Hydraulic loading device for rock mass through-fissures based on true triaxial Hopkinson pressure bar

Abstract

The present invention relates to the field of Hopkinson pressure bar experimental technology, specifically to a rock mass through-fissure water pressure loading device based on a true triaxial Hopkinson pressure bar. The device comprises: a true triaxial Hopkinson pressure bar experimental device, wherein sealing pads are provided on the loading surfaces of two transmission rods parallel to the rock mass through-fissure, and a connecting channel connected to the rock mass through-fissure is opened on the sealing pads. A dynamic water pressure monitoring component is provided in one of the connecting channels, and the other connecting channel is used to inject water into the rock mass through-fissure, and a sealing component is provided on the sealing pads. The present invention integrates water pressure loading and water pressure monitoring functions on the connecting channel to simulate the actual working conditions of deep rock mass, thereby better studying the influence of water pressure in closed through-fissures on rock mechanical properties. At the same time, under the combined action of pre-compression extrusion and fluid pressure, the sealing component eliminates microscopic water seepage channels, blocks capillary paths through which fluid may pass, and ensures the stability of the through-fissure water pressure loading.

Description

Technical Field

[0001] The invention relates to the technical field of Hopkinson pressure bar experiments, in particular to a rock mass through-fissure water pressure loading device based on a true triaxial Hopkinson pressure bar. Background Art

[0002] Deep rock mass engineering faces a complex environment characterized by the coupling of high geostress, high osmotic pressure, and strong dynamic disturbances. Uncovering the dynamic response of fractured rock masses under the coupled hydraulic-mechanical-dynamic mechanism is a core scientific issue for engineering safety. Under dynamic disturbances, the inconsistent responses of the fluid and rock mass to stress waves disrupt the original hydromechanical equilibrium system. The water pressure in water-bearing fractures fluctuates, altering the distribution of effective stress and concentrated stress at the crack tip. This disruption of the hydromechanical equilibrium triggers a dynamic response in the surrounding rock system and exacerbates crack propagation within the rock mass. Dynamic disturbance-induced failure of water-bearing fractures includes microcrack initiation, propagation, and rock bridge fracture, as well as macrocrack opening, slippage, and penetration. The coupling of high geostress and water pressure further complicates the dynamic mechanical properties of water-bearing fractured rock masses. Therefore, it is necessary to study the initiation modes and mechanisms of water-bearing fractures, taking into account high energy storage and high water dynamic capacity, to deepen theoretical understanding of the mechanisms of water inrush hazards in underground engineering projects within deep, water-rich fractured rock masses.

[0003] As an experimental method for testing the mechanical properties of materials under dynamic loads, the Hopkinson bar test apparatus primarily consists of a launch system, a rod system (impact bar, incident bar, transmission bar, and absorption bar), a data acquisition system (strain gauges, oscilloscope, and ultra-dynamic strain gauge), and a damping and absorption system. It is often used to measure the stress-strain relationship of specimens under high strain rates. However, existing separate Hopkinson bar test equipment primarily focuses on mechanical properties under one- and two-dimensional combined dynamic and static loading. It lacks an integrated through-fracture water pressure loading and monitoring module and lacks effective coordinated control and monitoring capabilities for through-fracture water pressure. This is clearly not suitable for the actual working conditions in deeply fractured rock masses, and it is unable to capture the transient fluctuation response of fracture water pressure under impact loading, making it impossible to study the influence of closed through-fracture water pressure on rock mechanical properties. At the same time, the existing split-Hopkinson pressure bar experimental equipment rarely considers the three-dimensional high-stress environment of deep fractured rock masses, especially the lack of relevant research on the combined influence of fracture water pressure and external dynamic disturbance, and the lack of clarification of the micro-crack initiation and dynamic propagation mechanism and penetration mode of water-containing fractured rock masses under true triaxial stress state.

