Rock-like resin-based engineering rock mass anchoring instability simulation test piece and preparation method thereof

Abstract

The application discloses a kind of engineering rock mass anchoring instability simulation test piece based on rock-like resin and its preparation method, to solve the problem that existing simulation test piece cannot intuitively and clearly observe the evolution law and effect of anchoring structure and fault and other adverse geological body on slope engineering instability.The test piece for engineering rock mass anchoring instability simulation is obtained by selecting and burying fault structure and anchoring structure with good simulation characteristics in high brittleness transparent resin.The preparation method includes resin casting material preparation, pouring mold setting, fault structure layout, pre-stressed anchor layout, pouring and curing.The formed simulation test piece can be used to simulate various rock mass geological conditions, and the deformation, displacement and other conditions of rock mass anchoring instability process under load can be clearly observed, as well as the evolution law of geological fault on shear slip surface.

Description

Technical Field

[0001] This invention application relates to the field of rock mass model simulation test technology, specifically to a simulation specimen for the anchoring instability of engineering rock mass based on rock-like resin and its preparation method. Background Technology

[0002] Currently, rock mass anchoring technology has been widely applied in various engineering fields, one of which is slope reinforcement. Slope anchoring instability is a common geological hazard widely distributed worldwide, directly threatening people's lives and property, major engineering construction, and the safety of the ecological environment. Prestressed anchoring is a commonly used technique for slope reinforcement and has been widely applied in slope protection projects in many fields such as highways, railways, water conservancy, and construction. However, the prestress of the anchoring structure changes with factors such as rock mass temperature, rock mass creep, steel relaxation, and groundwater. In addition, under the influence of loads and various sudden external factors, the anchoring structure will also face damage accumulation, leading to various forms of anchoring system failure such as bond failure, anchor breakage or shear failure, and anchor failure, thus affecting the stability of the rock mass structure and threatening engineering safety. Currently, research both domestically and internationally on the deterioration process and influencing mechanism of slope stability after prestressed anchor failure is limited. This lagging theoretical research has led to varying degrees of anchored slope instability accidents during or after engineering construction, severely disrupting traffic, damaging the environment and ecological balance, and ultimately causing significant economic losses. Studying the impact mechanism of anchor failure on slope stability is of significant theoretical importance and practical application value for guiding engineering practice and construction quality.

[0003] Due to the characteristics of geotechnical engineering and slope engineering, anchoring structures and adverse geological masses are important factors affecting slope stability. The opacity of natural rock masses makes it impossible to intuitively understand the failure evolution of their internal structure. Traditional testing methods such as strain gauges and load sensors, CT scans, and nuclear magnetic resonance imaging are time-consuming, material-intensive, and expensive, and still lack intuitiveness. Some domestic and foreign scholars have used rock and mortar as similar materials to simulate the fracture evolution of slope rock masses, but the drawback is that the materials are opaque, making it impossible to intuitively observe the failure evolution process of the internal structure of the rock mass, and it is difficult to simulate real engineering conditions.

[0004] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The inventors discovered through research that current research on the failure mechanisms of slope anchorage instability stems from several challenges: the inability to clearly and intuitively observe the effect of anchorage structures on slope instability, the inability to effectively simulate slope surfaces, and the difficulties in embedding anchorage structures. To address these issues, this application constructs test specimens suitable for simulating anchorage instability in engineering rock masses by embedding fault structures and anchorage structures with good simulation characteristics in highly brittle transparent resin. A method for preparing these simulation specimens that ensures specimen quality is also provided.

[0006] According to one aspect of this application, a simulation specimen for the anchoring instability of engineering rock mass based on rock-like resin is provided to test and simulate the damage evolution law of the support structure and the entire process of deformation and failure of the rock mass when the anchoring of the engineering rock mass is unstable. It includes a rock-like mass for simulating engineering rock mass and the support structure and geological structure embedded therein, which is cast from a highly brittle transparent resin.

[0007] The support structure includes prestressed anchors, which are formed by applying prestress to corresponding scaled anchor rods through pre-tensioning or post-tensioning methods; the geological structure includes fault models; the high-brittle transparent resin is a mixture of CY-39 epoxy resin and YS-T31 curing agent in a mass ratio of 100:30 to 35, and it has good rock-like properties at -15 to -10℃.

