A rock variable-angle tensile-shear, compression-shear and variable-angle triaxial test device with confining pressure

Abstract

The application discloses a rock variable-angle tensile shear, compressive shear and variable-angle triaxial test device capable of adding confining pressure, which comprises a counterforce frame, a hydraulic loading system, a variable-angle shear test module and a variable-angle triaxial test module arranged on the counterforce frame, and can be used for rock sample variable-angle compressive shear test under a condition without lateral confining pressure, rock sample variable-angle tensile shear test under a condition without lateral confining pressure, rock sample variable-angle shear test under a condition with lateral confining pressure, cubic rock sample variable-angle triaxial test, and small-scale rock mass "first loading and then excavation" stress path simulation test under a true triaxial stress condition. The loading structure of the testing machine is simplified, the number of loading oil cylinders is reduced, the simplicity of multiple tests is enhanced, multiple functions can be effectively integrated, and one machine can be used for multiple purposes.

Description

Technical Field

[0001] This invention relates to the field of indoor rock testing technology, and in particular to a rock variable angle tensile shear, compression shear and variable angle triaxial testing device that can be subjected to confining pressure. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the continuous construction of infrastructure in transportation, energy, water conservancy and hydropower, the proportion of rock engineering projects is constantly increasing. As the construction environment shifts towards western mountainous areas and deep underground spaces, the stress environment and failure modes of rock masses are becoming increasingly complex. Various disaster types, such as slope landslides, collapses, tunnel collapses, and rock bursts, pose serious threats to the safe construction of projects. Revealing the failure and catastrophic mechanisms of rock masses under complex stress conditions is a prerequisite for rock mass stability analysis and disaster monitoring and early warning, while laboratory rock tests are an important means of studying these catastrophic mechanisms.

[0004] Shear failure is one of the most common types of rock failure. Currently, direct shear tests and triaxial tests are mainly used to address this type of failure. Both of these tests focus on the compressive-shear stress state. However, with the continuous emergence of shallow-buried ultra-long-span tunnels and deep-buried ultra-long tunnels, rock mass failure caused by tensile-shear stress state is increasing. At present, there is still a lack of testing equipment that can efficiently carry out tensile-shear failure tests on rocks.

[0005] In addition, the existing shear testing equipment, whether for direct shear testing or variable angle shear testing, is limited by the structure of the testing machine and the testing technology, and cannot carry out shear tests under lateral confining pressure conditions. As a result, the test phenomena and results are somewhat different from the actual rock mass failure in engineering. Specifically, the rock cohesion parameters are smaller than the triaxial test measurement results.

[0006] Although existing true triaxial testing machines can provide test conditions that are close to the original in-situ stress, the devices are complex in structure and expensive to produce, the test process is relatively cumbersome, and it is not conducive to the rapid acquisition of rock shear parameters. In terms of test simplicity and engineering practicality, they are weaker than direct shear tests.

[0007] For monitoring multi-dimensional information in rock failure processes, the traditional true triaxial testing machine has a relatively closed six-sided loading structure. Taking the real-time observation of internal failure of porous rock samples under triaxial loading conditions as an example, the existing true triaxial testing machine structure is not convenient for installing devices such as in-hole cameras and infrared thermal imagers, and the capture of optical monitoring information is quite difficult.

[0008] In addition, traditional true triaxial testing machines, which use prefabricated porous rock samples to simulate overload failure, can only simulate the stress path of "excavation first, loading later", which does not match the actual tunnel excavation process. The simulation of the "loading first, excavation later" stress path can currently only be achieved through large-scale model tests, which are costly and have long construction cycles, making it difficult to conduct experimental research on a large number of working conditions. Summary of the Invention

[0009] To address the aforementioned issues, this invention proposes a rock variable-angle tensile-shear, compressive-shear, and variable-angle triaxial testing device capable of applying confining pressure. This simplifies the loading structure of the testing machine, reduces the number of loading cylinders, enhances the ease of conducting various types of tests, and effectively integrates multiple functions. Specific functions include: compressive-shear and tensile-shear tests with / without confining pressure, true triaxial tests of cubic rock samples with / without pre-fabricated holes, and simulation tests of excavation of complete cubic rock samples under true triaxial stress conditions, thus achieving multi-purpose functionality.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a rock variable angle tensile shear, compression shear and variable angle triaxial test device that can be subjected to confining pressure, comprising: a reaction frame, and a hydraulic loading system, a variable angle shear test module and a variable angle triaxial test module disposed on the reaction frame;

[0012] The hydraulic loading system includes a vertical bidirectional loading cylinder located at the top of the reaction frame and a first horizontal unidirectional loading cylinder and a second horizontal unidirectional loading cylinder located on both sides of the reaction frame.

[0013] The variable angle shear test module includes a bottom support, a first variable angle shear component, and a second variable angle shear component. The bottom support is located at the bottom of the reaction frame, and the second variable angle shear component is connected to the bottom support via a connector. The first variable angle shear component is connected to a vertical bidirectional loading cylinder via a connector.

[0014] The first variable angle shear member and the second variable angle shear member both include a load-bearing shear sliding seat and a shear sliding block that are slidably connected. The two shear sliding blocks are arranged opposite each other and a rock sample is placed in the middle. The vertical bidirectional loading cylinder applies vertical tensile load and compressive load to the rock sample, and the first horizontal unidirectional loading cylinder and the second horizontal unidirectional loading cylinder apply lateral confining pressure to the rock sample.

[0015] The variable angle triaxial test module includes a triaxial test platform, a variable angle triaxial device and a load-bearing pad mounted on the triaxial test platform. The triaxial test platform is located on the bottom platform. A first horizontal unidirectional loading cylinder and a second horizontal unidirectional loading cylinder are respectively connected to a variable angle triaxial device. A rock sample is placed between the two variable angle triaxial devices. A load-bearing pad is placed on the rock sample and connected to a vertical bidirectional loading cylinder.

[0016] As an alternative implementation, the first variable angle shearing member is connected to the vertical bidirectional loading cylinder in sequence through a first groove-shaped connector and a first I-shaped connector; a first tension-compression dual-purpose ball bearing is provided between the first I-shaped connector and the first groove-shaped connector;

[0017] The second variable angle shearing member is connected to the bottom support platform in sequence by the second groove-shaped connector and the second I-shaped connector; a second tension and compression dual-purpose ball bearing is provided between the second I-shaped connector and the second groove-shaped connector.

