Displacement, stress and strain measurement device and model test equipment

Abstract

The invention discloses a displacement, stress and strain measurement device and model test equipment, the displacement, stress and strain measurement device comprises a supporting and fixing assembly, a displacement measurement assembly, a stress and strain measurement assembly and a control terminal, and the supporting and fixing assembly comprises a metal pipe which extends in the vertical direction and is hollow; the displacement measuring assembly comprises a pull rope displacement sensor and a hollow disc, the pull rope displacement sensor is arranged at the top end of the metal pipe, the hollow disc is arranged outside the metal pipe in a sleeving mode, and the hollow disc is connected with a pull head of the pull rope displacement sensor and can be stressed to move in the vertical direction relative to the metal pipe; the stress-strain measurement assembly is arranged on the metal tube and comprises an optical fiber stress sensor and an optical fiber strain sensor; the control terminal is electrically connected with the pull rope displacement sensor, the optical fiber stress sensor and the optical fiber strain sensor; therefore, displacement measurement and stress-strain measurement of the measured rock-soil body are realized, and the measurement precision is ensured; the structure is simple, the production cost is low and the operation is convenient.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a displacement, stress and strain measuring device and a model testing device. Background Art

[0002] In civil engineering, especially in the field of geotechnical engineering, the research objects and contents are closely related to rock and soil. For problems such as slope management, soil settlement, ground collapse, tunnel deformation, etc., the research objects are special, and it is of great significance to use model test methods for research. By reasonably scaling and simulating key boundary conditions, model tests can reproduce the mechanical properties and deformation and failure mechanisms of rock and soil, providing an intuitive physical basis for revealing complex engineering phenomena. At the same time, model tests can verify and calibrate the accuracy of numerical simulation methods and improve the credibility of theoretical analysis. This method not only provides a scientific basis for design optimization and risk assessment, but also provides valuable guidance for decision-making in engineering practice.

[0003] In model tests, measuring physical and mechanical parameters such as displacement, stress, and strain is the core link in studying geotechnical engineering problems and is of great significance. These parameters are the basic quantities that describe the response behavior of materials and structures under external loads, and can reflect the deformation, failure mode, and mechanical properties of rock and soil. By measuring displacement, the deformation law of each part in the model can be revealed, which helps to judge the stability and deformation trend of the structure; the measurement of stress and strain can directly reflect the stress condition and internal force distribution of the material, and is an important basis for studying the constitutive relationship and material failure of rock and soil. Especially under the simulation of complex geological conditions or extreme loads, accurate displacement and strain data can provide the necessary measured basis for the verification and optimization of numerical models, and also provide scientific decision-making support for subsequent engineering design and risk assessment. Therefore, measuring these key parameters not only helps to deeply understand the mechanical properties of rock and soil, but also improves the reliability of model test results.

[0004] At present, the domestic measurement methods for displacement, stress and strain in model tests include: measuring soil deformation displacement by means of photogrammetry and three-dimensional laser scanning, measuring soil stress and pore water pressure in the model by earth pressure gauge and pore water pressure gauge, and measuring strain by strain gauge. The above measurement methods still have certain limitations in model tests. For example, when using photogrammetry and three-dimensional laser scanning to measure displacement, only the surface objects of the rock and soil can be monitored. In the test, the displacement of the rock and soil at different depths often has certain differences, which cannot well reflect the internal displacement. In addition, the cost is high, the actual operation process is cumbersome, and the subsequent data processing takes a long time. For some models that need to consider the influence of water pressure, if earth pressure gauges and strain gauges are used for stress and strain measurement, the exposed metal devices are prone to rust after long-term use, which has a certain impact on the measurement results of the data. Summary of the invention

[0005] The main purpose of the present invention is to provide a displacement, stress and strain measurement device and a model testing device, aiming to solve the above problems.

[0006] To achieve the above-mentioned purpose, the present invention proposes a displacement, stress and strain measuring device, which is used for model testing in a model testing device. The displacement, stress and strain measuring device comprises:

[0007] A supporting and fixing assembly includes a metal pipe, wherein the metal pipe is used to be arranged in the model box in the model test, extends in the up-down direction, and is hollow;

[0008] A displacement measurement assembly, comprising a pull-wire displacement sensor and a hollow disc, wherein the pull-wire displacement sensor is arranged at the top end of the metal tube, the hollow disc is sleeved outside the metal tube and buried in the rock and soil body to be measured in the model box, the hollow disc is connected to the pull head of the pull-wire displacement sensor, and can be subjected to force and move relative to the metal tube in the up and down direction;

[0009] a stress and strain measurement assembly, arranged on the metal tube, comprising an optical fiber stress sensor and an optical fiber strain sensor; and,

[0010] A control terminal is electrically connected to the pull-rope displacement sensor, the optical fiber stress sensor and the optical fiber strain sensor.

