Reduced scale mechanical test system and method for backfill body

Abstract

The invention provides a backfill body reduced scale mechanical test system and method, and relates to the field of mine engineering tests. The backfill body reduced scale mechanical test system comprises a loading testing machine, a mold, a first blocking piece and a second blocking piece, the loading testing machine comprises a rack, a lifting piece, a loading piece, a sensor and a controller, the rack is provided with a table top, the lifting piece moves relative to the table top in the first direction, and the loading piece and the lifting piece are arranged at intervals in the first direction; the mold is placed on the table top and used for bearing the backfill body, the sensor is pre-buried in the backfill body, and the two ends of the mold are provided with an opening and an opening respectively; the first plugging piece is matched with the opening; and the second plugging piece is matched with the opening. The mechanical test is carried out on the backfill body in the mold, the stress state change of the backfill body in the continuous backfill process and the damage behavior of the backfill body in the mining exposure process are simulated, and research on the complex mechanical characteristics of the backfill body is achieved.

Description

Technical Field

[0001] The present application relates to the field of mining engineering tests, and in particular to a backfill scale mechanical test system and method. Background Art

[0002] With the continuous deepening of mining development in my country, the number of deep open pit backfill projects formed after the conversion from open pit to underground mining is increasing. In this type of project, the deep backfill body formed by continuous backfilling has significant differences in mechanical properties and deformation characteristics from conventional backfill bodies due to its particularity.

[0003] Especially under the high-pressure conditions formed at great depths, the mechanical behavior of the backfill body exhibits obvious nonlinear characteristics, and traditional test methods are difficult to accurately simulate and study such complex working conditions. In addition, when the backfill body is exposed in later mining activities, it is very easy to cause engineering accidents due to the lack of in-depth understanding of its failure mode. At present, the industry still lacks a systematic research method for the mechanical behavior of deep backfill bodies under high-pressure conditions, which seriously restricts the safety assessment and optimization design of open pit backfill projects. Summary of the invention

[0004] The purpose of this application is to provide a scaled-down mechanical testing system and method for backfill, which can effectively simulate the mechanical properties of deep backfill, observe and analyze the failure mode of backfill during mining exposure, and at the same time, the test has good repeatability, relatively low cost, is closer to engineering practice, and the research results have higher practical value.

[0005] In a first aspect, the present invention provides a scaled mechanical testing system for a backfill body, the scaled mechanical testing system for a backfill body comprising: A loading tester, comprising a frame and a lifting member, a loading member, a sensor and a controller mounted on the frame, wherein the frame is provided with a table, the lifting member moves relative to the table in a first direction to a first position and a second position, the first position is flush with the table, and the second position is arranged below the first position, the loading member and the lifting member are arranged at intervals in the first direction, and the loading member is located on a side of the table away from the lifting member, and the controller is electrically connected to the lifting member, the loading member and the sensor respectively; A mold is placed on the table, the mold is used to carry the backfill body, the sensor is pre-buried in the backfill body, and an opening and an opening are respectively provided at two ends of the mold, the opening and the opening are arranged along a first direction, and the cross-sectional area of ​​the opening is larger than the cross-sectional area of ​​the opening; A first blocking member, adapted to the opening, wherein the loading member is close to or away from the first blocking member; The second blocking member is matched with the opening, and the lifting member is close to or away from the second blocking member.

[0006] In an optional embodiment, the sensor includes a stress and strain sensing body, a lead boss and a data line, the stress and strain sensing body is placed in the backfill body, the data line is passed through the lead boss, and both ends of the data line are respectively connected to the stress and strain sensing body and the controller.

[0007] In an optional embodiment, the mold is provided with a through hole, the through hole is located on the side wall of the mold, and the lead boss is embedded in the through hole.

[0008] In an optional embodiment, the through hole includes a first hole and a second hole, the first hole is located at the bottom of the second hole, the diameter of the first hole is larger than the diameter of the second hole, and the first hole and the second hole extend along a second direction, and the second direction is perpendicular to the first direction.

[0009] In an optional embodiment, the loading tester further includes a data acquisition device, and the sensor and the controller are electrically connected via the data acquisition device.

[0010] In an optional embodiment, the mold is made of a transparent material, and a scale is disposed outside the mold, and the scale is disposed along the first direction.

[0011] In an optional embodiment, the inner side wall of the mold is configured as a smooth surface or a rough surface.

[0012] In an optional embodiment, the loading member is provided with a loading end, and a cross-sectional area of ​​the loading end is smaller than a cross-sectional area of ​​the first blocking member.