[0018] As an alternative implementation, the load-bearing shear sliding seat is provided with a slide rail, and the shear sliding block is provided with a sliding groove. The load-bearing shear sliding seat is connected to the sliding groove through the slide rail, so that the shear sliding block slides along the slide rail in an arc shape, and different forms of tests can be carried out on the rock sample by changing the angle of the shear sliding block.

[0019] As an alternative implementation, the load-bearing shear sliding seat is provided with a shear angle positioning bolt, and the shear sliding block is provided with a shear angle positioning hole that matches the shear angle positioning bolt, so that after the shear sliding block determines the sliding angle, the position is fixed by the shear angle positioning hole and the shear angle positioning bolt.

[0020] As an alternative implementation, the outer surface of the load-bearing shear sliding seat is provided with a scale.

[0021] As an alternative implementation, during the variable angle compression-shear test, the rock sample is naturally placed between the first variable angle shear member and the second variable angle shear member, with the upper and lower surfaces of the rock sample freely attached to the shear sliding block.

[0022] During the variable angle tensile shear test, the upper and lower surfaces of the rock sample were bonded to the shear sliding block using high-strength adhesive.

[0023] When conducting a lateral confining pressure variable angle shear test, the variable angle shear test module is rotated 90° around its own vertical centerline. The free surface of the rock sample is directly facing the horizontal one-way loading cylinders on both sides, and load-bearing pads are installed on the two free sides of the rock sample. Lateral confining pressure of a specific force value is applied to the rock sample through the first horizontal one-way loading cylinder and the second horizontal one-way loading cylinder.

[0024] As an alternative implementation, the variable angle triaxial device is used for variable angle triaxial tests on intact cubic rock samples, including an intact rock sample triaxial bearing sliding seat, an intact rock sample triaxial sliding block, a triaxial variable angle positioning bolt, and a triaxial variable angle positioning hole;

[0025] The complete rock sample three-axis force sliding seat and the complete rock sample three-axis sliding block are slidably connected and their positions are fixed by three-axis variable angle positioning bolts and three-axis variable angle positioning holes.

[0026] As an alternative implementation, the variable angle triaxial device is used for variable angle triaxial tests on cubic rock samples containing circular holes, and includes a three-axis force sliding seat for rock samples containing circular holes, a three-axis sliding block for rock samples containing circular holes, a triaxial variable angle positioning screw, and a triaxial variable angle positioning hole.

[0027] The three-axis sliding seat containing the rock sample with circular holes and the three-axis sliding block containing the rock sample with circular holes are slidably connected and their positions are fixed by the three-axis variable angle positioning bolt and the three-axis variable angle positioning hole.

[0028] The rock sample with circular holes has a pre-reserved observation hole on its three-bearing force sliding seat. This hole is used for direct optical observation of the internal damage phenomenon of the rock sample during the overload test with pre-made holes, or as an excavation hole for the complete rock sample under true triaxial stress conditions.

[0029] As an alternative implementation, after the angle of the triaxial sliding block is determined, the horizontal centerline of the rock sample coincides with the centerline of the variable angle triaxial device and the centerlines of the first horizontal unidirectional loading cylinder and the second horizontal unidirectional loading cylinder, and a load-bearing pad is installed on the upper surface of the rock sample.

[0030] The rock sample is loaded with confining pressure to a specific force value by the first and second horizontal unidirectional loading cylinders, and then vertical load is applied to the rock sample by the vertical bidirectional loading cylinder until the rock sample is destroyed.

[0031] Secondly, the present invention provides a method for conducting rock variable angle tensile shear, compression shear and variable angle triaxial tests with confining pressure, comprising: using the rock variable angle tensile shear, compression shear and variable angle triaxial test device with confining pressure described in the first aspect to conduct rock sample variable angle compression shear test without lateral confining pressure, rock sample variable angle tensile shear test without lateral confining pressure, rock sample variable angle shear test with lateral confining pressure and cubic rock sample variable angle triaxial test.

[0032] As an alternative implementation, the rock sample variable angle compression-shear test under no lateral confining pressure conditions includes:

[0033] Bilateral jointed cubic rock samples were used;

[0034] The first variable angle shear component above the rock sample is installed sequentially with the first groove-type connector and the first I-shaped connector through a snap-fit ​​structure and fixed to the vertical loading oil.

[0035] The second variable angle shear component below the rock sample is sequentially installed with the second I-shaped connector and the second groove-shaped connector using a snap-fit ​​method and fixed to the bottom support platform;

[0036] The rock sample is placed freely between the first variable angle shear component and the second variable angle shear component. The angle between the shear sliding block and the load-bearing shear sliding seat is adjusted. After determining the angle between the rock sample joint and the vertical centerline, the relative positions of the shear sliding block and the load-bearing shear sliding seat are fixed by the shear variable angle positioning hole and the shear variable angle positioning bolt.

[0037] A vertical compressive load is applied to the rock sample using a vertical bidirectional loading cylinder until the rock sample undergoes compressive-shear failure.

[0038] As an alternative implementation, the rock sample variable angle tensile-shear test under no lateral confining pressure conditions includes:

[0039] Bilateral jointed cubic rock samples were used;

[0040] The rock sample is bonded and fixed to the second variable angle shear component with high-strength adhesive. After bonding, the second variable angle shear component is connected and fixed to the bottom support platform in sequence with the second I-shaped connector and the second groove-shaped connector through a snap-fit ​​structure.

[0041] The first variable angle shearing component is installed sequentially with the first groove-shaped connector and the first I-shaped connector through a snap-fit ​​structure and fixed to the vertical bidirectional loading cylinder. The position of the first variable angle shearing component is adjusted by the vertical bidirectional loading cylinder so that it fits with the rock sample and is bonded and fixed with high-strength adhesive.

[0042] After adjusting the angle between the shear sliding block and the load-bearing shear sliding seat and determining the angle between the rock sample joint and the vertical centerline, fix the relative positions of the shear sliding block and the load-bearing shear sliding seat through the shear angle positioning hole and the shear angle positioning bolt.

