental model;

[0046] And / or, the testing device further includes a substrate mold, and the substrate mold is used to make the substrate.

[0047] Through the above technical solution, it can be seen that this application has the following beneficial effects:

[0048] The testing method provided in the present application fixes a substrate to a fault plane position and determines the coordinate position of the substrate to accurately obtain the spatial coordinate position of the substrate in the experimental model; sets a strain detection member on the substrate and connects the strain detection member to a strain gauge, so that the strain detection member transmits the detected strain component to the strain gauge, and the strain gauge calculates the stress value based on the strain component to obtain the strain analysis under the plane state of the fault plane; applies in-situ triaxial stress and disturbance to the experimental model to obtain the normal stress and shear stress when the fault plane is unstable, thereby realizing the capture of the dynamic evolution of the stress field in the neighborhood when the disturbance induces fault instability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0050] FIG1 is a flow chart of a testing method provided in an embodiment of the present application;

[0051] FIG2 is a schematic diagram of the three-dimensional structure of a substrate provided in an embodiment of the present application;

[0052] FIG3 is a schematic diagram of a three-dimensional structure of a substrate provided in an embodiment of the present application installed in an experimental model;

[0053] FIG4 is a schematic diagram of a base mold provided in an embodiment of the present application.

[0054] In Figures 1 to 4:

[0055] Base 101, preset surface 101a, strain detection member 102, first strain gauge 102-1, second strain gauge 102-2, third strain gauge 102-3, experimental model 103, side edge 103a, water injection channel 103b, fault plate 104, lead 105, base mold 106. DETAILED DESCRIPTION

[0056] The present application will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are merely for explaining the related application and are not intended to limit the application. The described embodiments are merely a portion of the embodiments of the present application and are not intended to be exhaustive. All other embodiments derived by persons of ordinary skill in the art based on the embodiments in the present application without creative effort are intended to fall within the scope of protection of the present application.

[0057] In conjunction with Figures 1-4, this application provides a method for testing the evolution of the stress field in the vicinity of a fault during instability, addressing the problem in existing research that it is impossible to monitor the dynamic evolution of the stress field in the vicinity of the fault plane under in-situ triaxial stress. As shown in Figure 1, the testing method includes steps S1, S2, S3, S4, S5, and S6.

[0058] Step S1: manufacturing a substrate 101 .

[0059] Specifically, the substrate 101 can be a cubic structure. An embodiment of the present application discloses that the various faces of the substrate 101 are arranged perpendicular to each other, as shown in Figure 2, that is, the angle is 90°, the maximum deviation does not exceed 0.25°, the maximum side length error does not exceed 0.1mm, and the inclination of each face is less than 0.05mm.

[0060] It should be noted that the above structure of the base 101 is only a specific embodiment of the present application. In actual applications, the base 101 can also be set to other shapes.

[0061] In order to facilitate the provision of a smooth connection surface for subsequent installation or connection with other components, an embodiment of the present application discloses that after the base 101 is manufactured, the six surfaces of the base 101 are ground and polished to ensure the flatness of each surface.

[0062] Step S2: selecting a predetermined surface 101 a of the substrate 101 to fix the strain sensing member 102 .

[0063] 2 , the strain detection member 102 may be bonded to a predetermined surface 101 a of the substrate 101. It should be noted that the predetermined surface 101 a refers to a flat and smooth surface of the substrate 101.

[0064] In order to ensure the firmness of the connection between the strain detection member 102 and the substrate 101, an embodiment of the present application discloses that before bonding the strain detection member 102, the preset surface 101a is first cleaned, and the strain detection member 102 is seamlessly bonded to the preset surface 101a. Specifically, the preset surface 101a can be cleaned by wiping it clean with anhydrous alcohol. After wiping it clean, industrial-grade moisture-proof instant glue is used for bonding. After bonding, press for 30 seconds to ensure that the strain detection member 102 and the substrate 101 are completely bonded without any gaps. The industrial-grade instant glue has a temperature resistance of -40°C to 120°C, a viscosity of 110mPa.s, and a maximum shear strength of 20MPa.