[0013] In an optional embodiment, the lifting member is provided with a lifting end, and a cross-sectional area of ​​the lifting end is larger than a cross-sectional area of ​​the second blocking member.

[0014] In a second aspect, the present invention provides a backfill scaled mechanical test method, using the backfill scaled mechanical test system described in the above embodiment, the backfill scaled mechanical test method comprises: Test preparation: Place the second plugging piece into the opening, then pour the rubber tailing sand into the mold through the opening, embed the sensor during the pouring process, and after the pouring is completed, cure the rubber tailing sand for a preset age to form a backfill body, and cover it with the first plugging piece; Backfill process simulation: The controller controls the lifting part to rise to the first position, and the mold is placed on the table. Then the controller controls the loading part to load the backfill body in the mold at the preset target value and loading rate, and the stress and strain of the backfill body during the whole loading process are tested, and the morphological changes of the backfill body are observed. According to the test results, the mechanical properties of the lateral pressure coefficient, stress and deformation law in the simulated backfill process are obtained, the state of the backfill body is observed, and whether the backfill body is damaged during the backfill process is evaluated; High-pressure backfill exposure simulation: While maintaining the target loading value of the loader, the controller controls the lifting member to descend to the second position, observes the failure form of the backfill, and tests the pressure and strain laws; stops loading the loader, takes out the mold, observes the state of the mold and the backfill in the opening, and evaluates the failure mode and mechanical behavior of the high-pressure backfill during the mining exposure process.

[0015] Compared with the prior art, the beneficial effects of this application are: The present application uses a loading test machine to perform mechanical tests on the backfill body in the mold, uses a loading part to continuously load the first sealing part to simulate the change in the stress state of the deep backfill body during the continuous backfilling process, and then uses a lifting part to push or move away from the second sealing part to simulate the destructive behavior of the high-pressure backfill body in the mining exposure process, thereby realizing a systematic study of the complex mechanical characteristics of the backfill body. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A connection schematic diagram of a scaled mechanical test system for backfill bodies in some embodiments is shown (the lifting member is in the rising state); Figure 2 Another connection schematic diagram of a scaled mechanical testing system for backfill bodies in some embodiments is shown (some elements are omitted); Figure 3 A connection schematic diagram of a scaled mechanical test system for backfill bodies in some embodiments is shown (in a state where the lifting member is lowered); Figure 4 A schematic diagram showing the connection between the mold, the sensor and the second blocking member in some embodiments is shown; Figure 5 Another schematic diagram of the connection between the mold, the sensor and the second blocking member in some embodiments is shown.

[0018] Description of main component symbols: 100-loading test machine; 110-frame; 120-lifting member; 130-loading member; 140-sensor; 141-stress and strain sensor body; 142-lead boss; 143-data line; 150-controller; 160-data acquisition instrument; 200-mold; 210-opening; 220-opening; 230-through hole; 240-inner wall; 300-first blocking member; 400-second blocking member; 500-backfilling body. DETAILED DESCRIPTION

[0019] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0020] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0022] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0024] Embodiment 1 This embodiment is applicable to the backfill test of the rubber tailings.

[0025] See also Figure 1 The present embodiment provides a scaled-down mechanical testing system for a backfill body, and the scaled-down mechanical testing system for a backfill body includes a loading testing machine 100 , a mold 200 , a first blocking member 300 , and a second blocking member 400 .

[0026] The loading tester 100 includes a frame 110 , and a lifting member 120 , a loading member 130 , a sensor 140 , and a controller 150 installed on the frame 110 .

[0027] The frame 110 is provided with a table top. In this embodiment, the frame 110 is made of high-rigidity steel, and the table top is a horizontal surface.

[0028] The lifting member 120 moves along a first direction relative to the table surface between a first position and a second position. The first position is flush with the table surface, and the second position is set lower than the first position. In actual use, the first direction is a vertical direction, and the lifting member 120 is installed in the accommodating cavity of the frame 110.

[0029] The size of the lifting member 120 is 15 cm in diameter.

[0030] The loading member 130 and the lifting member 120 are arranged at intervals along the first direction, and the loading member 130 is located on the side of the table away from the lifting member 120, that is, the loading member 130 is located above the table, and the lifting member 120 is located below the table.

[0031] The loading member 130 applies high pressure loading to the backfill body 500 , so that the backfill body 500 is at a high stress level of 10-15 MPa.