[0011] Optionally, the tube wall of the metal tube is provided with four notches, the four notches are spaced apart along the circumference of the metal tube, and each of the notches is extended along the up-down direction;

[0012] The pull head of the pull rope displacement sensor is arranged in the metal tube, and the pull head is arranged corresponding to the notch to be connected with the hollow disc through the notch.

[0013] Optionally, the displacement measurement assembly further comprises a hexagonal square nut, the hexagonal square nut is arranged in the metal tube, a first screw is arranged on the hexagonal square nut, the first screw is arranged on the upper side of the hexagonal square nut and is threadedly connected with the pull head;

[0014] The hollow disc is inserted with four second screws, which are spaced apart along the circumference of the hollow disc and arranged one by one corresponding to the four circumferential side surfaces of the hexagonal nut, and each second screw is extended radially along the hollow disc to be threadedly connected with the hexagonal nut through the notch of the metal tube.

[0015] Optionally, scale lines are provided on the outer wall of the metal tube corresponding to the notches.

[0016] Optionally, the optical fiber stress sensor includes a first laser, a first input optical fiber, a first output optical fiber, at least one first measuring unit and a first photoelectric converter, wherein the first measuring unit is arranged outside the metal tube and connected to the first laser through the first input optical fiber, and connected to the first photoelectric converter through the first output optical fiber;

[0017] The optical fiber strain sensor comprises a second laser, a second input optical fiber, a second output optical fiber, at least one second measuring unit and a second photoelectric converter, wherein the second measuring unit is arranged outside the metal tube and connected to the second laser through the second input optical fiber and connected to the second photoelectric converter through the second output optical fiber;

[0018] The first measuring unit and the second measuring unit are respectively arranged on two sides of the metal pipe;

[0019] The control terminal is electrically connected to the first laser, the first photoelectric converter, the second laser, and the second photoelectric converter.

[0020] Optionally, one end of the first input optical fiber is arranged in the metal tube and connected to the first laser, and the other end extends out of the metal tube through one of two adjacent slots among the four slots to be connected to the first measuring unit; one end of the first output optical fiber is arranged in the metal tube and connected to the first photoelectric converter, and the other end extends out of the metal tube through the other of the two adjacent slots to be connected to the first measuring unit;

[0021] One end of the second input optical fiber is arranged in the metal tube and connected to the second laser, and the other end extends out of the metal tube through one of the other two adjacent slots among the four slots to be connected to the second measuring unit. One end of the second output optical fiber is arranged in the metal tube and connected to the second photoelectric converter, and the other end extends out of the metal tube through the other of the two adjacent slots to be connected to the second measuring unit.

[0022] Optionally, three of the first measuring units and three of the second measuring units are provided respectively.

[0023] Optionally, the optical fiber stress sensor and the optical fiber strain sensor are arranged above the hollow disk.

[0024] Optionally, the supporting and fixing assembly further comprises a base, and the base is used to be arranged at the bottom of the model box or in the soil layer in the model box;

[0025] The metal pipe is fixedly mounted on the base.

[0026] The present invention also provides a model test device, comprising:

[0027] A model box, wherein the rock and soil to be measured is placed; and

[0028] Displacement, stress and strain measuring devices are arranged in the model box;

[0029] Wherein, the displacement, stress and strain measuring device comprises:

[0030] A supporting and fixing assembly includes a metal pipe, wherein the metal pipe is used to be arranged in the model box in the model test, extends in the up-down direction, and is hollow;

[0031] A displacement measurement assembly, comprising a pull-wire displacement sensor and a hollow disc, wherein the pull-wire displacement sensor is arranged at the top end of the metal tube, the hollow disc is sleeved outside the metal tube and buried in the rock and soil body to be measured in the model box, the hollow disc is connected to the pull head of the pull-wire displacement sensor, and can be subjected to force and move relative to the metal tube in the up and down direction;

[0032] a stress and strain measurement assembly, arranged on the metal tube, comprising an optical fiber stress sensor and an optical fiber strain sensor; and,

[0033] A control terminal is electrically connected to the pull-rope displacement sensor, the optical fiber stress sensor and the optical fiber strain sensor.