[0065] Step S3: Fix the substrate 101 to the position of the fault plane in the experimental model 103, and determine the coordinate position of the substrate 101 according to the inclination angle of the fault plane.

[0066] Specifically, the preset surface 101a of the substrate 101 faces downward and is arranged perpendicular to the fault plane. As shown in Figure 3, the lead 105 of the strain detection piece 102 on the substrate 101 is led out from the side edge 103a of the experimental model 103 to ensure that it does not affect the six-sided force of the experimental model 103.

[0067] It should be noted that the number of substrates 101 is not limited to one, and may be two or more, and each substrate 101 is disposed at a position on the fault plane at intervals.

[0068] Step S4: Connect the strain detection member 102 to the strain gauge.

[0069] Specifically, the strain sensing element 102 is connected to the strain gauge via a lead 105, thereby enabling signal transmission. Each strain sensing element 102 on the substrate 101 can be connected to the same strain gauge via a lead 105, which reduces the number of strain gauges required and improves the accuracy of the test data, thereby achieving effectiveness testing.

[0070] Step S5: applying in-situ triaxial stress to the experimental model 103 , and applying disturbance to the experimental model 103 after the experimental model 103 is balanced.

[0071] The loading device is based on the in-situ stress σ h , in-situ stress σ z and in-situ stress σ HThe experimental model 103 is subjected to triaxial servo loading until the target load is reached. The in-situ triaxial stresses are all surface forces uniformly distributed on the surface of the experimental model 103. The disturbance is applied after the experimental model 103 reaches equilibrium.

[0072] Specifically, the disturbance includes hydraulic fracturing disturbance. It should be noted that the disturbance including hydraulic fracturing disturbance is only one specific embodiment of the present application. In actual applications, the disturbance may also include coal mine tunnel excavation disturbance, or the disturbance may include coal mine tunnel excavation disturbance and hydraulic fracturing disturbance, etc.

[0073] Step S6: Calculate the stress value based on the strain component measured by the strain gauge to capture the dynamic evolution of the neighborhood stress field when the fault plane is unstable due to the disturbance.

[0074] In this embodiment, taking hydraulic fracturing disturbance as an example of disturbance, this application applies in-situ triaxial stress and hydraulic fracturing disturbance to the experimental model 103 to obtain the normal stress and shear stress when the fault plane becomes unstable, thereby realizing the capture of the dynamic evolution of the neighborhood stress field when the hydraulic fracturing disturbance induces fault instability.

[0075] In one embodiment of the present application, the strain detection element 102 in step S2 includes a first strain gauge 102-1, a second strain gauge 102-2, and a third strain gauge 102-3. The first strain gauge 102-1, the second strain gauge 102-2, and the third strain gauge 102-3 are sequentially arranged at a preset angle on the preset surface 101a of the substrate 101.

[0076] Specifically, in one embodiment of the present application, as shown in FIG2 , the substrate 101 has a cubic structure with a predetermined angle of 45°. The first strain gauge 102-1 is disposed on the predetermined surface 101a along the Y direction, the third strain gauge 102-3 is disposed on the predetermined surface 101a along the Z direction, and the second strain gauge 102-2 is disposed between the first strain gauge 102-1 and the third strain gauge 102-3, and the angles formed with the first strain gauge 102-1 and the third strain gauge 102-3 are both 45°. The predetermined surface 101a is perpendicular to the fault plane, and therefore, the distance from the surface of the substrate 101 opposite the predetermined surface 101a to the predetermined surface 101a is in the X direction, as shown in FIG3 .

[0077] In one embodiment of the present application, the strain sensing element 102 further includes a base material layer 102-4. The first strain gauge 102-1, the second strain gauge 102-2, and the third strain gauge 102-3 are all disposed on the base material layer 102-4. The base material is phenolic-epoxy, and the base material layer 102-4 has a base length x base width of 9 mm x 9 mm. The operating temperature range is -20°C to 80°C, and the sensitivity coefficient is 1±1%. The provision of the base material layer 102-4 facilitates the installation of the first strain gauge 102-1, the second strain gauge 102-2, and the third strain gauge 102-3 on the substrate 101.

