Test, measurement device and method for volume change of rock and soil under low triaxial stress and water seepage conditions

Abstract

The present invention discloses a rock and soil volume change test, measurement device and method under low triaxial stress and water seepage conditions, including an axial pressure loading device, a confining pressure loading device, and a volume change measuring device; the volume change measuring device includes a radial displacement measuring device and a vertical displacement measuring device, the radial displacement measuring device is sleeved on the side of the specimen to measure the radial deformation of the specimen, the vertical displacement measuring device is installed on the top of the specimen to measure the height change of the specimen, the radial displacement measuring device adopts a radial displacement meter, and the radial displacement meter that directly converts the deformation of the specimen into the angle change of the retractable rod is used to measure the diameter change of the specimen, and the specimen volume change is obtained in combination with the specimen height change measured by the vertical displacement measuring device. By applying confining pressure by electromagnetic, constant loading of confining pressure can be achieved; by cooperating with a wire drum, a fixed pulley, a loading plate, a bottom plate and a pull rope, the pull rope is stretched to achieve continuous loading of low triaxial stress.

Description

Technical Field

[0001] The invention belongs to the technical field of highway engineering and geotechnical engineering, and relates to a rock and soil volume change test and measurement device and method under low triaxial stress and water seepage conditions. Background Art

[0002] Since rock and soil have the property of volume change under stress and water seepage conditions, and the volume change of expansive rock and soil under the same conditions is more significant, the volume change of rock and soil caused by rainwater infiltration and external load conditions has become an issue that cannot be ignored in the fields of highway engineering and geotechnical engineering. Therefore, measuring the volume deformation of rock and soil when it encounters water and is subjected to stress is of extraordinary significance for studying such issues.

[0003] At present, there are some problems with the method and device used to measure the radial deformation of cylindrical specimens: when the strain gauge is posted on the surface of the cylindrical specimen of rock and soil for measurement, the strain gauge will not be firmly adhered due to the phenomenon of slag falling off the rock and soil specimen during the force process, thus causing measurement errors; using the existing circumferential extensometer for measurement will damage the soil cylindrical specimen, and the circumferential extensometer is expensive.

[0004] At present, triaxial testing machines are commonly used in mechanical tests on standard cylindrical specimens of rock and soil. Such testing machines can accurately apply axial pressure and confining pressure to circular rock and soil specimens using hydraulics and confining pressure chambers with servo systems, and can achieve a variety of loading methods. However, such loading methods have high technical content, high requirements on personnel, and are expensive. Once a problem occurs, the maintenance time is long, the cost is high, and the space required is large. It is not economical for long-term low triaxial stress loading. Summary of the invention

[0005] The purpose of the embodiments of the present invention is to provide a rock and soil volume change test and measurement device and method under low triaxial stress and water seepage conditions, so as to solve the problems that the existing rock and soil volume change measurement device causes measurement errors due to the use method and device characteristics, and causes damage to the soil cylindrical specimens, and the existing rock and soil volume change test and measurement method uses a triaxial testing machine for axial confining pressure loading, which has high personnel requirements, high costs, and is not economical.

[0006] The technical solution adopted in the embodiment of the present invention is: a rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions, including an axial pressure loading device, a confining pressure loading device, and a volume change measurement device;

[0007] The volume change measuring device comprises:

[0008] A radial displacement measuring device is mounted on the side of the specimen to measure the radial deformation of the specimen;

[0009] Vertical displacement measuring device,The vertical displacement measuring device is installed on the top of the specimen to measure the height change of the specimen.

[0010] Furthermore, the radial displacement measuring device adopts a radial displacement meter;

[0011] The radial displacement meter includes:

[0012] A retractable ring is sleeved on the outside of the confining pressure loading device on the side of the specimen, and includes:

[0013] A plurality of light arc rods and an arc-shaped housing arranged at intervals and connected to form a ring;

[0014] Both ends of each lightweight arc rod extend into the corresponding arc-shaped housing, and both ends of each lightweight arc rod are slidably connected to the corresponding arc-shaped housing;

[0015] In the initial state, the diameter of the ring formed by connecting multiple lightweight arc rods and the arc-shaped shell is smaller than the diameter of the specimen;

[0016] Under the action of external force, the two ends of each lightweight arc rod can move inside the corresponding arc-shaped shell to increase the diameter of the formed ring;

[0017] The circular ring radial displacement measuring device comprises:

[0018] A base, wherein a scale is provided on the base and the base is fixed on the bottom plate;

[0019] A telescopic rod, one end of which is movably connected to the base via a rotating shaft, and the other end of which is movably connected to the telescopic ring via a fixed shaft;

[0020] When the telescopic ring is telescopically changed, the telescopic rod moves with the telescopic ring and rotates around the rotation axis, and the angle and position of the telescopic rod change, corresponding to different scales of the scale.