[0008] The geometric, physical, and mechanical parameters of the simulated specimen can be determined by the similarity ratio of conventional model tests.

[0009] In some embodiments disclosed in this application, the scaled-down anchor bolt includes an anchor head, a rod body, and an anchoring tail seat sequentially screwed together. The top of the anchor head is conical, and its outer circumference is provided with threaded grooves to increase the anchoring force. The anchoring tail seat includes a washer plate and a hexagonal nut that passes through the washer plate for screwing the rod body. The anchoring tail seat can be a single piece, with an overall shape consisting of a washer plate with gradually varying thickness and a hexagonal nut with a variable cross-section. The increased cross-section allows it to withstand high stress, and the hexagonal nut has internal threads for connecting with the rod body and fixing it to the slope.

[0010] In some embodiments disclosed in this application, the scaled-down anchor bolt further includes:

[0011] An extended rod, cast from highly brittle transparent resin, has one end wrapped around and fixed to the anchor head, and the other end a clamping part for connecting to a corresponding tensioning device, to achieve the application of pre-tensioning prestress; or

[0012] A thin-walled impermeable sleeve, cast from highly brittle transparent resin, is used to fit over the rod body to prevent the rock-like castable from bonding with the rod body, thereby enabling the application of post-tensioning prestress to the scaled-down anchor rod.

[0013] In some embodiments disclosed in this application, the fault model is made of a transparent PP plate based on the simulated rock mass fault structure.

[0014] According to one aspect of this application, a method for preparing a simulation specimen for rock mass anchoring instability is provided, comprising the following steps:

[0015] (1) Preparation of casting material: Take CY-39 epoxy resin and YS-T31 curing agent and mix them at a mass ratio of 100:32.5. After stirring evenly, remove air bubbles under vacuum to obtain resin casting material for later use.

[0016] (2) Setting up the specimen casting mold: Based on the scale of the test, cut out the mold plate with the corresponding shape and size, and a PLA plastic block to simulate the slope, and surround it to form the specimen casting mold with the corresponding shape.

[0017] (3) Fault structure setting: The fault model plate is cut from transparent PP sheet into the shape required for the simulation test, and the fault model plate is fixed in the corresponding spatial position in the specimen casting mold based on the simulated geological conditions; for example, after determining the fault position according to the geological conditions, holes with a diameter of 1 mm are drilled at multiple corners of the fault model plate, cotton thread is threaded through them, and the position is adjusted appropriately by the other end of the cotton thread, and then it is fixed to the mold with strong adhesive.

[0018] (4) Installation of prestressed anchor bolts: Drill holes in the PLA block, insert the corresponding scaled anchor bolts through them and seal them in place; and apply prestress as follows:

[0019] ①Pre-tensioning method: One end of the extended rod cast by the resin casting material is wrapped and fixed to the anchor head, and the other end and the tail end of the anchor rod are respectively connected to the tensioning equipment to perform simultaneous mechanical tensioning at both ends;

[0020] ② Post-tensioning method: The seepage-proof sleeve formed by the resin casting material is fitted onto the outside of the rod and sealed at both ends. After the specimen is cast and cured, the anchor rod is tensioned, and then the resin casting material is densely filled into the seepage-proof sleeve for secondary curing.

[0021] (5) Casting and curing: The resin casting material is poured into the casting mold of the specimen with corresponding anchor rods and fault models, and the air bubbles are removed. The specimen is dried and cured at 24℃ for 48 h. When the mechanical strength of the casting specimen is ≥40MPa, it is demolded and then dried and cured at 80℃ for 60 h.

[0022] In some embodiments disclosed in this application, during step (4), when the prestressed anchor rod is installed, its relative position to the fault model is at least one of the following conditions:

[0023] The anchor head is used to simulate and compare the effects of fault structure on anchorage instability by having it not pass through the fault, having it in the fault, and having it pass through the fault.

[0024] In some embodiments disclosed in this application, in step (3), the PP sheet has a thickness ranging from 0.3 to 200 mm, a white semi-transparent appearance, and a density of 1.92 g / cm³. 3 The tensile and compressive strengths are 29 and 45 MPa, respectively.