[0078] In step S6, capturing the dynamic evolution of the neighborhood stress field when the fault plane is unstable due to the disturbance specifically includes obtaining the shear stress and normal stress on the fault plane.

[0079] Obtain the linear strain in any direction of the preset surface 101a Among them, ε y is the linear strain of the preset surface along the Y direction, ε z is the linear strain of the preset surface along the Z direction, γ xz is the shear strain of the preset surface, and α is the angle between any direction of the preset surface and the Y direction.

[0080] From Figure 3 we can get: y =ε0,ε z =ε 90 ; Wherein, ε0 is the linear strain on the preset surface 101a with an angle of 0° with the Y direction, ε 90 It is a linear strain on the preset surface 101 a with an angle of 90° with the Y direction.

[0081] Set α to 45°, ε y =ε0,ε z =ε 90 Substituting into the linear strain formula, we can get: The shear strain γ of the preset surface 101a is xz =ε0+ε 90 -2ε 45 .

[0082] The shear stress τ of the preset surface 101a can be calculated by Hooke's law: xz =Gγ xz , the shear modulus of the substrate 101 E is the elastic modulus of the substrate 101 .

[0083] According to the shear reciprocity theorem, the shear stress τ on the fault plane can be obtained zx =τ xz , that is, τ zx =Gγ xz .

[0084] According to Hooke's law of elasticity, the normal stress on the fault plane can be calculated as σ=Eε z =Eε 90 .

[0085] It is understandable that the above-disclosed arrangement of the stress detection component, which includes the first strain gauge 102-1, the second strain gauge 102-2, and the third strain gauge 102-3, which are sequentially spaced at a 45° angle on the predetermined surface 101a of the substrate 101, is only one specific embodiment of the present application. In actual applications, the stress detection component may also include the first strain gauge 102-1, the second strain gauge 102-2, and the third strain gauge 102-3, which are sequentially spaced at a 90° angle between the first strain gauge 102-1 and the third strain gauge 102-3, and the second strain gauge 102-2 is disposed between the first strain gauge 102-1 and the third strain gauge 102-3, and is disposed at a 30° angle to the first strain gauge 102-1 and a 60° angle to the third strain gauge 102-3. Of course, the stress detection component may also include four or more strain gauges, etc. As long as the corresponding angles are substituted into the above-mentioned linear strain formula to obtain the shear stress and normal stress on the fault plane, the method falls within the scope of protection of the present application.

[0086] In one embodiment of the present application, fixing the substrate 101 to the fault plane position in the experimental model 103 in step S3 specifically includes: fixing the substrate 101 to the fault plate 104, and embedding the substrate 101 into the interior of the experimental model 103 by casting; after demolding the experimental model 103, removing the fault plate 104, and using the same material as the experimental model 103 to fill the gap between the substrate 101 and the fault plane.

[0087] Specifically, fixing the substrate 101 to the experimental model 103 in step S3 specifically includes: bonding the plurality of substrates 101 to the fault plate 104 respectively through adhesive layers.

[0088] The bonding layer may specifically be a high-viscosity waterproof nano-glue layer, and the high-viscosity waterproof nano-glue can ensure the connection firmness between the substrate 101 and the fault plate 104 .

[0089] The fault plate 104 can be made of a zinc plate with a thickness of 0.5 mm, which is not easy to deform and is corrosion-resistant, and can ensure the flatness of the fault surface. According to research needs, a certain number of substrates 101 are installed and arranged on the fault plate 104 using a high-viscosity waterproof nano-glue with a thickness of 0.2 mm. The preset surface 101a of the substrate 101 is perpendicular to the fault plate 104 and is at the bottom of the substrate 101. The lead 105 of the strain brick is led out from the side edge 103a of the experimental model 103 to ensure that it does not affect the six-sided force of the experimental model 103.