[0034] In the technical solution of the present invention, the displacement measurement of the rock and soil body to be measured is realized by driving the pull head of the pull rope displacement sensor to move along with the settlement or uplift of the rock and soil body to be measured by the hollow disc, and the measurement accuracy is high, and the displacement of different positions of the rock and soil body to be measured can be measured arbitrarily according to the needs; the optical fiber stress sensor and the optical fiber strain sensor are used to realize the stress and strain measurement of the rock and soil body to be measured, which is not easy to be corroded and damaged compared with the soil pressure gauge and stress sheet, thereby ensuring the measurement accuracy. In addition, the displacement, stress and strain measurement device 100 provided by the present invention has a simple structure, low production cost, and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0036] Figure 1 A schematic structural diagram of an embodiment of a displacement, stress and strain measuring device provided by the present invention;

[0037] Figure 2 for Figure 1 Schematic diagram of some structures of the displacement, stress and strain measuring device;

[0038] Figure 3 for Figure 1 Schematic diagram of some structures of the displacement, stress and strain measuring device;

[0039] Figure 4 for Figure 1 Side view of the displacement, stress and strain measurement device.

[0040] Description of Figure Numbers:

[0041]

[0042] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0045] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] At present, the domestic measurement methods for displacement, stress and strain in model tests include: measuring soil deformation displacement by means of photogrammetry and three-dimensional laser scanning, measuring soil stress and pore water pressure in the model by earth pressure gauge and pore water pressure gauge, and measuring strain by strain gauge. The above measurement methods still have certain limitations in model tests. For example, when using photogrammetry and three-dimensional laser scanning to measure displacement, only the surface objects of the rock and soil can be monitored. In the test, the displacement of the rock and soil at different depths often has certain differences, which cannot well reflect the internal displacement. In addition, the cost is high, the actual operation process is cumbersome, and the subsequent data processing takes a long time. For some models that need to consider the influence of water pressure, if earth pressure gauges and strain gauges are used for stress and strain measurement, the exposed metal devices are prone to rust after long-term use, which has a certain impact on the measurement results of the data.

[0047] In view of this, the present invention provides a displacement, stress and strain measuring device 100, which is used for performing model tests in a model test device. Figures 1 to 4 This is an embodiment of a displacement, stress and strain measurement device 100 provided by the present invention.

[0048] See also Figures 1 to 4The displacement, stress and strain measuring device 100 includes a supporting and fixing component 1, a displacement measuring component 2, a stress and strain measuring component 3 and a control terminal. The supporting and fixing component 1 includes a metal tube 11, which is used to be arranged in the model box in the model test, and is extended in the up-down direction and is hollow; the displacement measuring component 2 includes a pull-wire displacement sensor 21 and a hollow disk 22, the pull-wire displacement sensor 21 is arranged at the top of the metal tube 11, the hollow disk 22 is sleeved outside the metal tube 11, and is buried in the rock and soil body to be measured in the model box, the hollow disk 22 is connected to the pull head 211 of the pull-wire displacement sensor 21, and can be subjected to force and move relative to the metal tube 11 in the up-down direction; the stress and strain measuring component 3 is arranged in the metal tube 11, and includes an optical fiber stress sensor 31 and an optical fiber strain sensor 32; the control terminal is electrically connected to the pull-wire displacement sensor 21, the optical fiber stress sensor 31 and the optical fiber strain sensor 32.

[0049] In the technical solution of the present invention, the displacement measurement of the rock and soil body to be measured is realized by driving the pull head 211 of the pull rope displacement sensor 21 to move as the rock and soil body to be measured sinks or rises through the hollow disk 22. The measurement accuracy is high, and the displacement of different positions of the rock and soil body to be measured can be measured arbitrarily according to the needs. The optical fiber stress sensor 31 and the optical fiber strain sensor 32 are used to realize the stress and strain measurement of the rock and soil body to be measured. Compared with soil pressure gauges and stress sheets, they are not prone to rust and damage, and the measurement accuracy is guaranteed. In addition, the displacement, stress and strain measurement device 100 provided by the present invention has a simple structure, low production cost, and is easy to operate.

[0050] It should be noted that, in the present invention, the measurement signals of the pull-wire displacement sensor 21 , the optical fiber stress sensor 31 and the optical fiber strain sensor 32 are all transmitted to the control terminal for processing to obtain the final measurement result.