[0021] Furthermore, a limiting block is fixed to each end of each lightweight arc rod, and each limiting block is located in a corresponding arc-shaped housing and is slidably connected to the interior of the arc-shaped housing;

[0022] A second spring is fixed to the side of each limiting block, the end of the lightweight arc rod where each limiting block is located passes through the second spring and is fixedly connected to the limiting block, and one end of each second spring away from the limiting block where it is located is fixedly connected to the arc-shaped housing;

[0023] When each second spring is at its original length, the inner diameter of the telescopic ring is smaller than the test piece;

[0024] The scale is a displacement scale or an angle scale;

[0025] When the scale is a displacement scale, i.e., a diameter change scale of the specimen, the setting height of the retractable ring is a fixed value, the initial angle of the retractable rod of the radial displacement meter is fixed, and the displacement scale corresponding to the initial angle of the retractable rod of the radial displacement meter is 0; when the angle of the retractable rod of the radial displacement meter changes, the displacement value corresponding to the current angle value is obtained by converting the current angle value with the initial angle value to form a displacement scale;

[0026] The radial displacement meter includes at least one circular radial displacement measuring device;

[0027] When multiple circular ring radial displacement measuring devices are provided, the multiple circular ring radial displacement measuring devices are evenly distributed on the side surface of the specimen.

[0028] Furthermore, the confining pressure loading device comprises:

[0029] A confining pressure loading sheet, the two sides of which are crossed to form a cylindrical structure, and the two sides of which are folded outwards by 90° after crossing;

[0030] Electromagnets are respectively arranged on two sides of the confining pressure loading sheet that are crossed and folded outwards 90 degrees and close to each other.

[0031] Furthermore, a plurality of first springs are installed on one side of the electromagnet away from the intersection on the confining pressure loading plate. The first springs are arranged horizontally, and both ends of each first spring intersect with the confining pressure loading plate and are fixedly connected one by one on both sides after being folded outward 90°.

[0032] Furthermore, a cylindrical structure is formed in the middle portion of the confining pressure loading sheet;

[0033] The two side ends of the confining pressure loading sheet are provided with matching and intersecting slots in the longitudinal direction in a square wave shape, and the two sides of the confining pressure loading sheet intersect through the slots;

[0034] The two sides of the confining pressure loading sheet are respectively fixedly connected with the electromagnet bearing steel plates after crossing, and the electromagnet bearing steel plates are perpendicular to the side of the cylindrical structure formed in the middle part of the confining pressure loading sheet;

[0035] The electromagnets are correspondingly arranged on the sides of the two electromagnet bearing steel plates close to each other;

[0036] A reserved opening is provided at the intersection of the confining pressure loading plate, and a certain arc-shaped outer shell of the retractable ring of the radial displacement measuring device is divided into left and right parts which are detachably connected by a mortise and tenon structure. The retractable ring is disconnected by disassembling the mortise and tenon structure, and the disconnected retractable ring is sleeved on the side wall of the confining pressure loading plate through the reserved opening.

[0037] Furthermore, the axial pressure loading device comprises:

[0038] A loading plate, the loading plate is arranged on the upper permeable stone, and the upper permeable stone is arranged on the top of the test piece;

[0039] The wire reel is fixed at the top center of the loading plate;

[0040] Fixed pulleys, multiple fixed pulleys are evenly distributed and installed on the loading plate;

[0041] Bottom plate, the bottom plate is arranged at the bottom of the lower permeable stone, and the lower permeable stone is arranged at the bottom of the specimen;

[0042] A pull rope, one end of each pull rope is fixed to the bottom plate of the test device, and the other end is fixedly wound on the wire drum through a corresponding fixed pulley. Multiple pull ropes are evenly distributed around the loading plate through corresponding fixed pulleys, and the winding directions of multiple pull ropes on the wire drum are the same;

[0043] The part of each pull rope located above the fixed pulley is arranged horizontally, and the part of each pull rope located below the fixed pulley is arranged vertically.

[0044] Furthermore, a water collecting tank is provided on the bottom plate, and a drainage outlet is provided on one side of the water collecting tank;

[0045] The test specimen is placed on the sump of the bottom plate;

[0046] A water inlet is arranged on the loading plate, and the water inlet is arranged above the upper permeable stone.

