CN110793870A - Rock joint double-face shear strength testing device and testing method - Google Patents
Rock joint double-face shear strength testing device and testing method Download PDFInfo
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Abstract
The invention discloses a rock joint double-sided shear strength testing device and a testing method, which comprises a fixing system and a pressurizing system, wherein a double-joint sample comprises three test blocks which are sequentially and tightly arranged from top to bottom, and a joint surface is arranged between every two adjacent test blocks; the two test blocks at the upper end and the lower end are respectively fixedly connected with the fixing system; the first pressurizing system is arranged at the upper part of the upper end test block and is used for applying normal stress relative to the joint surface; the second pressurizing system and the third pressurizing system are symmetrically arranged on two sides of a middle test block and are used for applying cyclic static force or cyclic reciprocating force to the test block; according to the invention, the upper test block and the lower test block in the double-joint sample are respectively fixed with the fixing system, and the pressurizing system is arranged at the upper end of the double-joint sample, so that normal stress is applied to a joint surface; the two pressurizing systems are symmetrically arranged, so that cyclic reciprocating stress application on the middle test block is realized, and systematic comprehensive analysis on the cyclic shearing failure characteristics and the mechanical characteristics of the double-joint plane is realized.
Description
Technical Field
The invention relates to the technical field of rock indoor shear tests, in particular to a rock joint double-sided shear strength testing device and a testing method.
Background
At present, in large-scale hydraulic engineering construction, deep-buried tunnel excavation, mineral resource exploitation and urban underground space development, excavation disturbance is inevitably carried out on underground rock masses, and particularly, the mechanical characteristics and deformation characteristics of damage along joint surfaces of the jointed rock masses containing joints are most prominent; therefore, the joint shear strength test of the stratified rock mass is particularly important.
The rock mass destruction mainly takes compression destruction and shear destruction as main parts, and because the rock mass is rich in joints, the rock mass destruction mainly takes the shear destruction as a research object in theoretical research. In actual stratified rock mass destruction, the intact rock mass is not destroyed along a certain plane, but along a plurality of planes; for jointed rock mass, especially stratified rock mass, after excavation disturbance, the rock mass near the joint surface is easy to dislocate and slide along the joint, and especially under the action of circulating dynamic load, the mechanical parameter value of the joint surface is reduced rapidly. Therefore, the joint face strength characteristics determine the fracture mechanics and deformation characteristics of the jointed rock mass.
At present, the test research on the failure characteristics of jointed rock mainly takes a single-sided shear test as a main part, a special tool is used for splitting the single-sided shear test to form a secondary joint surface, and then a direct shear device is used for carrying out the shear test. The single-sided direct shear test is easy to obtain the damage characteristic and the shear mechanical property along the joint. However, in the case of stratified rock mass, the failure mode is not only single-sided shear failure, but double-sided or multi-sided shear failure, and the specific failure mode is mainly determined by the joint distribution characteristics. Therefore, the reliability of the single-sided shear test data is insufficient, and the calculation of the actual engineering stability is influenced.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention aims to provide a device and a method for testing the double-sided shear strength of a rock joint, so as to solve the technical problems of single data and low reliability in a method for researching the destruction of a jointed rock mass in the conventional single-sided shear test.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a rock joint double-sided shear strength testing device which comprises a fixing system and a pressurizing system, wherein the fixing system is used for fixing a double-joint sample; the double-joint test sample comprises a first test block, a second test block and a third test block which are sequentially and tightly arranged from top to bottom, a first joint surface is arranged between the first test block and the second test block, a second joint surface is arranged between the second test block and the third test block, and the first joint surface and the second joint surface are both horizontally arranged; the first test block and the third test block are respectively and fixedly connected with the fixing system;
the pressurizing system comprises a first pressurizing system, a second pressurizing system and a third pressurizing system, wherein the first pressurizing system is arranged at the upper end of the first test block and is used for applying normal stress relative to the first joint surface or the second joint surface to the double-joint test sample; the second pressurizing system and the third pressurizing system are symmetrically arranged on two sides of the second test block and are respectively used for applying cyclic static force or cyclic reciprocating force to the second test block.