[0043] A vertical tensile load is applied to the rock sample using a vertical bidirectional loading cylinder until the rock sample fails under tensile and shear conditions.

[0044] As an alternative implementation, the rock sample variable angle shear test under lateral confining pressure conditions includes:

[0045] Bilateral jointed cubic rock samples were used;

[0046] The first variable angle shearing component above the rock sample is installed in sequence with the first groove-shaped connector and the first I-shaped connector through a snap-fit ​​structure. The second variable angle shearing component below the rock sample is installed in sequence with the second I-shaped connector and the second groove-shaped connector through a snap-fit ​​structure. The entire variable angle shearing module is rotated 90° around the vertical centerline and fixed to the bottom support platform.

[0047] In the tensile shear test, the rock sample was bonded to the shear sliding block with high-strength adhesive, while in the compressive shear test, the rock sample was placed freely and attached to the shear sliding block.

[0048] After adjusting the angle between the rock sample joint and the vertical centerline, it is fixed by using shear angle positioning holes and shear angle positioning bolts;

[0049] The load-bearing pads are installed on the two free sides of the rock sample. After being loaded to a specific lateral confining pressure by the first and second horizontal unidirectional loading cylinders, the rock sample is then loaded to shear failure by the vertical bidirectional loading cylinder.

[0050] As an alternative implementation, the cubic rock sample variable angle triaxial test includes:

[0051] Use either intact cubic rock samples or cubic rock samples containing circular pores;

[0052] Install the triaxial test platform onto the bottom platform, place the rock sample on top of the triaxial test platform and make it fit against the variable angle triaxial device, adjust the angle between the triaxial sliding block and the triaxial bearing force sliding seat, and fix the position using triaxial variable angle positioning bolts in combination with triaxial variable angle positioning holes;

[0053] Ensure that the horizontal centerline of the rock sample coincides with the horizontal centerline of the variable angle triaxial device and the horizontal loading cylinders on both sides. Install the load-bearing pad onto the upper surface of the rock sample. After loading the horizontal cylinders on both sides to a specific confining pressure value, start the vertical bidirectional loading cylinder to apply a vertical load to the rock sample until it is damaged.

[0054] When using cubic rock samples with circular holes for testing, the internal damage phenomena of the rock sample are directly observed through the reserved observation holes on the triaxial sliding block.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] This invention provides a rock testing device and method for variable-angle tensile-shear, compressive-shear, and variable-angle triaxial tests, which is based on the concept of variable angle. It simplifies the loading structure of the testing machine, minimizes the number of loading cylinders, controls the production cost of the testing device, enhances the ease of conducting various types of tests, improves testing efficiency, and effectively expands the testing functions of the device. It can conduct a series of tests including compressive-shear, tensile-shear, true triaxial, free shear under non-axial force, shear under lateral pressure, uniaxial tension, and uniaxial compression. A single testing device can effectively integrate multiple functions, achieving multi-purpose functionality. Specifically, by using the same cubic rock sample and coordinating the variable-angle structure with the loading structure, a seamless connection of the entire spatial stress state—"tension-tensile-shear-direct shear-compressive-shear-compression"—can be achieved, providing important experimental technical support for revealing the differential evolution of rock failure mechanisms under complex stress states.

[0057] This invention provides a rock variable angle tensile shear, compression shear and variable angle triaxial test device and method with confining pressure. By adopting a vertical bidirectional loading cylinder and optimizing the design of the variable angle shear auxiliary loading structure, variable angle tensile shear and variable angle compression shear tests can be realized.

[0058] This invention provides a rock variable angle tensile shear, compression shear and variable angle triaxial test device and method with confining pressure. The novel variable angle shear structure can realize variable angle shear test under lateral confining pressure conditions by rotating the whole body 90° and cooperating with two horizontal loading cylinders, which is closer to the original stress conditions of the project.

[0059] This invention provides a rock variable-angle tensile shear, compression shear and variable-angle triaxial testing device and method with confining pressure. It fully utilizes the concept of component forces and proposes a variable-angle triaxial testing approach for the first time. This greatly simplifies the structure of the true triaxial testing machine, reduces the number of hydraulic cylinders, and lowers the production cost of the testing machine. Moreover, this testing method can facilitate the intuitive observation or monitoring of internal failure phenomena in true triaxial tests of porous rock samples.

[0060] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0061] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0062] Figure 1 This is a schematic diagram of the overall planar structure with variable angle tension-shear and compression-shear functions under no lateral confining pressure conditions provided in Embodiment 1 of the present invention.

[0063] Figure 2 This is a schematic diagram of the overall three-dimensional structure of the variable angle tension-shear and compression-shear functions under no lateral confining pressure conditions provided in Embodiment 1 of the present invention.

[0064] Figures 3(a)-3(b) This is a three-dimensional structural diagram of the connector in the variable angle shear test module provided in Embodiment 1 of the present invention;

[0065] Figure 4 This is a schematic diagram showing the connection between the first variable angle shear member and the connector provided in Embodiment 1 of the present invention;

[0066] Figure 5 This is a schematic diagram showing the connection between the second variable angle shear member and the connector provided in Embodiment 1 of the present invention;

[0067] Figure 6 This is a three-dimensional structural schematic diagram of the variable angle shear member provided in Embodiment 1 of the present invention;

[0068] Figure 7 This is a schematic diagram of the rock sample installation method in the shear test provided in Embodiment 1 of the present invention;

[0069] Figure 8 (a)- Figure 8 (f) is a schematic diagram of the angle-changing function in the angle-changing shear test module provided in Embodiment 1 of the present invention;

[0070] Figure 9 This is a three-dimensional structural schematic diagram of the variable angle tension-shear and compression-shear functions under lateral confining pressure conditions provided in Embodiment 1 of the present invention;

[0071] Figure 10 This is a schematic diagram of the overall structure of the variable-angle triaxial functional planar structure provided in Embodiment 1 of the present invention;

[0072] Figure 11 This is a schematic diagram of the overall three-dimensional structure of the variable angle triaxial function provided in Embodiment 1 of the present invention;

[0073] Figure 12 This is a schematic diagram of a partial structure of variable-angle triaxial loading provided in Embodiment 1 of the present invention;

[0074] Figures 13(a)-13(b) This is a schematic diagram of a complete cubic rock sample subjected to triaxial loading with varying angles, provided in Embodiment 1 of the present invention.

