Device for measuring interface cracking parameters of stratified rock mass
By designing a device including a scissoring experimental bench and a measurement system, the problem of the rock body tensioning failure test device in the prior art is difficult to achieve uniform load application and insufficient measurement accuracy on both sides of the crack, and the layered shape is achieved Accurate measurement of rock mass interface cracking parameters provides strong guidance on the construction of layered rock mass engineering.
Patent Information
- Application Number
- CN202420288566.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-07
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2034-02-07
AI Technical Summary
The existing rock mass tensioning failure test device is difficult to achieve uniform application of tensioning loads on both sides of the crack, and cannot meet the accurate measurement of cracking parameters in the interfacial cracking of layered rock mass, especially in the continuous displacement of crack opening and instantaneous data measurement of crack opening. There are difficulties in the aspect.
A device including a scissoring test bench and measurement system was designed, using a bidirectional forward and reverse teeth precision screw set and a differential transformer-type displacement sensor, which can achieve uniform application of tension loads on both sides of the crack and crack opening displacement. Continuous measurement, the loading plate is achieved by using cantilever beam sensor and motor drive system to move in the opposite direction while the loading plate is moved to ensure the accuracy and continuity of the measurement.
Real-time and accurate measurement of crack opening displacement and load changes during tension failure of layered rock mass, meeting the continuity of crack opening displacement and measurement of instantaneous data of crack opening, and is suitable for engineering construction of layered rock mass Activity.
Smart Images
Figure CN222232168U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of civil engineering, in particular to a device for measuring cracking parameters of layered rock interface. Background Art
[0002] Layered rock mass is a typical rock mass widely existing in nature. The dominant structural surface is usually the material differentiation surface, and the interlayer difference is significant. At the same time, the fine joints throughout the rock mass make the physical and mechanical properties more complex, showing strong transverse isotropy or orthogonal anisotropy. For underground engineering construction in layered rock mass, the most prominent problem is the stability of the surrounding rock. The deformation and destruction of rock mass is mainly controlled by the strength of the rock itself and the characteristics of the structural surface. Compared with general continuous media, the structural surface characteristics are more significant factors affecting the deformation and destruction of layered rock mass; compared with broken block cracking media, the macroscopic large-scale layered structural surface has strong spatial continuity and is more sensitive to internal and external stress changes. Under construction disturbance, the rock mass interface layer becomes the dominant path for crack expansion. Because the interlayer bonding force is generally weak, and the deformation of each rock layer is discontinuous and uncoordinated in space, the layered rock mass is very likely to experience tension cracking or even delamination at the interface layer, which in turn causes chain instability. The macroscopic and microscopic structural planes formed in the layered rock mass are widely distributed. Under the action of these initial damage factors, the deformation and destruction of the layered rock mass are manifested as non-continuous, non-homogeneous and anisotropic slab-fracture medium mechanical properties. Correctly understanding the basic mechanical properties of the interface layer of the layered rock mass is of great significance for the stability analysis and safety evaluation of the rock mass.
[0003] The existing rock mass tensile failure test device is difficult to achieve uniform application of tensile loads on both sides of the crack; due to the low interlayer bonding strength of the layered rock mass, once a crack appears, it will quickly expand along the bedding plane, and the continuous measurement accuracy of the crack opening displacement cannot meet the requirements, and it is difficult to measure the displacement change at the moment of tensile cracking. Therefore, it is very necessary to establish a test device suitable for the tensile cracking failure of layered rock mass, and then obtain the fracture parameters of the layered structural surface through quantitative analysis to provide guidance for engineering construction activities that cross layered rock mass. Utility Model Content
[0004] In order to solve the above-mentioned deficiencies in the prior art, the utility model provides a device for measuring cracking parameters of layered rock interface, which can continuously measure the crack mouth opening displacement and the tensile load applied on both sides of the crack during the tensile failure process of the layered rock.
[0005] In order to achieve the above technical purpose, the technical solution adopted by the utility model is:
[0006] A device for measuring cracking parameters of layered rock interface comprises a tensile test bench, the tensile test bench comprises a lower platform base and an upper platform bottom plate arranged from bottom to top, a height adjustment unit is arranged between the lower platform base and the upper platform bottom plate, the center of the upper platform bottom plate is hollowed out, U-shaped brackets are fixed at both ends of the upper platform bottom plate, and the U-shaped brackets support a loading unit; the loading unit is provided with two loading plates, the loading plates are connected to a power module, the power module drives the two loading plates to move in opposite directions at the same time, and a cantilever beam sensor is connected between the loading plates and the power module; the measuring system also comprises a measuring system, the measuring system comprises a differential transformer displacement sensor, the differential transformer displacement sensor is used to measure the displacement at the crack opening during the stretching process; one end of the differential transformer displacement sensor is fixed to one side of the loading plate, and the other end abuts against the other loading plate.