Further, the fixing system comprises an annular frame, a top movable plate, a bottom movable plate and a sample fixing device; the top movable plate and the bottom movable plate are arranged in the annular frame in parallel at intervals, the top movable plate is arranged above the bottom movable plate, and the top movable plate or the bottom movable plate is movably connected with the annular frame; the first test block is fixedly connected with the top movable plate through the test sample fixing device, and the third test block is fixedly connected with the bottom movable plate through the test sample fixing device.
Further, the sample fixing device comprises an L-shaped restraint plate and a fixed connecting rod, one end of the L-shaped restraint plate is fixedly connected with the top movable plate or the bottom movable plate, and the other end of the L-shaped restraint plate is arranged in a manner of being attached to the side wall of the first test block or the third test block; the fixed connecting rod sequentially penetrates through the L-shaped restriction plate and the top movable plate or the bottom movable plate, and the L-shaped restriction plate is fixedly connected with the top movable plate or the bottom movable plate through the fixed connecting rod.
Furthermore, the pressurizing system comprises a hydraulic control system, a hydraulic loading device and a hydraulic loading device fixing plate; the oil outlet end of the hydraulic control system is connected with the oil inlet end of the hydraulic loading device; the hydraulic loading device is fixedly arranged on the fixing system through a hydraulic loading device fixing plate.
Furthermore, a hydraulic control box is adopted in the hydraulic control system, and a hydraulic telescopic pressurizing column is adopted in the hydraulic loading device; the oil inlet end of the hydraulic telescopic pressurizing column is connected with the oil outlet end of the hydraulic control box, and the hydraulic telescopic pressurizing column is vertically arranged on the hydraulic loading device fixing plate.
Furthermore, a plurality of first telescopic rods are uniformly arranged between the top movable plate and the annular frame, the upper ends of the first telescopic rods are fixedly connected with a top plate of the annular frame, and the lower ends of the first telescopic rods are fixedly connected with the top movable plate; a plurality of second telescopic links are uniformly arranged between the bottom movable plate and the annular frame, the lower ends of the second telescopic links are fixedly connected with the bottom plate of the annular frame, and the upper ends of the second telescopic links are fixedly connected with the bottom movable plate.
Furthermore, first telescopic link and second telescopic link all adopt the screw thread telescopic link.
The invention also provides a method for testing the double-sided shear strength of the rock joint, which comprises the following steps:
and 4, obtaining the shear failure law of the double-joint sample under the condition of the circulating static force by using the circulating static force loading times and the loading time recorded in the step 3.
Further, in the step 1, a splitting method or a pouring method is adopted to manufacture the double-joint sample.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a rock joint double-sided shear strength testing device, which is characterized in that a fixing system is arranged to fix a double-joint sample; the pressurizing systems symmetrically arranged on the two sides of the double-joint sample realize the application of cyclic static force or cyclic reciprocating force on the second test block, and the normal stress is arranged at the upper end of the double-joint sample, so that the real simulation of the actual load of the rock mass is met, and the accuracy of the test result of the rock shear strength is improved; the testing device is simple in structure and convenient to use; by adopting the double-joint sample, the shearing failure characteristics and the mechanical characteristics of the rock joints are comprehensively analyzed systematically, and the test data is comprehensive.
Furthermore, the two ends of the double-joint sample are respectively fixed on the top movable plate and the bottom movable plate, so that the double-joint sample testing device meets the requirement for testing the double-joint samples with different specifications and sizes, simultaneously ensures that the middle parts of the double-joint samples are aligned with the corresponding pressurizing systems, and ensures that the reciprocating load applied to the double-joint samples realizes the circular direct shearing of the double-joint samples.
Furthermore, the accurate fixation of the double-joint sample is ensured by adopting the L-shaped constraint plate and the fixed connecting piece, and the accuracy of the test result is improved.
Furthermore, the hydraulic control system adopts a hydraulic control box, the hydraulic loading device adopts a hydraulic telescopic pressurizing column, and the hydraulic telescopic pressurizing column is telescopic or shortened by controlling an oil way of the hydraulic control system, so that the effective control of the circulating reciprocating force is realized, and the loading rate of the circulating reciprocating force is further controlled; the one-way loading or the reciprocating cyclic loading is met, and the system test of the double-joint sample is realized.