[0047] Another technical solution adopted by the embodiment of the present invention is: a rock and soil volume change test and measurement method under low triaxial stress and water seepage conditions, using the rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions as described above, and the specific steps are as follows:

[0048] Step S1: Place the specimen in the water collection tank of the bottom plate, place corresponding upper permeable stones and lower permeable stones on the top and bottom of the specimen, and sleeve the confining pressure loading device on the side of the specimen;

[0049] Step S2: Install the axial pressure loading device, fix the bottom plate, and rotate the wire drum to make the loading plate fit with the upper permeable stone;

[0050] Step S3: Install the radial displacement measuring device and the vertical displacement measuring device, connect the water inlet on the loading plate and the water supply tank with a hose, open the water outlet valve of the water supply tank, conduct a water seepage test, rotate the wire reel to apply axial pressure, energize the electromagnet, generate repulsive force to apply confining pressure;

[0051] Step S4: During the test, the readings of the radial displacement measuring device and the vertical displacement measuring device are recorded, and the drain valve of the sump is opened at regular intervals to discharge the seepage water in time until the seepage test is completed;

[0052] Step S5: Clean the instruments and equipment, process the recorded experimental data, and obtain the volume change results of the rock and soil mass under low triaxial stress and water seepage conditions.

[0053] Furthermore, in step S2, the wire drum of the axial pressure loading device, the installation position of each fixed pulley, and the fixed positions of the two ends of the corresponding pull rope need to ensure that each pull rope does not deviate or tilt;

[0054] When the reading of the radial displacement measuring device recorded in step S4 is the angle of the retractable rod of the radial displacement measuring device before and after the volume change of the specimen, the diameter change of the specimen after the test is obtained by the following conversion:

[0055] x1=y / tanα;

[0056] x2=y / tanβ;

[0057] Δx = x1- x2;

[0058] Wherein, y is the setting height of the retractable ring of the radial displacement measuring device, α is the angle of the retractable rod before the test, β is the angle of the retractable rod after the test, x1 is the projection length of the retractable rod on the horizontal axis before the test, x2 is the projection length of the retractable rod on the horizontal axis after the test, and Δx is the diameter change of the specimen after the test;

[0059] In step S4, when the radial displacement measuring device adopts a radial displacement meter, and the radial displacement meter includes multiple circular radial displacement measuring devices, the average value of the measurement results recorded by the multiple circular radial displacement measuring devices is taken as the final measurement result;

[0060] Step S5 obtains the volume change result of the rock and soil mass under low triaxial stress and water seepage conditions through the diameter change of the test piece after the test and the height change of the test piece measured by the vertical displacement measuring device.

[0061] The beneficial effects of the embodiments of the present invention are:

[0062] 1. The radial displacement meter that directly converts the deformation of the specimen into the angle change of the telescopic rod is used to measure the diameter change after the test. It has high measurement accuracy, light structure and little impact on the specimen. It is low in cost, simple in structure and easy to implement. It avoids the measurement error caused by the use of strain gauges and will not cause damage to the specimen. It solves the problem that the existing device for measuring the volume change of rock and soil causes measurement errors due to the use method and device characteristics, and causes damage to the cylindrical soil specimens.

[0063] 2. Through the coordination of the wire drum, fixed pulley, loading plate, bottom plate and pull rope, the pull rope is stretched to achieve low triaxial stress loading; the pull rope is used to gradually apply axial pressure, which can achieve continuous loading compared with the commonly used lever loading method; the electromagnetic force can be changed according to the deformation of the sample to keep the confining pressure constant; and the axial pressure loading device and the confining pressure loading device have simple structures, are easy to implement, require small space, and have high economic applicability. Compared with the commonly used triaxial testing machine, it is more suitable for rock and soil tests under various low stress conditions, and solves the problems of high personnel requirements, high cost and lack of economic applicability in the existing rock and soil volume change test and measurement method using triaxial testing machine for axial confining pressure loading;

[0064] 3. The axial deformation and radial deformation of rock and soil bodies under different low triaxial stress and water seepage conditions can be simulated and tested. At the same time, the measurement system of the embodiment of the present invention has high accuracy and precision, and can obtain reliable axial deformation and radial deformation, and then obtain the overall volume change according to the axial deformation and radial deformation;

[0065] 4. The overall test and measurement equipment has low requirements on the experimental environment and occupies little space. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] 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 these drawings without paying creative work.

[0067] Figure 1 It is a schematic diagram of the structure of the rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions of this embodiment.

[0068] Figure 2 It is a top view schematic diagram of the axial pressure loading device of this embodiment.

[0069] Figure 3 It is a top view schematic diagram of the confining pressure loading device of this embodiment.

[0070] Figure 4 It is a first structural stereoscopic schematic diagram of the confining pressure loading device of this embodiment.

[0071] Figure 5 It is a second structural stereoscopic schematic diagram of the confining pressure loading device of this embodiment.

[0072] Figure 6 Schematic diagram of the structure of the radial displacement meter of this embodiment.

[0073] Figure 7Schematic diagram of the structure of the retractable ring of this embodiment.

