A dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test device

Abstract

The present invention provides a dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test device, which is mainly composed of a loading frame system, a rock rod system, an electromagnetic pulse emission system, an axial pressure servo control loading system, and a data monitoring and acquisition system. The loading frame system is mainly composed of a support platform, a connecting rod, a rock rod support, and an axial pressure loading fixed baffle, which plays a role in providing a support platform and guiding the centering of the rock rod. The rock rod system is composed of rock rods with equal diameters, different lengths and quantities, and equal or different materials to meet different test requirements. The electromagnetic pulse emission system is mainly composed of an electromagnetic pulse stress wave excitation cavity and its control system. The axial pressure servo control loading system is composed of a hydraulic loading cylinder, an axial pressure loading piston, and an axial pressure servo control system. The function of the axial pressure servo control loading system is to programmatically control the loading, holding, and unloading of the oil source system, which can ensure that the static axial pressure remains relatively stable during the test process.

Description

Technical Field

[0001] The present invention belongs to the field of research on stress wave propagation in rock mass, and more specifically, relates to a dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device for studying stress wave propagation and attenuation law in rock mass. Background Art

[0002] Rock materials are different from other engineering materials. They contain a large number of pre-existing defects, such as micro-pores, micro-cracks, joints, joint groups, and structural planes. These pre-existing defects not only control the mechanical properties of rock materials, but also significantly affect the wave characteristics of rock mass (such as stress wave propagation and attenuation). Therefore, studying the wave characteristics of rock materials and rock mass structures, especially the propagation and attenuation laws of stress waves by joints or joint groups inside the rock mass, is particularly important for analyzing and evaluating the safety and stability of rock mass engineering under the action of seismic waves or explosion waves. At present, there are two main methods to study the influence of defects such as pre-existing joints and cracks inside the rock on the wave propagation and attenuation laws. One is to use an ultrasonic measurement system to perform high-frequency, low-amplitude ultrasonic propagation measurements on jointed rock samples or rock samples with internal defects to analyze the influence of joints and cracks on ultrasonic propagation and attenuation laws; the other is to use a traditional one-dimensional Hopkinson bar to perform high-amplitude, low-frequency one-dimensional stress wave propagation tests on rock samples with a single prefabricated joint to study the influence of a single joint on the propagation and attenuation laws of stress waves. The existing methods have greatly promoted people's understanding and mastering of the wave propagation and attenuation laws of rock joints. However, the above two methods are based on experimental research on small-sized rock joints with an equivalent diameter and length of less than or equal to 50 mm, and cannot carry out research on the propagation and attenuation laws of stress waves in large-scale rock masses (rock mass length reaches meters) close to actual working conditions. Therefore, the existing technology needs to be improved. Summary of the invention

[0003] In order to solve the problem that existing experimental devices and test methods are unable to carry out research on stress wave propagation and attenuation laws in large-scale rock structures (rock length reaches meters) close to actual conditions, the present invention proposes a dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device, which makes up for the defects of existing experimental research devices for stress wave propagation in rock masses, especially solves the technical difficulty that existing devices are unable to carry out research on stress wave propagation in rock masses under the conditions of initial static stress of the rock masses, and can provide important technical support for the design, protection, safety and stability evaluation of rock engineering.

[0004] The dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device is mainly composed of a loading frame system, a rock bar system, an electromagnetic pulse emission system, an axial pressure servo control loading system, and a data monitoring and acquisition system.

[0005] The loading frame system is mainly composed of a support platform, connecting rods, rock rod supports and axial pressure loading fixed baffles, which play the role of providing a support platform and guiding the centering of rock rods. The rock rod system is mainly composed of rock rods of equal diameter, different lengths and quantities, and equal or different materials to meet different test requirements. The electromagnetic pulse emission system is mainly composed of an electromagnetic pulse stress wave excitation cavity and its control system. The axial pressure servo control loading system is mainly composed of a hydraulic loading cylinder, an axial pressure loading piston and an axial pressure servo control system. The function of the axial pressure servo control loading system is to programmatically control the loading, holding and unloading of the oil source system, which can ensure that the static axial pressure remains relatively stable during the test process. The data monitoring and acquisition system is mainly composed of a multi-channel high-speed synchronous recorder, a strain gauge, a Wheatstone bridge and a strain signal amplifier, which can ensure that the stress wave propagation test data in the rock mass is recorded and stored completely and effectively.

