A method and system for preparing and testing a combined rock mass- backfill specimen

Abstract

This invention provides a method and system for preparing and testing composite specimens of fractured rock mass and infill material, relating to the field of rock mass and infill material performance testing technology. The preparation method includes: processing homogeneous rock blocks into initial rock specimens; performing pre-splitting treatment and detecting the rock mass quality grade of the specimens; determining whether the rock mass quality grade of the specimens matches the target rock mass quality grade and using the matched pre-splitting rock specimen as the target fractured rock specimen; setting up a formwork space and pouring infill slurry and curing. Through homogeneous rock block processing and adjustable pre-splitting, the defects of easy damage and large dispersion in on-site core sampling are avoided; based on the comparison between the detected fracture grade and the on-site target grade, an iterative closed-loop mechanism of dynamically adjusting pre-splitting parameters can be used to repeatedly prepare rock samples under the same conditions as the on-site fracture degree in batches; the cast composite specimens highly replicate the actual engineering structure, laying a reliable material basis for accurately conducting complex comparative mechanical tests.

Description

Technical Field

[0001] This invention relates to the field of rock mass-fill material performance testing technology, and more specifically, to a method and system for preparing and testing fractured rock mass-fill composite specimens. Background Technology

[0002] Mining is a crucial means of acquiring mineral resources. Influenced by geological mineralization and mining depth, a large amount of mineral resources are concentrated in fractured rock masses with complex geological conditions. Under deep, high-stress environments, the stability of fractured rock masses is prone to deterioration, posing extremely high requirements for the stability assessment of the stope space. Backfill mining is a commonly used method for such complex geological conditions. Its core lies in utilizing backfill materials to form a shared load-bearing structure with the original rock. The combined structure of the fractured rock mass and the backfill body is the basic load-bearing unit of the stope. Accurately assessing the mechanical performance parameters of this combined structure is a crucial basis for stope structural design and safety assessment.

[0003] To obtain the mechanical property parameters of rock masses or composite structures, laboratory rock mechanics tests are typically required. Currently, the common method for obtaining samples for rock mechanics tests is to directly obtain natural rock core samples through geological drilling at the engineering site. After obtaining the core samples, they are processed into standard dimensions and then subjected to mechanical tests such as uniaxial compression and triaxial compression. For cases requiring evaluation of the interaction with the infill material, the extracted natural core sample is combined with the infill material before testing.

[0004] However, the existing technology relying on direct core sampling has significant drawbacks in practical applications. Because fractured rock masses naturally contain numerous randomly distributed joints, fissures, and other discontinuous structural surfaces, directly core sampling within these masses is extremely prone to causing secondary fracturing or disturbance of the original rock. This results in core samples with varying degrees of fracturing and fissure distribution, exhibiting significant dispersion. Furthermore, since it is impossible to obtain several representative samples with completely identical initial fracturing conditions under natural conditions, it is difficult to accurately conduct mechanical comparative tests (such as triaxial tests requiring different confining pressures) that necessitate multiple sets of samples under identical conditions.

[0005] In summary, existing methods for obtaining and preparing samples suffer from significant destructive sampling and high sample dispersion. Their core drawback lies in the inability to controllably and repeatedly obtain multiple rock samples with similar degrees of fragmentation that accurately match the actual rock mass quality grade at the engineering site. This directly leads to a lack of representativeness in the subsequently constructed rock-fill composite samples, resulting in the measured mechanical properties of the composite failing to accurately reflect the macroscopic mechanical characteristics of the engineering site.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a method and system for preparing and testing composite specimens of fractured rock mass and filling material. The preparation method uses a closed-loop iterative mechanism that allows for the reproducible batch preparation of composite specimens under the same conditions as the actual fracture degree in the field. This overcomes the shortcomings of traditional natural sampling, which has large dispersion and makes it difficult to conduct comparative tests.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing a composite sample of fractured rock mass and filling material, comprising: Obtain a homogeneous rock block, process the homogeneous rock block into several initial rock samples of the same size, and process the end face of the initial rock sample to a preset roughness; The initial rock sample is pre-cracked using a pre-cracking method with adjustable parameters to generate cracks inside it, resulting in a pre-cracked rock sample; and the degree of fragmentation of the pre-cracked rock sample is detected and converted into a sample rock mass quality grade. Determine whether the quality grade of the sample rock mass matches the quality grade of the target rock mass at the engineering site; If so, the matched pre-cracked rock sample shall be used as the target fractured rock sample; If not, adjust the adjustable parameters of the pre-splitting method according to the comparison difference, and repeat the steps of pre-splitting treatment, detecting the degree of fragmentation and converting the quality grade of the sample rock mass until the quality grade of the sample rock mass matches the quality grade of the target rock mass. The pre-splitting rock sample that matches the target fractured rock sample is then used as the target fractured rock sample. A support space is set around the target fractured rock sample, and filling slurry is poured into the support space. After cementing and curing, the fractured rock mass-filling body composite sample is obtained.

[0009] In an optional embodiment, the homogeneous rock block is processed into several initial rock samples of the same size, including: The homogeneous rock block is processed into cylindrical, disc-shaped, cuboid, or cubic rock specimens using core drilling or cutting methods; wherein the diameter of the cylindrical or disc-shaped rock specimen is 25mm~100mm and the height is 25mm~200mm; and / or, the length, width, and height of the cuboid or cubic rock specimen are all within the range of 25mm~300mm; and / or, Processing the end faces of the initial rock sample to a predetermined roughness includes: processing one end face, or two opposing end faces, of the initial rock sample into a planar end face, a serrated end face, a dotted columnar end face, or an irregular end face, to simulate different contact surface morphological characteristics between fractured rock mass and infill material; and / or, The pre-cracking method includes at least one of the following: high-temperature pre-cracking, low-temperature pre-cracking, corrosive solution immersion pre-cracking, microwave irradiation pre-cracking, and laser irradiation pre-cracking; and / or The adjustable parameters include: when high-temperature pre-cracking is used, adjusting the heating temperature, heating rate, heating time, and number of heating cycles; and / or, when low-temperature pre-cracking is used, adjusting the freezing temperature, freezing time, and number of freeze-thaw cycles; and / or, when pre-cracking is used by immersion in a corrosive solution, adjusting the acidity, alkalinity, concentration, and immersion time of the corrosive solution; and / or, when pre-cracking is used by microwave irradiation, adjusting the microwave irradiation intensity and irradiation time; and / or, when pre-cracking is used by laser irradiation, adjusting the laser power and irradiation time.

[0010] In an optional implementation, when high-temperature pre-cracking is used, the control of heating temperature, heating rate, and heating time includes: The heating rate is controlled within 1℃ / min to 20℃ / min. After heating to the specified heating temperature within 100℃ to 1000℃, it is maintained for 0.5h to 5h. Finally, natural heat dissipation or water cooling is used for cooling.

[0011] In an optional embodiment, the method for detecting the degree of fragmentation of the pre-fractured rock sample includes at least one of the following: rock sample density test, resistivity test, permeability coefficient test, mercury intrusion porosimetry test, ultrasonic wave velocity test, computed tomography scan test, and nuclear magnetic resonance test.

[0012] In an optional embodiment, when the method for detecting the degree of fragmentation of the pre-fractured rock sample is ultrasonic wave velocity testing, the step of converting the degree of fragmentation into a sample rock mass quality grade includes: The ultrasonic transmitting probe and ultrasonic receiving probe are placed on both sides of the pre-split rock sample, respectively, and the average acoustic time is measured and the ultrasonic wave velocity of the pre-split rock sample is calculated. Based on the rock mass geological strength preparation and ultrasonic wave velocity conversion model, the ultrasonic wave velocity is converted into the corresponding geological strength index GSI value. Based on the correspondence between the geological strength index and the rock mass quality grade, the geological strength index GSI value is converted into the corresponding sample rock mass quality grade; wherein, the sample rock mass quality grade includes Grade I, Grade II, Grade III, Grade IV and Grade V.

[0013] In an optional implementation, the step of adjusting the adjustable parameters of the pre-splitting method based on the comparison difference, performing the pre-splitting treatment again, detecting the degree of fragmentation, and converting the sample rock mass quality grade includes: If the quality grade of the sample rock mass is higher than that of the target rock mass, the value of the adjustable parameter is increased, and the pre-splitting treatment, the degree of fragmentation, and the quality grade of the sample rock mass are recalculated for the current pre-splitting rock sample. If the quality grade of the sample rock mass is lower than that of the target rock mass, the value of the adjustable parameter is reduced, the initial rock sample is re-acquired, and the steps of pre-splitting treatment, detecting the degree of fragmentation, and converting the quality grade of the sample rock mass are performed again. The target rock mass quality grade is obtained by investigating the engineering site using at least one of the following methods: RQD, RMR, MRMR, Q method, GSI method, and BQ method; and / or, A support space is set around the target fractured rock sample, and filling grout is poured into the support space. After cementing and curing, the fractured rock mass-filled body composite sample is obtained, comprising: The target fractured rock sample is loaded into a mold with an inner cavity size larger than the target fractured rock sample size in at least one direction, and cemented filling slurry is poured into the mold space. After the sample is poured, it is left to stand for 12h~48h, and then placed in a constant temperature and humidity curing chamber for curing before demolding; the curing temperature of the curing chamber is 20±2℃ and the humidity is 95±2%.

[0014] Secondly, the present invention provides a method for testing the mechanical properties of a composite specimen of fractured rock mass and filling material, comprising: Using the preparation method described in any one of the foregoing embodiments, several fractured rock mass-filling body composite samples under the same conditions were prepared. Sensors were arranged around the fractured rock mass-filled body composite sample. Mechanical tests were conducted using several of the fractured rock mass-filled body composite specimens as a group of samples. The mechanical property parameters of the fractured rock mass-filled body composite specimens were calculated using the test data collected by the sensor.