[0090] After the bonding layer is removed along with the fault plate 104 , a gap exists between the substrate 101 and the fault surface. The gap is filled with the same material as that of the experimental model 103 to make the end surface smooth.

[0091] It should be noted that one side of the fault plate 104 extends outside the test model 103. When disassembly is required, the portion extending outside the test model 103 can be used to pull the fault plate 104 out of the test model 103. To facilitate the removal of the fault plate 104, a handle can be installed on the portion of the fault plate 104 extending outside the test model 103, or a hole or groove for handholding can be provided.

[0092] In order to achieve consistent coordination of stress conduction, an embodiment of the present application discloses that the material of the substrate 101 is the same as the material of the implementation model.

[0093] In one embodiment of the present application, step S7 is further included between step S2 and step S3: providing a protective layer on the surface of the strain detection member 102 and the edge where it is bonded to the preset surface 101 a .

[0094] The protective layer prevents moisture from getting between the strain gauge 102 and the base 101, which could cause the strain gauge 102 to fall off. Specifically, the protective layer can be made of transparent silicone rubber. While providing protection, it can also detect the status of the strain gauge, facilitating subsequent testing. The transparent silicone rubber has a tensile strength of 4 MPa, an operating temperature range of -60°C to 200°C, a shear strength of 4 MPa, and cures within 24 hours at 25°C. To ensure coordinated deformation, the base 101 is clean except for the glue on the surface and edges of the strain gauge 102.

[0095] In one embodiment of the present application, step S8 is further included before step S1: 3D printing the base mold 106 , where the base mold 106 is used to manufacture the base 101 .

[0096] Specifically, the base mold 106 is made of Vero Clear (transparent material), and a circular hole with a diameter equal to the side length of the base 101 is opened at the bottom of the base mold 106 to facilitate demoulding. When the base 101 is manufactured, the circular hole is sealed with tape.

[0097] The present application also provides a testing device for the evolution of the stress field in the neighborhood of a fault during instability, which is used to implement the testing method in any of the above embodiments. The testing device includes an experimental model 103, a substrate 101, a strain detector 102, a strain gauge, and a loading device.

[0098] The experimental model 103 is arranged in a cubic shape, and an inclined fault plane is arranged in the experimental model 103 . As shown in FIG3 , the inclination angle of the fault plane is β.

[0099] The substrate 101 is fixed at the fault plane position within the experimental model 103. Specifically, the substrate 101 is fixed to the fault plate 104 and embedded into the interior of the experimental model 103 by casting. After the experimental model 103 is demolded, the fault plate 104 is removed, and the gap between the substrate 101 and the fault plane is filled with the same material as the experimental model 103, thereby achieving the fixation of the substrate 101 at the fault plane position.

[0100] A strain sensing element 102 is fixed to a predetermined surface 101a of the substrate 101. Specifically, the strain sensing element 102 includes a first strain gauge 102-1, a second strain gauge 102-2, and a third strain gauge 102-3. The first strain gauge 102-1, the second strain gauge 102-2, and the third strain gauge 102-3 are sequentially arranged on the predetermined surface 101a of the substrate 101 at a predetermined angle. The substrate 101 has a cubic structure with a predetermined angle of 45°. The first strain gauge 102-1 is arranged along the Y direction on the predetermined surface 101a, and the third strain gauge 102-3 is arranged along the Z direction on the predetermined surface 101a. The second strain gauge 102-2 is arranged between the first strain gauge 102-1 and the third strain gauge 102-3, and the angles formed with the first strain gauge 102-1 and the third strain gauge 102-3 are both 45°. The preset surface 101 a is perpendicular to the fault plane, so the distance from the surface of the substrate 101 opposite to the preset surface 101 a to the preset surface 101 a is in the X direction, as shown in FIG. 2 .

[0101] The strain gauge is connected to the strain detection member 102 to achieve signal transmission. Specifically, the strain detection member 102 and the strain gauge are connected via leads 105, and the leads 105 are led out from the side edges 103a of the test model 103 to ensure that the six sides of the test model 103 are not affected.