Furthermore, by arranging the telescopic rod between the top movable plate or the bottom movable plate and the annular frame, the position of the top movable plate or the bottom movable plate is adjusted by adjusting the telescopic rod, and then the position of the double-joint sample is adjusted.
The invention also provides a method for testing the double-sided shear strength of the rock joint, two pressurizing systems are symmetrically arranged on two sides of the double-joint sample, the two pressurizing systems are used for applying circulating static force and circulating reciprocating force to the second test block, the shearing rate is controlled, and static shearing and dynamic shearing are contrastively analyzed, so that the comprehensive analysis of the circulating shearing failure characteristics and the mechanical characteristics of the double-joint surface is realized, and the reliability of the test result is improved.
Drawings
FIG. 1 is a schematic cross-sectional view of a rock joint double-sided shear strength testing device according to the present invention;
FIG. 2 is a schematic sectional view A-A of a rock joint double-sided shear strength testing device according to the present invention;
FIG. 3 is a schematic cross-sectional view B-B of a rock joint double-sided shear strength testing device according to the present invention;
fig. 4 is a schematic structural view of a double-joint sample mold according to the present invention.
The device comprises a fixing system 1, a pressurizing system 2, a double-joint sample 3, a lateral baffle 4, an inner baffle 5, an outer side restraint rod 6 and a joint template 7; 11 an annular frame, 12 a top movable plate, 13 a bottom movable plate, 14 a sample fixing device, 15 a first telescopic rod and 16 a second telescopic rod; 21 a first pressurization system, 22 a second pressurization system, 23 a third pressurization system; 31 a first test block, 32 a second test block, 33 a third test block, 34 a first joint surface and 35 a second joint surface; 201 hydraulic control system, 202 hydraulic loading device and 203 hydraulic loading device fixing plate; 141L type restraint board, 142 fixed link.
Detailed Description
The technical solutions of the embodiments of the present invention are explained and illustrated below with reference to the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, and not all embodiments. Based on the embodiments in the implementation, other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present invention.
The invention provides a rock joint double-sided shear strength testing device which comprises a fixing system 1 and a pressurizing system 2, wherein the fixing system 1 is used for fixing a double-joint sample 3, and the pressurizing system 2 is used for applying load to the double-joint sample 3;
the fixing system 1 comprises an annular frame 11, a top movable plate 12, a bottom movable plate 13, a sample fixing device 14, a first telescopic rod 15 and a second telescopic rod 16, wherein the top movable plate 12 and the bottom movable plate 13 are parallelly arranged in the annular frame 11 at intervals, and the top movable plate 12 is arranged above the bottom movable plate 13; the first telescopic rod 15 is arranged between the top movable plate 12 and the annular frame 11, the upper end of the first telescopic rod 15 is fixedly connected with the top plate of the annular frame 11, and the lower end of the first telescopic rod 15 is fixedly connected with the top movable plate 12; the second telescopic rod 16 is arranged between the bottom movable plate 13 and the annular frame 11, the upper end of the second telescopic rod 16 is fixedly connected with the bottom movable plate 13, and the lower end of the second telescopic rod 16 is fixedly connected with the bottom plate of the annular frame 11; the double-joint sample 3 is arranged between the top movable plate 12 and the bottom movable plate 13, and the double-joint sample 3 comprises a first test block 31, a second test block 32 and a third test block 33 which are tightly arranged from top to bottom; a first joint surface 34 is arranged between the first test block 31 and the second test block 32, a second joint surface 35 is arranged between the second test block 32 and the third test block 33, and the first joint surface 34 and the second joint surface 35 are both horizontally arranged; the first test block 31 is fixedly connected with the top movable plate 12 through the sample fixing device 14, and the third test block 33 is fixedly connected with the bottom movable plate 13 through the sample fixing device 14; the sample fixing device 14 comprises an L-shaped restraining plate 141 and a fixed connecting rod 142, a horizontal end of the L-shaped restraining plate 141 is fixedly connected with the top movable plate 12 or the bottom movable plate 13, and a vertical end of the L-shaped restraining plate 141 is closely attached to a side wall of the first test block 31 or the third test block 33; the fixed connecting rod 142 sequentially penetrates between the L-shaped restraining plate 141 and the top movable plate 12 or the bottom movable plate 13, and the L-shaped restraining plate 141 and the top movable plate 12 or the bottom movable plate 13 are fixedly connected together by the fixed connecting rod 142.