[0007] Furthermore, the loading unit includes a screw seat connected to the middle part of the U-shaped bracket, a bidirectional positive and negative thread precision screw set is installed between the two screw seats, one end of the screw is connected to the motor and the reducer through a coupling, and the two screw nuts are respectively fixedly connected to a shift plate. The two screw nuts of the bidirectional positive and negative thread precision screw set are driven by a motor to realize the simultaneous movement of the two shift plates in opposite directions; the lower parts of the opposite sides of the two shift plates are respectively connected to cantilever beam sensors, and the lower part of the cantilever beam sensor is fixedly connected to the loading pull plate.
[0008] Furthermore, a horizontal guide rod is connected between the two U-shaped brackets, and the upper end of the shift plate is slidably connected to the horizontal guide rod.
[0009] Furthermore, two horizontal guide rods are provided, which are symmetrically arranged on both sides of the bidirectional positive and negative thread precision screw set.
[0010] Furthermore, a sleeve is slidably provided on the horizontal guide rod, the shift plate is passed through the sleeve, and one end of the sleeve is connected to a locking nut.
[0011] Furthermore, a motor mounting bracket is provided at one end of the upper platform bottom plate, and the motor and the reducer are mounted on the motor mounting bracket.
[0012] Furthermore, the height adjustment unit is a height adjustment screw.
[0013] Furthermore, a fixture base is fixed on each of the loading plates on both sides, one end of the differential transformer type displacement sensor is fixed in the fixture base on one side, an angle iron is fixed in the fixture base on the other side, and the other end of the differential transformer type displacement sensor is abutted against the angle iron.
[0014] Preferably, the differential transformer type displacement sensor is a rebound type displacement sensor.
[0015] Furthermore, it also includes a host, which is electrically connected to the motor, the cantilever beam sensor, and the differential transformer displacement sensor; the host controls the start and stop and working parameters of the power module, and the host receives real-time monitoring data of the cantilever beam sensor and the differential transformer displacement sensor.
[0016] The beneficial effects of the utility model are:
[0017] The utility model can measure the change of the tension applied by the loading tension plate and the change of the opening displacement of the crack mouth in real time, has simple operation and accurate measurement, and can meet the measurement requirements of the continuity of the crack opening displacement and the instantaneous data of the cracking.
[0018] The utility model adopts a bidirectional positive and negative thread precision screw set structure, which can realize the simultaneous (same speed) and uniform movement of the left and right loading tension plates in opposite directions under one input rotation speed, thereby realizing the tensile cracking effect on the test piece. The device is also well applicable to uniform isotropic materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0020] Figure 1 It is a front view of an embodiment of the utility model;
[0021] Figure 2 yes Figure 1 Left view of;
[0022] Figure 3 yes Figure 1 A top view of
[0023] Figure 4 It is a schematic diagram of the connection between the U-shaped bracket and the upper platform bottom plate;
[0024] Figure 5 yes Figure 4 Left view of;
[0025] Figure 6 This is a schematic diagram of the structure of a bidirectional positive and negative thread screw set;
[0026] Figure 7 It is a structural diagram of the paddle.
[0027] Figure markings: 1-lower platform base, 3-height adjustment screw, 4-single-sided notched cubic specimen, 5-loading plate, 6-cantilever beam sensor, 7-U-shaped bracket, 9-upper platform base plate, 10-shift plate, 11-screw seat, 14-bidirectional forward and reverse thread screw set, 19-coupling, 20-motor mounting bracket, 21-reducer, 22-locking nut, 24-horizontal guide rod, 25-sleeve. DETAILED DESCRIPTION
[0028] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work are within the scope of protection of the present application.
[0029] A device for measuring cracking parameters of layered rock interface, such as Figure 1-Figure 7 As shown, it includes a tensile test bench, which includes a lower platform base 1 and an upper platform bottom plate 9 arranged from bottom to top, and a height adjustment unit is provided between the lower platform base 1 and the upper platform bottom plate 9, and preferably, the height adjustment unit is a height adjustment screw 3; the center of the upper platform bottom plate 9 is hollow, and U-shaped brackets 7 are fixed at both ends of the upper platform bottom plate 9, and the U-shaped brackets 7 support the loading unit; the loading unit is provided with two loading plates 5, and the loading plates 5 are connected to a power module, and the power module drives the two loading plates 5 to move in opposite directions, and a cantilever beam sensor 6 is connected between the loading plates 5 and the power module; it also includes a measurement system, and the measurement system includes a differential transformer displacement sensor, and the differential transformer displacement sensor is used to measure the displacement at the crack opening during the stretching process; one end of the differential transformer displacement sensor is fixed to one side of the loading plate, and the other end abuts against the other loading plate.