[0075] Figure 14 This is a schematic diagram of the variable-angle triaxial device for a cubic rock sample containing circular holes provided in Embodiment 1 of the present invention;

[0076] Figures 15(a)-15(b) This is a schematic diagram of triaxial loading of a cubic rock sample with circular holes provided in Embodiment 1 of the present invention.

[0077] Figure 16 This is a schematic diagram of the triaxial loading component force principle of the rock sample with variable angle provided in Embodiment 1 of the present invention;

[0078] Among them, 1. Reaction frame; 2-1. Vertical bidirectional loading cylinder; 2-2. First horizontal unidirectional loading cylinder; 2-3. Second horizontal unidirectional loading cylinder; 3. Bottom support; 4-1. First I-beam connector; 4-2. Second I-beam connector; 5-1. First groove connector; 5-2. Second groove connector; 6-1. First variable angle shear component; 6-1-1. Load-bearing shear sliding seat; 6-1-2. Shear sliding block; 6-1-3. Shear variable angle positioning hole; 6-1-4. Shear variable angle positioning bolt; 6-1-5. Sliding groove; 6-1-6. Slide rail; 6-2. Second variable angle shear component; 7- 1. First tension-compression dual-purpose ball bearing bank; 7-2. Second tension-compression dual-purpose ball bearing bank; 8-1. Double-sided jointed cubic rock sample; 8-2. Complete cubic rock sample; 8-3. Cube rock sample with circular holes; 9. High-strength adhesive; 10. Load-bearing pad; 11. Variable angle triaxial device; 11-1-1. Complete rock sample three-bearing force sliding seat; 11-1-2. Rock sample with circular holes three-bearing force sliding seat; 11-2-1. Complete rock sample triaxial sliding block; 11-2-2. Rock sample with circular holes triaxial sliding block; 11-3. Triaxial variable angle positioning bolt; 11-4. Triaxial variable angle positioning hole; 12. Triaxial test platform; 13. Load-bearing pad. Detailed Implementation

[0079] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0080] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0081] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. Furthermore, it should be understood that the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0082] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0083] Example 1

[0084] This embodiment provides a rock variable angle tensile shear, compression shear and variable angle triaxial testing device with confining pressure, including a reaction frame, a hydraulic loading system, a variable angle shear test module and a variable angle triaxial test module. The testing device is described in detail below.

[0085] In this embodiment, as Figures 1-2 As shown, the reaction frame 1 includes columns on the left and right sides and crossbeams on the top and bottom sides, serving as the testing site and loading reaction structure; the columns and crossbeams are integrally welded from high-strength steel plates to ensure that the reaction frame itself does not deform during the test, thus meeting the high precision requirements of the test.

[0086] In this embodiment, the hydraulic loading system includes a hydraulic loading cylinder and a corresponding servo hydraulic control system, which is automatically controlled by a computer to apply a specific force load to the rock sample.

[0087] like Figures 1-2 As shown, the hydraulic loading cylinder includes a vertical bidirectional loading cylinder 2-1 located at the top of the reaction frame and a first horizontal unidirectional loading cylinder 2-2 and a second horizontal unidirectional loading cylinder 2-3 located on both sides of the reaction frame. It can apply vertical tensile and compressive loads and horizontal centering compressive loads to the rock sample according to specific force values.

[0088] Specifically, the vertical bidirectional loading cylinder 2-1 is a large-stroke tension / compression bidirectional loading cylinder, which is installed on the upper crossbeam of the reaction frame 1 to simultaneously meet the loading requirements of vertical pressure and tension.

[0089] The first horizontal unidirectional loading cylinder 2-2 and the second horizontal unidirectional loading cylinder 2-3 are large-stroke unidirectional loading cylinders, which are centered and installed on the columns on both sides of the reaction frame 1. The center lines of the first horizontal unidirectional loading cylinder 2-2 and the second horizontal unidirectional loading cylinder 2-3 coincide to ensure the centered application of the horizontal loads.

[0090] As an alternative implementation, the vertical bidirectional loading cylinder 2-1, the first horizontal unidirectional loading cylinder 2-2, and the second horizontal unidirectional loading cylinder 2-3 are all 1000kN high-force loading cylinders, each employing an independent servo hydraulic control system. The different cylinders cooperate with each other but do not interfere with each other.

[0091] As an alternative implementation, the vertical bidirectional loading cylinder 2-1, the first horizontal unidirectional loading cylinder 2-2, and the second horizontal unidirectional loading cylinder 2-3 are all equipped with load sensors. The load sensors cooperate with the servo hydraulic control system to apply a specific force load.

[0092] In this embodiment, the variable angle shear test module is suitable for variable angle tensile shear and variable angle compressive shear tests on bilateral jointed cubic rock samples under conditions of no lateral confining pressure and with lateral confining pressure;

[0093] The following section will elaborate on the variable angle shear test module under the condition of no side confining pressure, in which case there is no need to use a horizontal unidirectional loading cylinder.

[0094] like Figures 1-2 As shown, the variable angle shear test module includes: a bottom support 3, and a first test sub-module and a second test sub-module disposed on the bottom support 3;

[0095] The first test submodule includes a first I-shaped connector 4-1, a first groove-shaped connector 5-1, a first variable angle shear member 6-1, and a first tension-compression dual-purpose ball bearing assembly 7-1;

[0096] The second test submodule includes a second I-shaped connector 4-2, a second groove-shaped connector 5-2, a second variable angle shear member 6-2, and a second tension and compression dual-purpose ball bearing array 7-2;

[0097] Specifically, the top end of the first I-shaped connector 4-1 is fixedly connected to the vertical bidirectional loading cylinder 2-1 and used as a pressure plate;

[0098] like Figure 4 As shown, the bottom end of the first I-shaped connector 4-1 is sequentially connected to the first groove-shaped connector 5-1 and the first variable angle shear member 6-1 via a snap fastener;

[0099] As shown in Figure 3(a), a first tension-compression dual-purpose ball bearing array 7-1 is installed between the first I-shaped connector 4-1 and the first groove-shaped connector 5-1.