[0015] In an optional embodiment, sensors are arranged around the fractured rock mass-filled body composite sample, including: Strain gauges are arranged parallel to and perpendicular to the sample axis on the surface of the filling body and the surface of the pre-split rock sample of the fractured rock mass-filling body composite sample, respectively. Positioning speckle patterns were drawn on one side of the fractured rock mass-filling body composite sample, and digital image correlation equipment was set up. A high-frequency acoustic emission probe and a low-frequency acoustic emission probe are arranged on the side of the fractured rock mass-filled body composite sample; and / or, The mechanical tests conducted include at least one of the following: uniaxial compression test, conventional triaxial compression test, true triaxial compression test, direct tensile test, Brazilian splitting test, variable angle shear test, or direct shear test; When the mechanical test is the conventional triaxial compression test and / or the true triaxial compression test, at least three fractured rock mass-fill body composite specimens under the same conditions are used as a group of samples, and different confining pressures are applied to each specimen to obtain the cohesion and internal friction angle.

[0016] Thirdly, the present invention provides a system for preparing a composite sample of fractured rock mass and filling material, comprising: The sample processing module is used to obtain homogeneous rock blocks, process the homogeneous rock blocks into several initial rock samples of the same size, and process the end faces of the initial rock samples to a preset roughness. The pre-splitting / activation module is used to pre-splitting the initial rock sample using a pre-splitting method with adjustable parameters to generate cracks inside it, thereby obtaining a pre-splitting rock sample. The non-destructive testing module is used to detect the degree of fragmentation of the pre-split rock sample and convert the degree of fragmentation into the rock mass quality grade of the sample. The control module is communicatively connected to both the pre-splitting / activation module and the non-destructive testing module. The control module is configured to: determine whether the quality grade of the sample rock mass matches the quality grade of the target rock mass at the engineering site; if yes, use the matched pre-splitting rock sample as the target fractured rock sample; if no, adjust the values ​​of the adjustable parameters of the pre-splitting / activation module based on the comparison difference, and control the pre-splitting / activation module and the non-destructive testing module to perform the corresponding operations again until the quality grade of the sample rock mass matches the quality grade of the target rock mass. The combined specimen molding module is used to provide a support space around the target fractured rock specimen, so that filling slurry can be poured into the support space and cured by cementing and filling to obtain the fractured rock mass-filling body combined specimen.

[0017] Fourthly, the present invention provides a mechanical property testing system for a composite specimen of fractured rock mass and filling material, comprising: The preparation system for the fractured rock mass-filled body composite specimen as described in the foregoing embodiments is used to prepare several fractured rock mass-filled body composite specimens under the same conditions. A mechanical loading device is used to hold the fractured rock mass-filled body composite sample output by the preparation system and to apply mechanical loads to the fractured rock mass-filled body composite sample to carry out mechanical tests. A multi-source sensor network is arranged around the fractured rock mass-filled body composite specimen on the mechanical loading device. The multi-source sensor network includes strain gauges, digital image correlation devices, and acoustic emission probes, which are used to simultaneously acquire strain field and acoustic loading response data of the fractured rock mass-filled body composite specimen during the mechanical test. The data analysis host is communicatively connected to the mechanical loading device and the multi-source sensor network, respectively, and is used to control the loading execution process of the mechanical loading device, receive and process the load response data collected by the multi-source sensor network, and calculate the mechanical performance parameters of the fractured rock mass-filling body composite sample.

[0018] Compared with existing technologies, the preparation method provided by this invention effectively avoids the secondary fracture and disturbance damage caused by directly core sampling from fractured rock masses in engineering sites by processing homogeneous rock blocks into initial samples of the same size and pre-setting the end-face roughness. This process overcomes the inherent defect of the high dispersion of natural core samples, providing a reliable guarantee for obtaining standardized test materials subsequently.

[0019] By employing a pre-splitting method with adjustable parameters to generate cracks inside the sample, the randomly distributed discontinuous structural surfaces in real rock masses can be scientifically simulated. Simultaneously, by detecting the degree of fragmentation and converting it into specific rock mass quality grades, a quantitative conversion channel is established between laboratory-scale preparation and macroscopic engineering geological indicators. This effectively simulates the joint and fracture structure network of fractured rock masses in engineering applications, forming a small-scale equivalent fractured rock sample preparation method that can be used for indoor mechanical testing.

[0020] By directly comparing the quality grade of the sample rock mass with the target grade at the engineering site, and dynamically adjusting the pre-splitting parameters iteratively to correct any mismatch, a precise closed-loop control preparation process was achieved. This process overcomes the bottleneck of the highly random nature of traditional acquisition methods, enabling the stable and repeatable batch preparation of representative samples with internal fracture characteristics and degree of fragmentation highly consistent with the actual field conditions.

[0021] By pouring backfill grout around a precisely matched target fractured rock sample and then cementing and curing it, the resulting composite specimen can highly reproduce the actual physical structure of the rock mass and backfill jointly bearing load during deep ore body mining. This composite specimen eliminates the interference of discrete internal conditions, laying a solid material foundation for subsequent comparative mechanical testing requiring multiple sets of specimens under identical conditions, and ensuring that performance evaluation accurately reflects the macroscopic mechanical characteristics of the engineering site. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 A flowchart of the preparation method provided in the embodiments of this application; Figure 2 Schematic diagrams of end face shapes with different preset roughness; Figure 3 This is a schematic diagram showing the shape and size characteristics of different rock samples in Table 1; Figure 4 This is a schematic diagram of the temperature control curve during high-temperature pre-cracking treatment. Figure 5 This is a schematic diagram of the ultrasonic wave velocity test setup for pre-fractured rock samples. Figure 6 Comparison of rock samples with different degrees of fragmentation and engineering rock masses; Figure 7 A schematic cross-sectional view of the filling grout pouring and formwork structure; Figure 8 This is a schematic diagram of the arrangement of multi-source sensors for combined samples; Figure 9 This is a schematic diagram of the assembly of the combined specimen for loading and testing in a servo testing machine. Figure 10 A schematic diagram of the module connections of the preparation system for the fractured rock mass-filled body composite sample; Figure 11 This is a diagram of the architecture of a mechanical property testing system for a composite sample of fractured rock mass and filling material.

[0024] Figure label: 1. Ultrasonic transmitting / receiving probe; 2. Coupling agent; 3. Ultrasonic wave velocity tester data cable; 4. Cast filling slurry; 5. Contact surface between rock sample and filling body; 6. Pre-cracked rock sample; 7. Mold support; 8. Axial strain gauge; 9. Transverse strain gauge; 10. Positioning speckle; 11. Low-frequency acoustic emission probe; 12. High-frequency acoustic emission probe; 13. Rigid base; 14. Telescopic shaft; 15. Loading disk; 16. Cylindrical fractured rock mass-filling body composite sample; 17. Rigid testing machine support.

[0025] 100. Mechanical property testing system for fractured rock mass-filled body composite specimens; 20. Preparation system for fractured rock mass-filled body composite specimens; 21. Specimen processing module; 22. Pre-splitting / activation module; 23. Non-destructive testing module; 24. Control module; 25. Composite specimen forming module; 30. Mechanical loading equipment; 40. Multi-source sensor network; 50. Data analysis host. Detailed Implementation

[0026] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0027] refer to Figure 1 This application provides a method for preparing a composite sample of fractured rock mass and filling material, comprising: Step S1: Obtain a homogeneous rock block, process the homogeneous rock block into several initial rock samples of the same size, and process the end face of the initial rock sample to a preset roughness.

[0028] In this step, a complete homogeneous rock block without obvious visible defects is obtained. Depending on the type of mechanical test to be conducted (e.g., uniaxial compression, triaxial compression, or shear test), the homogeneous rock block is processed into several initial rock samples with identical geometric dimensions (e.g., cylindrical samples with a diameter of 50 mm and a height of 50 mm) using core drilling or cutting equipment. To accurately simulate the frictional and interlocking mechanical characteristics of the interface between fractured rock and filling material in actual engineering, one or two opposing end faces of the initial rock sample are pre-processed to a predetermined roughness. This roughness can specifically be planar, serrated at a specific angle, dotted, or irregular based on the JRC coefficient standard.

[0029] To simulate the characteristics of actual mine walls, the initial sample end face can be machined to various desired roughnesses; see details below. Figure 2 . Figure 2 Figures a through j respectively illustrate a planar end face, a sawtooth end face with different angles, a dotted cylindrical end face, and an irregular end face with different JRC roughness coefficients. Specifically, a represents a planar end face; b, c, and d represent sawtooth end faces with angles of 30°, 45°, and 60° respectively; e, f, and g represent dotted cylindrical end faces with short, medium, and high dotted cylindrical surfaces respectively; and h, i, and j represent irregular end faces with JRC roughness coefficients of 2, 10, and 18 respectively.

[0030] Step S2: The initial rock sample is pre-cracked using a pre-cracking method with adjustable parameters to generate cracks inside it, resulting in a pre-cracked rock sample; and the degree of fragmentation of the pre-cracked rock sample is detected, and the degree of fragmentation is converted into the rock mass quality grade of the sample.

[0031] To simulate the randomly distributed discontinuous structural surfaces (joints, fissures) within natural rock masses without causing drilling disturbance or damage, this embodiment employs a pre-splitting method with adjustable parameters to treat the initial rock sample. Pre-splitting methods can include high-temperature heating, low-temperature freezing, immersion in a corrosive solution, or microwave / laser irradiation. During the treatment, energy input causes localized thermal or expansion stresses exceeding the tensile strength of the minerals within the rock sample, thereby initiating a crack network and obtaining a pre-splitted rock sample.