[0030] It also includes a host, which is electrically connected to the motor, the cantilever beam sensor, and the differential transformer displacement sensor; the host controls the start and stop and working parameters of the power module, and receives real-time monitoring data from the cantilever beam sensor and the differential transformer displacement sensor.
[0031] In a specific embodiment, the loading unit includes a screw seat connected to the middle part of the U-shaped bracket 7, a bidirectional positive and negative thread precision screw set 14 is installed between the two screw seats, one end of the screw is connected to the motor and the reducer 21 through a coupling 19, and the two screw nuts are respectively fixedly connected to a shift plate 10. The two screw nuts of the bidirectional positive and negative thread precision screw set 14 are driven by a motor to realize the simultaneous movement of the two shift plates 10 in opposite directions; the lower parts of the opposite sides of the two shift plates 10 are respectively connected to cantilever beam sensors 6, and the lower part of the cantilever beam sensor 6 is fixedly connected to the loading pull plate 5.
[0032] Furthermore, a horizontal guide rod 24 is connected between the two U-shaped brackets 7, and the upper end of the shift plate 10 is slidably connected to the horizontal guide rod 24. Two horizontal guide rods 24 are provided, symmetrically arranged on both sides of the bidirectional positive and negative thread precision screw set 14. Preferably, a sleeve 25 is slidably arranged on the horizontal guide rod 24, and the shift plate 10 is inserted into the sleeve 25, and one end of the sleeve 25 is connected to the locking nut 22. A motor mounting bracket 20 is provided at one end of the upper platform bottom plate 9, and the motor and reducer 21 are installed on the motor mounting bracket 20.
[0033] Furthermore, the differential transformer displacement sensor is a rebound displacement sensor. When the object to be measured undergoes a slight deformation, the internal iron core or magnetic rod of the rebound displacement sensor moves, causing the magnetic induction intensity in the coil to change, thereby generating an induced voltage signal, the size of which is related to the displacement. The probe of the rebound displacement sensor adopts high-hardness wear-resistant material silicon nitride ceramic, and the moving part of the measuring axis adopts a precision guide rail, with high measurement resolution and good repeatability. The rebound displacement sensor is equipped with an external transmitter to output a standard DC signal. It adopts a convenient single power supply of +12~30VDC. The electronic circuit is sealed in a 304 stainless steel metal tube and can work in harsh environments such as humidity and dust. The output signal is a standard 0-5V, 0-10V, 4-20mA or RS485 output that can be used by a computer or PLC. Considering the high rigidity of the loading plate 5, a fixture base is fixed on each of the two loading plates 5, one end of the differential transformer displacement sensor is fixed in the fixture base on one side, and an angle iron is fixed in the fixture base on the other side, and the other end of the differential transformer displacement sensor is abutted against the angle iron. During the loading process, the loading plate is always tightly against the notch wall of the specimen, and the displacement measured by the differential transformer displacement sensor is the linear displacement at the crack opening.
[0034] The method of using this device is:
[0035] 1. Prepare the test piece: select a layered rock mass with hard rock, dense rock mass and no obvious small-scale structural surface, and make a single-sided notch with a length, width and height of 150×150×150mm on the rock mass; make a prefabricated crack in the middle of the notch, with an initial crack height ratio of H1 / D=0.2, where H1 is the crack height and D is the notch height; the crack width is 2-3mm, and the crack tip is V-shaped.
[0036] 2. Adjust the support height adjustment screw 3 of the upper platform bottom plate 9 so that the bottom of the loading plate 5 is a certain distance higher than the specimen notch. Place the specimen at a predetermined position on the lower platform base 1, ensure that the notch direction is parallel to the loading plate 5, and fix it.
[0037] 3. Start the motor and input a lower reverse speed. As the left and right side shift plates 10 slowly approach each other, gradually reduce the speed. When the distance between the two outer sides of the loading plate 5 is less than a certain distance of the slot width, stop adjusting.