[0100] Specifically, the bottom support 3 is located at the bottom of the reaction frame 1 and is connected to the lower crossbeam of the reaction frame 1 as a whole;

[0101] The upper surface of the bottom support 3 is sequentially connected to the second groove-shaped connector 5-2, the second I-shaped connector 4-2, and the second variable angle shear member 6-2;

[0102] The bottom end of the second groove-shaped connector 5-2 is fixed to the bottom support 3, such as... Figure 5 As shown, the top end of the second groove-shaped connector 5-2 is sequentially connected to the second I-shaped connector 4-2 and the second variable angle shear member 6-2 via a snap fastener;

[0103] As shown in Figure 3(b), a second tension-compression dual-purpose ball bearing array 7-2 is installed between the second I-shaped connector 4-2 and the second groove-shaped connector 5-2.

[0104] As an alternative implementation, the first tension-compression dual-purpose ball bearing row 7-1 and the second tension-compression dual-purpose ball bearing row 7-2 can reduce the friction between components when tension or compression is applied; whether vertical tensile load or compressive load is applied, the I-shaped connector and the grooved connector can slide freely relative to each other with low resistance, reducing the influence of friction on the test results.

[0105] In this embodiment, as Figure 6 As shown, the first variable angle shearing component 6-1 and the second variable angle shearing component 6-2 both include a load-bearing shearing sliding seat 6-1-1, a shearing sliding block 6-1-2, a shearing variable angle positioning hole 6-1-3, a shearing variable angle positioning bolt 6-1-4, a sliding groove 6-1-5, and a slide rail 6-1-6;

[0106] Specifically, the inner surface of the load-bearing shear sliding seat 6-1-1 is provided with a slide rail 6-1-6 and a shear angle positioning bolt 6-1-4, and the outer surface of the load-bearing shear sliding seat 6-1-1 is provided with a scale.

[0107] The shearing sliding block 6-1-2 is provided with a sliding groove 6-1-5 that matches the slide rail 6-1-6, and a shearing angle positioning hole 6-1-3 that matches the shearing angle positioning bolt 6-1-4;

[0108] The load-bearing shear sliding seat 6-1-1 is connected to the sliding groove 6-1-5 via the slide rail 6-1-6, so that the shear sliding block 6-1-2 slides in an arc along the slide rail 6-1-6;

[0109] After the sliding angle is determined by the arc sliding of the shearing sliding block 6-1-2, its position is fixed by the cooperation of the shearing angle positioning hole 6-1-3 and the shearing angle positioning bolt 6-1-4.

[0110] As an alternative implementation, the outer surface of the load-bearing shear sliding seat 6-1-1 is marked with graduations at 5° intervals.

[0111] In this embodiment, when performing the variable angle compression-shear test, the bilateral jointed cubic rock sample 8-1 only needs to be naturally placed between the first variable angle shear member 6-1 and the second variable angle shear member 6-2, that is, the upper and lower surfaces of the bilateral jointed cubic rock sample 8-1 are freely attached to the shear sliding block 6-1-2.

[0112] During the variable-angle tensile-shear test, the upper and lower surfaces of the bilaterally jointed cubic rock sample 8-1 were bonded to the shear sliding block 6-1-2 using high-strength adhesive 9. Figure 7 As shown, this ensures the effective transfer of vertical tensile loads.

[0113] In this embodiment, as Figure 8 (a)- Figure 8 As shown in (f), different forms of experimental research can be achieved by changing the angle of the shear sliding block 6-1-2; specifically, when the angle between the joint and the vertical centerline of the bilateral jointed cubic rock sample 8-1 is 0° and 90°, it is regarded as two ultimate stress conditions, and at this time, non-directional force free shear test, uniaxial compression test and uniaxial tensile test can be carried out respectively; when the angle between the joint and the vertical centerline is between 0° and 90°, variable angle tensile shear or variable angle compressive shear test can be carried out.

[0114] In this embodiment, when conducting a variable angle shear test with lateral confining pressure, the installation method of the variable angle shear module is the same as that of the variable angle shear test module without lateral confining pressure. After installation, the variable angle shear test module is rotated 90° around its vertical centerline. The two free faces of the bilateral jointed cubic rock sample 8-1 are respectively facing two horizontal unidirectional loading cylinders. A specific force value of lateral confining pressure is applied to the bilateral jointed cubic rock sample 8-1 using the two horizontal unidirectional loading cylinders and the support pad 10. Figure 9 As shown.

[0115] In this embodiment, the variable-angle triaxial test module is suitable for true triaxial tests on intact cubic rock samples and cubic rock samples containing circular pores; such as Figures 10-12 As shown, it includes: a variable angle triaxial device 11, a triaxial test platform 12, and a load-bearing pad 13;

[0116] The triaxial test platform 12 is installed on the bottom platform 3. The first horizontal unidirectional loading cylinder 2-2 and the second horizontal unidirectional loading cylinder 2-3 are respectively connected to a variable angle triaxial device 11. The complete cubic rock sample is placed on the triaxial test platform 12 in close contact with the variable angle triaxial devices on both sides. The rock sample is placed in the middle of the variable angle triaxial devices on both sides. The load-bearing pad 13 is set on the rock sample. The load-bearing pad 13 is connected to the vertical bidirectional loading cylinder 2-1.

[0117] In this embodiment, a variable-angle triaxial test was conducted on a complete cubic rock sample, such as... Figures 13(a)-13(b) As shown, the variable angle triaxial device 11 includes a complete rock sample three-bearing force sliding seat 11-1-1, a complete rock sample triaxial sliding block 11-2-1, a triaxial variable angle positioning bolt 11-3, and a triaxial variable angle positioning hole 11-4;

[0118] For triaxial tests on cubic rock samples containing circular pores with varying angles, such as Figure 14 As shown, the variable angle triaxial device 11 includes a three-axis force sliding seat 11-1-2 containing a rock sample with a circular hole, a three-axis sliding block 11-2-2 containing a rock sample with a circular hole, a three-axis variable angle positioning bolt 11-3, and a three-axis variable angle positioning hole 11-4.