The pressurizing system 2 comprises a first pressurizing system 21, a second pressurizing system 22 and a third pressurizing system 23, wherein the first pressurizing system 21 is arranged at the upper end of the first test block 31 and is used for applying normal stress relative to the first joint surface 34 or the second joint surface 35 to the double-joint test sample 3; the second pressurizing system 22 and the third pressurizing system 23 are symmetrically arranged on two sides of the second test block 32, and are respectively used for applying a cyclic reciprocating force to the second test block 32.
The pressurizing system 2 comprises a hydraulic control system 201, a hydraulic loading device 202 and a hydraulic loading device fixing plate 203; the oil outlet end of the hydraulic control system 201 is connected with the oil inlet end of the hydraulic loading device 202; the hydraulic loading device 202 is fixedly arranged on the fixing system 1 through a hydraulic loading device fixing plate 203.
Principle of operation
According to the rock joint double-sided shear strength testing device, the double-joint sample is adopted, and the fixing system is utilized to fix the first test block and the third test block in the double-joint sample with the fixing system respectively; applying normal stress on the upper end of the first test block to form an initial loading state; then, the pressurizing systems arranged on the two sides of the second test block are used for loading circulating static force or circulating reciprocating force on the second test block, so that the dynamic shear strength or the static shear strength of the double-joint test sample is tested.
The hydraulic control system adopts a method for controlling an oil way to realize the extension or the shortening of the hydraulic loading device, thereby realizing the application of a cyclic static force or a cyclic reciprocating force to the double-joint test sample; an oil pressure gauge is arranged in the hydraulic control system, and a corresponding load loading value is ensured through the oil pressure gauge in the load loading process. And controlling the pressurizing rate, namely controlling the circulating loading rate by using a loading rate controller arranged on a hydraulic control system, and controlling the left and right loading sequence by using a computer to obtain the change rule of the loading value of the circulating static force or the circulating reciprocating force and the displacement value of the double-joint sample.
The first pressurization system applies normal stress relative to the joint surface on the top of the double-joint sample; the second pressurizing system and the third pressurizing system which are symmetrically arranged on two sides not only control the unidirectional loading strength and speed, but also control the cyclic loading mode.
The size of the bottom surface of the double-joint sample and the double-joint distance are not limited, and the samples with different heights and joint distances are selected for carrying out multi-group comparison analysis by controlling the positions of the top movable plate and the bottom movable plate. And the upper and lower samples are laterally constrained by the L-shaped plate.
Examples
As shown in fig. 1-4, the device for testing the double-sided shear strength of the rock joint comprises a fixing system 1 and a pressurizing system 2, wherein the fixing system 1 is used for fixing a double-joint sample 3; the fixing system 1 comprises an annular frame 11, a top movable plate 12, a bottom movable plate 13, a plurality of sample fixing devices 14, a plurality of first telescopic rods 15 and a plurality of second telescopic rods 16;
the annular frame 11 adopts a square frame structure; the top movable plate 12 and the bottom movable plate 13 are both horizontally arranged in the annular frame 11, the top movable plate 12 and the bottom movable plate 13 are arranged in parallel at intervals, and the top movable plate 12 is arranged above the bottom movable plate 13; a plurality of first telescopic rods 15 are uniformly arranged between the annular frame 11 and the top movable plate 12, the upper ends of the first telescopic rods 15 are fixedly connected with the top plate of the annular frame 11, and the lower ends of the first telescopic rods 15 are fixedly connected with the top movable plate 12; a plurality of second telescopic rods 16 are uniformly distributed between the annular frame 11 and the bottom movable plate 13, the lower ends of the second telescopic rods 16 are fixedly connected with the bottom plate of the annular frame 11, and the upper ends of the second telescopic rods 16 are fixedly connected with the bottom movable plate 13; the position of the top movable plate 12 is adjusted by adjusting the length of the first telescopic rod 15, the position of the bottom movable plate 13 is adjusted by adjusting the length of the second telescopic rod 16, and the distance between the top movable plate 12 and the bottom movable plate 13 is adjusted, so that the fixation of the double-joint samples 3 with different sizes and specifications is met; the first telescopic rod 15 and the second telescopic rod 16 are both threaded telescopic rods.