[0025] In some embodiments disclosed in this application, the manufacturing steps of the extension rod in step (4) are as follows:

[0026] S1 provides a cylindrical or square-shaped silicone mold, and the lower part of the silicone mold is provided with a structure for forming an extension rod clamping part accordingly;

[0027] S2. A clamping device is set to clamp the corresponding part of the anchor rod body so that the anchor head is vertically inserted into the corresponding depth position of the silicone mold; the clamping device includes a base, an L-shaped support frame mounted on the base, and a clamp mounted on the L-shaped support frame; by changing the clamping position of the anchor rod, the insertion depth of the anchor head in the silicone mold is adjusted to adapt to molds and anchor rods of different shapes and sizes;

[0028] S3. The resin casting material is poured into the silicone mold, and after curing, an extended rod is formed in which the casting resin tightly wraps with the anchor head.

[0029] In some embodiments disclosed in this application, in step (4), the seepage-proof sleeve is a thin-walled cylindrical shape with a wall thickness of 3 mm and a length of 320 mm, and the end connected to the anchor head is provided with a thread with a depth of 1.5 mm and a spacing of 3 mm.

[0030] In some embodiments disclosed in this application, in step (2), the specimen casting mold is assembled from four steel plates and a triangular prism-shaped PLA plastic block. The bottom steel plate is 500 mm long, 300 mm wide, and 20 mm thick, and has a groove that engages with the three upper side steel plates and the PLA plastic block. The groove is 8 mm wide and 10 mm deep. The upper opposite steel plates are 500 mm long, 300 mm wide, and 18 mm thick, and have grooves on their inner sides. The grooves are 6 mm wide and 9 mm deep. The two steel plates are fixed together by studs and nuts. The PLA plastic block is translucent, has a melting point of 175°C, and tensile and compressive strengths of 103 and 145 MPa, respectively. The surface that contacts the casting material is a slope shaping surface (which can be shaped by hot melting and polishing).

[0031] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0032] 1. The simulation specimen described in this application can simulate various rock mass geological conditions, clearly observe the rock mass anchoring instability process and internal deformation and displacement under load, as well as the effect of geological faults on the evolution of shear slip surface, etc. The results are accurate and reliable, and the preparation method is simple, easy to implement, and low in cost.

[0033] 2. The prestressed anchorage structure in this application not only includes post-tensioned prestressed anchors that conform to actual working conditions, but also includes specific implementation methods of pre-tensioned prestressed anchors, making it suitable for various application scenarios.

[0034] 3. The resin casting material used is made of transparent epoxy resin and curing agent according to the corresponding mixing ratio. Compared with opaque materials, the failure process of the anchoring structure in different areas and the evolution law of slope anchoring instability can be clearly and intuitively observed during the test.

[0035] 4. The anchor rods used are set according to the corresponding scale ratio. The anchor rods, anchor heads and trays are connected by threads, which have high tensile strength and large preload. Compared with the existing technology that only uses steel wire or copper wire to simulate anchor rods and anchor cables, it has more practical engineering significance.

[0036] 5. The cast-in-place anchor bolt anti-seepage sleeve can effectively prevent the anchor bolt surface from being covered by the cast material during the casting process, thereby avoiding problems such as the inability to post-tension the anchor bolt, stress concentration during the tensioning process, and failure of the anchoring structure.

[0037] 6. The selected PLA plastic blocks used for slope surface molding are hot-melted and polished. Their surfaces are made into irregular curved surfaces that conform to the actual working conditions according to the scale ratio, which can better simulate the slope model under real working conditions. Attached Figure Description

[0038] Figure 1 In one embodiment of this application, the resin casting material is wherein (a) is CY-39 type epoxy resin and YS-T31 type curing agent, and (b) is a resin specimen sample obtained after casting, demolding and curing of the casting material.

[0039] Figure 2 This is a schematic diagram of the structure of a simulation specimen casting mold in one embodiment of this application.

[0040] Figure 3 This is a schematic diagram of the anchor head structure in one embodiment of this application.

[0041] Figure 4 This is a schematic diagram of the assembly structure of the anchor rod body in one embodiment of this application.

[0042] Figure 5 This is a schematic diagram of the structure of the anchor tail seat in one embodiment of this application.

[0043] Figure 6 This is a schematic diagram of the anchoring system in one embodiment of this application.