[0051] For further information, see Figure 2The metal tube 11 has four notches 111 formed on its wall, and the four notches 111 are spaced apart along the circumference of the metal tube 11, and each notch 111 is extended along the up-down direction; the pull head 211 of the pull rope displacement sensor 21 is disposed in the metal tube 11, and the pull head 211 is disposed corresponding to the notches 111, so as to be connected to the hollow disc 22 through the notches 111. In this way, the metal tube 11, as a supporting structure, has high strength and is not prone to bending. In long-term use, the pull head 211 of the pull rope displacement sensor 21 is not prone to being blocked from moving in the metal tube 11 due to deformation, thereby ensuring the accuracy of the displacement measurement result. In addition, the metal tube 11 is provided with four slots 111 for connecting the pull head 211 inside the metal tube 11 with the hollow disc 22 outside the metal tube 11. Furthermore, when the hollow disc 22 is subjected to force and moves under the action of the measured rock and soil body, it can drive the pull head 211 to move inside the metal tube 11 and generate an electrical signal which is transmitted to the control terminal for processing, thereby obtaining the displacement measurement result of the measured rock and soil body.

[0052] It should be noted that, in the present invention, the connection method between the slider 211 and the hollow disc 22 is not limited, and can be a threaded connection or a snap connection.

[0053] It should also be noted that the hollow disc 22 should be kept in the middle position of the slot 111 during installation. Specifically, the rock and soil to be measured in the model box should be filled to the middle position of the slot 111 first, and then the hollow disc 22 should be pulled down to the surface of the rock and soil to be measured, and then the hollow disc 22 should continue to be filled with soil to fix it.

[0054] For further information, see Figure 2 In one embodiment of the present invention, the displacement measuring assembly 2 further comprises a hexagonal square nut 23, the hexagonal square nut 23 is arranged in the metal tube 11, a first screw 24 is arranged on the hexagonal square nut 23, the first screw 24 is arranged on the upper side of the hexagonal square nut 23, and is threadedly connected with the pull head 211; four second screws 25 are inserted into the hollow disc 22, and the four second screws 25 are distributed at intervals along the circumference of the hollow disc 22 and are connected with the four hexagonal square nut 23. The circumferential side surfaces are arranged in one-to-one correspondence, and each of the second screws 25 is extended along the radial direction of the hollow disc 22 to be threadedly connected with the hexagonal square nut 23 through the notch 111 of the metal tube 11; in this way, it is convenient to disassemble or assemble the hexagonal square nut 23, the pull head 211 and the hollow disc 22, and the hollow disc 22 is connected to the pull head 211 through the notch 111 by four mutually perpendicular second screws 25, which can avoid the deflection of the hollow disc 22 and is beneficial to improving the measurement accuracy.

[0055] More specifically, in one embodiment of the present invention, the size of the hexagonal nut is 10mm×10mm×6mm×M3, and the size of the first screw and the second screw are both 40mm×M3. In order not to affect the movement of the hexagonal nut in the metal tube, the inner diameter of the metal tube is greater than or equal to 2cm.

[0056] Specifically, in the present invention, before using the displacement, stress and strain measurement device 100 for measurement, it is necessary to calibrate the rope displacement sensor 21 to obtain a more accurate measurement result.

[0057] More specifically, in one embodiment of the present invention, a scale line is provided on the outer wall of the metal tube 11 corresponding to the notch 111. Thus, the calibration process of the rope displacement sensor 21 is as follows: the hollow disc 22 is pulled down to the maximum range, and a value is read through the scale line beside the notch 111, and compared with the measurement result of the rope displacement sensor 21, and the proportional coefficient between the measured value and the actual value is obtained, and modified in the control terminal.

[0058] It should be noted that, in the present invention, the scale lines may be directly engraved on the outer wall of the metal tube 11 , or may be formed by pasting a scale on the outer wall of the metal tube 11 .