The double-joint sample 3 is fixedly arranged between the top movable plate 12 and the bottom movable plate 13, the double-joint sample 3 comprises a first test block 31, a second test block 32 and a third test block 33 which are sequentially and tightly arranged from top to bottom, a first joint surface 34 is arranged between the first test block 31 and the second test block 32, a second joint surface 35 is arranged between the second test block 32 and the third test block 33, and the first joint surface 34 and the second joint surface 35 are both horizontally arranged;
the first test block 31 is fixedly connected with the top movable plate 12 through a plurality of sample fixing devices 14, and the plurality of sample fixing devices 14 are uniformly arranged around the first test block 31 to limit the first test block 31 in the horizontal direction; the third test block 33 is fixedly connected with the bottom movable plate 13 through a plurality of sample fixing devices 14, and the plurality of sample fixing devices 14 are uniformly arranged around the third test block 33, so that the limitation of the third test block 33 in the horizontal direction is realized.
The sample fixing device 14 comprises an L-shaped restraining plate 141 and a fixed connecting rod 142, one end of the L-shaped restraining plate 141 is fixedly connected with the top movable plate 12 or the bottom movable plate 13, and the other end of the L-shaped restraining plate 141 is closely attached to the side wall of the first test block 31 or the third test block 33; the fixed connecting rod 142 sequentially penetrates between the L-shaped restraining plate 141 and the top movable plate 12 or the bottom movable plate 13, and the L-shaped restraining plate 141 and the top movable plate 12 or the bottom movable plate 13 are fixedly connected together by the fixed connecting rod 142.
The pressurizing system 2 comprises a first pressurizing system 21, a second pressurizing system 22 and a third pressurizing system 23, wherein the first pressurizing system 21 is arranged at the upper end of the first test block 31 and is used for applying normal stress relative to the first joint surface 34 or the second joint surface 35 to the double-joint test sample 3; the first pressurizing system 21 comprises a first hydraulic control system, a first hydraulic telescopic pressurizing column and a first hydraulic loading device fixing plate, wherein the oil outlet end of the first hydraulic control system is connected with the oil inlet end of the first hydraulic telescopic pressurizing column, the first hydraulic loading device fixing plate is fixedly arranged on the top plate of the annular frame 11, the first hydraulic loading device fixing plate is arranged right above the first test block 31, the first hydraulic telescopic pressurizing column is arranged between the first hydraulic loading device fixing plate and the first test block 31, and one end of the first hydraulic telescopic pressurizing column is fixedly connected with the first hydraulic loading device fixing plate; the middle part of the top movable plate 12 is provided with a loading through hole, the other end of the first hydraulic telescopic pressurizing column penetrates through the loading through hole and then is fixedly connected with the first test block 31, and the first hydraulic telescopic pressurizing column and the first test block 31 are provided with loading plates.
The second pressurizing system 22 and the third pressurizing system 23 are symmetrically arranged on two sides of the second test block 32, the second pressurizing system 22 comprises a second hydraulic control system, a second hydraulic telescopic pressurizing column and a second hydraulic loading device fixing plate, the oil outlet end of the second hydraulic control system is connected with the oil inlet end of the second hydraulic telescopic pressurizing column, the second hydraulic loading device fixing plate is fixedly arranged on one side plate of the fantasy frame 11, the second hydraulic loading device fixing plate is arranged on the right side of the second test block 32, and the second hydraulic telescopic pressurizing column is arranged between the second hydraulic loading device fixing plate and the second test block 32; one end and the second hydraulic loading device fixed plate fixed connection of second hydraulic pressure telescopic pressurization post, the other end and one side fixed connection of second test block 32 of second hydraulic pressure telescopic pressurization post, second hydraulic pressure telescopic pressurization post and second test block 32 are provided with the load plate.