[0032] Subsequently, non-destructive testing techniques (such as ultrasonic wave velocity testing) were used to quantitatively determine the degree of fragmentation in the pre-fractured rock samples. Specifically, ultrasonic transmitting and receiving probes were placed on both sides of the sample, the acoustic time was measured, and the measured ultrasonic wave velocity was calculated. Based on the physical law of positive correlation between wave velocity and rock mass integrity, the ultrasonic wave velocity was converted into the corresponding geological strength index (GSI) value using a geological strength conversion model (such as formula calculation). Furthermore, according to the established correspondence between rock mass strength grades, the GSI value was strictly mapped and converted into the sample rock mass quality grades from Grade I to Grade V.

[0033] Step S3: Determine whether the quality grade of the sample rock mass matches the quality grade of the target rock mass at the engineering site.

[0034] Step S4: If so, the matched pre-cracked rock sample is used as the target fractured rock sample. Step S5: If not, adjust the adjustable parameters of the pre-splitting method according to the comparison difference, and repeat the steps of pre-splitting treatment, detecting the degree of fragmentation and converting the quality grade of the sample rock mass until the quality grade of the sample rock mass matches the quality grade of the target rock mass. The pre-splitting rock sample that matches the target fractured rock sample is then used as the target fractured rock sample.

[0035] It should be noted that, due to the inherent uncertainty of a single pre-splitting process, a closed-loop comparison and feedback matching system is implemented to ensure that the samples accurately represent the engineering site conditions. The target rock mass quality grade obtained through exploration methods (such as RMR or BQ methods) is numerically compared with the sample rock mass quality grade calculated in the previous step.

[0036] If the two are consistent, it indicates that the fragmentation network characteristics of the current sample are highly consistent with the macroscopic mechanical characteristics of the fracture zone in the field, and the pre-fractured rock sample can be directly used as the target fractured rock sample.

[0037] If the two do not match, an iterative adjustment mechanism is triggered: (1) If the quality grade of the rock mass of the sample is higher than the target grade (i.e. the sample is too intact and not sufficiently fractured), the adjustable parameters of the pre-splitting method are increased (e.g., the heating temperature is increased or the heating time is extended), and the current pre-splitting rock sample is subjected to pre-splitting and detection conversion steps again.

[0038] (2) If the quality grade of the rock mass of the sample is lower than the target grade (i.e. the sample is excessively fractured), the current sample is invalidated, the adjustable parameters of the pre-splitting method are reduced accordingly, and a new initial rock sample is taken and the above pre-splitting and detection conversion steps are performed.

[0039] The above-described cyclical process continues until the quality grades of the two samples are completely consistent. This closed-loop error correction mechanism completely solves the technical problems of large sample dispersion and inability to conduct multiple control tests caused by traditional random core sampling.

[0040] Step S6: A support space is set around the target fractured rock sample, and filling slurry is poured into the support space. After cementing and curing, the fractured rock mass-filling body combined sample is obtained.

[0041] After obtaining a successfully matched target fractured rock sample, this step involves creating a mold space of a specific size around it (e.g., using a cylindrical mold with an inner diameter larger than the sample diameter to fit the sample). A cemented filling grout with an engineering-defined mix ratio (e.g., a specific cement-sand ratio) is poured into the mold space. Under the influence of gravity and fluidity, the grout adheres tightly to the sample's end face with a preset roughness and penetrates into surface cracks. After pouring, the sample is allowed to stand for a period of time and then placed in a constant temperature and humidity curing chamber for standardized curing (e.g., temperature 20±2℃, humidity 95±2%). Once the hydration and cementation reaction is complete, the sample is demolded, resulting in a structurally complete fractured rock mass-filled body composite sample with a realistic bonding surface, which can then be used for parallel mechanical property testing of multiple sets of samples.

[0042] In summary, by using homogeneous rock blocks to process initial samples and performing adjustable pre-splitting, the problems of secondary fracture and large sample dispersion caused by direct core sampling in the field are effectively avoided. By detecting the degree of fragmentation and converting the sample rock mass quality grade to a target grade in the engineering field, and by dynamically adjusting the pre-splitting parameters based on the differences when mismatches occur, iterative closed-loop correction can be performed. This allows for the stable and repeatable batch acquisition of representative samples under identical conditions, perfectly matching the actual fragmentation degree in the field. The composite samples obtained by casting and curing based on these precisely matched rock samples highly replicate the common load-bearing structure in the actual engineering, providing a standardized and highly representative physical carrier for subsequent comparative mechanical tests, ensuring that the test results accurately reflect the macroscopic mechanical characteristics in the field.

[0043] In some embodiments, the homogeneous rock block is processed into several initial rock samples of the same size, including: The homogeneous rock block is processed into cylindrical, disc-shaped, cuboid, or cubic rock samples by means of core drilling or cutting; wherein the diameter of the cylindrical or disc-shaped rock sample is 25mm~100mm and the height is 25mm~200mm; and / or the length, width, and height of the cuboid or cubic rock sample are all within the range of 25mm~300mm.

[0044] To adapt to different types of mechanical testing systems, core drilling or cutting methods are used for sample processing. Specifically, for uniaxial compression, conventional triaxial compression, or Brazilian splitting tests, a core drilling rig is used to process homogeneous rock blocks into cylindrical or disc-shaped rock samples.

[0045] For cylindrical or disc-shaped rock samples, the diameter ranges from 25 mm to 100 mm (e.g., 25 mm, 30 mm, 40 mm, 50 mm, 60 mm, 75 mm, 85 mm, 90 mm, 95 mm, 100 mm, etc.), and the height ranges from 25 mm to 200 mm (e.g., 25 mm, 50 mm, 75 mm, 100 mm, 120 mm, 150 mm, 160 mm, 180 mm, 190 mm, 200 mm, etc.).

[0046] For direct shear tests or variable-angle shear tests requiring shear box fixtures, a large-block rock cutter is used to process homogeneous rock blocks into cuboid or cubic rock specimens. The length, width, and height are all controlled within the range of 25mm to 300mm (e.g., 25mm, 50mm, 80mm, 100mm, 150mm, 200mm, 220mm, 250mm, 280mm, 300mm, etc.). This size range is based on the size effect principle, ensuring that the specimen can accommodate a sufficient number of fractures to achieve macroscopic engineering representativeness, while also meeting the loading space and load limitations of conventional indoor servo testing machines.

[0047] In order to meet the limitations of boundary conditions in different mechanical tests, the specimens need to be processed into specific shapes. As shown in Table 1, this application lists the shape and size characteristics of cuboid, cube, cylindrical and disk-shaped specimens in conventional mechanical tests and their corresponding applicable ranges.

[0048] Table 1. Constraints of Different Shapes and Corresponding Boundary Conditions

[0049] In some embodiments, the end face of the initial rock sample is processed to a preset roughness, including: processing one end face or two opposing end faces of the initial rock sample into a planar end face, a sawtooth end face, a dot-column end face, or an irregular end face, in order to simulate different contact surface morphological characteristics between fractured rock mass and filling body.

[0050] In this embodiment, regarding the pre-processing of end-face roughness, in order to accurately simulate the influence of rough rock walls of different shapes in the underground goaf on the interlocking force of the composite body interface, the end faces of the initial rock sample are pre-processed with a pre-defined roughness. Depending on the experimental requirements, one end face of the initial rock sample can be processed into a rough surface (for subsequent preparation of the "rock mass-filling body" two-section composite), or both opposite end faces can be processed into rough surfaces (for subsequent preparation of the "filling body-rock mass-filling body" three-section composite). The roughness morphology of the end face includes processing into a planar end face, a serrated end face with a specific angle, a dotted columnar end face, or an irregular end face based on a specific JRC roughness coefficient, thereby exploring the mechanism by which the contact surface morphology characteristics affect shear strength and deformation modulus.

[0051] In some embodiments, the pre-cracking method includes at least one of the following: high-temperature pre-cracking, low-temperature pre-cracking, corrosive solution immersion pre-cracking, microwave irradiation pre-cracking, and laser irradiation pre-cracking.

[0052] In some embodiments, the adjustable parameters include: when high-temperature pre-cracking is used, adjusting the heating temperature, heating rate, heating time, and number of heating cycles; and / or, when low-temperature pre-cracking is used, adjusting the freezing temperature, freezing time, and number of freeze-thaw cycles; and / or, when pre-cracking is used by immersion in a corrosive solution, adjusting the acidity / alkalinity, concentration, and immersion time of the corrosive solution; and / or, when pre-cracking is used by microwave irradiation, adjusting the microwave irradiation intensity and irradiation time; and / or, when pre-cracking is used by laser irradiation, adjusting the laser power and irradiation time.

[0053] In the above embodiments, regarding the selection of pre-fracture methods and control parameters, the sensitive means for implementing pre-fracture also differ due to the differences in mineral composition among different ore types. This application provides at least one or a combination of high-temperature pre-fracture, low-temperature pre-fracture, corrosive solution immersion pre-fracture, microwave irradiation pre-fracture, or laser irradiation pre-fracture. To achieve the "closed-loop iterative adjustment of parameters when mismatched" described in the previous embodiment, each pre-fracture method has specific adjustable parameters, as detailed below: (1) When high-temperature pre-cracking is used to induce thermal stress fracture, the adjustable parameters include heating temperature, heating rate, heating time and the number of cycles of alternating hot and cold heating; (2) When low-temperature pre-cracking (such as liquid nitrogen or freezer) is used to induce cold shrinkage and cracking, the adjustable parameters include the target freezing temperature, the holding freezing time and the number of cycles of freeze-thaw treatment; (3) When using a corrosive solution to dissolve mineral cement, the adjustable parameters include the acidity or alkalinity of the corrosive solution, the percentage of solution concentration, and the soaking duration; (4) When microwave irradiation is used for pre-cracking, the thermal expansion effect generated by the absorption of microwaves by the internal moisture is utilized. The adjustable parameters include the microwave irradiation intensity of the equipment and the single irradiation time. (5) When laser irradiation is used for pre-cracking, the peeling effect caused by the fixed-point heating of the high-energy beam is utilized. The adjustable parameters include laser output power and laser irradiation time.