[0059] For details, please refer to Figure 3 The optical fiber stress sensor 31 includes a first laser, a first input optical fiber 311, a first output optical fiber 312, at least one first measuring unit 313 and a first photoelectric converter, wherein the first measuring unit 313 is arranged outside the metal tube 11, and is connected to the first laser through the first input optical fiber 311, and is connected to the first photoelectric converter through the first output optical fiber 312; the optical fiber strain sensor 32 includes a second laser, a second input optical fiber 321, a second output optical fiber 322, at least one second measuring unit 323 and a second photoelectric converter, wherein the second measuring unit 323 is arranged outside the metal tube 11, and is connected to the second laser through the second input optical fiber 321, and is connected to the second photoelectric converter through the second output optical fiber 322; the first measuring unit 313 and the second measuring unit 323 are respectively arranged on both sides of the metal tube 11; the control terminal is electrically connected to the first laser, the first photoelectric converter, the second laser and the second photoelectric converter.

[0060] Thus, the measurement process of the optical fiber stress sensor 31 and the optical fiber strain sensor 32 is as follows: the optical signal output by the laser reaches the measurement unit through the input optical fiber, the optical signal changes due to the deformation of the measured rock and soil body, and reaches the photoelectric converter through the output optical fiber to convert the optical signal into an electrical signal and transmit it to the control terminal for processing, thereby obtaining the stress and strain measurement results.

[0061] Furthermore, in the prior art, when using instruments such as earth pressure boxes to monitor stress changes at a certain point in the soil, the sensor head is generally placed at the monitoring point first, and then the soil is filled to fix it. However, during the subsequent filling work, the sensor is prone to displacement. Therefore, please refer to Figure 3 One end of the first input optical fiber 311 is arranged in the metal tube 11 and connected to the first laser, and the other end extends out of the metal tube 11 through one of two adjacent slots 111 among the four slots 111 to be connected to the first measuring unit 313; one end of the first output optical fiber 312 is arranged in the metal tube 11 and connected to the first photoelectric converter, and the other end extends out of the metal tube 11 through the other of the two adjacent slots 111 to be connected to the first measuring unit 313; one end of the second input optical fiber 321 is arranged in the metal tube 11 and connected to the second laser, and the other end extends out of the metal tube 11 through one of the other two adjacent slots 111 among the four slots 111 to be connected to the second measuring unit 323; one end of the second output optical fiber 322 is arranged in the metal tube 11 and connected to the second photoelectric converter, and the other end extends out of the metal tube 11 through the other of the two adjacent slots 111 to be connected to the second measuring unit 323.

[0062] In this way, the input optical fiber and the output optical fiber in the optical fiber stress sensor 31 and the optical fiber strain sensor 32 are both passed through the slot 111 of the metal tube 11. Compared with the measurement method using instruments such as an earth pressure box, the change of the measuring point position caused by filling can be effectively avoided, thereby improving the measurement accuracy.

[0063] It should be noted that, in the present invention, the number of the first measurement unit 313 and the number of the second measurement unit 323 are not limited and can be selected according to the test requirements, and can be one, two, three or more. Figure 3 In one embodiment of the present invention, three of the first measuring units 313 and three of the second measuring units 323 are provided respectively.

[0064] For details, please refer to Figure 1 , Figure 3 and Figure 4, the optical fiber stress sensor 31 and the optical fiber strain sensor 32 are arranged above the hollow disc 22. In this way, the optical fibers of the optical fiber stress sensor 31 and the optical fiber strain sensor 32 penetrate into the metal tube 11 above the hollow disc 22, and the optical fiber, as a flexible material, can bend with the deformation of the rock and soil body to be measured during the test, which can avoid affecting the movement of the hollow disc 22 in the up and down directions, thereby ensuring the accuracy of the measurement results.

[0065] For details, please refer to Figure 1 and Figure 4 The supporting and fixing assembly 1 further includes a base 12, which is used to be arranged at the bottom of the model box or in the soil layer in the model box; the metal pipe 11 is fixedly installed on the base 12. In this way, the supporting and fixing assembly 1 can be prevented from being displaced with the movement of the rock and soil body to be measured by the base 12, thereby ensuring the accuracy of the displacement measurement result.

[0066] The present invention also provides a model test device, comprising a model box and a displacement, stress and strain measuring device 100; the model box contains a rock and soil body to be tested; and the displacement, stress and strain measuring device 100 is arranged in the model box.

[0067] It should be noted that the above-mentioned displacement, stress and strain measuring device 100 adopts the displacement, stress and strain measuring device 100 as described above, that is, the model testing equipment has all the technical features of all the embodiments of the above-mentioned displacement, stress and strain measuring device 100, and also has all the technical effects brought by all the above-mentioned technical features, which will not be described one by one here.