[0004] In summary, the above-mentioned defects have caused the real-time correlation mechanism between the transient fluctuation response of the fracture water pressure in the rock mass with through-fractures under impact load and the propagation of stress waves and crack extension to remain in a "black box" state for a long time under real stress conditions, which has seriously restricted the breakthrough of the theory of dynamic catastrophe of deep rock masses. At present, there is still a lack of test equipment at home and abroad that can effectively couple the through-fracture water pressure loading system with the true triaxial dynamic and static combined loading system, especially the Hopkinson pressure bar device that can implement true triaxial dynamic and static combined loading under preset through-fracture water pressure conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a rock mass through-fissure water pressure loading device based on a true triaxial Hopkinson pressure bar to address the deficiencies of the existing technology. The device can load and seal the prefabricated through-fissure rock mass with water pressure while applying a triaxial dynamic and static combined load to the true triaxial Hopkinson pressure bar, thereby solving the problems existing in the above-mentioned existing technology.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A water pressure loading device for rock mass through-fissures based on true triaxial Hopkinson pressure bars comprises three groups of loading rods distributed in a three-dimensional space and perpendicular to each other, the loading rods being used to abut and clamp a rock mass with through-fissures, two of the three groups of loading rods being horizontal loading rods and one being vertical loading rods, one group of horizontal loading rods being parallel to the through-fissures of the rock mass, one group of loading rods being perpendicular to the through-fissures of the rock mass comprising an incident rod and a transmission rod, and the remaining two groups of loading rods comprising two transmission rods respectively, sealing pads being provided on the loading surfaces of the two transmission rods parallel to the through-fissures of the rock mass, connecting channels being provided on the sealing pads communicating with the through-fissures of the rock mass, a dynamic water pressure monitoring component being provided in one of the connecting channels for dynamically monitoring the water pressure in the through-fissures of the rock mass in real time, the other connecting channel being used to inject water into the through-fissures of the rock mass, and a sealing component being provided on the sealing pads for sealing between the sealing pads and the rock mass.

[0008] Furthermore, the sealing assembly includes a groove opened on the end face where the sealing gasket and the rock body abut each other, and a seal that can be deformed under force is provided in the groove. The coverage range of the seal is larger than the range of the through-fissure area of ​​the rock body, and the volume of the seal is larger than the volume of the groove cavity. After deformation, the seal fills the groove cavity and abuts against the rock body.

[0009] Furthermore, the groove is an annular groove, and the corresponding sealing member is an annular sealing member.

[0010] Furthermore, loading pads are provided on the loading surfaces of the loading rods perpendicular to the through cracks.

[0011] Furthermore, the dynamic water pressure monitoring assembly includes a sensor probe that is parallel to the rock mass through-fissure and extends into the rock mass through-fissure.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] Based on the true triaxial Hopkinson pressure bar test equipment, the present invention provides a sealing pad on the loading rod parallel to the through-fissures in the rock mass, and opens a connecting channel connected to the through-fissures in the rock mass on the sealing pad. The connecting channel integrates water pressure loading and water pressure monitoring functions to simulate the actual working conditions of deep rock mass, thereby better studying the influence of water pressure in closed through-fissures on the mechanical properties of rock.

[0014] In addition, a sealing component is provided between the sealing gasket and the rock mass. Under the combined action of pre-compression extrusion and fluid pressure, the sealing component is tightly fitted between the sealing gasket and the rock surface. This tight fit eliminates microscopic water seepage channels, blocks capillary paths through which fluids may pass, and ensures the stability of water pressure loading through the fissures, thereby realizing a simulation scheme for water pressure loading through the fissures in the rock mass.