[0119] In this embodiment, when conducting a true triaxial test using a cubic rock sample 8-3 with circular holes, the triaxial sliding seat and triaxial sliding block of the intact rock sample are replaced with the triaxial sliding seat 11-1-2 and the triaxial sliding block 11-2-2 of the rock sample with circular holes, respectively. The angle setting and loading method are the same as those for the true triaxial test of the intact cubic rock sample. At this time, the internal damage phenomenon of the rock sample can be directly observed or monitored optically through the reserved observation holes on the triaxial sliding seat 11-1-2 and the triaxial sliding block 11-2-2 of the rock sample with circular holes. Figures 15(a)-15(b) As shown.

[0120] In this embodiment, the connection between the intact rock sample three-bearing force sliding seat 11-1-1 and the intact rock sample three-axis sliding block 11-2-1, and the connection between the rock sample three-bearing force sliding seat 11-1-2 with circular holes and the rock sample three-axis sliding block 11-2-2 with circular holes, are all similar to the connection between the slide rail 6-1-6 and the sliding groove 6-1-5 in the variable angle shear component.

[0121] The relative positions of the three-axis sliding block and the three-bearing force sliding seat are fixed by the cooperation of the three-axis variable angle positioning hole 11-4 and the three-axis variable angle positioning bolt 11-3. The three-axis sliding block also slides at 5° intervals.

[0122] In this embodiment, after determining the angle of the triaxial sliding block, the horizontal centerline of the complete cubic rock sample 8-2 or the cubic rock sample 8-3 containing circular holes is ensured to coincide with the centerline of the variable angle triaxial device 11 and the centerlines of the first horizontal unidirectional loading cylinder 2-2 and the second horizontal unidirectional loading cylinder 2-3.

[0123] Activating the first horizontal unidirectional loading cylinder 2-2 and the second horizontal unidirectional loading cylinder 2-3 applies confining pressure to a specific force value. The minimum principal stress and intermediate principal stress values ​​of the rock sample can be calculated using the force decomposition method, which are Fsinα and Fcosα, respectively. Figure 16 As shown;

[0124] After the confining pressure loading is completed, place the load-bearing pad 13 on the upper surface of the complete cubic rock sample 8-2 or the cubic rock sample 8-3 with circular holes, and start the vertical bidirectional loading cylinder 2-1 to apply the load until the rock sample is destroyed.

[0125] Example 2

[0126] This embodiment provides an experimental method for a rock variable angle tensile shear, compression shear and variable angle triaxial test device with confining pressure, including: rock sample variable angle compression shear test without lateral confining pressure, rock sample variable angle tensile shear test without lateral confining pressure, rock sample variable angle shear test with lateral confining pressure and cubic rock sample variable angle triaxial test;

[0127] Specifically, the rock sample variable angle compression-shear test under no lateral confining pressure conditions includes:

[0128] (1) Double-jointed cubic rock sample 8-1 was used;

[0129] (2) The first variable angle shearing component 6-1 above the rock sample is installed in sequence with the first groove-type connector 5-1 and the first I-shaped connector 4-1 through a snap-fit ​​structure. The second variable angle shearing component 6-2 below the rock sample is also connected to the second I-shaped connector 4-2 and the second groove-type connector 5-2 through a snap-fit ​​structure and fixed to the bottom support 3.

[0130] (3) The double-jointed cubic rock sample 8-1 is freely placed between the first variable angle shear member 6-1 and the second variable angle shear member 6-2. The angle between the shear sliding block 6-1-2 and the load-bearing shear sliding seat 6-1-1 is adjusted to determine the values ​​and relative proportions of the normal pressure and shear force. After adjusting the angle between the rock sample joint and the vertical centerline, the relative positions of the shear sliding block 6-1-2 and the load-bearing shear sliding seat 6-1-1 are fixed through the shear variable angle positioning hole 6-1-3 and the shear variable angle positioning bolt 6-1-4.

[0131] (4) Start the vertical bidirectional loading cylinder 2-1 to apply vertical compressive load to the rock sample until the rock sample undergoes compressive shear failure.

[0132] Specifically, the rock sample variable angle tensile-shear test under no lateral confining pressure conditions includes:

[0133] (1) Bilateral jointed cubic rock samples were used;

[0134] (2) The rock sample is bonded and fixed to the second variable angle shear member 6-2 with high-strength adhesive. After bonding, the second variable angle shear member 6-2 is connected and fixed to the bottom support 3 in sequence with the second I-shaped connector 4-2 and the second groove connector 5-2 through a snap-fit ​​structure.

[0135] (3) The first variable angle shearing component 6-1, the first groove-type connector 5-1, and the first I-shaped connector 4-1 are installed in sequence through a snap-fit ​​structure and finally fixed to the vertical bidirectional loading cylinder 2-1. The vertical bidirectional loading cylinder 2-1 is started to adjust the position of the first variable angle shearing component 6-1 so that it gradually comes into contact with the rock sample and is fixed with high-strength adhesive.

[0136] (4) Adjust the angle between the shear sliding block 6-1-2 and the load-bearing shear sliding seat 6-1-1, determine the values ​​and relative proportions of the normal tensile force and the shear force, adjust the angle between the rock sample joint and the vertical centerline, and then fix the relative positions of the shear sliding block 6-1-2 and the load-bearing shear sliding seat 6-1-1 through the shear angle positioning hole 6-1-3 and the shear angle positioning bolt 6-1-4;

[0137] (5) Start the vertical bidirectional loading cylinder 2-1 to apply a vertical tensile load to the rock sample until the rock sample fails under tensile and shear conditions.

[0138] Specifically, rock sample variable angle shear tests under lateral confining pressure conditions include:

[0139] (1) Bilateral jointed cubic rock samples were used;

[0140] (2) The installation steps of each component in the compression shear test and the tensile shear test are the same as the corresponding steps of the first two tests. In the tensile shear test, the rock sample and the shear sliding block are bonded with high-strength adhesive. In the compression shear test, the rock sample is placed freely and attached to the shear sliding block.