[0102] The loading device is used to perform three-axis servo loading on the experimental model 103 according to the in-situ three-axis stress until the preset target load is reached, and when the experimental model 103 is balanced, the loading device is also used to apply disturbance to the experimental model 103. Specifically, the loading device is used to perform three-axis servo loading on the experimental model 103 according to the in-situ stress σ h , in-situ stress σ z and in-situ stress σ H The experimental model 103 is subjected to triaxial servo loading until the target load is reached. The in-situ triaxial stresses are all surface forces uniformly distributed on the surface of the experimental model 103. The disturbance is applied after the experimental model 103 reaches equilibrium.

[0103] In one embodiment of the present application, the testing device further includes a protective layer. The strain sensing element 102 is bonded to the predetermined surface 101a, and the protective layer covers the surface of the strain sensing element 102 and the edge where it is bonded to the predetermined surface 101a. The provision of the protective layer prevents moisture from getting between the strain sensing element 102 and the substrate 101, which could cause the strain sensing element 102 to fall off.

[0104] To facilitate the processing of the substrate 101, in one embodiment of the present application, the testing device further includes a substrate mold 106, which is used to manufacture the substrate 101. As shown in FIG4 , the substrate mold 106 is provided with a plurality of cavities for manufacturing the substrate 101, thereby improving the manufacturing efficiency of the substrate 101.

[0105] In one embodiment of the present application, a water injection channel 106 is further provided in the experimental model 103 to achieve hydraulic fracturing disturbance. The possible slip direction of the fault plane is shown in the arrow direction in FIG3 .

[0106] Specifically, the water injection channel 106 can be formed by drilling a hole in the cast block after the casting is completed; the water injection channel 106 can also be formed by placing a tube in the empty test model 103 before casting, with one end of the tube extending outside the test model 103, and then injecting casting material into the test model 103. After solidification, the tube is removed.

[0107] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the descriptions of the similarities and differences between the various embodiments. The methods disclosed in the embodiments are described briefly because they correspond to the devices disclosed in the embodiments. For relevant details, refer to the device descriptions.

[0108] It should also be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0109] The above description of the disclosed embodiments will enable those skilled in the art to implement or use various modifications of these embodiments, and it will be apparent to those skilled in the art that the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for testing the evolution of stress field in the neighborhood when a fault fails, characterized in that: include: Step S1: preparing a substrate (101); Step S2: selecting a predetermined surface (101a) of the substrate (101) to fix the strain detection member (102); Step S3: fixing the substrate (101) to the position of the fault plane in the experimental model (103), and determining the coordinate position of the substrate (101) according to the inclination angle of the fault plane; Step S4: connecting the strain detection member (102) to the strain gauge; Step S5: applying in-situ triaxial stress to the experimental model (103), and applying disturbance to the experimental model (103) after the experimental model (103) is balanced; Step S6: Calculating stress values ​​according to the strain components measured by the strain gauges to capture the dynamic evolution of the neighborhood stress field when the fault plane is unstable due to disturbance.

2. The method for testing the evolution of the neighborhood stress field during fault instability according to claim 1, characterized in that: The strain detection component (102) in step S2 includes a first strain gauge (102-1), a second strain gauge (102-2) and a third strain gauge (102-3); The first strain gauge (102-1), the second strain gauge (102-2), and the third strain gauge (102-3) are sequentially arranged at a preset angle on a preset surface (101a) of the base (101); The preset surface (101a) is arranged perpendicular to the fault plane.