[0068] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A displacement, stress and strain measuring device, used for model testing in a model testing device, characterized in that: The displacement, stress and strain measuring device comprises: A supporting and fixing assembly includes a metal pipe, wherein the metal pipe is used to be arranged in the model box in the model test, extends in the up-down direction, and is hollow; A displacement measurement assembly, comprising a pull-wire displacement sensor and a hollow disc, wherein the pull-wire displacement sensor is arranged at the top end of the metal tube, the hollow disc is sleeved outside the metal tube and buried in the rock and soil body to be measured in the model box, the hollow disc is connected to the pull head of the pull-wire displacement sensor, and can be subjected to force and move relative to the metal tube in the up and down direction; a stress and strain measurement assembly, arranged on the metal tube, comprising an optical fiber stress sensor and an optical fiber strain sensor; and, A control terminal is electrically connected to the pull-rope displacement sensor, the optical fiber stress sensor and the optical fiber strain sensor.

2. The displacement, stress and strain measuring device according to claim 1, characterized in that: The tube wall of the metal tube is provided with four notches, the four notches are spaced apart along the circumference of the metal tube, and each of the notches is extended along the up-down direction; The pull head of the pull rope displacement sensor is arranged in the metal tube, and the pull head is arranged corresponding to the notch to be connected with the hollow disc through the notch.

3. The displacement, stress and strain measuring device according to claim 2, characterized in that: The displacement measuring assembly further comprises a hexagonal square nut, the hexagonal square nut is arranged in the metal tube, a first screw is arranged on the hexagonal square nut, the first screw is arranged on the upper side of the hexagonal square nut and is threadedly connected with the pull head; The hollow disc is inserted with four second screws, which are spaced apart along the circumference of the hollow disc and arranged one by one corresponding to the four circumferential side surfaces of the hexagonal nut, and each second screw is extended radially along the hollow disc to be threadedly connected with the hexagonal nut through the notch of the metal tube.

4. The displacement, stress and strain measuring device according to claim 2, characterized in that: The outer wall of the metal tube is provided with scale lines corresponding to the notches.

5. The displacement, stress and strain measuring device according to claim 2, characterized in that: The optical fiber stress sensor comprises a first laser, a first input optical fiber, a first output optical fiber, at least one first measuring unit and a first photoelectric converter, wherein the first measuring unit is arranged outside the metal tube and connected to the first laser through the first input optical fiber, and connected to the first photoelectric converter through the first output optical fiber; The optical fiber strain sensor comprises a second laser, a second input optical fiber, a second output optical fiber, at least one second measuring unit and a second photoelectric converter, wherein the second measuring unit is arranged outside the metal tube and connected to the second laser through the second input optical fiber and connected to the second photoelectric converter through the second output optical fiber; The first measuring unit and the second measuring unit are respectively arranged on two sides of the metal pipe; The control terminal is electrically connected to the first laser, the first photoelectric converter, the second laser, and the second photoelectric converter.

6. The displacement, stress and strain measuring device according to claim 5, characterized in that: One end of the first input optical fiber is arranged in the metal tube and connected to the first laser, and the other end extends out of the metal tube through one of two adjacent slots among the four slots to be connected to the first measuring unit; one end of the first output optical fiber is arranged in the metal tube and connected to the first photoelectric converter, and the other end extends out of the metal tube through the other of the two adjacent slots to be connected to the first measuring unit; One end of the second input optical fiber is arranged in the metal tube and connected to the second laser, and the other end extends out of the metal tube through one of the other two adjacent slots among the four slots to be connected to the second measuring unit. One end of the second output optical fiber is arranged in the metal tube and connected to the second photoelectric converter, and the other end extends out of the metal tube through the other of the two adjacent slots to be connected to the second measuring unit.

7. The displacement, stress and strain measuring device according to claim 5 or 6, characterized in that: There are three first measuring units and three second measuring units, respectively.

8. The displacement, stress and strain measuring device according to any one of claims 2 to 6, characterized in that: The optical fiber stress sensor and the optical fiber strain sensor are arranged above the hollow disk.

9. The displacement, stress and strain measuring device according to claim 1, characterized in that: The supporting and fixing assembly further comprises a base, and the base is used to be arranged at the bottom of the model box or in the soil layer in the model box; The metal pipe is fixedly mounted on the base.

10. A model test device, characterized in that: include: A model box, wherein the rock and soil to be measured is placed; and The displacement, stress and strain measuring device as described in any one of claims 1 to 9 is arranged in the model box.

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