[0054] (6) Operators can precisely increase or decrease the values ​​of the corresponding parameters based on the aforementioned grade differences, thereby achieving quantitative closed-loop control of the degree of sample breakage.

[0055] In some embodiments, when high-temperature pre-cracking is used, the control of heating temperature, heating rate, and heating time includes: controlling the heating rate within 1℃ / min to 20℃ / min, heating to a specified heating temperature within 100℃ to 1000℃, maintaining it for 0.5h to 5h, and finally cooling down by natural heat dissipation or water cooling.

[0056] In the preferred embodiment where high-temperature pre-cracking is used as the implementation method, the control of specific heating process parameters is crucial, and the specific methods can be as follows: The prepared initial rock sample is placed in a heating device (e.g., a servo muffle furnace). During the heating phase, the heating rate must be strictly controlled within 1℃ / min to 20℃ / min (e.g., 1℃ / min, 3℃ / min, 5℃ / min, 8℃ / min, 10℃ / min, 12℃ / min, 15℃ / min, 18℃ / min, 19℃ / min, 20℃ / min, etc.). This rate is limited because rocks have poor thermal conductivity; excessively rapid heating will cause severe surface thermal shock damage, leading to direct disintegration of the sample. Maintaining a constant, slow heating rate ensures that heat is evenly conducted into the sample, causing mild localized thermal stress due to differences in thermal expansion among different mineral particles, thereby initiating uniformly distributed microcracks.

[0057] It should be noted that when high-temperature pre-cracking is used, the temperature control curve can be found in [reference needed]. Figure 4 .like Figure 4 As shown, the process strictly follows the control logic of constant slow heating (≤10℃ / min), holding the temperature constant for 2 hours after reaching the target temperature of different gradients, and finally cooling down naturally, thereby inducing thermal damage microcracks of different degrees.

[0058] After slowly heating to the set specified heating temperature, a isothermal holding phase is triggered. The specified heating temperature can be flexibly selected within the range of 100℃ to 1000℃, depending on the required rock mass quality grade for the engineering site (e.g., 100℃, 200℃, 350℃, 400℃, 500℃, 650℃, 800℃, 850℃, 900℃, 1000℃, etc.). Generally speaking, the higher the temperature, the more severe the mineral dehydration, the greater the deformation difference between adjacent different types of minerals, and the denser and more interconnected the crack network generated inside the sample, thus corresponding to a worse rock mass quality grade.

[0059] After reaching the specified heating temperature, it is necessary to maintain the temperature for 0.5h to 5h (e.g., 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, etc.). This isothermal process aims to eliminate the thermal gradient between the inner and outer layers of the sample, ensuring that the sample core and surface reach complete thermal equilibrium. This allows for the full development of microcrack initiation and propagation, ensuring the isotropic nature of the overall sample fragmentation and preventing the phenomenon of peripheral fracture while the core remains intact.

[0060] After the isothermal process, the sample is cooled to solidify the cracks. Depending on the further requirements for the degree of cracking, natural heat dissipation or water cooling can be selected. Natural heat dissipation (such as furnace cooling) can smoothly solidify existing heat-induced cracks and is suitable for the preparation of most rock mass grades; while water cooling (i.e., rapidly quenching the high-temperature sample in cold water) will induce a large number of secondary penetrating cracks inside the sample by utilizing the severe tensile stress generated by rapid cooling contraction. Therefore, when it is necessary to prepare extremely fractured rock samples, and simply increasing the heating temperature is not effective, water cooling can be used as an effective means of supplementing pre-crack strength.

[0061] In some embodiments, the method for detecting the degree of fragmentation of the pre-fractured rock sample includes at least one of the following: rock sample density test, resistivity test, permeability coefficient test, mercury intrusion porosimetry test, ultrasonic wave velocity test, computed tomography scan test, and nuclear magnetic resonance test.

[0062] After obtaining the pre-fractured rock sample, it is necessary to quantitatively characterize the crack network induced within it in order to convert the degree of physical damage into a numerical index that can be used for engineering comparison. This application provides a complete library of methods for detecting the degree of fragmentation. In specific implementation, at least one of the following methods can be used for determination: rock sample density test, resistivity test, permeability coefficient test, mercury intrusion porosimetry test, ultrasonic wave velocity test, computed tomography scan test, and nuclear magnetic resonance test.

[0063] Specifically, the implementation principles and effects of various detection methods are as follows: (1) When using rock sample density test, by comparing and analyzing the changes in apparent density of the sample before and after pre-crack treatment, the macroscopic reduction rate of density can directly characterize the increase in total fracture volume due to the expansion of internal micro-cracks.

[0064] (2) When using resistivity testing, the positive correlation between rock fracture degree and resistivity is utilized. By applying an electric field, the apparent resistivity of the sample is measured. The change in this resistance value can quantitatively reflect the connectivity and penetration degree of the internal crack network.

[0065] (3) When using the permeability coefficient test, the rate at which the fluid penetrates the sample is tested according to Darcy's law. The magnitude of the permeability coefficient is directly positively correlated with the width and connectivity of the microcrack channels in the sample.

[0066] (4) When using mercury intrusion porosimetry, the principle that the non-wetting phase mercury needs to overcome the capillary pressure to enter can be used to obtain the internal microcrack pore size distribution law and the total volume of microcracks with extremely high precision.

[0067] (5) When using computed tomography (CT) for testing, the significant difference in the attenuation coefficient of X-rays in the rock skeleton and the air in the fracture can be used to construct a three-dimensional spatial visualization model of the microcracks inside the sample. This not only quantitatively obtains the fracture rate, but also allows for intuitive analysis of the randomness and isotropic characteristics of the crack distribution.

[0068] (6) When using nuclear magnetic resonance (NMR) testing, the relaxation time spectrum of hydrogen protons in water molecules is tested after the sample is saturated with water. By utilizing the relaxation difference of hydrogen protons in different scales of crack space, the development degree of crack network can be determined non-destructively and accurately.

[0069] (7) When using ultrasonic wave velocity testing, the dynamic mechanism of the reflection and diffraction of elastic waves when they encounter crack interfaces, which leads to the extension of sound time, is utilized. The wave velocity of the sound waves penetrating the sample is read by transmitting and receiving probes. The attenuation amplitude of the wave velocity can be quantitatively reflected to reflect the degree of deterioration of rock integrity in a very stable manner.

[0070] In practice, testing personnel can flexibly select one or more of the above methods in combination, depending on the configuration of the laboratory equipment. The measured physical quantities (such as wave velocity, porosity, permeability, etc.) can all be mapped to the sample rock mass quality grade, which characterizes the macroscopic mechanical properties, through corresponding mature empirical models or geomechanical conversion formulas, thus providing reliable quantitative input for subsequent verification and comparison with the grade at the engineering site.

[0071] For the setup of ultrasonic wave velocity detection, please refer to [reference needed]. Figure 5 During testing, the ultrasonic transmitting / receiving probes are placed on both ends of the sample and connected to the host via the ultrasonic wave velocity tester data cable to accurately obtain the wave velocity parameters.

[0072] In some embodiments, when the method for detecting the degree of fragmentation of the pre-fractured rock sample is ultrasonic wave velocity testing, step S2, converting the degree of fragmentation into a sample rock mass quality grade, includes: Step S21: Place the ultrasonic transmitting probe and the ultrasonic receiving probe on both sides of the pre-splitting rock sample, measure the average acoustic time, and calculate the ultrasonic wave velocity of the pre-splitting rock sample.

[0073] In this embodiment, in order to balance the non-destructive nature of the test with the high efficiency of data processing, ultrasonic wave velocity testing is used as a quantitative detection method for the degree of fragmentation of pre-fractured rock samples.

[0074] In this method, the acoustic transmission parameters of the pre-cracked rock sample are first measured using a non-metallic ultrasonic testing and analysis instrument. The ultrasonic transmitting probe and ultrasonic receiving probe are placed on opposite end faces of the pre-cracked rock sample. To ensure efficient coupling and transfer of acoustic energy, a coupling agent is uniformly applied between the probe and the sample contact surface. During the test, the same sample is tested multiple times (e.g., three times), and the average acoustic time is recorded and calculated to effectively eliminate random errors caused by operation and environment. Subsequently, the ultrasonic wave velocity is obtained using the wave velocity calculation formula (Formula 1): C p =l / t; Among them, C p denoted as , where is the ultrasonic wave velocity of the pre-cracked rock sample (unit: km / s), l is the effective penetration length of the sample parallel to the line connecting the two probes (unit: mm), and t is the measured average acoustic time (unit: μs). The attenuation amplitude of the wave velocity can sensitively reflect the density of microcracks inside the sample.

[0075] Step S22: Based on the geological strength conversion model, the ultrasonic wave velocity is converted into the corresponding geological strength index GSI value.

[0076] In this step, the ultrasonic wave velocity is converted into the corresponding geological strength index GSI value based on the rock mass geological strength index and the ultrasonic wave velocity conversion model.