[0015] At the same time, loading pads are fixedly installed on the remaining loading rods that are not equipped with sealing pads. The loading pads and sealing pads can improve the contact uniformity between the loading rod and the rock mass, ensure uniform force, and avoid direct contact force between the loading rod and the rock mass to protect the loading rod from direct damage, reduce experimental loss and material waste, extend the service life of the experimental device, and greatly improve the utilization rate of experimental resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the overall structure of a rock mass through-fissure hydraulic loading device based on a true triaxial Hopkinson pressure bar provided by the present invention;

[0017] Figure 2 A schematic diagram of the structure of a sealing gasket block equipped with a dynamic water pressure monitoring assembly in a rock mass through-fissure water pressure loading device based on a true triaxial Hopkinson pressure bar provided by the present invention;

[0018] Figure 3 A cross-sectional view of a rock mass through-fissure hydraulic loading device based on a true triaxial Hopkinson pressure bar provided by the present invention in a state where no axial preload is applied;

[0019] Figure 4 The present invention provides a cross-sectional view of a rock mass through-fissure hydraulic loading device based on a true triaxial Hopkinson pressure bar under an axial preload condition.

[0020] Wherein, the accompanying drawings are marked as follows:

[0021] 1. Rock mass; 11. Through-going fracture; 2. Incident rod; 3. Transmission rod; 4. Sealing pad; 41. Connecting channel; 42. Groove; 43. Seal; 5. Loading pad; 6. Dynamic water pressure monitoring assembly; 61. Water pressure sensor probe; 7. Rubber plug. DETAILED DESCRIPTION

[0022] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0023] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0024] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or to implicitly indicate the quantity of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0026] For easier understanding, see Figures 1 to 4This embodiment provides a rock mass through-fissure hydraulic loading device based on a true triaxial Hopkinson pressure bar. The device includes three sets of loading rods arranged in the horizontal, longitudinal, and vertical directions (equivalent to the X, Y, and Z axes in a three-dimensional rectangular coordinate system). The surfaces of the loading rods used to abut and clamp the rock mass 1 to be tested serve as loading surfaces. The rock mass 1 to be tested has an X-shaped through-fissure 11 in the horizontal and longitudinal directions (the shape of the through-fissure 11 can be freely adjusted). The horizontal loading rods include an incident rod 2 and a transmission rod 3. The loading rods in the horizontal and vertical directions each include two transmission rods 3. The loading surfaces of the two transmission rods 3 in the horizontal and longitudinal directions are fixedly connected to sealing blocks 4. The sealing blocks 4 have an L-shaped connecting channel 41. One end of the connecting channel 41 opens in the vertical direction, and the other end opens in the horizontal and longitudinal direction and communicates with the through-fissure 11 in the rock mass 1. One of the connecting channels 41 serves as a water injection channel, used to inject water into the through-fissure 11 of the rock mass 1 to simulate the hydraulic pressure loading of the rock mass 1 through the through-fissure 11. A dynamic water pressure monitoring assembly 6 is fixedly installed in the other connecting channel 41. The dynamic water pressure monitoring assembly 6 is used to dynamically monitor the water pressure within the through-fissure 11 of the rock mass 1 in real time. A sealing assembly is provided on the sealing gasket 4 to seal between the sealing gasket 4 and the rock mass 1, ensuring that no water seepage occurs at the connection between the sealing gasket 4 and the rock mass 1 during the experiment.