[0038] 4. Adjust the support height adjustment screw 3 of the upper platform bottom plate 9 again to lower the platform height so that the bottom of the loading plate 5 is about to touch the bottom of the specimen notch; start the motor, input a lower forward speed, adjust the left and right side paddles to move slowly toward the slot wall, and make fine adjustments near the position where the cantilever beam sensor shows a small reading to determine the initial position of zero load.
[0039] 5. Install the differential transformer displacement sensor at the opening of the crack of the specimen; one end of the differential transformer displacement sensor is fixed in the fixture base on one side of the loading plate, and the other end is abutted against the angle iron on the other loading plate.
[0040] 6. Initialize the displacement of the differential transformer displacement sensor, start the motor to slowly apply tension, and as the load on the specimen approaches the peak value, the microcracks and pores at the front end of the crack continue to evolve. When a macro crack appears along the extension line of the prefabricated gap and extends to the edge of the specimen, the specimen undergoes tension failure and the loading is stopped.
[0041] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims attached to the present invention.
Claims
1. A device for measuring cracking parameters of layered rock interface, characterized in that: The tensile cracking test bench comprises a lower platform base (1) and an upper platform bottom plate (9) which are arranged from bottom to top; a height adjustment unit is arranged between the lower platform base (1) and the upper platform bottom plate (9); the center of the upper platform bottom plate (9) is hollowed out; U-shaped brackets (7) are fixed at both ends of the upper platform bottom plate (9); the U-shaped brackets (7) support a loading unit; the loading unit is provided with two loading plates (5); the loading plates (5) are connected to a power module; the power module drives the two loading plates (5) to move in opposite directions at the same time; a cantilever beam sensor (6) is connected between the loading plates (5) and the power module; It also includes a measuring system, which includes a differential transformer displacement sensor, which is used to measure the displacement at the crack opening during the stretching process; one end of the differential transformer displacement sensor is fixed to one side of the loading plate, and the other end abuts against the other loading plate.
2. The device for measuring cracking parameters of layered rock interface according to claim 1, characterized in that: The loading unit comprises a screw seat (11) connected to the middle of the U-shaped bracket (7); a bidirectional positive and negative thread precision screw set (14) is installed between the two screw seats (11); one end of the screw is connected to the motor and the reducer (21) through a coupling (19); two screw nuts are respectively fixedly connected to a shift plate (10); the two screw nuts of the bidirectional positive and negative thread precision screw set (14) are driven by a motor to realize that the two shift plates (10) move in opposite directions at the same time; the lower parts of the two shift plates (10) facing each other are respectively connected to cantilever beam sensors (6); the lower part of the cantilever beam sensor (6) is fixedly connected to the loading plate (5).
3. The device for measuring cracking parameters of layered rock interface according to claim 1, characterized in that: A horizontal guide rod (24) is also connected between the two U-shaped brackets (7), and the upper end of the shift plate (10) is slidably connected to the horizontal guide rod (24).
4. The device for measuring cracking parameters of layered rock interface according to claim 3, characterized in that: Two horizontal guide rods (24) are provided, and are symmetrically arranged on both sides of the bidirectional positive and negative thread precision lead screw set (14).
5. The device for measuring cracking parameters of layered rock interface according to claim 3, characterized in that: A sleeve (25) is slidably arranged on the horizontal guide rod (24), the shift plate (10) is inserted into the sleeve (25), and one end of the sleeve (25) is connected to a locking nut (22).
6. The device for measuring cracking parameters of layered rock interface according to claim 1, characterized in that: A motor mounting bracket (20) is provided at one end of the upper platform bottom plate (9), and the motor and the reducer (21) are mounted on the motor mounting bracket (20).
7. The device for measuring cracking parameters of layered rock interface according to claim 1, characterized in that: The height adjustment unit is a height adjustment screw rod (3).
8. The device for measuring cracking parameters of layered rock interface according to claim 1, characterized in that: A clamp base is fixed on each of the loading plates (5) on both sides, one end of the differential transformer type displacement sensor is fixed in the clamp base on one side, an angle iron is fixed in the clamp base on the other side, and the other end of the differential transformer type displacement sensor abuts against the angle iron.
9. The device for measuring cracking parameters of layered rock interface according to claim 8, characterized in that: The differential transformer type displacement sensor is a rebound type displacement sensor.
10. The device for measuring cracking parameters of layered rock interface according to claim 1, characterized in that: It also includes a host, which is electrically connected to the motor, the cantilever beam sensor, and the differential transformer displacement sensor; the host controls the start and stop and working parameters of the power module, and receives real-time monitoring data from the cantilever beam sensor and the differential transformer displacement sensor.