[0077] For specific conversion, the following fitting calculation formula (Formula 2) can be used: ; Among them, symbols (This represents the rounding function). To ensure the reasonableness of the model's boundaries, when the measured wave velocity is extremely high, for example, Cp ≥ 7.46 km / s, the sample is characterized as extremely intact, and the GSI value is taken as the upper limit of 100; conversely, when the wave velocity is extremely low, for example, Cp ≤ 0.84 km / s, the sample is characterized as extremely broken, and the GSI value is taken as the lower limit of 10.

[0078] Step S23: Based on the correspondence of rock mass strength grades, convert the geological strength index GSI value into the corresponding sample rock mass quality grade; wherein, the sample rock mass quality grade includes grades I to V.

[0079] Finally, based on the correspondence between the geological strength index and the rock mass quality grade, the geological strength index GSI value is converted into the corresponding sample rock mass quality grade; wherein, the sample rock mass quality grade includes Grade I, Grade II, Grade III, Grade IV and Grade V, where Grade I represents the best rock mass quality and the highest integrity, while Grade V represents the worst rock mass quality and extreme fragmentation.

[0080] For example, specific GSI segment intervals can be set to establish mapping relationships with grades I to V sequentially. Through the above three-step transformation of "wave velocity-GSI-rock mass grade", the microscopic random fracture network prepared in the laboratory is successfully quantified and expressed as a macroscopically comparable engineering geological grade, thus providing a unified standardized evaluation benchmark for subsequent comparison and parameter iteration.

[0081] For example, the geological strength index GSI can be converted into the corresponding rock mass strength grade (sample rock mass quality grade) using the following formula 3.

[0082] ; Among them, I, II, III, IV, and V correspond to rock masses of grades I, II, III, IV, and V, respectively. In the comparison, the quality of grade I rock mass is considered to be equal to or higher than that of grade II, and so on.

[0083] In determining whether the quality grade of the sample rock mass matches the quality grade of the target rock mass at the engineering site, this embodiment constructs a closed-loop iterative control strategy based on the irreversible characteristics of rock damage. The target rock mass quality grade is not subjectively set, but rather obtained through on-site investigation and evaluation using at least one of the following methods: Rock Quality Determination (RQD), Rock Geomechanical Classification (RMR), Modified Rock Mass Quality (MRMR), Barton Rock Mass Quality (Q), Geological Strength Index (GSI), and National Standard Rock Mass Basic Quality (BQ). This ensures the engineering authenticity of the test target.

[0084] In this embodiment, step S5, which involves adjusting the adjustable parameters of the pre-splitting method based on the comparison difference, and performing the pre-splitting treatment again, detecting the degree of fragmentation, and converting the sample rock mass quality grade, includes: Step S51: If the quality grade of the sample rock mass is higher than the quality grade of the target rock mass, then increase the value of the adjustable parameter, and perform the pre-splitting treatment, detect the degree of fragmentation, and convert the quality grade of the sample rock mass again on the current pre-splitting rock sample.

[0085] Step S52: If the quality grade of the sample rock mass is lower than the quality grade of the target rock mass, then reduce the value of the adjustable parameter, reacquire the initial rock sample, and repeat the steps of pre-splitting treatment, detecting the degree of fragmentation, and converting the quality grade of the sample rock mass. The target rock mass quality grade is obtained by investigating the engineering site using at least one of the following methods: RQD method, RMR method, MRMR method, Q method, GSI method, and BQ method.

[0086] Specifically, if the two do not match, the following two differential adjustment paths will be strictly followed: Firstly, if the quality grade of the sample rock mass is higher than that of the target rock mass, it indicates that the internal fracture density of the sample is insufficient and the degree of damage is low. In this case, the values ​​of the adjustable parameters of the pre-splitting method are increased by the control system (e.g., increasing the heating temperature or increasing the microwave irradiation time), and the current pre-splitting rock sample is subjected to enhanced energy input again to continue to generate new microcracks on the basis of the original damage. Then, the detection and conversion steps are performed again.

[0087] Secondly, if the quality grade of the sample rock mass is lower than that of the target rock mass, it indicates that the internal structure of the sample has been excessively damaged and that this damage is physically irreversible. In this case, the control system needs to reduce the value of the adjustable parameter, discard the current excessively damaged sample, and obtain a brand new initial rock sample. Under the reduced parameter conditions, the pre-splitting, detection, and conversion steps are performed again. The above trial-and-error and approximation process is repeated until the sample grade completely corresponds to the target grade in the field.

[0088] The matching effect between the pre-scraping degree of the sample and the actual rock mass at the engineering site in this application can be found in [reference]. Figure 6 .like Figure 6 As shown in the figure, from left to right, the process of gradually increasing the pre-crack strength is represented (e.g., by increasing the heating temperature, increasing the concentration of the corrosive solution, increasing the intensity of microwave or laser irradiation, and decreasing the freezing temperature). Figure 6 A, B, and C in the image show the characteristics of cylindrical pre-cracked rock samples prepared under different pre-cracking intensities. The real-world photos below each sample show the fractured state of the actual mining face at the corresponding mine site.

[0089] Specifically: Figure 6 The A in the model corresponds to a Class II rock mass: This type of sample contains only a small number of joints and fissures, with low fissure penetration and large spacing, exhibiting obvious anisotropic characteristics in macroscopic mechanics. Figure 6B in the model corresponds to Class III rock mass: as the pre-splitting strength increases, the density of joints and fissures inside the sample increases significantly, and the fissures begin to intersect and partially connect, exhibiting approximately isotropic characteristics in macroscopic mechanics. Figure 6 C in the model corresponds to Class IV rock mass: under higher pre-splitting strength, the sample is densely packed with joints and fissures, and the degree of penetration and connection of the fissures is extremely high (it is extremely difficult to directly use a drilling rig to sample in actual engineering), and it exhibits completely isotropic characteristics in macroscopic mechanics.

[0090] The comparison chart visually demonstrates that this application, through a closed-loop iterative control strategy, can overcome the difficulty of sampling extremely fractured rock masses and accurately reproduce the true structural state of rock masses of various grades, from intact to extremely fractured, in the laboratory.

[0091] As the pre-splitting strength increases (e.g., by increasing heating temperature, corrosive solution concentration, or laser irradiation intensity), the sample gradually transitions from a Class II rock mass containing a few cracks to a Class IV rock mass with dense joints and high interconnection. The macroscopic failure behavior of this sample closely matches the fracture state of the actual mining face in the mine, intuitively demonstrating the reliability of the closed-loop iterative control strategy of this application.

[0092] In some embodiments, step S6 involves setting up a formwork space around the target fractured rock sample, pouring filling grout into the formwork space, and then curing the sample after cementing and filling to obtain the fractured rock mass-filling body composite sample, comprising: Step S61: The target broken rock sample is loaded into a mold with an inner cavity size larger than the target broken rock sample size in at least one direction, and cemented filling slurry is poured into the mold space.

[0093] It should be noted that in this embodiment, after obtaining the matching target fractured rock sample, the combined casting and curing of the assembly are carried out. Specifically, the target fractured rock sample is placed into a specific mold, the inner cavity of which is larger than the size of the target fractured rock sample in at least one direction (e.g., radial or axial), thereby forming an annular or end-shaped mold space around the sample. Subsequently, a cementitious filling grout with a specific ratio is poured into the mold space. The grout not only coats the sample but also penetrates into the rough undulations of the sample's end face, forming a tight mechanical interlock.

[0094] For the setting of formwork and casting space for rock samples of different shapes, please refer to [reference needed]. Figure 7 . Figure 7 The cross-sectional structures of the cuboid and cylindrical specimens placed in the mold are shown respectively, clearly demonstrating the physical state of the filling slurry being poured above the rock contact surface and forming a binary composite structure.

[0095] Step S62: After the sample is poured, it is left to stand for 12h~48h, and then placed in a constant temperature and humidity curing chamber for curing before demolding; the curing temperature of the curing chamber is 20±2℃ and the humidity is 95±2%.

[0096] To ensure the filling slurry undergoes sufficient hydration and to prevent shrinkage cracks from affecting the bonding interface strength, the samples should be left to stand in the mold for 12 to 48 hours after casting (e.g., 12, 15, 20, 24, 30, 36, 40, 45, 48 hours, etc.) until they initially set and become self-standing. Then, the entire sample is placed in a constant temperature and humidity curing chamber for pre-demolding curing. To simulate the relatively constant temperature and humidity environment downhole, the curing temperature in the curing chamber is precisely controlled at 20±2℃, i.e., within the range of 18℃ to 22℃ (e.g., 18.0℃, 18.5℃, 19.0℃, 19.5℃, 20.0℃, 20.5℃, 21.0℃, 21.5℃, 22.0℃, etc.); the ambient humidity is controlled at 95±2%, i.e., within the range of 93% to 97% (e.g., 93.0%, 93.5%, 94.0%, 94.5%, 95.0%, 95.5%, 96.0%, 96.5%, 97.0%, etc.). After curing at a standard age (e.g., 28 days), the cemented backfill material is tightly consolidated with the fractured rock, ultimately yielding a fractured rock mass-backfill composite specimen suitable for mechanical failure testing.

[0097] Based on the materials obtained by the aforementioned high-precision closed-loop preparation method, this invention further provides a method for testing the mechanical properties of the aforementioned fractured rock mass-filled body composite specimen, in order to accurately evaluate the structural stability of deep-filled mining areas. This application provides a method for testing the mechanical properties of a fractured rock mass-filled body composite specimen, comprising: Step S100: Using the preparation method described in any of the preceding embodiments, several fractured rock mass-filling body composite samples under the same conditions are prepared.