The third pressurizing system 23 comprises a third hydraulic control system, a third hydraulic telescopic pressurizing column and a third hydraulic loading device fixing plate, wherein the oil outlet end of the third hydraulic control system is connected with the oil inlet end of the third hydraulic telescopic pressurizing column, the third hydraulic loading device fixing plate is fixedly arranged on the other side plate of the fantasy frame 11, the third hydraulic loading device fixing plate is arranged at the right side of the second test block 32, and the third hydraulic telescopic pressurizing column is arranged between the third hydraulic loading device fixing plate and the second test block 32; one end of a third hydraulic telescopic pressurizing column is fixedly connected with a third hydraulic loading device fixing plate, the other end of the third hydraulic telescopic pressurizing column is fixedly connected with the other side of the second test block 32, and a loading plate is arranged between the third hydraulic telescopic pressurizing column and the second test block 32.
The invention also provides a method for testing the double-sided shear strength of the rock joint, which comprises the following steps:
when the splitting method is adopted to manufacture the double-joint sample, the method specifically comprises the following steps:
splitting the square rock by a cleaver by utilizing a Brazilian splitting test method to obtain a first test block, a second test block and a third test block with equal sizes; in the test process, a first test block, a second test block and a third test block are sequentially and tightly attached from top to bottom to form a double-joint sample containing two groups of joint surfaces; the joint formed by the splitting method is regarded as a primary joint, the joint surface on the surface of the test block is ensured not to drop in the splitting process, and the problem that the joint surface in the double-joint test sample is not tightly attached or holes appear to cause test errors is avoided.
When a pouring method is adopted to manufacture the double-joint sample, the method specifically comprises the following steps:
specifically, the sample mold comprises two lateral baffles 4, two inner side baffles 5 and two outer side restraint rods 6; the two lateral baffles 4 are arranged in parallel at intervals, the two inner side baffles 5 are arranged between the two lateral baffles at parallel intervals, one end of each inner side baffle 5 is connected with one lateral baffle 4 in a matched manner, and the other end of each inner side baffle 5 is connected with the other lateral baffle 4 in a matched manner; the two lateral baffles 4 and the two lateral baffles 5 are sequentially connected to form a rectangular frame structure; the two outer side restraint rods 6 are respectively arranged at two ends of the lateral baffle 4, the two lateral baffles 4 are fixedly connected together through the two outer side restraint rods 6, two template grooves are uniformly formed in the inner sides of the lateral baffles 4, the lateral baffles are equally divided into three sections by the two template grooves, a joint template 7 is respectively arranged in the two template grooves, and the rectangular frame structure is equally divided into three pouring areas by the two joint templates 7; one end of the outer side restraint rod 6 is movably connected to one end of the lateral baffle 4, and the other end of the outer side restraint rod is provided with a buckle, so that the outer side restraint rod is convenient to disassemble; oiling treatment is carried out on the inner surfaces of the joint template 7, the lateral baffle 4 and the inner side baffle 5, so that the later-stage sample mold is convenient to disassemble;
and 14, pouring cement mortar or lime in the three pouring areas in the sample mold, maintaining after surface smoothing, removing the mold to obtain three test blocks, and tightly connecting the three test blocks from top to bottom in sequence to form the double-joint sample.
When a pouring method is adopted to manufacture the double-joint sample, the joint template obtained by using the 3D scanning and 3D printing methods is good in authenticity, and meanwhile, the characteristics of the joint surface can be systematically and comprehensively simulated, particularly the roughness coefficient of the joint surface is truly simulated, and the roughness coefficient of the joint surface is a main characteristic parameter for controlling the damage characteristics along the joint surface; when the comparative analysis of different joint surface roughness coefficients on rock destruction characteristics is researched, different joint templates with the joint surface roughness coefficients as control factors can be scanned and printed.
specifically, a first pressurizing system is adopted to apply normal stress to the upper end of a first test block, so that initial loading of a double-joint sample is realized; then, a second pressurizing system and a third pressurizing system are adopted to apply cyclic static force or cyclic reciprocating force on the left side and the right side of the second test block respectively;
the loading direction and the loading time of the second hydraulic telescopic rod and the third hydraulic telescopic rod are utilized to achieve the loading purpose of cyclic static force or cyclic reciprocating force; before the loading test, the second hydraulic telescopic rod and the third hydraulic telescopic rod are arranged in the gap between the side face of the double-joint sample in a preset mode, the preset gap is 1cm, and the number of times and the acting time of circulating static force can be conveniently recorded. In order to simulate actual dynamic shearing or vibration shearing, the frequency or period factor of the cyclic reciprocating force is applied, and the purpose is achieved by a hydraulic control box arranged on a hydraulic loading device.
determining a reciprocating vibration load time domain curve of the double-joint sample by utilizing the cyclic reciprocating force loading frequency recorded in the step 3 and adopting data monitoring and conversion of a computer and a hydraulic control box; and obtaining the shearing resistance and destruction resistance characteristics of the double-joint sample under the loading condition of the circulating reciprocating force.