[0074] Figure 8 Schematic diagram of the measurement principle of the radial displacement meter of this embodiment.

[0075] In the figure, 1. axial pressure loading device, 2. wire drum, 3. water inlet, 4. fixed pulley, 5. loading plate, 6. pull rope, 7. radial displacement meter, 8. bottom plate, 9. confining pressure loading device, 10. retractable ring, 11. upper permeable stone, 12. lower permeable stone, 13. micrometer, 14. vertical pole, 15. electromagnet, 16. first spring, 17. confining pressure loading sheet, 18. notch, 19. reserved opening, 20. lightweight arc rod, 21. arc-shaped shell, 22. fixed axis, 23. second spring, 24. limiting block, 25. mortise and tenon structure, 26. retractable rod, 27. base, 28. scale, 29. rotating shaft, 30 connecting structure. DETAILED DESCRIPTION

[0076] 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.

[0077] Example 1

[0078] This embodiment provides a rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions, which can accurately measure the volume deformation of a cylindrical rock and soil specimen under low triaxial stress and water seepage conditions, and has high economic practicality. Figure 1 As shown, it includes an axial pressure loading device 1, a confining pressure loading device 9, and a volume change measuring device, and the volume change measuring device includes:

[0079] A radial displacement measuring device is mounted on the side of the specimen to measure the radial deformation of the specimen;

[0080] Vertical displacement measuring device,The vertical displacement measuring device is installed on the top of the specimen to measure the height change of the specimen.

[0081] In some embodiments, the radial displacement measuring device uses a radial displacement meter 7, and the radial deformation, that is, the diameter change of the specimen is measured by the radial displacement meter 7. The radial displacement meter 7 includes:

[0082] A retractable ring 10, which is sleeved on the outer side of the confining pressure loading device 9 on the side of the specimen;

[0083] The circular ring radial displacement measuring device comprises:

[0084] A base 27, on which a scale 28 is provided, and the base 27 is fixed on the bottom plate 8;

[0085] A telescopic rod 26, one end of which is movably connected to the base 27 via a rotating shaft 29, and the other end of which is movably connected to the telescopic ring 10 via a fixed shaft 22;

[0086] When the telescopic ring 10 is telescopically changed, the telescopic rod 26 moves with the telescopic ring 10 and rotates around the rotation axis 29, and the angle and position of the telescopic rod 26 change, corresponding to different scales of the scale 28. When the specimen expands under the action of stress and water seepage, the telescopic ring 10 is deformed, its radius increases and moves outward, and the movement of the telescopic ring 10 drives the telescopic rod 26 to rotate outward, so that the angle and position of the telescopic rod 26 change, and the angle and / or position of the telescopic rod 26 are measured corresponding to different scales of the scale 28.

[0087] like Figure 7 As shown, the retractable ring 10 comprises:

[0088] A plurality of light arc rods 20 and an arc-shaped housing 21 arranged at intervals and connected to form a ring;

[0089] Both ends of each lightweight arc rod 20 extend into the corresponding arc-shaped housing 21, and both ends of each lightweight arc rod 20 are slidably connected to the corresponding arc-shaped housing 21;

[0090] In the initial state, the diameter of the ring formed by connecting the plurality of lightweight arc rods 20 and the arc-shaped housing 21 is smaller than the diameter of the specimen;

[0091] Under the action of external force, both ends of each lightweight arc rod 20 can move inside the corresponding arc-shaped housing 21 to increase the diameter of the formed circular ring.

[0092] In some embodiments, a limiting block 24 is fixed at each end of each lightweight arc rod 20, each limiting block 24 is located in a corresponding arc-shaped housing 21 and is slidably connected to the inside of the arc-shaped housing 21, and the arc-shaped housing 21 provides the required telescopic space for the lightweight arc rod 20;

[0093] A second spring 23 is fixed to the side of each limiting block 24, and the end of the lightweight arc rod 20 where each limiting block 24 is located passes through the second spring 23 and is fixedly connected to the limiting block 24, and one end of each second spring 23 away from the limiting block 24 where it is located is fixedly connected to the arc-shaped housing 21;

[0094] When each second spring 23 is at its original length, the inner diameter of the telescopic ring 10 is smaller than the test piece, and when installed on the test piece, it can provide elastic force to press the test piece.

[0095] In some embodiments, the telescopic ring 10 includes four lightweight arc rods 20 and four arc-shaped shells 21 .

[0096] In some embodiments, a certain arc-shaped shell 21 of the retractable ring 10 is divided into two left and right parts that are detachably connected by a mortise and tenon structure 25, so as to disassemble / close the retractable ring 10 and assemble and disassemble the retractable ring 10.