[0032] The controller 150 is electrically connected to the lifting member 120, the loading member 130, and the sensor 140. Therefore, the lifting member 120 and the loading member 130 are controlled by the control member, and can be automatically controlled with high precision, without manual operation of the lifting member 120 and the loading member 130, thereby reducing errors. In addition, the sensor 140 transmits the information detected by itself to the controller 150 in the form of data, and the controller 150 can analyze and evaluate it.

[0033] Specifically, the controller 150 is a computer, and the sensor 140 transmits data to the computer, which records and stores the data.

[0034] See also Figure 1 and Figure 2 The sensor 140 includes a stress-strain sensor body 141, a lead boss 142 and a data line 143. The stress-strain sensor body 141 is placed in the backfill body 500, the data line 143 is passed through the lead boss 142, and the two ends of the data line 143 are respectively connected to the stress-strain sensor body 141 and the controller 150.

[0035] The data line 143 is configured as a flexible cable, and an extra 2 to 3 cm is reserved for the data line 143 in the backfill body 500 to prevent the data line 143 from being broken due to damage to the backfill body 500 during the test.

[0036] See also Figure 1 , Figure 4 and Figure 5 The mold 200 is placed on the table, the mold 200 is used to support the backfill body 500, the sensor 140 is pre-buried in the backfill body 500, and an opening 210 and an opening 220 are respectively provided at both ends of the mold 200. The opening 210 and the opening 220 are arranged along the first direction, and the cross-sectional area of ​​the opening 210 is larger than the cross-sectional area of ​​the opening 220.

[0037] The opening 210 is disposed at the top of the mold 200 , and the opening 220 is disposed at the bottom of the mold 200 . On the table, the projection surface of the opening 220 is located within the projection surface of the opening 210 .

[0038] In this embodiment, the size of the mold 200 is 1m×1m×1m, which is used for pouring the glue tailing sand, and the size of the bottom square opening 220 is 10cm×10cm.

[0039] The first blocking member 300 is matched with the opening 210, and the loading member 130 is close to or away from the first blocking member 300. After the loading member 130 moves downward and approaches the first blocking member 300, the loading member 130 continues to descend and pushes the first blocking member 300 to apply a loading force downward to achieve a high stress level of the backfill body 500. After the test is completed, the loading member 130 moves upward and gradually moves away from the first blocking member 300, and the first blocking member 300 stops applying a loading force to the backfill body 500.

[0040] In this embodiment, the first blocking member 300 is configured as a plate-like structure with dimensions of 98cm×98cm×5cm, and the first blocking member 300 has high strength to meet the pressurization requirements of the loader 130 and prevent the first blocking member 300 from cracking under high pressure.

[0041] The second blocking member 400 is matched with the opening 220, and the lifting member 120 is close to or away from the second blocking member 400. When the lifting member 120 moves upward to the first position, the plane of the lifting member 120 is flush with the table surface. Figure 3 When the lifting member 120 moves downward to the second position, the lifting member 120 is away from the second blocking member 400. At this time, the lifting member 120 does not provide support force to the second blocking member 400, and the second blocking member 400 falls on the lifting member 120 due to gravity.

[0042] Specifically, the opening 220 is configured as a square, and correspondingly, the second blocking member 400 is configured as a block.

[0043] In this embodiment, the loading member 130 is provided with a loading end, the cross-sectional area of ​​the loading end is smaller than the cross-sectional area of ​​the first blocking member 300 , and the lifting member 120 is provided with a lifting end, the cross-sectional area of ​​the lifting end is larger than the cross-sectional area of ​​the second blocking member 400 .

[0044] Based on the above content, using the above-mentioned backfill body 500 scale mechanical test system, this embodiment also provides a backfill body 500 scale mechanical test method, and the backfill body 500 scale mechanical test method includes: S100. Test preparation: Place the second plugging member 400 into the opening 220, then pour the glue tailing sand into the mold 200 through the opening 210, embed the sensor 140 during the pouring process, and after the pouring is completed, cure the glue tailing sand for a preset age to form a backfill body 500, and cover it with the first plugging member 300.

[0045] Before embedding the sensor 140 , the sensor 140 is installed. First, the data line 143 is passed through the lead boss 142 , and then the lead boss 142 is placed in the through hole 230 , one end of the data line 143 is connected to the stress and strain sensor body 141 , and the other end is connected to the controller 150 .

[0046] The pouring method of the adhesive tailing sand can be adjusted according to the research purpose. It can be poured and cured as a whole at one time, or it can be poured in layers and cured in stages.