[0044] Figure 7 This is a schematic diagram of the anchor bolt extension clamping device and mold structure in one embodiment of this application.

[0045] In the above diagram, 1 is the PLA plastic block, 2 and 6 are the side steel plates, 3 is the rear steel plate, 4 is the fastening bolt, 5 is the base plate, 7 is the threaded groove, 8 is the threaded opening for connection with the seepage-proof sleeve, 9 is the threaded opening for connection with the rod body, 10 is the rod body, 11 is the hexagonal nut, 12 is the washer, 13 is the anchor head, 14 is the seepage-proof sleeve, 15 is the anchor tail seat, 16 is the anchor rod, 17 is the clamping device, 18 is the cylindrical silicone mold, and 19 is the square column silicone mold. Detailed Implementation

[0046] To better understand the technical solution of this application, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1

[0048] The preparation method of simulation specimens for anchorage instability of engineering rock mass based on rock-like resin mainly includes the following steps:

[0049] 1. Preparation of castable refractory

[0050] CY-39 epoxy resin and YS-T31 curing agent were weighed and mixed at a mass ratio of 100:32.5. After stirring evenly, the mixture was placed in a vacuum chamber for 25 minutes to remove air bubbles and improve the molding quality of the specimen.

[0051] Ordinary resins generate a large amount of heat during curing, and their poor thermal conductivity and uneven heat dissipation lead to poor specimen molding results and affect their mechanical properties over time. If anchoring or fracture structures are also incorporated, molding becomes even more difficult. In contrast, the CY-39 epoxy resin and YS-T31 curing agent selected in this example generate almost no heat during the curing process, making them easy to mold and suitable for producing larger specimens.

[0052] A high-transparency resin-based rock specimen can be formed by using CY-39 epoxy resin and YS-T31 curing agent at a mass ratio of 100:32.5 (see...). Figure 1It exhibits significant brittleness at -10 to -15℃, showing brittle fracture characteristics during compression testing, with a compressive-to-tensile strength ratio of up to 6.7. The main mechanical parameters of the resin material used in this example at -15 to -10℃ are shown in Table 1. In addition, Dyskin and Wong's test temperature was -50℃, and Song's test temperature was -20℃.

[0053] Table 1. Comparison of physical and mechanical parameters of resin materials, other transparent rock materials, and some real rocks in this example.

[0054] .

[0055] As can be seen from Table 1, the mechanical parameters of the cast resin sample selected in this example are close to those of real rocks, and therefore it can simulate such rock bodies to a certain extent.

[0056] 2. Preparation of specimen mold

[0057] First, based on the scale of the corresponding slope model, as shown in Table 2, the dimensions (bottom, top, width, and height) of the specimen were determined to be 400×300 mm, 300×250 mm, 300 mm, and 300 mm, respectively. Two side steel plates 2 and 6, each 500 mm long, 300 mm high, and 18 mm thick, were custom-made. A protrusion was provided at the bottom for connection with the base plate 5, and a groove with a width of 6 mm and a depth of 9 mm was provided on the inner side for the assembly and interlocking of the PLA block plastic and the rear side steel plate. The two opposite side steel plates were fastened and fixed together using bolts 4. A rear side steel plate 3, 300 mm long, 300 mm wide, and 18 mm thick, was custom-made, with a protrusion on its side for connection with the base plate 5 and the side steel plates 2 and 6. A steel plate 500 mm long, 320 mm wide, and 20 mm thick was also custom-made. The base plate is 8 mm wide and 10 mm deep, with a groove for assembly with the three upper steel plates and PLA plastic block 1. The PLA plastic block 1 is semi-transparent, with a melting point of 175℃ and tensile and compressive strengths of 103 MPa and 145 MPa, respectively. The side of the PLA plastic block 1 that contacts the castable is hot-melted and polished to form a slope shape that conforms to the actual working conditions, and holes are drilled at the corresponding positions to facilitate the insertion of the seepage-proof sleeve. After the mold is formed (e.g. Figure 2 As shown in the figure, it can not only effectively prevent the pouring material from seeping out of the mold gaps during pouring, but also has the structural advantage of easy anchor tensioning.

[0058] Table 2. Similarity ratios of various physical quantities in the model experiment.