[0141] (3) Rotate the entire variable angle shear module 90° around the vertical centerline, install the load-bearing pad 10 to the two free sides of the rock sample, start the first horizontal unidirectional loading cylinder 2-2 and the second horizontal unidirectional loading cylinder 2-3 to load to a specific lateral confining pressure, and then start the vertical bidirectional loading cylinder 2-1 to load until the rock sample is sheared and damaged.

[0142] Specifically, the triaxial test of cubic rock samples with varying angles includes:

[0143] (1) Use complete cubic rock samples or cubic rock samples containing circular holes;

[0144] (2) Install the triaxial test platform 12 onto the bottom platform 3, place the rock sample on the triaxial test platform 12 and make it fit with the variable angle triaxial device 11, adjust the angle between the triaxial sliding block and the triaxial bearing force sliding seat, and use the triaxial variable angle positioning bolt combined with the triaxial variable angle positioning hole to fix the relative position between the triaxial sliding block and the triaxial bearing force sliding seat.

[0145] (3) Ensure that the horizontal centerline of the rock sample coincides with the horizontal centerline of the variable angle triaxial device and the horizontal loading cylinders on both sides. Install the load-bearing pad 13 onto the upper surface of the rock sample. After starting the horizontal cylinders on both sides to load to a specific confining pressure value, start the vertical bidirectional loading cylinder 2-1 to apply a vertical load to the rock sample until it is damaged.

[0146] (4) When using cubic rock samples with circular holes for testing, the internal damage phenomenon of the rock sample is directly observed through the reserved observation holes on the triaxial sliding block.

[0147] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A rock variable-angle tensile-shear, compressive-shear and variable-angle triaxial test device with confining pressure, characterized in that, include: The reaction frame, and the hydraulic loading system, variable angle shear test module and variable angle triaxial test module mounted on the reaction frame; The hydraulic loading system includes a vertical bidirectional loading cylinder located at the top of the reaction frame and a first horizontal unidirectional loading cylinder and a second horizontal unidirectional loading cylinder located on both sides of the reaction frame. The variable angle shear test module includes a bottom support, a first variable angle shear component, and a second variable angle shear component. The bottom support is located at the bottom of the reaction frame, and the second variable angle shear component is connected to the bottom support via a connector. The first variable angle shear component is connected to a vertical bidirectional loading cylinder via a connector. The first variable angle shear member and the second variable angle shear member both include a load-bearing shear sliding seat and a shear sliding block that are slidably connected. The two shear sliding blocks are arranged opposite each other and a rock sample is placed in the middle. The vertical bidirectional loading cylinder applies vertical tensile load and compressive load to the rock sample, and the first horizontal unidirectional loading cylinder and the second horizontal unidirectional loading cylinder apply lateral confining pressure to the rock sample. The first variable angle shearing component is connected to the vertical bidirectional loading cylinder in sequence through the first groove-shaped connector and the first I-shaped connector; a first tension and compression dual-purpose ball bearing is provided between the first I-shaped connector and the first groove-shaped connector; The bottom support is connected to the second variable angle shear member in sequence by the second groove-shaped connector and the second I-shaped connector; a second tension and compression dual-purpose ball bearing is provided between the second I-shaped connector and the second groove-shaped connector; The load-bearing shear sliding seat is provided with a slide rail, and the shear sliding block is provided with a sliding groove. The load-bearing shear sliding seat is connected to the sliding groove through the slide rail, so that the shear sliding block slides along the slide rail in an arc shape, and different forms of tests can be carried out on the rock sample by changing the angle of the shear sliding block. The variable angle triaxial test module includes a triaxial test platform, a variable angle triaxial device and a load-bearing pad mounted on the triaxial test platform. The triaxial test platform is located on the bottom platform. A first horizontal unidirectional loading cylinder and a second horizontal unidirectional loading cylinder are respectively connected to a variable angle triaxial device. A rock sample is placed between the two variable angle triaxial devices. A load-bearing pad is placed on the rock sample and connected to a vertical bidirectional loading cylinder.

2. The rock variable-angle tensile-shear, compression-shear, and variable-angle triaxial testing device with confining pressure as described in claim 1, characterized in that, The load-bearing shear sliding seat is provided with a shear angle positioning bolt, and the shear sliding block is provided with a shear angle positioning hole that matches the shear angle positioning bolt, so that after the shear sliding block determines the sliding angle, the position is fixed by the shear angle positioning hole and the shear angle positioning bolt. Alternatively, the outer surface of the load-bearing shear sliding seat may be provided with a scale.

3. The rock variable-angle tensile-shear, compression-shear, and variable-angle triaxial testing device with confining pressure as described in claim 1, characterized in that, During the variable angle compression-shear test, the rock sample was placed naturally between the first variable angle shear member and the second variable angle shear member, with the upper and lower surfaces of the rock sample freely attached to the shear sliding block. During the variable angle tensile shear test, the upper and lower surfaces of the rock sample were bonded to the shear sliding block using high-strength adhesive. When conducting a lateral confining pressure variable angle shear test, the variable angle shear test module is rotated 90° around its own vertical centerline. The free surface of the rock sample is directly facing the horizontal one-way loading cylinders on both sides, and load-bearing pads are installed on the two free sides of the rock sample. Lateral confining pressure of a specific force value is applied to the rock sample through the first horizontal one-way loading cylinder and the second horizontal one-way loading cylinder.

4. The rock variable-angle tensile-shear, compression-shear, and variable-angle triaxial testing device with confining pressure as described in claim 1, characterized in that, The variable angle triaxial device is used for variable angle triaxial tests on intact cubic rock samples, and includes an intact rock sample triaxial bearing sliding seat, an intact rock sample triaxial sliding block, a triaxial variable angle positioning bolt, and a triaxial variable angle positioning hole; The complete rock sample three-axis force sliding seat and the complete rock sample three-axis sliding block are slidably connected and their positions are fixed by three-axis variable angle positioning bolts and three-axis variable angle positioning holes.