[0027] For easier understanding, please refer to Figures 1 to 4 The sealing assembly includes an annular groove 42, which is opened on the end face of the sealing gasket 4 abutting the rock mass 1. A force-deformable annular seal 43 is installed in the groove 42. The inner diameter of the seal 43 is larger than the area of ​​the through-fissure 11 of the rock mass 1, that is, the sealing range of the seal 43 can cover the through-fissure 11 of the rock mass 1, and the volume of the seal 43 is slightly larger than the volume of the cavity of the groove 42. When the horizontal longitudinal loading rod applies axial preload force to the rock mass 1, the sealing gasket 4 is subjected to axial extrusion force, and the sealing member 43 is squeezed and elastically deformed to fill the entire cavity of the groove 42, and fit tightly with the rock mass 1, thereby preliminarily sealing the two ends of the through-fissure 11 of the rock mass 1; after water is injected into the through-fissure 11 of the rock mass 1 through the water injection channel to load the hydraulic pressure, the water flows from the connecting channel 41 on one side through the through-fissure 11 and then flows to the connecting channel 41 on the other side. As the through-fissure 11 and the connecting channels 41 on both sides are gradually filled with water, the water pressure inside the through-fissure 11 will gradually increase, and the fluid pressure will make the sealing member 43 fit more closely with the groove 42 and the rock mass 1, eliminating the small gap between the sealing member 43 and the groove 42 and the surface of the rock mass 1, thereby playing a complete sealing role, and effectively avoiding water seepage between the sealing gasket 4 and the rock mass 1 during the experiment.

[0028] For easier understanding, please refer to Figures 1 to 4, loading pads 5 are fixedly provided on the loading surface of the loading rod in the horizontal and vertical directions. Furthermore, the loading pads 5 and the sealing pads 4 are made of the same material as the loading rod. Preferably, the areas of the end faces of the loading pads 5 and the sealing pads 4 in contact with the rock mass 1 are the same as the areas of each end face of the rock mass 1. Specifically, in this embodiment, the rock mass 1 is a cube with a side length of 50 mm, and the end faces of the loading pads 5 and the sealing pads 4 in contact with the rock mass 1 are both squares with a side length of 50 mm. Since the surface of the rock (especially the natural rock) will have microscopic unevenness after being cut into the rock mass 1 sample, the loading pads 5 and the sealing pads 4 can improve the contact uniformity between the loading rod and the rock mass 1, ensuring uniform force. At the same time, rock sample 1 is very hard and rough. Under the high-speed impact of the experiment, it is easy to cause local damage to the loading surface of the loading rod (especially the incident rod 2). At this time, the loading pad 5 and the sealing pad 4 can act as a sacrificial layer to absorb and transmit the impact energy, avoiding direct contact and force between the loading rod and the rock mass 1, protecting the loading rod from direct damage and extending the service life of the experimental device. Based on this, the user should conduct an external inspection of the sealing pad 4 and the loading pad 5 before and after the experiment. If any surface unevenness or damage is found, they should be replaced with new pads in a timely manner.

[0029] For easier understanding, please refer to Figures 1 to 4 The dynamic water pressure monitoring assembly 6 includes a water pressure sensor probe 61, a signal acquisition device, and a controller. The water pressure sensor probe 61, the signal acquisition device, and the controller are all electrically connected to each other via a signal cable. The water pressure sensor probe 61 is parallel to the through-fissure 11 of the rock mass 1. After the six loading rods apply a preload to the rock mass 1, the water pressure sensor probe 61 extends into the through-fissure 11 of the rock mass 1. During the experiment, the water pressure sensor probe 61 monitors the water pressure inside the through-fissure 11 of the rock mass 1 in real time. The data signal obtained is transmitted to the signal acquisition device via the signal cable, and then to the controller. The controller has data calculation and processing software that can quickly process and analyze the transmitted monitoring data and output the corresponding data.

