80 results about "Direct shear test" patented technology

The invention discloses a multifunctional geotechnical mechanical testing system for controlling temperature, humidity and salinity in an extreme environment, and relates to the technical field of ocean geotechnical engineering and geotechnical engineering. The system integrates a high-precision temperature and humidity and salinity control system, can accurately simulate the influence of complex environments such as extreme temperature and humidity, salt spray corrosion and the like on the mechanical properties of geotechnical materials, supports a direct shear test, a pull-out test, a soil body single-particle crushing test and a geosynthetic material stretching and puncturing test, can distinguish static, dynamic and long-term creep test modes, and can be used for testing the mechanical properties of the geotechnical materials. Comprising creep mechanical property testing under cyclic direct shear and continuous load. A visual monitoring assembly is additionally arranged, so that the microscopic deformation and damage process of the sample can be recorded in real time. Through multifunctional integration, temperature, humidity and salinity joint control, visual monitoring and dynamic and static coupling test devices, the technical bottlenecks of single function, environment simulation limitation and microcosmic observation deficiency of traditional equipment are solved, and high engineering application value and popularization potential are achieved.

The invention discloses a multilevel rock mass mechanical analysis method and system based on near field dynamics, and the method comprises the steps: generating a mica-matrix binary model matched with actual granite based on a K-L random field, mapping the model to a BB-PD model mass point through a DIP method, determining the distribution, the particle size and the content of mica, and determining the particle size of the mica; the mechanical weakening effect is simulated by reducing the normal and tangential stiffness of the mica phase, and the microstructure characterization of the rock is completed. Constructing a structural plane PD numerical model by combining the geometrical characteristics of the structural plane reconnaissance on site and the mechanical parameters of the indoor direct shear test, and analyzing the influence of the geometrical and mechanical characteristics of weak planes such as joints and fractures on the local mechanical properties of the rock mass; the method comprises the following steps of: constructing an engineering scale rock mass numerical model integrated with mechanical properties of a microscopic rock block and a microscopic structural surface by relying on field rock mass discontinuous surface distribution data and indoor test basic mechanical parameters, and finishing analysis on the influence of the overall mechanical properties of the engineering scale rock mass; and the problems of insufficient cross-scale collaboration and the like are solved.

The invention discloses a large-scale visualized direct shear test device and method for geosynthetics. The device comprises a main frame, an upper shear box, a lower shear box, a normal cyclic loading system, a horizontal cyclic shear loading system, a data acquisition system and a visualized monitoring system. The direct shear test device is characterized in that the direct shear test device can perform normal and horizontal cyclic loading at the same time, and normal stress with different frequencies and amplitudes can be applied according to needs to simulate a test of the characteristics of the reinforcement-soil interface under the cyclic loading effect; one side wall of the upper shear box and one side wall of the lower shear box are transparent observation windows, and a high-speed camera and a digital image analysis method are combined, so that the shear band evolution process can be visually observed and quantitatively analyzed; the shear box is large in size, and the size effect is effectively overcome. According to the invention, the interface characteristics under the cyclic load effect in the road engineering can be reflected more truly and comprehensively, the size and the function of the shear box are comprehensive, and the interface mechanical characteristics and the interaction mechanism under various working conditions can be simulated.

The invention relates to a UHPC-NC interface mechanical property prediction method and system considering a size effect, and the method comprises the steps: preparing a target test piece, collecting original data through a direct shear test and a pull-out test, and obtaining a shear stress-displacement curve and a tensile stress-displacement curve according to the original data; extracting shear performance parameters and a linear relation according to the curve, carrying out fitting analysis on the shear performance parameters to obtain a shear size effect law, further defining a shear macroscopic constitutive model, and carrying out fracture mechanical quantitative evaluation on the shear performance parameters to obtain a shear macroscopic constitutive model. Deriving and constructing a prediction expression of shear resistance and a shear-displacement constitutive model according to a quantitative evaluation result; extracting tensile property parameters according to the curve, performing series analysis on the tensile property parameters to obtain an interface tensile relationship, performing probability distribution analysis on the tensile property parameters to obtain a tensile size effect law, and performing derivation according to the interface tensile relationship and the tensile size effect law to obtain a tensile property prediction expression and a tensile-fracture constitutive model.

The invention provides a rapid evaluation method for shear strength of a rock structural plane under normal disturbance, and belongs to the technical field of geotechnical engineering and rock mechanics, the method comprises the following steps: S1, sample preparation and initial parameter acquisition; s2, normal disturbance direct shear test; s3, fitting test data and establishing an empirical model; and S4, rapidly evaluating the shear strength. According to the method, by introducing a normal disturbance stress parameter, an empirical calculation formula capable of rapidly predicting the shear strength after disturbance is established, and key parameters are provided for engineering design and stability analysis.

The invention discloses an integrated in-situ direct shear apparatus, and relates to the technical field of geotechnical engineering testing. Comprising a bottom plate, a shear box, a supporting column arranged on the bottom plate, a bracket capable of sliding up and down along the supporting column, a guide rail arranged on the bracket, a soil body stripping device arranged on the bracket, a normal loading device arranged on the bracket and a lateral loading device arranged on the bracket, the force sensors are arranged at the output ends of the lateral loading device and the normal loading device, the displacement sensor is arranged on the support and used for measuring the displacement of the shear box, and the control system is used for controlling the lateral loading device, the normal loading device and the soil body stripping device to act and collecting and processing data of the force sensors and the displacement sensor in real time. The guide rail is used for enabling the soil body stripping device to move along the circumferential direction of the shearing box; through modular integration and automatic control, simplification of the in-situ direct shear test is realized, and the in-situ direct shear test device is suitable for occasions requiring rapid, batch and high-precision on-site soil engineering tests.