[0098] First, in this step, several (e.g., at least 3 to 5) composite samples of fractured rock mass and infill body under identical conditions are rigorously prepared using the aforementioned preparation process. Since these samples maintain a high degree of consistency in rock block type, internal rock mass composition, end-face roughness, rock mass fracture degree, rock mass quality grade, and infill slurry ratio and curing age, the extreme dispersion caused by natural rock sampling is fundamentally eliminated. This provides a scientific physical basis for conducting parallel tests and parameter fitting (such as triaxial compression failure envelope testing) that require multiple sets of identical initial conditions.

[0099] Step S200: Arrange sensors around the fractured rock mass-filling body composite sample.

[0100] Subsequently, a multi-source sensor network is deployed around the fractured rock-fill composite specimen. Considering that this composite is a heterogeneous binary structure composed of rock and filler, exhibiting significant deformation differences and stress concentration under load, comprehensive surface monitoring is necessary. Specifically, quick-drying adhesive can be used to attach strain gauges parallel and perpendicular to the specimen's stress axis to the surfaces of the filler and rock sections, respectively, to capture the macroscopic strain responses of the two phases. Simultaneously, location speckle patterns can be plotted on the observation side of the specimen, and a digital image correlation (DIC) device can be deployed to capture and calculate the local strain field evolution of the composite in real time during the experiment. Furthermore, acoustic emission probes can be attached to the specimen surface for real-time monitoring and location of elastic wave signals released during the initiation and propagation of microcracks within the specimen.

[0101] Step S300: Using several of the fractured rock mass-filled body composite samples as a group of samples, mechanical tests are carried out, and the mechanical performance parameters of the fractured rock mass-filled body composite samples are calculated using the test data collected by the sensor.

[0102] Finally, several combined specimens with the sensors arranged as described above are used as a set of test samples and placed in a rigid servo testing machine or shear tester to carry out mechanical tests (e.g., uniaxial compression test, conventional triaxial compression test, or shear test). During the test, the loading system applies axial or radial loads to the specimens, and various sensors simultaneously collect test data such as load, displacement, local strain field, and acoustic emission signals.

[0103] After the test, the testing system, based on the collected stress-strain data and combined with continuum mechanics theory, calculated the mechanical property parameters of the fractured rock mass-filling body composite specimen. For example, by using the failure limit stress data of multiple sets of specimens under different confining pressures under the same conditions, and applying the Mohr-Coulomb strength criterion for mathematical regression fitting, the overall cohesion and internal friction angle of the rock mass-filling body composite structure at this level can be accurately calculated. This provides highly valuable quantitative data support for the support and filling design of fractured mining areas in mines.

[0104] In some embodiments, in step S200, sensors are arranged around the fractured rock mass-filled body composite sample, including: Step S210: Strain gauges parallel to and perpendicular to the sample axis are arranged on the surface of the filling body and the surface of the pre-split rock sample of the fractured rock mass-filling body composite sample, respectively.

[0105] It should be noted that, in order to comprehensively and accurately capture the load response characteristics and damage evolution law of the binary heterogeneous structure, a multi-source heterogeneous sensor monitoring network was constructed around the composite sample before mechanical loading was carried out on the fractured rock mass-filled body composite sample.

[0106] First, the macroscopic strain monitoring setup was implemented. Due to the significant difference in deformation modulus between the filling material and the fractured rock, axial strain gauges parallel to the stress axis and transverse strain gauges perpendicular to the axis were attached to the surface areas of the filling material and the pre-fractured rock of the composite specimen, respectively, using a binder. This separate arrangement allows for the recording of the elastic deformation and plastic yield trajectories of the two phases during loading, thereby quantitatively analyzing the collaborative deformation mechanism and mutual lateral constraint effects of the composite under shared load.

[0107] Step S220: Draw positioning speckles on one side of the fractured rock mass-filling body composite sample and set up a digital image correlation (DIC) device.

[0108] Secondly, a visualization monitoring setup for localized full-field strain and crack propagation was implemented. High-contrast positioning speckle patterns were uniformly sprayed onto the surface of the assembled specimen on the side without strain gauges, and a high-frame-rate camera and digital image correlation (DIC) device were mounted directly in front of it. The DIC system was used to perform continuous optical non-contact imaging throughout the loading process, tracking the sub-pixel displacement of the speckle using a built-in algorithm, thereby calculating and generating a full-field strain distribution cloud map of the specimen surface in real time. This technology can visually present the stress concentration phenomenon at rough contact surfaces, as well as the panoramic dynamic process of microcrack initiation, interface penetration, and macroscopic propagation.

[0109] Step S230: A high-frequency acoustic emission probe and a low-frequency acoustic emission probe are arranged on the side of the fractured rock mass-filling body composite sample.

[0110] In addition, a three-dimensional acoustic monitoring setup for internal damage was implemented. Acoustic emission probes were attached to the sides of the composite specimen. To ensure the integrity of the monitoring frequency band, high-frequency acoustic emission probes (e.g., resonant frequency of 150kHz) and low-frequency acoustic emission probes (e.g., resonant frequency of 60kHz) were respectively deployed, and a reasonable background noise threshold value (e.g., 45dB) was set. Among them, the high-frequency probe is more sensitive to the instantaneous initiation signal of microcracks inside brittle rock masses, while the low-frequency probe is good at capturing the plastic damage of the infill and the frictional slip signal of the macroscopic fracture surface. Working together, the two can realize the three-dimensional spatial localization of the fracture process of the composite specimen under load and the inversion of the damage mechanism.

[0111] To comprehensively monitor the loaded response of the two-phase material, the multi-source sensor layout on the above-mentioned combined sample can be found in [reference needed]. Figure 8 .like Figure 8As shown (a represents the strain gauge arrangement, b represents the speckle pattern arrangement, and c represents the acoustic emission probe arrangement), the left side illustrates the zonal arrangement of axial and transverse strain gauges on the filling material and rock mass; the right side shows the DIC speckle pattern arrangement on the back side; simultaneously, Figure 8 It also demonstrated the coordinated monitoring positions of high-frequency and low-frequency acoustic emission probes placed at different heights on the side.

[0112] In some embodiments, the mechanical tests include at least one of uniaxial compression tests, conventional triaxial compression tests, true triaxial compression tests, direct tensile tests, Brazilian splitting tests, variable angle shear tests, or direct shear tests.

[0113] Once the sensor network is in place, based on different engineering design requirements, the specimen can be placed in a servo-controlled rigid testing machine to carry out at least one of the above tests.

[0114] When the mechanical test is the conventional triaxial compression test and / or the true triaxial compression test, at least three fractured rock mass-fill body composite specimens under the same conditions are used as a group of samples, and different confining pressures are applied to each specimen to obtain the cohesion and internal friction angle.

[0115] It should be noted that, in order to obtain the core shear strength parameters for assessing the stability of the mining area structure, this embodiment fully utilizes the "high repeatability of the specimen" advantage provided by the aforementioned preparation method when the test conducted is a conventional triaxial compression test or a true triaxial compression test.

[0116] The specific operation can be as follows: Select at least three (usually three to five) composite specimens with the same degree of fragmentation and the same filling ratio as a set of standard samples; in the testing machine, apply constant confining pressures of different gradients to each specimen in this set of samples, and then perform axial loading until failure. Record the ultimate principal stress of each specimen under different confining pressure conditions. Finally, based on the Mohr-Coulomb strength criterion in continuum mechanics, use the ultimate peak stress data under these multiple confining pressures to perform mathematical regression fitting (i.e., draw and fit the common tangent of multiple sets of Mohr stress circles), thereby accurately calculating and obtaining the overall cohesion and internal friction angle of the composite specimen under the target rock mass quality grade. This testing procedure completely overcomes the fundamental defect that the randomness of fracture in natural rock samples previously prevented them from meeting the requirements for triaxial strength envelope fitting.

[0117] To further illustrate the loading process of the above mechanical tests, an example of the assembly of the overall test apparatus for combined specimen loading failure can be found in [reference needed]. Figure 9 .like Figure 9As shown (taking a cylindrical composite specimen for uniaxial compression test as an example), the composite specimen with prepared and arranged sensors is placed firmly on the rigid base in the rigid testing machine support. The loading disk above, in conjunction with the telescopic shaft, applies axial stress to the specimen until the specimen undergoes macroscopic failure, thereby simulating the entire mechanical failure process and collecting key data.

[0118] refer to Figure 10 This application also provides a system for preparing a composite sample of fractured rock mass and filling material, comprising: The sample processing module 10 is used to obtain homogeneous rock blocks, process the homogeneous rock blocks into several initial rock samples of the same size, and process the end faces of the initial rock samples to a preset roughness. The pre-splitting / activation module 20 is used to pre-splitting the initial rock sample using a pre-splitting method with adjustable parameters to generate cracks inside it, thereby obtaining a pre-splitting rock sample. The non-destructive testing module is used to detect the degree of fragmentation of the pre-split rock sample and convert the degree of fragmentation into the rock mass quality grade of the sample. The control module 30 is communicatively connected to both the pre-splitting / activation module and the non-destructive testing module. The control module is configured to: determine whether the quality grade of the sample rock mass matches the quality grade of the target rock mass at the engineering site; if yes, use the matched pre-splitting rock sample as the target fractured rock sample; if no, adjust the values ​​of the adjustable parameters of the pre-splitting / activation module based on the comparison difference, and control the pre-splitting / activation module and the non-destructive testing module to perform the corresponding operations again until the quality grade of the sample rock mass matches the quality grade of the target rock mass. The combined sample forming module 40 is used to provide a support space around the target fractured rock sample, so that filling slurry can be poured into the support space and cured by cementing and filling to obtain the fractured rock mass-filling body combined sample.