3. The method for testing the evolution of the stress field in the neighborhood during fault instability according to claim 2, characterized in that: The base (101) is a cubic structure, the preset angle is 45°, the first strain gauge (102-1) is arranged on the preset surface (101a) along the Y direction, and the third strain gauge (102-3) is arranged on the preset surface (101a) along the Z direction; The step S6 of capturing the normal stress and shear stress when the fault plane is unstable specifically includes: Obtaining the linear strain in any direction of the preset surface (101a) e y =ε0; e z =e 90 ; Among them, ε y is the linear strain of the preset surface along the Y direction, ε z is the linear strain of the preset surface along the Z direction, γ xz is the shear strain of the preset surface, α is the angle between any direction of the preset surface and the Y direction, ε0 is the linear strain on the preset surface with an angle of 0° with the Y direction, and ε 90 The linear strain when the angle between the preset surface and the Y direction is 90°; The shear strain γ of the preset surface xz =ε0+ε 90 -2ε 45 ; The shear stress τ of the preset surface can be calculated by Hooke's law of shear xz =Gγ xz ; Shear modulus of the matrix E is the elastic modulus of the substrate; According to the shear reciprocity theorem, the shear stress τ on the fault plane can be obtained as zx =τ xz ; According to Hooke's law of elasticity, the normal stress on the fault plane can be calculated as σ=Eε z =Eε 90 .

4. The method for testing the evolution of the neighborhood stress field during fault instability according to claim 1, characterized in that: The step S3 of fixing the substrate (101) to the fault plane position in the experimental model (103) specifically includes: Fixing the substrate (101) to the fault plate (104), and embedding the substrate (101) into the interior of the experimental model (103) by casting; After the experimental model (103) is demoulded, the fault plate (104) is removed, and the gap between the substrate (101) and the fault surface is supplemented with the same material as the experimental model (103), and the material of the substrate (101) is the same as that of the implementation model.

5. The method for testing the evolution of the stress field in the neighborhood during fault instability according to claim 4, characterized in that: The step S3 of fixing the substrate (101) to the experimental model (103) specifically includes: attaching a plurality of substrates (101) to the fault plate (104) through adhesive layers respectively; The gap between the substrate (101) and the fault plane is the gap between the substrate (101) and the fault plane after the bonding layer and the fault plate (104) are removed.

6. The method for testing the evolution of the stress field in the neighborhood during fault instability according to claim 1, characterized in that: The fixing of the strain detection member (102) in step S2 specifically includes: The preset surface (101a) is cleaned, and the strain detection component (102) is seamlessly attached and bonded to the preset surface (101a).

7. The method for testing the evolution of the stress field in the neighborhood during fault instability according to claim 6, characterized in that: The method further includes step S7 between step S2 and step S3: providing a protective layer on the surface of the strain detection member (102) and at the edge where the protective layer is bonded to the preset surface (101a).

8. The method for testing the evolution of the neighborhood stress field during fault instability according to any one of claims 1 to 7, characterized in that: In the step S4, the strain detection member (102) is connected to the strain gauge via a lead (105), and the lead (105) is led out from a side edge (103a) of the experimental model (103); Before step S1, step S8 is also included: 3D printing a base body (101) mold, wherein the base body (101) mold is used to manufacture the base body (101).

9. A device for testing the evolution of stress field in the neighborhood when a fault is unstable, characterized in that: For implementing the test method according to any one of claims 1 to 8, the test device comprises: An experimental model (103), wherein an inclined fault is provided in the experimental model (103); A substrate (101) is fixed at a fault plane position in the experimental model (103), wherein the substrate A strain detection member (102) is fixed to the preset surface (101a) of (101); a strain gauge connected to the strain detection member (102); A loading device is used to perform three-axis servo loading on the experimental model (103) according to in-situ three-axis stress until a preset target load is reached, and when the experimental model (103) is balanced, the loading device is also used to apply disturbance to the experimental model (103).

10. The testing device according to claim 9, characterized in that: It also includes a protective layer, the strain detection member (102) is bonded to the preset surface (101a), and the protective layer covers the surface of the strain detection member (102) and the edge bonded to the preset surface (101a); And / or, the strain detection member (102) is connected to the strain gauge via a lead (105), and the lead (105) is led out from a side edge (103a) of the experimental model (103); And / or, the testing device further comprises a substrate mold (106), wherein the substrate mold (106) is used to manufacture the substrate (101).

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