[0097] In some embodiments, a fixed shaft 22 is disposed outside a certain arc-shaped shell 21 of the telescopic ring 10 , and the telescopic rod 26 is connected to the fixed shaft 22 via a connecting structure 30 to achieve a movable connection with the telescopic ring 10 .

[0098] In some embodiments, when there are multiple circular ring radial displacement measuring devices, the multiple circular ring radial displacement measuring devices are evenly distributed on the side of the specimen, such as Figure 1 As shown, the average value of the measurement results of multiple circular ring radial displacement measuring devices is finally taken as the final measurement result to ensure the measurement accuracy.

[0099] In some embodiments, the scale 28 is an angle scale, and the radial displacement meter 7 measures the angle change of the telescopic rod 26. Before and after the volume change of the specimen, the angle change of the telescopic rod 26 is as follows: Figure 8 As shown, Figure 8 In the figure, y is the setting height of the telescopic ring 10, α is the angle of the telescopic rod 26 before the volume change of the specimen, that is, before the test, β is the angle of the telescopic rod 26 after the volume change of the specimen is stable, that is, after the test, x1 is the projection length of the telescopic rod 26 on the horizontal axis before the volume change of the specimen, that is, before the test, x2 is the projection length of the telescopic rod 26 on the horizontal axis after the volume change of the specimen is stable, that is, after the test, when the scale 28 is an angle scale, the change in the projection length of the telescopic rod 26 on the horizontal axis is obtained by the following conversion, that is, the change in the diameter of the specimen after the test:

[0100] x1=y / tanα;

[0101] x2=y / tanβ;

[0102] Δx = x1- x2;

[0103] Wherein, Δx is the diameter change of the test piece after the test, and the overall deformation of the test piece is obtained by combining the vertical displacement measured by the vertical displacement measuring device, namely the micrometer 13 , namely the height change of the test piece. The micrometer 13 is fixed on the bottom plate 8 by a vertical rod 14 .

[0104] In some embodiments, the scale 28 is a displacement scale, that is, a diameter change scale of the specimen. At this time, it is necessary to limit the setting height y of the retractable ring 10 to a fixed value, so that the initial angle of the retractable rod 26 of the radial displacement meter 7 is fixed, and the displacement scale corresponding to the initial angle of the retractable rod 26 of the radial displacement meter 7 is 0. When the specimen expands during the test, the angle of the retractable rod 26 of the radial displacement meter 7 changes. Through the above calculation process, each angle value corresponds to a diameter change value of the specimen, forming a scale 28.

[0105] In some embodiments, Figure 1~2 As shown, the axial pressure loading device 1 comprises:

[0106] A loading plate 5, the loading plate 5 is arranged on an upper permeable stone 11, and the upper permeable stone 11 is arranged on the top of the test piece;

[0107] The wire reel 2 is fixed at the top center of the loading plate 5;

[0108] A fixed pulley 4, wherein a plurality of fixed pulleys 4 are evenly distributed and installed on a loading plate 5;

[0109] Bottom plate 8, bottom plate 8 is arranged at the bottom of lower permeable stone 12, and lower permeable stone 12 is arranged at the bottom of the specimen;

[0110] Pull ropes 6, one end of each pull rope 6 is fixed on the bottom plate 8 of the test device, and the other end is fixedly wound on the wire drum 2 through the corresponding fixed pulley 4, and the multiple pull ropes 6 are evenly distributed around the loading plate 5 through the corresponding fixed pulleys 4, and the winding directions of the multiple pull ropes 6 on the wire drum 2 are the same;

[0111] The pull rope 6 is tightened and stretched by rotating the wire drum 2. Under the tension of the rotating disk 2, the pull rope 6 acts on the loading plate 5 through the fixed pulley 4. The loading plate 5 further applies the force received to the test piece to realize continuous loading of the axial pressure.

[0112] In some embodiments, each pull rope 6 is arranged in a vertical state, such as Figure 2 As shown, the portion of each pull rope 6 located above the fixed pulley 4 is horizontally arranged, and the portion of each pull rope 6 located below the fixed pulley 4 is vertically arranged. The installation position of the wire drum 2, each fixed pulley 4 and the corresponding fixed positions of the two ends of the pull rope 6 need to ensure that each pull rope 6 does not deviate or tilt, and ensure the uniformity and stability of the axial force loading.

[0113] In some embodiments, the positions of the wire drum 2 and the upper permeable stone 11 correspond to each other vertically, and the shape of the loading plate 5 can be set to a structural shape that is symmetrical in vertical direction and horizontal direction, such as a circle, a regular polygon (such as a square, a regular rhombus structure), etc., to ensure the uniformity and stability of the axial force loading.