[0119] Based on the above-mentioned method for preparing fractured rock mass-filled body composite specimens, this application also provides a corresponding preparation system. This system integrates physical hardware equipment and a logic control center for the entire process from raw rock processing to composite body formation. Specifically, it includes: a specimen processing module, such as a core drilling rig or rock cutting machine, used to prepare homogeneous rock blocks into initial rock specimens of the same size with preset roughness on the end faces; a pre-splitting / excitation module, such as a servo muffle furnace with a programmable parameter interface, a freezing chamber, or a microwave / laser generator, used to apply adjustable physical energy input to the initial specimens to induce internal microcracks; a non-destructive testing module, such as an ultrasonic wave velocity meter, used to measure and quantify the degree of fragmentation of the specimens for conversion into specimen rock mass quality grades; and a control module, serving as the core logic control center of the system (such as an industrial computer, PLC, or a host computer equipped with control algorithms), maintaining communication connections with both the pre-splitting / excitation module and the non-destructive testing module. The control module compares the measured sample grade with the target grade at the engineering site. When there is a mismatch, it triggers a closed-loop negative feedback mechanism, automatically issuing control commands to dynamically adjust the process parameters (such as temperature rise and fall) of the pre-splitting / excitation module, driving the pre-splitting and testing equipment to perform actions cyclically until a precise match is achieved. Finally, the system also includes a combined sample forming module (such as a mold tool with a specific mold support space) to provide space around the successfully matched target fractured rock sample for pouring filling slurry and performing consolidation curing, thereby stably and in batches outputting combined samples with highly consistent structural characteristics.

[0120] refer to Figure 11 This application also provides a mechanical property testing system for a fractured rock mass-filling body composite specimen, comprising: The preparation system for the fractured rock mass-filled body composite specimen as described in the foregoing embodiments is used to prepare several fractured rock mass-filled body composite specimens under the same conditions. A mechanical loading device is used to hold the fractured rock mass-filled body composite sample output by the preparation system and to apply mechanical loads to the fractured rock mass-filled body composite sample to carry out mechanical tests. A multi-source sensor network is arranged around the fractured rock mass-filled body composite specimen on the mechanical loading device. The multi-source sensor network includes strain gauges, digital image correlation devices, and acoustic emission probes, which are used to simultaneously acquire strain field and acoustic loading response data of the fractured rock mass-filled body composite specimen during the mechanical test. The data analysis host is communicatively connected to the mechanical loading device and the multi-source sensor network, respectively, and is used to control the loading execution process of the mechanical loading device, receive and process the load response data collected by the multi-source sensor network, and calculate the mechanical performance parameters of the fractured rock mass-filling body composite sample.

[0121] Based on the aforementioned method for testing the mechanical properties of combined specimens, this application further provides a mechanical property testing system for a fractured rock mass-filled body combined specimen. This system constructs a complete physical electromechanical testing platform, from standard specimen supply to multidimensional data acquisition and parameter inversion. Specifically, it includes: the aforementioned fractured rock mass-filled body combined specimen preparation system, responsible for continuously providing a library of combined standard samples with identical initial fracture conditions, identical filling ratios, and roughness interfaces for the mechanical testing stage; and a multi-source sensor network, composed of strain gauges attached to the specimen surface, high / low frequency acoustic emission probes, and a digital image correlation (DIC) optical camera mounted in front, constructing a three-dimensional monitoring network covering acoustic, optical, and electrical signals for simultaneous data acquisition during destructive mechanics testing. The system integrates macroscopic and microscopic load response data of the composite structure; mechanical loading equipment, such as a high-stiffness servo rock press or shearing apparatus, responsible for applying a specified physical load path (e.g., applying confining pressures of different gradients for triaxial compression loading) to several identical samples; and a data analysis host that communicates with the multi-source sensor network. This host uses a built-in continuum mechanics analysis model (e.g., the Mohr-Coulomb criterion regression algorithm) to perform mathematical calculations on the massive amounts of acoustic, optical, and electrical heterogeneous test data, ultimately accurately determining the core mechanical performance parameters of this type of fractured rock mass-filling composite structure, such as cohesion, internal friction angle, and deformation modulus.

[0122] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0123] Example 1: This embodiment provides a complete process for preparing a composite specimen of fractured rock mass and infill material based on a cylindrical sample, and testing its mechanical properties in a uniaxial compression test. This embodiment focuses on how to accurately prepare a composite specimen conforming to a specific rock mass quality grade through high-temperature pre-splitting and closed-loop feedback of ultrasonic testing, and then perform multi-source mechanical monitoring on it. The specific implementation steps are as follows: (1) Processing and interface preparation of initial rock samples: Experimental method: First, a complete and homogeneous rock block was obtained. Core sampling was performed on the homogeneous rock block, and it was processed into an initial cylindrical rock sample with a diameter of 50 mm and a height of 50 mm. Subsequently, one end face of the cylindrical rock sample was processed into a flat end face.

[0124] Analysis and Explanation: Processing to uniform size eliminates the geometric dispersion of the sample; a specific end face roughness is preset (planar in this embodiment) to simulate the specific engineering interface morphology that will subsequently come into contact with the filling material.

[0125] (2) Pre-cracking treatment of the specimen: Experimental Method: This embodiment uses a controllable high-temperature pre-splitting method. The prepared cylindrical rock sample was placed in a muffle furnace for heating. The initial heating temperature was set at 500℃, and the temperature was increased at a constant rate, strictly controlled within 10℃ / min. After the temperature reached the set 500℃, it was kept constant for 2 hours. Subsequently, it was cooled to room temperature by natural heat dissipation to obtain the pre-splitting rock sample.

[0126] Analysis and Explanation: Controlling the heating rate ensures uniform heating inside the rock sample, avoiding severe thermal shock damage; constant temperature maintenance and natural cooling cause the mineral particles to generate a uniform microcrack network inside due to differences in thermal expansion.

[0127] (3) Fracture degree detection and quality grade conversion: Experimental Method: The ultrasonic wave velocity of pre-cracked rock samples was measured using a non-metallic ultrasonic testing and analysis instrument. The ultrasonic probe was placed on opposite sides of a cylindrical sample, and coupling agent was applied to ensure close contact between the probe and the rock sample. Each rock sample was tested three times, the average acoustic time was calculated, and the ultrasonic wave velocity of the rock sample was calculated using Formula 1: In the formula, C p denoted as the ultrasonic wave velocity of the rock sample (unit: km / s), l is the length of the rock sample parallel to the line connecting the two probes (unit: mm), and t is the average acoustic time (unit: μs).

[0128] After measuring the wave velocity, the ultrasonic wave velocity was converted into the geological strength index GSI using the conversion model in Formula 2. In the formula, the boundary conditions are set as follows: when C... p When the speed is ≥7.46 km / s, GSI is taken as 100; when C p For speeds ≤0.84 km / s, the GSI is set to 10. Finally, based on the grading standards corresponding to the Geological Strength Index (GSI), it is converted into the corresponding Grade I to Grade V quality levels of the sample rock mass.

[0129] (4) Target level comparison and parameter closed-loop adjustment: Experimental method: Standard methods such as RMR were used to pre-determine the target rock mass quality grade at the engineering site. The sample rock mass quality grade calculated in the previous step was then compared and verified with the measured target rock mass quality grade.

[0130] If the quality grade of the prepared rock mass is the same as the measured grade, then proceed directly to the next step of casting.

[0131] If the rock mass quality grade of the sample is higher than the measured grade, the pre-splitting strength is increased (for example, the heating temperature is increased by 100°C to 600°C), and the current sample is reheated and tested for verification.

[0132] If the quality grade of the sample rock mass is lower than the measured grade, a brand new initial rock sample is reprocessed, and the pre-crack strength is reduced (for example, the heating temperature is reduced by 100°C to 400°C), and the heating and testing are repeated.

[0133] Experimental results: Through the above feedback adjustments, several target fractured rock samples that are completely consistent with the rock mass quality grade required by the engineering site can be finally prepared.

[0134] (5) Casting and curing of composite specimens: Experimental Method: Remove debris and dust from the surface of the successfully matched target fractured rock sample. Place the sample into a cylindrical mold with an inner diameter of 50 mm and a height of 100 mm. Fill the remaining space in the mold with a cementitious filling grout with a cement-sand ratio of 1:4. After casting, allow the sample to stand for 24 hours, then place it entirely in a constant temperature and humidity curing chamber for 28 days (curing temperature set at 20±2℃, humidity set at 95±2%). Upon reaching the required curing period, remove the sample from the mold to obtain the fractured rock mass-filled body composite sample.

[0135] (6) Multi-source sensor arrangement and uniaxial compression test: Experimental Methods: A sensor network was deployed on the prepared composite specimen. Using fast-drying adhesive, strain gauges parallel and perpendicular to the cylinder axis were attached to the surfaces of the infill section and the pre-fractured rock section of the specimen, respectively, and connected to a strain acquisition instrument. On the other side of the composite specimen, positioning speckle patterns were drawn at 15mm intervals, and a DIC (Digital Image Correlation) optical device was deployed on this side. A set of high-frequency (150kHz) and low-frequency (60kHz) acoustic emission probes were deployed on the infill and fractured rock surfaces of the composite specimen, respectively, with a threshold value set to 45dB.

[0136] After setup, the combined specimen was placed in a servo-controlled rigid testing machine for uniaxial compression testing. During the test, axial deformation was applied to the specimen via a loading disc.