5. The rock variable-angle tensile-shear, compression-shear, and variable-angle triaxial testing device with confining pressure as described in claim 1, characterized in that, The variable angle triaxial device is used for variable angle triaxial tests on cubic rock samples containing circular holes, and includes a three-axis force sliding seat for rock samples containing circular holes, a three-axis sliding block for rock samples containing circular holes, a triaxial variable angle positioning screw, and a triaxial variable angle positioning hole. The three-axis sliding seat containing the rock sample with circular holes and the three-axis sliding block containing the rock sample with circular holes are slidably connected and their positions are fixed by the three-axis variable angle positioning bolt and the three-axis variable angle positioning hole. The rock sample with circular holes has a pre-reserved observation hole on its three-bearing force sliding seat. This hole is used for direct optical observation of the internal damage phenomenon of the rock sample during the overload test with pre-made holes, or as an excavation hole for the complete rock sample under true triaxial stress conditions.

6. A rock variable-angle tensile-shear, compression-shear, and variable-angle triaxial testing device with confining pressure as described in claim 4 or 5, characterized in that, After the angle of the three-axis sliding block is determined, the horizontal centerline of the rock sample coincides with the centerline of the variable angle three-axis device and the centerline of the first horizontal one-way loading cylinder and the second horizontal one-way loading cylinder. Then, load-bearing pads are installed on the upper surface of the rock sample. The rock sample is loaded with confining pressure to a specific force value by the first and second horizontal unidirectional loading cylinders, and then vertical load is applied to the rock sample by the vertical bidirectional loading cylinder until the rock sample is destroyed.

7. A method for rock variable-angle tensile-shear, compressive-shear and variable-angle triaxial test device under confining pressure, characterized in that, include: Using the rock variable angle tensile shear, compression shear and variable angle triaxial test device with confining pressure as described in any one of claims 1-6, rock sample variable angle compression shear test without lateral confining pressure, rock sample variable angle tensile shear test without lateral confining pressure, rock sample variable angle shear test with lateral confining pressure and cubic rock sample variable angle triaxial test are carried out.

8. The experimental method of the rock variable-angle tensile-shear, compression-shear and variable-angle triaxial test device with confining pressure as described in claim 7, characterized in that, The rock sample variable angle compression-shear test under the condition of no lateral confining pressure includes: Bilateral jointed cubic rock samples were used; The first variable angle shear component above the rock sample is installed sequentially with the first groove-type connector and the first I-shaped connector through a snap-fit ​​structure and fixed to the vertical loading oil. The second variable angle shear component below the rock sample is sequentially installed with the second I-shaped connector and the second groove-shaped connector using a snap-fit ​​method and fixed to the bottom support platform; The rock sample is placed freely between the first variable angle shear component and the second variable angle shear component. The angle between the shear sliding block and the load-bearing shear sliding seat is adjusted. After determining the angle between the rock sample joint and the vertical centerline, the relative positions of the shear sliding block and the load-bearing shear sliding seat are fixed by the shear variable angle positioning hole and the shear variable angle positioning bolt. A vertical compressive load is applied to the rock sample using a vertical bidirectional loading cylinder until the rock sample undergoes compressive-shear failure. or, The rock sample variable angle tensile-shear test under the condition of no lateral confining pressure includes: Bilateral jointed cubic rock samples were used; The rock sample is bonded and fixed to the second variable angle shear component with high-strength adhesive. After bonding, the second variable angle shear component is connected and fixed to the bottom support platform in sequence with the second I-shaped connector and the second groove-shaped connector through a snap-fit ​​structure. The first variable angle shearing component is installed sequentially with the first groove-shaped connector and the first I-shaped connector through a snap-fit ​​structure and fixed to the vertical bidirectional loading cylinder. The position of the first variable angle shearing component is adjusted by the vertical bidirectional loading cylinder so that it fits with the rock sample and is bonded and fixed with high-strength adhesive. After adjusting the angle between the shear sliding block and the load-bearing shear sliding seat and determining the angle between the rock sample joint and the vertical centerline, fix the relative positions of the shear sliding block and the load-bearing shear sliding seat through the shear angle positioning hole and the shear angle positioning bolt. A vertical tensile load is applied to the rock sample using a vertical bidirectional loading cylinder until the rock sample fails under tensile and shear conditions. or, The rock sample variable angle shear test under lateral confining pressure conditions includes: Bilateral jointed cubic rock samples were used; The first variable angle shearing component above the rock sample is installed in sequence with the first groove-shaped connector and the first I-shaped connector through a snap-fit ​​structure. The second variable angle shearing component below the rock sample is installed in sequence with the second I-shaped connector and the second groove-shaped connector through a snap-fit ​​structure. The entire variable angle shearing module is rotated 90° around the vertical centerline and fixed to the bottom support platform. In the tensile shear test, the rock sample was bonded to the shear sliding block with high-strength adhesive, while in the compressive shear test, the rock sample was placed freely and attached to the shear sliding block. After adjusting the angle between the rock sample joint and the vertical centerline, it is fixed by using shear angle positioning holes and shear angle positioning bolts; The load-bearing pads are installed on the two free sides of the rock sample. After being loaded to a specific lateral confining pressure by the first and second horizontal unidirectional loading cylinders, the rock sample is then loaded to shear failure by the vertical bidirectional loading cylinder.

9. The experimental method of a rock variable-angle tensile-shear, compression-shear, and variable-angle triaxial testing device with confining pressure as described in claim 7, characterized in that, The cubic rock sample variable angle triaxial test includes: Use either intact cubic rock samples or cubic rock samples containing circular pores; Install the triaxial test platform onto the bottom platform, place the rock sample on top of the triaxial test platform and make it fit against the variable angle triaxial device, adjust the angle between the triaxial sliding block and the triaxial bearing force sliding seat, and fix the position using triaxial variable angle positioning bolts in combination with triaxial variable angle positioning holes; Ensure that the horizontal centerline of the rock sample coincides with the horizontal centerline of the variable angle triaxial device and the horizontal loading cylinders on both sides. Install the load-bearing pad onto the upper surface of the rock sample. After loading the horizontal cylinders on both sides to a specific confining pressure value, start the vertical bidirectional loading cylinder to apply a vertical load to the rock sample until it is damaged. When using cubic rock samples with circular holes for testing, the internal damage phenomena of the rock sample are directly observed through the reserved observation holes on the triaxial sliding block.

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