[0114] In some embodiments, a water collecting trough is provided on the bottom plate 8 , a drainage outlet is provided on one side of the water collecting trough, and the test piece is placed on the water collecting trough of the bottom plate 8 .

[0115] In some embodiments, a water inlet 3 is disposed on the loading plate 5 , and the water inlet 3 is disposed above the upper permeable stone 11 .

[0116] In some embodiments, Figures 3-5 As shown, the confining pressure loading device 9 includes:

[0117] The confining pressure loading sheet 17 has two sides intersecting to form a cylindrical structure, and the two sides of the confining pressure loading sheet 17 are folded outward 90° after being intersected. To ensure the confining pressure loading effect, the confining pressure loading sheet 17 can be made of a metal sheet such as a steel sheet that is relatively strong and can be bent to cover the specimen;

[0118] The electromagnet 15 and the confining pressure loading sheet 17 are crossed and folded outward 90°, and the electromagnets 15 are respectively arranged on the two sides close to each other. A pair of electromagnets 15 are used to generate repulsive force to pull the confining pressure loading sheet 17 to apply confining pressure. During the radial deformation process of the sample, the confining pressure can be kept constant by continuously adjusting the size of the electromagnetic force.

[0119] In some embodiments, Figures 3-5 As shown, a plurality of first springs 16 are installed on one side of the electromagnet 15 away from the intersection point on the confining pressure loading plate 17. The first springs 16 are arranged horizontally, and both ends of each first spring 16 are crossed with the confining pressure loading plate 17 and fixedly connected on both sides after being folded outward 90°. The first springs 16 prevent the end of the confining pressure loading plate 17 from moving outward and flipping around the turning point of the confining pressure loading plate 17 when the electromagnet 15 generates repulsive force.

[0120] In some embodiments, Figures 4 and 5 As shown, the middle part of the confining pressure loading sheet 17 forms a cylindrical structure to wrap the specimen when the confining pressure is applied. The two side ends of the confining pressure loading sheet 17 are correspondingly provided with mutually matching and intersecting notches 18 in the longitudinal direction. The two sides of the confining pressure loading sheet 17 are crossed through the notches 18. The use of the notches 18 in the longitudinal direction does not affect the confining pressure loading sheet 17 wrapping the specimen, and when the two electromagnets 15 generate repulsive force, they can drive the two sides of the confining pressure loading sheet 17 to move in the notches 18 to apply the confining pressure, making the loading of the confining pressure simple, convenient and fast. After crossing, the two sides of the confining pressure loading sheet 17 are respectively fixedly connected with the electromagnet bearing steel plates, and the electromagnet bearing steel plates are perpendicular to the side of the cylindrical structure formed by the confining pressure loading sheet 17, and the two electromagnets 15 are correspondingly arranged on the side of the electromagnet bearing steel plates close to each other.

[0121] In some embodiments, Figures 4 and 5As shown, a reserved opening 19 is opened at the intersection of the confining pressure loading plate 17. When installing the retractable ring 10, the mortise and tenon structure 25 is disassembled to turn the retractable ring 10 into an open structure, and the opening is expanded outward from the opening. The retractable ring 10 is sleeved on the side wall of the confining pressure loading plate 17 through the reserved opening 19. Thereafter, the mortise and tenon structure 25 is closed to turn the retractable ring 10 into an integral structure, thereby completing the installation of the retractable ring 10.

[0122] Example 2

[0123] This embodiment provides a rock and soil volume change test and measurement method under low triaxial stress and water seepage conditions, using the rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions as described in Example 1, and the specific steps are as follows:

[0124] Step S1: Place the specimen into the water collection tank of the bottom plate 8, and place corresponding upper permeable stones 11 and lower permeable stones 12 at the bottom and top of the specimen, and sleeve the confining pressure loading device 9 on the side of the specimen;

[0125] Step S2: Install the axial pressure loading device 1, keep the bottom plate 8 fixed, and rotate the wire drum 2 to make the loading plate 5 fit the upper permeable stone 11;

[0126] Step S3: Use a hose to connect the water inlet 3 on the loading plate 5 and the water supply tank, open the water outlet valve of the water supply tank, conduct a water seepage test, rotate the wire drum 2 to apply axial pressure, and energize the electromagnet 15 to generate repulsive force to apply confining pressure;

[0127] Step S4: During the test, the readings of the radial displacement measuring device and the vertical displacement measuring device are recorded, and the drain valve of the sump is opened at regular intervals to discharge the seepage water in time until the seepage test is completed;

[0128] Step S5: Clean the instruments and equipment, process the recorded experimental data, and obtain the volume change results of the rock and soil mass under low triaxial stress and water seepage conditions.