[0006] Figure 1 The three-dimensional diagram of the dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test device is shown. The test device is placed on the support platform 1, and is mainly composed of a loading frame system, a rock rod system, an electromagnetic pulse emission system, an axial pressure servo control loading system, and a data monitoring and acquisition system. The incident end axial pressure loading fixed baffle 2 is fixed to the incident end of the support platform 1, and a large circular hole and a small circular hole are respectively arranged in the center and around it. The large circular hole and the small circular hole here are relative terms, that is, the size of the circular hole arranged in the middle of the incident end axial pressure loading fixed baffle 2 is larger than the size of the circular holes arranged around it, so it is clear here. The large circular hole and the small circular hole of the transmission end axial pressure loading fixed baffle 11 are understood in the same way as here.

[0007] The electromagnetic pulse stress wave excitation cavity 3 passes through the central large circular hole of the incident end axial pressure loading fixed baffle 2 and is welded thereto to form an integral structure. The loading end of the electromagnetic pulse stress wave excitation cavity 3 contacts the incident end of the first rock rod 5; the first rock rod 5 is supported on the loading axis by the rock rod support 6, and the transmission end section of the first rock rod 5 contacts the incident end section of the second rock rod 7, and the two contact sections constitute a first joint 12; the second rock rod 7 is supported on the loading axis by the rock rod support 6, and the transmission end section of the second rock rod 7 contacts the incident end section of the third rock rod 8, and the two contact sections constitute a second joint 13; the third rock rod 8 is supported on the loading axis by the rock rod support 6, and its transmission end section contacts the axial pressure loading piston 9; the axial pressure loading piston 9 is connected as a whole with the hydraulic loading cylinder 10, and is used to transmit the oil pressure in the hydraulic loading cylinder to the rock rod; the hydraulic loading cylinder 10 passes through the central large circular hole of the transmission end axial pressure loading fixed baffle 11 and is welded therewith to form an integral structure; the transmission end axial pressure loading fixed baffle 11 is placed on the transmission end of the support platform, and can be moved back and forth on the support platform to adjust the length of the rock rod test system according to the length of the rock rod system; the connecting rod 4 passes through the small circular holes around the incident end axial pressure loading fixed baffle 2 and the transmission end axial pressure loading fixed baffle 11 respectively, and connects the loading frame system, the rock rod system, the electromagnetic pulse emission system and the axial pressure servo control loading system into an integral structure, which is used to realize the dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test research.

[0008] In order to solve the problems in the prior art, the present invention provides a dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test device, which is mainly composed of a loading frame system, a rock rod system, an electromagnetic pulse emission system, an axial pressure servo control loading system, and a data monitoring and acquisition system;

[0009] The loading frame system is mainly composed of a supporting platform, connecting rods, rock rod supports and axial pressure loading fixed baffles. The rock rod system is mainly composed of rock rods with equal diameters, different lengths and quantities, and equal or different materials to meet different test requirements; the electromagnetic pulse emission system is mainly composed of an electromagnetic pulse stress wave excitation cavity and its control system; the axial pressure servo control loading system is mainly composed of a hydraulic loading cylinder, an axial pressure loading piston and an axial pressure servo control system; the data monitoring and acquisition system is mainly composed of a multi-channel high-speed synchronous recorder, a strain gauge, a Wheatstone bridge and a strain signal amplifier;

[0010] The main components of the test device are: support platform, incident end axial pressure loading fixed baffle, electromagnetic pulse stress wave excitation cavity, first rock rod, second rock rod, third rock rod, axial pressure loading piston, hydraulic loading cylinder, transmission end axial pressure loading fixed baffle; the connection relationship of the above components is as follows:

[0011] The test device is placed on a supporting platform, and an incident end axial pressure loading fixed baffle is fixed to the incident end of the supporting platform, and a large circular hole and a small circular hole are respectively arranged in the center and around the baffle, where the large circular hole and the small circular hole are relative terms, that is, the size of the circular hole arranged in the middle of the incident end axial pressure loading fixed baffle is larger than the size of the circular holes arranged around the baffle, and the electromagnetic pulse stress wave excitation cavity passes through the central large circular hole of the incident end axial pressure loading fixed baffle, and the loading end of the electromagnetic pulse stress wave excitation cavity contacts the incident end of the first rock rod; the transmission end section of the first rock rod contacts the incident end section of the second rock rod, and the two contact sections constitute a first joint, and the transmission end section of the second rock rod contacts the first rock rod. The incident end sections of the three rock rods are in contact, and the two contact sections constitute the second joint; the transmission end section of the third rock rod is in contact with the axial pressure loading piston; the axial pressure loading piston is connected to the hydraulic loading cylinder as a whole, and the axial pressure loading piston transmits the oil pressure in the hydraulic loading cylinder to the rock rod; the hydraulic loading cylinder passes through the central large circular hole of the axial pressure loading fixed baffle at the transmission end; the axial pressure loading fixed baffle at the transmission end is placed on the transmission end of the support platform; the connecting rods pass through the small circular holes around the incident end axial pressure loading fixed baffle and the transmission end axial pressure loading fixed baffle respectively, connecting the loading frame system, the rock rod system, the electromagnetic pulse transmitting system and the axial pressure servo control loading system into an integral structure.

[0012] As a further improvement of the present invention, it also includes several rock rod supports, the first rock rod is supported by the rock rod support on the loading axis, the second rock rod is supported by the rock rod support on the loading axis, and the third rock rod is supported by the rock rod support on the loading axis.

[0013] As a further improvement of the present invention, the electromagnetic pulse stress wave excitation cavity passes through the central large circular hole of the incident end axial pressure loading fixed baffle and is welded thereto to form an integral structure.

[0014] As a further improvement of the present invention, the hydraulic loading cylinder passes through the central large circular hole of the transmission end axial pressure loading fixed baffle and is welded thereto to form an integral structure.

[0015] As a further improvement of the present invention, the transmission end axial pressure loading fixed baffle is arranged at the transmission end of the support platform, and is moved back and forth on the support platform to adjust the length of the rock rod test system according to the length of the rock rod system.

[0016] As a further improvement of the present invention, the first joint and the second joint constitute a pair of parallel joint groups.

[0017] As a further improvement of the present invention, a plurality of strain gauges are arranged on the surface of the rock rod, and the strain gauges are connected to the data monitoring and acquisition system through shielded wires.

[0018] As a further improvement of the present invention, a mixture is filled between the contact surfaces of the first rock rod and the second rock rod to form a filled first joint, and a mixture is filled between the second rock rod and the third rock rod to form a filled second joint. The first joint and the second joint constitute a pair of parallel joint groups, and according to test requirements, the material and water content of the filling materials of the two joints may be the same or different.

[0019] The beneficial effects of the present invention are:

[0020] (1) The rod system of the combined static and dynamic electromagnetic loading Hopkinson rock bar wave propagation test device is composed of long rock bars, which can be used to study the propagation and attenuation laws of stress waves in jointed rock masses under conditions close to actual working conditions. This makes up for the defect that the existing Hopkinson bar (metal bar) equipment cannot carry out experimental research on stress wave propagation in large-scale rock structures.

[0021] (2) The electromagnetic pulse conversion stress wave excitation system of the dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device can accurately control and highly repeatably generate high-amplitude and high-frequency incident stress waves, solving the problem that the existing Hopkinson bar equipment is difficult to accurately control and highly repeatably generate incident stress waves.

[0022] (3) The axial pressure servo control loading system of the combined static and dynamic electromagnetic loading Hopkinson rock rod wave propagation test device can realize the synchronous servo control loading of static axial pressure and can keep the static axial pressure in the rock rod relatively stable during the stress wave propagation process, making the research on the propagation and attenuation law of stress waves in jointed rock mass closer to the actual working conditions, and solving the technical problem that the existing equipment cannot carry out the research on the propagation of stress waves in rock mass under the condition of initial static stress of rock mass. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a three-dimensional diagram of the dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test device of the present invention;

[0024] Figure 2 It is a front view of the dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test device of the present invention;

[0025] Figure 3 This is a top view of the dynamic and static combined electromagnetic loading Hopkinson rock rod wave propagation test device.