The invention relates to a rock joint double-sided shear strength testing method, which utilizes the rock joint double-sided shear strength testing device to contrastively analyze the shear mechanical characteristics of a double-joint sample by controlling joint roughness coefficient, joint normal stress and cyclic shear rate; in order to better simulate the sliding damage condition of the stratified rock along the joint surface, the invention combines 3D scanning and 3D printing technologies to scan to obtain the joint distribution characteristics of the original stratified rock or generate three-dimensional joints with different roughness through software, and the characteristics of the invention mainly take the joint roughness coefficient to form a three-dimensional joint surface; printing a three-dimensional object curved surface on the joint surface formed by scanning by a 3D printing technology to form a joint template; the upper and lower surface morphology of joint template is unanimous, and the sample of being convenient for is closely laminated in the joint, and wherein 3D printing material can adopt plastic material, is convenient for the drawing of patterns. And taking the printed joint model as a sample pouring inserting plate, arranging the sample pouring inserting plate in the sample mould at equal intervals, and further pouring cement mortar or gypsum to form a double-joint sample. Compared with the splitting mode, the 3D scanning and printing technology is utilized, not only is a real joint surface obtained, but also systematic and comprehensive simulation is carried out on joint surface characteristics, particularly on the roughness coefficient of the joint surface, the parameters are main characterization parameters for controlling damage characteristics along the joint surface, and the determination of the values is particularly important. Therefore, in order to research the comparative analysis of different joint surface roughness coefficients on rock destruction characteristics, different joint templates with the joint surface roughness coefficients as control factors can be scanned and printed.
The joint surface roughness coefficient values of the first joint surface and the second joint surface are combined to form: the three conditions are the same, different greatly and different slightly, so that the damage characteristics and mechanical properties of the circular shearing along the joint surface under the three combined conditions are realized. The two modes are easy to obtain the anisotropic joint surfaces, and the anisotropic characteristics of the joint surfaces have good practical significance on the rock mass circulating shear test. In order to study the failure characteristics more deeply, the dual-joint surface circulating shear failure characteristics and the mechanical characteristics are systematically analyzed by controlling the circulating stress application direction of a sample and the normal stress of the joint surfaces, controlling the shear rate and carrying out static shear and dynamic shear comparative analysis. And (3) performing a cyclic direct shear test on the sample, and analyzing the mechanical characteristics and deformation characteristics of the sample along the joint surface damage under the conditions of different joint roughness coefficients, different joint normal stresses and different loading rates by a system. In order to achieve the purpose, the circulating direct shearing device is designed, so that the damage characteristics of the double-joint sample under the static shearing action can be analyzed, and the mechanics, deformation characteristics and dynamic shearing strength of the dynamic shearing damage of the double-joint sample under the dynamic shearing action can be analyzed.
In light of the above-described embodiments of the present invention, it is to be understood that various changes and modifications can be made by one skilled in the art without departing from the scope and spirit of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (9)
1. The device for testing the double-sided shear strength of the rock joint is characterized by comprising a fixing system (1) and a pressurizing system (2), wherein the fixing system (1) is used for fixing a double-joint sample (3); the double-joint test sample (3) comprises a first test block (31), a second test block (32) and a third test block (33) which are sequentially and tightly arranged from top to bottom, a first joint surface (34) is arranged between the first test block (31) and the second test block (32), a second joint surface (35) is arranged between the second test block (32) and the third test block (33), and the first joint surface (34) and the second joint surface (35) are both horizontally arranged; the first test block (31) and the third test block (33) are respectively fixedly connected with the fixing system (1);
the pressurizing system (2) comprises a first pressurizing system (21), a second pressurizing system (22) and a third pressurizing system (23), wherein the first pressurizing system (21) is arranged at the upper end of the first test block (31) and is used for applying normal stress relative to the first joint surface (34) or the second joint surface (35) to the double-joint test sample (3); the second pressurizing system (22) and the third pressurizing system (23) are symmetrically arranged on two sides of the second test block (32) and are respectively used for applying a cyclic static force or a cyclic reciprocating force to the second test block (32).