[0129] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A device for measuring the volume change of rock and soil under low triaxial stress and water seepage conditions, comprising an axial pressure loading device (1) and a confining pressure loading device (9), characterized in that: Also included is a volume change measuring device; The volume change measuring device comprises: A radial displacement measuring device is mounted on the side of the specimen to measure the radial deformation of the specimen; A vertical displacement measuring device is installed on the top of the specimen to measure the height change of the specimen; The radial displacement measuring device adopts a radial displacement meter (7); The radial displacement meter (7) comprises: The retractable ring (10) is sleeved on the outside of the confining pressure loading device (9) on the side of the specimen, and comprises: A plurality of light arc rods (20) and an arc-shaped housing (21) arranged at intervals and connected to form a ring; Both ends of each lightweight arc rod (20) extend into the corresponding arc-shaped housing (21), and both ends of each lightweight arc rod (20) are slidably connected to the corresponding arc-shaped housing (21); In an initial state, the diameter of the ring formed by connecting the plurality of lightweight arc rods (20) and the arc-shaped housing (21) is smaller than the diameter of the test piece; Under the action of external force, the two end portions of each lightweight arc rod (20) can move inside the corresponding arc-shaped housing (21) to increase the diameter of the formed circular ring; The circular ring radial displacement measuring device comprises: A base (27), the base (27) is provided with a scale (28), and the base (27) is fixed on the bottom plate (8); A telescopic rod (26), one end of the telescopic rod (26) is movably connected to the base (27) via a rotating shaft (29), and the other end of the telescopic rod (26) is movably connected to the telescopic ring (10) via a fixed shaft (22); When the telescopic ring (10) is telescopically changed, the telescopic rod (26) moves along with the telescopic ring (10) and rotates around the rotation axis (29), and the angle and position of the telescopic rod (26) change, corresponding to different scales of the scale (28); The confining pressure loading device (9) comprises: A confining pressure loading sheet (17), wherein two sides of the confining pressure loading sheet (17) intersect to form a cylindrical structure, and the two sides of the confining pressure loading sheet (17) are folded outwards by 90° after intersecting; The electromagnet (15) and the confining pressure loading sheet (17) are crossed and folded outwards by 90 degrees, and the two sides close to each other are respectively provided with an electromagnet (15).

2. The rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions according to claim 1 is characterized in that: A limiting block (24) is fixed to each of the two ends of each lightweight arc rod (20), and each limiting block (24) is located in a corresponding arc-shaped housing (21) and is slidably connected to the interior of the arc-shaped housing (21); A second spring (23) is fixed to the side of each limiting block (24); an end of the lightweight arc rod (20) where each limiting block (24) is located passes through the second spring (23) and is fixedly connected to the limiting block (24); and an end of each second spring (23) away from the limiting block (24) where the second spring (23) is located is fixedly connected to the arc-shaped housing (21); When each second spring (23) is at its original length, the inner diameter of the telescopic ring (10) is smaller than the test piece; The scale (28) is a displacement scale or an angle scale; When the scale (28) is a displacement scale, i.e., a diameter change scale of the specimen, the setting height of the telescopic ring (10) is a fixed value, the initial angle of the telescopic rod (26) of the radial displacement meter (7) is fixed, and the displacement scale corresponding to the initial angle of the telescopic rod (26) of the radial displacement meter (7) is 0; when the angle of the telescopic rod (26) of the radial displacement meter (7) changes, the displacement value corresponding to the current angle value is obtained by converting the current angle value with the initial angle value to form a displacement scale; The radial displacement meter (7) comprises at least one circular radial displacement measuring device; When multiple circular ring radial displacement measuring devices are provided, the multiple circular ring radial displacement measuring devices are evenly distributed on the side surface of the specimen.

3. The rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions according to claim 1 is characterized in that: A plurality of first springs (16) are installed on one side of the electromagnet (15) away from the intersection point on the confining pressure loading sheet (17). The first springs (16) are arranged horizontally, and both ends of each first spring (16) are fixedly connected to the two sides after crossing the confining pressure loading sheet (17) and being folded outwards 90 degrees in a one-to-one correspondence.

4. The rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions according to claim 1 is characterized in that: The middle portion of the confining pressure loading sheet (17) forms a cylindrical structure; The two side ends of the confining pressure loading sheet (17) are provided with correspondingly matching and intersecting notches (18) in the shape of square waves in the longitudinal direction, and the two sides of the confining pressure loading sheet (17) intersect through the notches (18); The two sides of the confining pressure loading sheet (17) are respectively fixedly connected with an electromagnet bearing steel plate after crossing, and the electromagnet bearing steel plate is perpendicular to the side of the cylindrical structure formed in the middle part of the confining pressure loading sheet (17); The electromagnet (15) is correspondingly arranged on the side where the two electromagnet bearing steel plates are close to each other; A reserved opening (19) is provided at the intersection of the confining pressure loading plate (17); a certain arc-shaped housing (21) of the retractable circular ring (10) of the radial displacement measuring device is divided into two left and right parts which are detachably connected via a mortise and tenon structure (25); the retractable circular ring (10) is disconnected by disassembling the mortise and tenon structure (25), and the disconnected retractable circular ring (10) is sleeved on the side wall of the confining pressure loading plate (17) via the reserved opening (19).