[0026] The names of the components corresponding to the numbers in the figure are as follows:

[0027] 1-support platform, 2-incident end axial pressure loading fixed baffle, 3-electromagnetic pulse stress wave excitation cavity, 4-connecting rod, 5-first rock rod, 6-rock rod support, 7-second rock rod, 8-third rock rod, 9-axial pressure loading piston, 10-hydraulic loading cylinder, 11-transmission end axial pressure loading fixed baffle, 12-first joint, 13-second joint, 14-strain gauge. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Best Mode 1

[0030] The Anshan rock rods with a diameter of 50 mm and a length of 1500 mm, 1000 mm, and 1500 mm respectively processed and polished are used as the first rock rod 5, the second rock rod 7, and the third rock rod 8. The first rock rod and the second rock rod are in smooth contact to form an approximately closed first joint 12, and the second rock rod and the third rock rod are still in smooth contact to form an approximately closed second joint 13. The first joint 12 and the second joint 13 form a pair of parallel joint groups. The closed joint we refer to is that two smooth surfaces are in contact and fit together to form a closed joint surface.

[0031] According to the experimental test requirements and the duration of the incident stress wave, several strain gauges 14 are pasted on the surface of the rock rod, and the strain gauges are connected to the data monitoring and acquisition system through shielded wires. During the experiment, according to the experimental design, the axial pressure servo control loading system is first adjusted, and the axial pressure loading cylinder 10 and the axial pressure loading piston 9 are used to apply an axial static pressure of 3MPa to the rock rod system along the axial direction of the rock rod to simulate the deadweight stress of the rock structure at a depth of about 100m underground. Then, the electromagnetic pulse stress wave excitation cavity 3 is used to excite and generate an incident stress wave with a corresponding amplitude and wavelength of 200MPa and 300μs respectively according to the experimental design requirements. The stress wave then propagates along the first, second, and third rock rods, and passes through the first and second joints in turn, and generates a transmission wave and a reflection wave at the first and second joints. The strain gauges pasted on the surface of the rock rod can be used to monitor and record the signals of the incident stress wave, the reflected stress wave, and the transmitted stress wave on the rock rod at different positions. Finally, based on the experimental monitoring data, the propagation and attenuation law of the stress wave in the rock mass containing two parallel joints can be calculated and analyzed according to the one-dimensional stress wave theory.

[0032] Best Mode 2

[0033] The intact granite rock rods with a diameter of 50 mm and a length of 1500 mm, 1500 mm, and 1500 mm respectively processed and polished are used as the first rock rod 5, the second rock rod 7, and the third rock rod 8. A mixture of 30% kaolin and 70% quartz sand (particle size less than 1 mm) with a thickness of 2 mm is filled between the contact surface of the first rock rod and the second rock rod to form a filled first joint 12, and a mixture of 30% kaolin and 70% quartz sand (particle size less than 1 mm) with a thickness of 2 mm is filled between the second rock rod and the third rock rod to form a filled second joint 13. The first joint 12 and the second joint 13 form a pair of parallel joint groups, and the water content of the two joint fillings is the same and is 10%. Subsequently, a set of strain gauges 14 are symmetrically pasted at the midpoint of the surface of each granite rock rod, and the strain gauges are connected to the data monitoring and acquisition system through shielded wires. Next, according to the experimental design, the axial pressure servo control system is adjusted, and the axial pressure loading cylinder 10 and the axial pressure loading piston 9 are used to apply an axial static pressure of 27 MPa to the rock rod system along the axial direction of the rock rod to simulate the deadweight stress of the rock structure at a depth of 1000 m underground. Subsequently, the electromagnetic pulse stress wave excitation cavity 3 is used to excite and generate an incident stress wave with a wavelength duration and an amplitude of 200 μs and 100 MPa, respectively. The stress wave then propagates along the first, second, and third rock rods, and passes through the first and second filling joints in turn, and generates a transmission wave and a reflection wave at the first and second joints. The strain gauges attached to the surface of the rock rod can be used to monitor and record the signals of the incident stress wave, the reflected stress wave, and the transmitted stress wave on different rock rods. Finally, based on the experimental monitoring data, the propagation and attenuation laws of the stress wave in the rock mass containing two parallel joints can be calculated and analyzed according to the one-dimensional stress wave theory.