[0047] The curing age is set at 28 days.

[0048] S200. Backfill process simulation: The controller 150 controls the lifting member 120 to rise to the first position, and places the mold 200 on the table. Then the controller 150 controls the loading member 130 to load the backfill body 500 in the mold 200 at a preset target value and loading rate, and tests the stress and strain of the backfill body 500 during the entire loading process, and observes the morphological changes of the backfill body 500. According to the test results, the mechanical properties of the lateral pressure coefficient, stress and deformation law in the simulated backfill process are obtained, the state of the backfill body 500 is observed, and it is evaluated whether the backfill body 500 is damaged during the backfill process.

[0049] It is understandable that when placing the mold 200 , the mold 200 should be placed in the center position so that the second blocking member 400 is located within the movement range of the lifting member 120 .

[0050] Gradient loading can be achieved by setting the loading target value and loading rate according to the research purpose, which is used to simulate the actual working conditions of continuous backfilling. The set value is calculated based on the gravity change of the overlying backfill tailings during the backfilling process of the backfill body 500.

[0051] S300. High-pressure backfill body 500 exposure simulation: While maintaining the loading target value of the loader 130, the controller 150 controls the lifting member 120 to descend to the second position, observes the failure form of the backfill body 500, and tests the law of pressure and strain; stops loading by the loader 130, takes out the mold 200, observes the state of the backfill body 500 in the mold 200 and the opening 220, and evaluates the failure mode and mechanical behavior of the backfill body 500 during the mining exposure process.

[0052] The test system provided in this embodiment is reasonably designed, easy to operate, and has good repeatability of test results. It simulates the changes in the stress state of a deep backfill body 500 during continuous backfilling. This embodiment can provide reliable technical support for engineering practice and realize a systematic study of the compaction effect and mechanical behavior of the backfill body 500. In addition, this embodiment reveals the stress redistribution law and stability problems of the backfill body 500 during mining activities, providing guidance for mining design and safe construction.

[0053] Embodiment 2 See also Figure 4 and Figure 5 Based on the first embodiment, this embodiment is improved in that the mold 200 is provided with a through hole 230 , the through hole 230 is located on the side wall of the mold 200 , and the lead boss 142 is embedded in the through hole 230 .

[0054] Specifically, the through hole 230 includes a first hole and a second hole, the first hole is located at the bottom of the second hole, the aperture of the first hole is larger than the aperture of the second hole, and the first hole and the second hole extend along a second direction, the second direction is perpendicular to the first direction, that is, the second direction is a horizontal direction.

[0055] Specifically, the second hole has a diameter of 5 mm, and the first hole has a diameter of 10 mm.

[0056] Embodiment 3 See also Figure 1 Based on the first embodiment, this embodiment is improved in that the loading tester 100 further includes a data acquisition device 160 , and the sensor 140 and the controller 150 are electrically connected via the data acquisition device 160 .

[0057] When the sensor 140 is installed, one end of the data line 143 is connected to the stress-strain sensor body 141 , and the other end is connected to the controller 150 through the data acquisition device 160 .

[0058] Embodiment 4 See also Figure 1 and Figure 2 Based on the first embodiment, this embodiment is improved in that the mold 200 is made of a transparent material, and a scale is arranged outside the mold 200, and the scale is arranged along a first direction. The first direction here is a vertical direction, and the scale is used to measure the compression amount of the backfill body 500.

[0059] In this embodiment, the second blocking member 400 is also made of a transparent material. When the second blocking member 400 is inserted into the opening 220 , the entire mold 200 is a transparent structure, which facilitates the test personnel to observe the state of the backfill body 500 .

[0060] The mold 200 is made of acrylic plate, tempered glass plate or hard plastic plate, and can bear a pressure of more than 3MPa. In this embodiment, it can be set that the mold 200 is made of acrylic plate, and can bear a pressure of 5MPa, and the second blocking member 400 is also made of acrylic plate.

[0061] This embodiment can intuitively observe and record the deformation characteristics and failure modes of the backfill body 500 under high pressure conditions, and provide a scientific basis for predicting and preventing the instability and failure of the backfill body 500.

[0062] Embodiment 5 See also Figure 1 , Figure 4 and Figure 5 Based on the first embodiment, this embodiment is improved in that the inner side wall 240 of the mold 200 is configured as a smooth surface or a rough surface.

[0063] exist Figure 1 and Figure 4 In the example, the smooth surface is used to simulate the boundary morphology between the backfill bodies 500. Figure 1 and Figure 5 In the figure, the rough surface is used to simulate the boundary morphology of the contact surface between the backfill body 500 and the surrounding rock.