[0059] physical quantity Geometric similarity constants Stress similarity constant similarity constant of elastic modulus Strain similarity constant Multiple similarity constant Actual working conditions 14 14 14 1 1

[0060] 3. Fabrication of scaled-down anchor bolts

[0061] The anchor bolt model is made of steel and includes (see...) Figures 3 to 6 Anchor head 13 has a threaded groove 7 on its outer circumference, with a vertical spacing of 8 mm between the threads and a thread depth of 4 mm. The bottom has threaded ports 8 and 9 for screwing into the rod body 10 and the rod anti-seepage sleeve. The interface depths with the rod body and the anti-seepage sleeve are 25 mm and 15 mm, respectively. The rod body 10 of the anchor rod is 350 mm long and 6 mm in diameter. Its shape is similar to an unribbed steel bar, and the rod body is threaded to facilitate connection with the anchor head and anchor. The anchoring tail seat 15 is composed of a steel washer 12 with gradually varying thickness and a steel hexagonal nut 11 with variable cross-section. The washer is 20 mm long, 20 mm wide, and 8 mm thick, respectively. The nut is threaded inside to facilitate screwing into the rod body 10 of the anchor rod.

[0062] 4. Preparation of Anchor Bolt Seepage Prevention Sleeves

[0063] Anchor bolt seepage-proof sleeves are made from resin castable refractory using a mold casting method. See also Figure 7 The cylindrical silicone mold 18 or the square prism silicone mold 19 is fixed on the platform of the clamping device 17. A thin glass rod is used to guide the casting material into the silicone mold. After initial curing, the silicone mold is cut open to complete the fabrication. See also... Figure 6 The manufactured seepage-proof sleeve is a thin-walled cylinder with a wall thickness of 3 mm and a length of 320 mm. The outer ring near the anchor head 13 is threaded to facilitate screwing with the anchor head 13. This can effectively prevent the castable material from wrapping around the anchor rod 10 during the pouring process, thus preventing the prestressing tension (post-tensioning method) from being achieved.

[0064] 5. Simulation and layout of fault structures

[0065] Transparent PP (polypropylene) plastic sheets were used to simulate the fault, offering the advantage of easy observation of the internal structure. Based on geological exploration data, the fault shape was created by cutting and heat processing to match the actual working conditions, resulting in good molding effects. If the anchor head is located at or passes through the fault, holes were pre-drilled at the corresponding projection positions on the PP sheet. After preliminary processing, small holes with a diameter of 1 mm were drilled at the corners of the fault, cotton thread was threaded through and tied securely, and the other end of the cotton thread was glued to the corresponding position on the mold using strong adhesive, thus simulating the spatial position of the fault.

[0066] 6. Anchor bolt installation and prestressing application

[0067] The anchor bolts are installed in pre-drilled holes in the PLA plastic blocks. They are installed in three rows of six bolts, with two bolts for each of the three scenarios: anchor heads not passing through faults, anchor heads within faults, and anchor heads passing through faults. The vertical distance between the bolt sections in each row is 8 mm. The first row of anchor bolts is 8 mm vertically from the top, and the first and second rows of anchor bolts are 10 mm horizontally from their adjacent sides.

[0068] Prestressing application in the pre-tensioning method: mechanical tensioning is applied simultaneously at both ends of the anchor rod; Prestressing application in the post-tensioning method: mechanical tensioning is applied to the anchor rods extending beyond the slope surface after the specimen has been completely cured.

[0069] 7. Casting, molding, and curing of specimens

[0070] CY-39 epoxy resin and YS-T31 curing agent were mixed at a mass ratio of 100:32.5. After mixing, the mixture was placed in a vacuum chamber for 30 minutes to remove air bubbles. The prepared mold was placed on a workbench, and the casting material was poured into the mold using a glass rod to form the specimen. After pouring, the mold was placed in a vacuum chamber again for 30 minutes to remove air bubbles, and then placed in a 20℃ constant temperature drying oven for 48 hours to complete the curing process. Once the specimen achieved a mechanical strength greater than 40 MPa, the mold was removed, ensuring that the appearance of the specimen was not damaged during demolding. The demolded specimen was then placed in a constant temperature forced-air drying oven at 80℃ for 60 hours to complete the specimen fabrication.