[0034] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device, characterized in that: The test device is mainly composed of a loading frame system, a rock rod system, an electromagnetic pulse emission system, an axial pressure servo control loading system, and a data monitoring and acquisition system; The loading frame system is mainly composed of a supporting platform, connecting rods, rock rod supports and axial pressure loading fixed baffles. The rock rod system is mainly composed of rock rods with equal diameters, different lengths and quantities, and equal or different materials to meet different test requirements; the electromagnetic pulse emission system is mainly composed of an electromagnetic pulse stress wave excitation cavity and its control system; the axial pressure servo control loading system is mainly composed of a hydraulic loading cylinder, an axial pressure loading piston and an axial pressure servo control system; the data monitoring and acquisition system is mainly composed of a multi-channel high-speed synchronous recorder, a strain gauge, a Wheatstone bridge and a strain signal amplifier; The main components of the test device are: a support platform (1), an incident end axial pressure loading fixed baffle (2), an electromagnetic pulse stress wave excitation cavity (3), a first rock rod (5), a second rock rod (7), a third rock rod (8), an axial pressure loading piston (9), a hydraulic loading cylinder (10), and a transmission end axial pressure loading fixed baffle (11); the connection relationship of the above components is as follows: The test device is placed on a support platform (1). An incident end axial pressure loading fixed baffle (2) is fixed to the incident end of the support platform (1). A large circular hole and a small circular hole are respectively arranged at the center and around the baffle. The large circular hole and the small circular hole are relative terms, that is, the size of the circular hole arranged in the middle of the incident end axial pressure loading fixed baffle (2) is larger than the size of the circular holes arranged around the baffle. The electromagnetic pulse stress wave excitation cavity (3) passes through the central large circular hole of the incident end axial pressure loading fixed baffle (2) and is welded thereto to form an integral structure. The loading end of the electromagnetic pulse stress wave excitation cavity (3) contacts the incident end of the first rock rod (5); the transmission end section of the first rock rod (5) contacts the incident end section of the second rock rod (7), and the two contact sections constitute a first joint (12). The transmission end section of the second rock rod (7) contacts the incident end section of the third rock rod (8), and the two contact sections The second joint (13) is formed; the transmission end section of the third rock rod (8) contacts the axial pressure loading piston (9); the axial pressure loading piston (9) is connected to the hydraulic loading cylinder (10) as a whole, and the axial pressure loading piston (9) transmits the oil pressure in the hydraulic loading cylinder to the rock rod; the hydraulic loading cylinder (10) passes through the central large circular hole of the transmission end axial pressure loading fixed baffle (11) and is welded thereto to form an integral structure; the transmission end axial pressure loading fixed baffle (11) is placed on the transmission end of the support platform, and is moved forward and backward on the support platform to adjust the length of the rock rod test system according to the length of the rock rod system; the connecting rod (4) passes through the small circular holes around the incident end axial pressure loading fixed baffle (2) and the transmission end axial pressure loading fixed baffle (11), respectively, to connect the loading frame system, the rock rod system, the electromagnetic pulse transmitting system and the axial pressure servo control loading system into an integral structure.

2. The dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device according to claim 1, characterized in that: It also comprises a plurality of rock rod supports (6), wherein the first rock rod (5) is supported by the rock rod support (6) on the loading axis, the second rock rod (7) is supported by the rock rod support (6) on the loading axis, and the third rock rod (8) is supported by the rock rod support (6) on the loading axis.

3. The dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device according to claim 1, characterized in that: The first joint (12) and the second joint (13) form a pair of parallel joint groups.

4. The dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device according to claim 1, characterized in that: Several strain gauges are set on the surface of the rock rod, and the strain gauges are connected to the data monitoring and acquisition system through shielded wires.

5. The dynamic and static combined electromagnetic loading Hopkinson rock bar wave propagation test device according to claim 1, characterized in that: The mixture is filled between the contact surface of the first rock rod and the second rock rod to form a filled first joint, and the mixture is filled between the second rock rod and the third rock rod to form a filled second joint. The first joint (12) and the second joint (13) form a pair of parallel joint groups, and according to test requirements, the material and water content of the filling material of the two joints can be the same or different.

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