2. The rock joint double-sided shear strength test device according to claim 1, wherein the fixing system (1) comprises an annular frame (11), a top movable plate (12), a bottom movable plate (13) and a sample fixing device (14); the top movable plate (12) and the bottom movable plate (13) are arranged in the annular frame (11) in parallel at intervals, the top movable plate (12) is arranged above the bottom movable plate (13), and the top movable plate (12) or the bottom movable plate (13) is movably connected with the annular frame (11); the first test block (31) is fixedly connected with the top movable plate (12) through the test sample fixing device (14), and the third test block (33) is fixedly connected with the bottom movable plate (13) through the test sample fixing device (14).
3. The double-sided shear strength test device for the rock joints as claimed in claim 2, wherein the sample fixing device (14) comprises an L-shaped restraining plate (141) and a fixed connecting rod (142), one end of the L-shaped restraining plate (141) is fixedly connected with the top movable plate (12) or the bottom movable plate (13), and the other end of the L-shaped restraining plate (141) is arranged in close contact with the side wall of the first test block (31) or the third test block (33); the fixed connecting rod (142) sequentially penetrates through the L-shaped restriction plate (141) and the top movable plate (12) or the bottom movable plate (13), and the L-shaped restriction plate (141) is fixedly connected with the top movable plate (12) or the bottom movable plate (13) through the fixed connecting rod (142).
4. The rock joint double-sided shear strength testing device according to claim 1, wherein the pressurizing system (2) comprises a hydraulic control system (201), a hydraulic loading device (202) and a hydraulic loading device fixing plate (203); the oil outlet end of the hydraulic control system (201) is connected with the oil inlet end of the hydraulic loading device (202); the hydraulic loading device (202) is fixedly arranged on the fixing system (1) through a hydraulic loading device fixing plate (203).
5. The rock joint double-sided shear strength testing device is characterized in that a hydraulic control box is adopted by a hydraulic control system (201), and a hydraulic telescopic pressurizing column is adopted by a hydraulic loading device (202); the oil inlet end of the hydraulic telescopic pressurizing column is connected with the oil outlet end of the hydraulic control box, and the hydraulic telescopic pressurizing column is vertically arranged on a hydraulic loading device fixing plate (203).
6. The double-sided shear strength test device for the rock joints according to claim 2, wherein a plurality of first telescopic rods (15) are uniformly arranged between the top movable plate (12) and the annular frame (11), the upper ends of the first telescopic rods (15) are fixedly connected with the top plate of the annular frame (11), and the lower ends of the first telescopic rods (15) are fixedly connected with the top movable plate (12); a plurality of second telescopic rods (16) are uniformly arranged between the bottom movable plate (13) and the annular frame (11), the lower ends of the second telescopic rods (16) are fixedly connected with the bottom plate of the annular frame (11), and the upper ends of the second telescopic rods (16) are fixedly connected with the bottom movable plate (13).
7. The device for testing the double-full shear strength of the rock joint according to claim 6, wherein the first telescopic rod (15) and the second telescopic rod (16) are both threaded telescopic rods.
8. A rock joint double-sided shear strength test method, characterized in that the rock joint double-sided shear strength test device of any one of claims 1 to 7 is used, and the method comprises the following steps:
step 1, manufacturing a double-joint sample (3);
step 2, fixedly mounting the double-joint sample (3) manufactured in the step 1 on a fixing system (1);
step 3, performing a circulating direct shear test on the double-joint sample (3) by adopting the pressurizing system (2) until the joint surface of the double-joint sample (3) is damaged and the shear strength reaches stable residual strength; respectively recording the loading times and the loading time of the cyclic static force applied to the second test block (32) and the loading frequency of the cyclic reciprocating force;
and 4, obtaining the shear failure law of the double-joint sample under the condition of the circulating static force by using the circulating static force loading times and the loading time recorded in the step 3.
9. The method for testing the double-sided shear strength of the rock joint according to claim 8, wherein in the step 1, a splitting method or a pouring method is adopted to manufacture the double-joint test sample (3).
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