[0071] Example 2 Verification Experiment

[0072] 1. Preparation of slope model specimens using anchored structures

[0073] (1) Fabrication and arrangement of anchor bolts

[0074] The specimens were prepared using the respective preparation methods described in Example 1. The vertical distance between the center of the cross section of the first row of two anchor rods and the top of the specimen was 8 mm, and the vertical distance between the center of the cross section of the second row of anchor rods was 8 mm. The vertical distance between the second row of anchor rods and the third row of anchor rods was 8 mm. The horizontal distance between the first row of anchor rods and its parallel right side was 10 mm, and the horizontal distance between the second row of anchor rods and its parallel right side was 10 mm.

[0075] (2) Geological fault structure layout

[0076] The specimen was made using the method described in Example 1. In the 3D modeling software, the front, back, left and right views of the specimen were switched, and the corresponding positions on the four sides of the specimen were captured and marked. The corresponding projection points were drawn on the four sides of the casting mold. The corners of the PP board were tied with cotton thread and pasted to the determined position of the mold to fix it. Then, it was poured into the specimen in layers.

[0077] (3) Specimen casting

[0078] CY-39 epoxy resin and YS-T31 modified amine curing agent were mixed at a mass ratio of 100:32.5. After mixing, the mixture was placed in a vacuum chamber for 30 minutes to remove air bubbles and improve the molding quality of the specimen. The prepared mold was placed on a worktable, and the casting material was guided into the mold using a glass rod for casting. After casting, the mold was placed in a vacuum chamber again for 30 minutes to remove air bubbles, and then placed in a constant temperature drying oven at 18℃ for 36 hours to complete the initial curing.

[0079] (4) Tensioning of anchor bolts

[0080] For prestressed anchors achieved by pre-tensioning and post-tensioning methods, three control groups were set up with initial anchor prestress of 50 N, 100 N, and 200 N, respectively.

[0081] (5) Demolding and curing

[0082] Once the specimen has achieved a mechanical strength of 40 MPa, the mold is removed, ensuring that the appearance of the specimen is not damaged during demolding. After demolding, the specimen is placed in a 75℃ constant temperature forced-air drying oven for 72 hours to complete the specimen preparation.

[0083] 2. Loading test

[0084] The loading device is a mechanical testing and simulated rock mechanics test system (MTS815).

[0085] The specimen was clamped and fixed on both sides using 20 mm thick plexiglass. The test process employed progressive loading with simultaneous monitoring of stress changes and specimen evolution. Model tests were conducted using both pre-tensioning and post-tensioning methods, considering the following scenarios: the failure surface morphology of a slope without anchors; slope failure when the upper anchors fail; slope failure when the middle anchors fail; slope failure when the lower anchors fail; slope failure when the upper anchor force decreases; slope failure when the middle anchor force decreases; and slope failure when the lower anchor force decreases.

[0086] The prepared specimen was subjected to a loading test under uniaxial compression at a loading rate of 50 N / s, and the entire process of specimen deformation under pressure was recorded by a camera.

[0087] As the load at the top of the slope gradually increases, the specimen begins to deform. Before the shear slip surface appears, the upper row of anchor cables is stressed first, while the lower row is unloaded; after the shear slip surface appears, the lower row of anchor cables begins to be stressed, and the displacement changes at the slope surface and top intensify. In the group anchors, the load on the upper row of anchor cables is greater than that on the lower row, and the anchor cable tension is transferred due to the sliding of the sliding body and the development of the fault, until the stress concentration areas of each anchor cable overlap to form a relatively complete compression zone. The prestressing effect of the group anchors improves the uneven stress state in the slope rock mass, and the experimental results are shown in Table 3.

[0088] Table 3 Cracking and failure loads of slope specimens under three conditions

[0089] .