[0137] Analysis and Result Extraction: During the loading process, the axial stress and axial / transverse strain of the specimen were recorded simultaneously; local full-field strain was calculated by capturing images using a DIC device; and microcrack rupture signals were recorded using a multi-channel acoustic emission device. Finally, the monitoring data were summarized, and stress-strain curves were plotted to accurately calculate the elastic modulus, breaking strength, and other mechanical properties of the specimen for this specific grade combination.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite specimen of fractured rock mass and infill material, characterized in that, include: Obtain a homogeneous rock block, process the homogeneous rock block into several initial rock samples of the same size, and process the end face of the initial rock sample to a preset roughness; The initial rock sample is pre-cracked using a pre-cracking method with adjustable parameters to generate cracks inside it, resulting in a pre-cracked rock sample; and the degree of fragmentation of the pre-cracked rock sample is detected and converted into a sample rock mass quality grade. Determine whether the quality grade of the sample rock mass matches the quality grade of the target rock mass at the engineering site; If so, the matched pre-cracked rock sample shall be used as the target fractured rock sample; If not, adjust the adjustable parameters of the pre-splitting method according to the comparison difference, and repeat the steps of pre-splitting treatment, detecting the degree of fragmentation and converting the quality grade of the sample rock mass until the quality grade of the sample rock mass matches the quality grade of the target rock mass. The pre-splitting rock sample that matches the target fractured rock sample is then used as the target fractured rock sample. A support space is set around the target fractured rock sample, and filling slurry is poured into the support space. After cementing and curing, the fractured rock mass-filling body composite sample is obtained.

2. The method for preparing the fractured rock mass-filling body composite sample as described in claim 1, characterized in that, The homogeneous rock block is processed into several initial rock samples of the same size, including: The homogeneous rock block is processed into cylindrical, disc-shaped, cuboid, or cubic rock specimens using core drilling or cutting methods; wherein the diameter of the cylindrical or disc-shaped rock specimen is 25mm~100mm and the height is 25mm~200mm; and / or, the length, width, and height of the cuboid or cubic rock specimen are all within the range of 25mm~300mm; and / or, Processing the end faces of the initial rock sample to a predetermined roughness includes: processing one end face, or two opposing end faces, of the initial rock sample into a planar end face, a serrated end face, a dotted columnar end face, or an irregular end face, to simulate different contact surface morphological characteristics between fractured rock mass and infill material; and / or, The pre-cracking method includes at least one of the following: high-temperature pre-cracking, low-temperature pre-cracking, corrosive solution immersion pre-cracking, microwave irradiation pre-cracking, and laser irradiation pre-cracking; and / or The adjustable parameters include: when high-temperature pre-cracking is used, adjusting the heating temperature, heating rate, heating time, and number of heating cycles; and / or, when low-temperature pre-cracking is used, adjusting the freezing temperature, freezing time, and number of freeze-thaw cycles; and / or, when pre-cracking is used by immersion in a corrosive solution, adjusting the acidity, alkalinity, concentration, and immersion time of the corrosive solution; and / or, when pre-cracking is used by microwave irradiation, adjusting the microwave irradiation intensity and irradiation time; and / or, when pre-cracking is used by laser irradiation, adjusting the laser power and irradiation time.

3. The method for preparing the fractured rock mass-filling body composite sample as described in claim 2, characterized in that, When high-temperature pre-cracking is used, the control of heating temperature, heating rate, and heating time includes: The heating rate is controlled within 1℃ / min to 20℃ / min. After heating to the specified heating temperature within 100℃ to 1000℃, it is maintained for 0.5h to 5h. Finally, natural heat dissipation or water cooling is used for cooling.

4. The method for preparing the fractured rock mass-filling body composite sample as described in claim 1, characterized in that, The methods for detecting the degree of fragmentation of the pre-fractured rock sample include at least one of the following: rock sample density test, resistivity test, permeability coefficient test, mercury intrusion porosimetry test, ultrasonic wave velocity test, computed tomography scan test, and nuclear magnetic resonance test.

5. The method for preparing the fractured rock mass-filling body composite sample as described in claim 4, characterized in that, When the method for detecting the degree of fragmentation of the pre-fractured rock sample is ultrasonic wave velocity testing, the step of converting the degree of fragmentation into a sample rock mass quality grade includes: The ultrasonic transmitting probe and ultrasonic receiving probe are placed on both sides of the pre-split rock sample, respectively, and the average acoustic time is measured and the ultrasonic wave velocity of the pre-split rock sample is calculated. Based on the rock mass geological strength index and ultrasonic wave velocity conversion model, the ultrasonic wave velocity is converted into the corresponding geological strength index GSI value. Based on the correspondence between the geological strength index and the rock mass quality grade, the geological strength index GSI value is converted into the corresponding sample rock mass quality grade; wherein, the sample rock mass quality grade includes Grade I, Grade II, Grade III, Grade IV and Grade V.

6. The method for preparing the fractured rock mass-filling body composite sample as described in claim 1, characterized in that, The process of adjusting the adjustable parameters of the pre-splitting method based on the comparison difference, performing the pre-splitting treatment again, detecting the degree of fragmentation, and converting the quality grade of the sample rock mass includes: If the quality grade of the sample rock mass is higher than that of the target rock mass, the value of the adjustable parameter is increased, and the pre-splitting treatment, the degree of fragmentation, and the quality grade of the sample rock mass are recalculated for the current pre-splitting rock sample. If the quality grade of the sample rock mass is lower than that of the target rock mass, the value of the adjustable parameter is reduced, the initial rock sample is re-acquired, and the steps of pre-splitting treatment, detecting the degree of fragmentation, and converting the quality grade of the sample rock mass are performed again. The target rock mass quality grade is obtained by investigating the engineering site using at least one of the following methods: RQD, RMR, MRMR, Q method, GSI method, and BQ method; and / or, A support space is set around the target fractured rock sample, and filling grout is poured into the support space. After cementing and curing, the fractured rock mass-filled body composite sample is obtained, comprising: The target fractured rock sample is loaded into a mold with an inner cavity size larger than the target fractured rock sample size in at least one direction, and cemented filling slurry is poured into the mold space. After the sample is poured, it is left to stand for 12h~48h, and then placed in a constant temperature and humidity curing chamber for curing before demolding; the curing temperature of the curing chamber is 20±2℃ and the humidity is 95±2%.

7. A method for testing the mechanical properties of a composite specimen of fractured rock mass and filling material, characterized in that, include: Using the preparation method described in any one of claims 1-6, several composite samples of fractured rock mass-filling body under the same conditions were prepared. Sensors were arranged around the fractured rock mass-filled body composite sample. Mechanical tests were conducted using several of the fractured rock mass-filled body composite specimens as a group of samples. The mechanical property parameters of the fractured rock mass-filled body composite specimens were calculated using the test data collected by the sensor.

8. The method for testing the mechanical properties of the fractured rock mass-filling body composite specimen as described in claim 7, characterized in that, Sensors are arranged around the fractured rock mass-filled body composite sample, including: Strain gauges are arranged parallel to and perpendicular to the sample axis on the surface of the filling body and the surface of the pre-split rock sample of the fractured rock mass-filling body composite sample, respectively. Positioning speckle patterns were drawn on one side of the fractured rock mass-filling body composite sample, and digital image correlation equipment was set up. A high-frequency acoustic emission probe and a low-frequency acoustic emission probe are arranged on the side of the fractured rock mass-filled body composite sample; and / or, The mechanical tests conducted include at least one of the following: uniaxial compression test, conventional triaxial compression test, true triaxial compression test, direct tensile test, Brazilian splitting test, variable angle shear test, or direct shear test; When the mechanical test is the conventional triaxial compression test and / or the true triaxial compression test, at least three fractured rock mass-fill body composite specimens under the same conditions are used as a group of samples, and different confining pressures are applied to each specimen to obtain the cohesion and internal friction angle.

9. A system for preparing a composite sample of fractured rock mass and infill material, characterized in that, include: The sample processing module is used to obtain homogeneous rock blocks, process the homogeneous rock blocks into several initial rock samples of the same size, and process the end faces of the initial rock samples to a preset roughness. The pre-splitting / activation module is used to pre-splitting the initial rock sample using a pre-splitting method with adjustable parameters to generate cracks inside it, thereby obtaining a pre-splitting rock sample. The non-destructive testing module is used to detect the degree of fragmentation of the pre-split rock sample and convert the degree of fragmentation into the rock mass quality grade of the sample. The control module is communicatively connected to both the pre-splitting / activation module and the non-destructive testing module; the control module is configured to: determine whether the quality grade of the sample rock mass matches the quality grade of the target rock mass at the engineering site; if so, the pre-splitting rock sample that matches is used as the target fractured rock sample; If not, adjust the values ​​of the adjustable parameters of the pre-splitting / activation module according to the comparison difference, and control the pre-splitting / activation module and the non-destructive testing module to perform the corresponding operations again until the quality grade of the sample rock mass matches the quality grade of the target rock mass; The combined specimen molding module is used to provide a support space around the target fractured rock specimen, so that filling slurry can be poured into the support space and cured by cementing and filling to obtain the fractured rock mass-filling body combined specimen.

10. A mechanical property testing system for a composite specimen of fractured rock mass and filling material, characterized in that, include: The preparation system for the fractured rock mass-filled body composite specimen as described in claim 9 is used to prepare several fractured rock mass-filled body composite specimens under the same conditions. A mechanical loading device is used to hold the fractured rock mass-filled body composite sample output by the preparation system and to apply mechanical loads to the fractured rock mass-filled body composite sample to carry out mechanical tests. A multi-source sensor network is arranged around the fractured rock mass-filled body composite specimen on the mechanical loading device. The multi-source sensor network includes strain gauges, digital image correlation devices, and acoustic emission probes, which are used to simultaneously acquire strain field and acoustic loading response data of the fractured rock mass-filled body composite specimen during the mechanical test. The data analysis host is communicatively connected to the mechanical loading device and the multi-source sensor network, respectively, and is used to control the loading execution process of the mechanical loading device, receive and process the load response data collected by the multi-source sensor network, and calculate the mechanical performance parameters of the fractured rock mass-filling body composite sample.

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