[0030] The method of using the present invention is as follows: fixed sealing pads 4 are respectively installed on the loading surfaces of a group of loading rods in the direction of the rock mass 1 penetrating the cracks 11, and sealing members 43 are pre-installed on the two sealing pads 4. A water pressure sensor probe 61 is installed in the connecting channel 41 of one of the sealing pads 4, and the end is sealed by a rubber plug 7 at the upper outlet of the connecting channel 41; fixed loading pads 5 are respectively installed on the loading surfaces of the remaining two groups of loading rods, thereby completing the preliminary installation of the pads. The rock mass 1 is mounted on the loading platform of a true triaxial Hopkinson pressure bar, and axial static loads are applied simultaneously in three loading directions. At this time, the connecting channels 41 on both sides are connected to the through-fissure 11 of the rock mass 1, and the seal 43 deforms and fits tightly with the inner cavity of the groove 42 and the rock mass 1 to form a seal, and the water pressure sensor probe 61 extends into the through-fissure 11 of the rock mass 1; water is injected from the upper opening of the water injection channel to load the through-fissure 11 with water pressure until the connecting channels 41 on both sides and the through-fissure 11 are filled with water (or after the preset water pressure is reached), then the water injection is stopped, and the upper opening of the water injection channel is sealed by the rubber plug 7. At this time, the fluctuation of the water pressure in the through-fissure 11 is monitored in real time by the water pressure sensor probe 61. The experimental equipment is turned on, and the impact rod hits the incident rod 2 at high speed, thereby generating a stress pulse in the incident rod 2. The pulse propagates to the rock mass 1 to generate a dynamic compression load. During this process, the fluctuation of the water pressure in the crack 11 of the rock mass 1 is monitored by the dynamic water pressure probe to simulate and monitor the changes in the crack water pressure under different working conditions.

[0031] Although the present invention has been described using the above preferred embodiments, they are not intended to limit the scope of protection of the present invention. Any person skilled in the art who makes various changes and modifications to the above embodiments without departing from the spirit and scope of the present invention still fall within the scope of protection of the present invention.

Claims

1. A rock mass through-fissure hydraulic loading device based on true triaxial Hopkinson pressure bars, comprising three groups of loading bars distributed in three-dimensional space and perpendicular to each other, the loading bars being used to abut and clamp a rock mass (1) having through-fissures (11), two of the three groups of loading bars being horizontal loading bars and one being a vertical loading bar, characterized in that: A group of horizontal loading rods is parallel to the through-fissure (11) of the rock mass (1), and the other two groups of loading rods are perpendicular to the through-fissure (11) of the rock mass (1). The group of loading rods perpendicular to the through-fissure (11) of the rock mass (1) is composed of an incident rod (2) and a transmission rod (3), and each of the other groups of loading rods is composed of two transmission rods (3). The loading surfaces of the two transmission rods (3) parallel to the through-fissure (11) of the rock mass (1) are both provided with sealing pads (4). The sealing pads (4) are provided with connecting channels (41) connected to the through-fissure (11) of the rock mass (1). A dynamic water pressure monitoring component (6) for real-time dynamic monitoring of the water pressure in the through-fissure (11) of the rock mass (1) is provided in one of the connecting channels (41). The other connecting channel (41) is used to inject water into the through-fissure (11) of the rock mass (1). The sealing pads (4) are provided with a sealing component for sealing. The sealing assembly comprises a groove (42) formed on the end surface where the sealing pad (4) contacts the rock mass (1); a force-deformable sealing member (43) is provided in the groove (42); the coverage area of ​​the sealing member (43) is larger than the area of ​​the through-fissure (11) of the rock mass (1); the volume of the sealing member (43) is larger than the volume of the cavity of the groove (42); and the sealing member (43) fills the cavity of the groove (42) after deformation.

2. The rock mass through-fissure hydraulic loading device based on true triaxial Hopkinson pressure bar according to claim 1 is characterized in that: The groove (42) is an annular groove (42), and the corresponding sealing member (43) is an annular sealing member (43).

3. The rock mass through-fissure hydraulic loading device based on true triaxial Hopkinson pressure bar according to claim 1 is characterized in that: Loading pads (5) are provided on the loading surfaces of the loading rods perpendicular to the through cracks (11).

4. The rock mass through-fissure hydraulic loading device based on true triaxial Hopkinson pressure bar according to claim 1, characterized in that: The dynamic water pressure monitoring assembly (6) comprises a water pressure sensor probe (61) which is parallel to the through-fissure (11) of the rock mass (1) and extends into the through-fissure (11) of the rock mass (1).

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