[0090] Although some preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0091] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of the invention. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for preparing a rock-like resin-based engineering rock mass anchoring instability simulation test piece, which is used to test the damage evolution law of a support structure and the deformation and failure process of a rock mass when the engineering rock mass is in anchoring instability, and which comprises a rock-like body formed by a high-brittleness transparent resin and used to simulate the engineering rock mass, and a support structure and geological structure embedded in the rock-like body; the support structure comprises a pre-stressed anchor device formed by a corresponding scaled anchor rod by pre-tensioning; and the geological structure comprises a fault model plate; The method for preparing the engineering rock mass anchoring instability simulation test piece comprises the following steps: (1) resin casting material preparation: CY-39 type epoxy resin and YS-T31 type curing agent are mixed and stirred uniformly at a mass ratio of 100:30-35, and then bubbles are removed in a vacuum environment to obtain high-brittleness transparent resin casting material; (2) test piece casting mold setting: based on the scaled ratio of the test, a mold plate of a corresponding size and a PLA plastic block used to simulate a slope are cut to form a test piece casting mold of a corresponding shape by surrounding the test piece casting mold; (3) fault structure layout: a transparent PP plate is cut into a fault model plate of a shape required by the test, and the fault model plate is fixed at a corresponding spatial position in the test piece casting mold based on the simulated geological conditions; (4) pre-stressed anchor rod layout: a drill hole is formed in the PLA plastic block, a corresponding scaled anchor rod is inserted into the drill hole and is sealed and fixed, the scaled anchor rod comprises an anchor head, a rod body and an anchoring tail seat which are sequentially screwed, the top of the anchor head is conical, a thread groove for increasing anchoring force is arranged on the outer circumferential surface of the anchor head, the anchoring tail seat comprises a pad and a hexagonal nut inserted into the pad and used to screw the rod body, and pre-stress is applied in the following manner: pre-tensioning method: one end of an elongated rod formed by casting the high-brittleness transparent resin casting material is wrapped and fixed with the anchor head, and the other end and the tail end of the anchor rod are respectively used to correspondingly connect a tensioning device to perform mechanical tensioning at both ends at the same time; (5) casting and curing: the high-brittleness transparent resin casting material is cast into the test piece casting mold in which the corresponding anchor rod and the fault model plate are arranged, de-bubbling treatment is performed, the cast test piece is dried and cured at 24°C for 48 h, the test piece is demolded when the mechanical strength of the test piece is greater than or equal to 40 MPa, and the test piece is dried and cured at a constant temperature of 80°C for 60 h.

2. The production method according to claim 1, characterized by, In the step (4), when the pre-stressed anchor rod is laid out, the relative position condition of the pre-stressed anchor rod and the fault model is at least one of the following conditions: the anchor head does not pass through the fault, the anchor head is in the fault, and the anchor head passes through the fault, which are used to simulate the effects of different fault structures on anchoring instability.

3. The preparation method according to claim 1, characterized in that, In the step (3), the PP plate thickness ranges from 0.3 to 200 mm, the appearance is white and semi-transparent, the density is 1.92 g / cm 3 , and the tensile and compressive strengths are 29 MPa and 45 MPa, respectively.

4. The method of claim 1, wherein, In the step (4), the elongated rod is made in the following steps: S1: a cylindrical or square columnar silica gel mold is set, and a structure for correspondingly forming an elongated rod clamping portion is arranged at the lower part of the silica gel mold; S2 set clamping device clamping anchor rod body corresponding parts, so that its anchor head vertically downward into the corresponding depth position of the silicone mold; the clamping device comprises a base, an L-shaped support mounted on the base, a clamp mounted on the L-shaped support; by changing the clamping position of the anchor rod to adjust the immersion depth of the anchor head in the silicone mold, to adapt to different shapes and sizes of the mold and the anchor rod; S3 pouring the resin casting material into the silicone mold, and forming an elongated rod after curing, which is tightly wrapped with the anchor head.

5. The preparation method according to claim 1, characterized in that, In the step (2), the test specimen pouring mold is assembled by four steel plates and a three-prism-shaped PLA plastic block, wherein the bottom steel plate is 500 mm long, 300 mm wide and 20 mm thick, and is provided with a groove for clamping the three side steel plates and the PLA plastic block, the groove is 8 mm wide and 10 mm deep; the opposite side steel plates are 500 mm long, 300 mm wide and 18 mm thick, and are provided with clamping grooves on the inner side, the grooves are 6 mm wide and 9 mm deep, and the opposite side steel plates are fixed by studs and nuts; the tensile and compressive strengths of the PLA plastic block are 103 MPa and 145 MPa respectively, and the surface in contact with the casting material is a slope shaping surface.

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