[0064] Therefore, this embodiment can simulate different interface effects between the backfill body 500 and the surrounding rock mass, study the shear characteristics and bonding properties of the interface between the backfill body 500 and the rock mass, and provide a basis for interface treatment and design solutions.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0066] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A backfill scale mechanical test system, characterized in that: include: A loading tester, comprising a frame and a lifting member, a loading member, a sensor and a controller mounted on the frame, wherein the frame is provided with a table, the lifting member moves relative to the table in a first direction to a first position and a second position, the first position is flush with the table, and the second position is arranged below the first position, the loading member and the lifting member are arranged at intervals in the first direction, and the loading member is located on a side of the table away from the lifting member, and the controller is electrically connected to the lifting member, the loading member and the sensor respectively; A mold is placed on the table, the mold is used to carry the backfill body, the sensor is pre-buried in the backfill body, and an opening and an opening are respectively provided at two ends of the mold, the opening and the opening are arranged along a first direction, and the cross-sectional area of ​​the opening is larger than the cross-sectional area of ​​the opening; A first blocking member, adapted to the opening, wherein the loading member is close to or away from the first blocking member; The second blocking member is matched with the opening, and the lifting member is close to or away from the second blocking member.

2. The backfill body scaled mechanical testing system according to claim 1, characterized in that: The sensor comprises a stress-strain sensor body, a lead convex head and a data line. The stress-strain sensor body is placed in the backfill body, the data line is passed through the lead convex head, and two ends of the data line are respectively connected to the stress-strain sensor body and the controller.

3. The backfill body scaled mechanical testing system according to claim 2, characterized in that: The mold is provided with a through hole, the through hole is located on the side wall of the mold, and the lead protrusion is embedded in the through hole.

4. The backfill body scaled mechanical testing system according to claim 3, characterized in that: The through hole includes a first hole and a second hole, the first hole is located at the bottom of the second hole, the diameter of the first hole is larger than the diameter of the second hole, and the first hole and the second hole extend along a second direction, and the second direction is perpendicular to the first direction.

5. The backfill body scaled mechanical testing system according to any one of claims 1 to 4, characterized in that: The loading test machine further comprises a data acquisition instrument, and the sensor is electrically connected to the controller via the data acquisition instrument.

6. The backfill body scaled mechanical testing system according to any one of claims 1 to 4, characterized in that: The mold is made of a transparent material, and a scale is arranged outside the mold, and the scale is arranged along a first direction.

7. The backfill body scaled mechanical testing system according to any one of claims 1 to 4, characterized in that: The inner side wall of the mold is configured as a smooth surface or a rough surface.

8. The backfill body scaled mechanical testing system according to any one of claims 1 to 4, characterized in that: The loading component is provided with a loading end, and the cross-sectional area of ​​the loading end is smaller than the cross-sectional area of ​​the first blocking component.

9. The backfill body scaled mechanical testing system according to claim 1, characterized in that: The lifting member is provided with a lifting end, and the cross-sectional area of ​​the lifting end is larger than the cross-sectional area of ​​the second blocking member.

10. A backfill scale mechanical test method, characterized in that: Utilizing the backfill body scaled mechanics test system according to any one of claims 1 to 9, the backfill body scaled mechanics test method comprises: Test preparation: Place the second plugging piece into the opening, then pour the rubber tailing sand into the mold through the opening, embed the sensor during the pouring process, and after the pouring is completed, cure the rubber tailing sand for a preset age to form a backfill body, and cover it with the first plugging piece; Backfill process simulation: The controller controls the lifting part to rise to the first position, and the mold is placed on the table. Then the controller controls the loading part to load the backfill body in the mold at the preset target value and loading rate, and the stress and strain of the backfill body during the whole loading process are tested, and the morphological changes of the backfill body are observed. According to the test results, the mechanical properties of the lateral pressure coefficient, stress and deformation law in the simulated backfill process are obtained, the state of the backfill body is observed, and whether the backfill body is damaged during the backfill process is evaluated; High-pressure backfill exposure simulation: While maintaining the target loading value of the loader, the controller controls the lifting member to descend to the second position, observes the failure form of the backfill, and tests the pressure and strain laws; stops loading the loader, takes out the mold, observes the state of the mold and the backfill in the opening, and evaluates the failure mode and mechanical behavior of the high-pressure backfill during the mining exposure process.

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