5. The rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions according to any one of claims 1 to 4, characterized in that: The axial pressure loading device (1) comprises: A loading plate (5), the loading plate (5) being arranged on an upper permeable stone (11), and the upper permeable stone (11) being arranged on the top of the test piece; A wire reel (2), the wire reel (2) being fixed at the top center position of the loading plate (5); A fixed pulley (4), wherein a plurality of fixed pulleys (4) are evenly distributed and mounted on the loading plate (5); A bottom plate (8), the bottom plate (8) is arranged at the bottom of the lower permeable stone (12), and the lower permeable stone (12) is arranged at the bottom of the test piece; A pull rope (6), one end of each pull rope (6) is fixed to a bottom plate (8) of the test device, and the other end is fixedly wound on a wire drum (2) via a corresponding fixed pulley (4); a plurality of pull ropes (6) are evenly distributed around the loading plate (5) via corresponding fixed pulleys (4), and the winding directions of the plurality of pull ropes (6) on the wire drum (2) are the same; The portion of each pull rope (6) located above the fixed pulley (4) is arranged horizontally, and the portion of each pull rope (6) located below the fixed pulley (4) is arranged vertically.

6. The rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions according to claim 5 is characterized in that: A water collecting trough is provided on the bottom plate (8), and a drainage outlet is provided on one side of the water collecting trough; The test piece is placed on the water collection tank of the bottom plate (8); A water inlet (3) is provided on the loading plate (5), and the water inlet (3) is provided above the upper permeable stone (11).

7. A method for measuring the volume change of rock and soil under low triaxial stress and water seepage conditions, characterized in that: Using the rock and soil volume change test and measurement device under low triaxial stress and water seepage conditions as claimed in claim 6, the specific steps are as follows: Step S1: placing the test piece into the water collection tank of the bottom plate (8), placing corresponding upper permeable stones (11) and lower permeable stones (12) on the top and bottom of the test piece, and sleeve the confining pressure loading device (9) on the side of the test piece; Step S2: installing the axial pressure loading device (1), making the bottom plate (8) stationary, and rotating the wire drum (2) so that the loading plate (5) fits the upper permeable stone (11); Step S3: installing a radial displacement measuring device and a vertical displacement measuring device, connecting the water inlet (3) on the loading plate (5) and the water supply tank with a hose, opening the water outlet valve of the water supply tank, performing a water seepage test, rotating the wire reel (2) to apply axial pressure, and energizing the electromagnet (15) to generate a repulsive force to apply a confining pressure; Step S4: During the test, the readings of the radial displacement measuring device and the vertical displacement measuring device are recorded, and the drain valve of the sump is opened at regular intervals to discharge the seepage water in time until the seepage test is completed; Step S5: Clean the instruments and equipment, process the recorded experimental data, and obtain the volume change results of the rock and soil mass under low triaxial stress and water seepage conditions.

8. The method for measuring rock and soil volume change under low triaxial stress and water seepage conditions according to claim 7 is characterized in that: In step S2, the installation position of the wire drum (2) of the axial pressure loading device (1), each fixed pulley (4), and the fixed positions of the two ends of the corresponding pull rope (6) need to ensure that each pull rope (6) does not deviate or tilt; When the reading of the radial displacement measuring device recorded in step S4 is the angle of the telescopic rod (26) of the radial displacement measuring device before and after the volume change of the specimen, the diameter change of the specimen after the test is obtained by the following conversion: ； in, is the setting height of the retractable ring (10) of the radial displacement measuring device, is the angle of the telescopic rod (26) before the test, is the angle of the telescopic rod (26) after the test, is the projected length of the telescopic rod (26) on the horizontal axis before the test, is the projected length of the telescopic rod (26) on the horizontal axis after the test, is the diameter change of the specimen after the test; In step S4, when the radial displacement measuring device adopts a radial displacement meter (7), and the radial displacement meter (7) includes a plurality of circular radial displacement measuring devices, an average value of the measurement results recorded by the plurality of circular radial displacement measuring devices is taken as the final measurement result; Step S5 obtains the volume change result of the rock and soil mass under low triaxial stress and water seepage conditions through the diameter change of the test piece after the test and the height change of the test piece measured by the vertical displacement measuring device.

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