This invention discloses a combined shear-resistivity testing device and method for soil-rock mixed fillers, belonging to the field of geotechnical engineering testing technology. It addresses the shortcomings of existing combined testing methods, such as unstable contact resistance, fluctuating electrical signals, and asynchronous data. The device includes a direct shear test, resistivity test, and data acquisition and control system. The shear test chamber has a multi-layered composite structure integrated electrode embedded in its inner wall, coupled with an array of spring needles, and features a stress-driven electrical connection and hardware synchronous triggering structure. The method completes the test through steps including sample preparation, system initialization, stress-driven electrical connection establishment, and synchronous triggering of the combined test. This invention achieves synchronous and accurate acquisition of shear mechanics and resistivity data, enabling real-time non-destructive characterization of the internal structural damage evolution of the sample, significantly improving testing accuracy and stability, and providing reliable technical support for the mechanical research and engineering applications of soil-rock mixed fillers.

The utility model belongs to the technical field of sandy soil sampling, and particularly relates to an undisturbed soil sampling device suitable for an indoor direct shear test, which comprises a plain-end cutting ring, a cutting ring with a blade, a sleeve, a rectangular cutting plate, a cutting plate with a blade, a circular cover plate and a flat-angle cover plate. Then the cutting ring and the sleeve are pushed into soil, the upper surface and the lower surface of the cutting ring are scraped to be flat through a cutting plate, the cutting plate is fixed up and down through bolts, sealed storage is conducted, after the cutting ring is sent to a test room, the bolts are removed, cutting ring samples with cover plates are placed into a shear box, meanwhile, adhesive tape between the cutting ring samples is cut open through a small knife, and a test is prepared; according to the device, disturbance to surrounding sandy soil is reduced, the integrity and accuracy of the sampling process are ensured through the cutting and collecting functions of the sampling device, and reliable basic data support is provided for sandy soil research.

The application discloses a vertical load device for large-scale direct shear test in situ, which mainly comprises a crossbeam, a counterweight, an anchor, a counterweight plate, a roller, a first jack, a pressure sensor and a sliding module. During the test, a hard layer is first laid on the soil on both sides of a sample, and then the counterweight and the crossbeam are erected on the hard layer; during the erection, the locking block and the locking block are locked to avoid the movement of the counterweight and the crossbeam again, thereby affecting the shear test; then, a shear box is sleeved on the sample, and a third steel plate and the first jack are placed on the shear box; then, the sliding module is installed between the first jack and the crossbeam, and finally, the force of the first jack pushing the crossbeam upward is adjusted to meet the requirement of different loads on the sample. In addition, after the completion of the current experiment, the roller is released to push the counterweight and the crossbeam to the next sample, and the next sample can be tested, so that the operation is simple, convenient, flexible, fast and the like.

The invention discloses a composite foundation design method based on the influence of soil around a pile on the strength of a gravel pile and application, and the design method comprises the steps that each soil layer is subdivided, and the relation between the undrained shear strength value and the depth of each subdivided soil layer is recorded; performing statistics on the data by adopting a mean square error method according to the dynamic sounding hammering number data of the gravel pile, so as to obtain the dynamic sounding hammering number N of each subdivided soil layer; counting the statistical relationship between the undrained shear strength value of each soil layer and the dynamic sounding hammering number N of the gravel pile, and evaluating the compactness of the soil layer; crushing gravel with different compactness through a large direct shear test or a large triaxial test, and establishing a relationship between the different compactness of the gravel and an internal friction angle; establishing an empirical relationship between the strength of the soil around the pile and the value of the internal friction angle of the gravel; and composite foundation parameters are selected according to the subdivided soil layer parameters. The internal friction angle parameter of the gravel pile can be obtained in a layered mode according to the distribution of the soil layer, and the actual mechanical property can be better reflected.

The present application relates to the cross technical field of geotechnical engineering and machine learning, especially a concrete-sand interface bearing capacity prediction method and system based on machine learning, the method comprising the following steps: obtaining core input parameters to obtain multi-working condition test variables; preparing a concrete sample, constructing a multi-working condition direct shear test through a test device; carrying out the multi-working condition direct shear test and collecting data during the test to obtain a multi-dimensional original data set; obtaining a modeling data set according to the multi-dimensional original data set, combining machine learning to construct a concrete-sand interface bearing capacity prediction model; performing model optimization and generalization capability verification to obtain a bearing capacity prediction optimization model; obtaining a bearing capacity prediction result according to the bearing capacity prediction optimization model, and obtaining a characteristic influence analysis result. The present application studies the concrete-sand interface shear resistance bearing law under the coupling action of multiple factors, and provides a scientific basis for the design and construction of geotechnical engineering.

The invention belongs to the field of rock mechanical property evaluation, and particularly relates to a rock structural surface shear brittleness index obtaining method and a shear brittleness evaluation method. And carrying out a direct shear test on the rock structural surface to obtain a shear stress-displacement whole-process curve, calculating according to the shear stress-displacement whole-process curve to obtain a pre-peak brittleness parameter S1 and a post-peak brittleness parameter S2, and multiplying the pre-peak brittleness parameter S1 and the post-peak brittleness parameter S2 to obtain the shear brittleness index SI of the rock structural surface. According to the method, the shear stress rise rate in the pre-peak loading stage, the shear stress drop amplitude in the post-peak stage and the relative displacement in the residual deformation stage are comprehensively considered, the whole-process shear deformation characteristics of the rock structural surface can be comprehensively reflected, and the required parameters are easily measured through a mechanical test.

This utility model relates to the field of rock mechanics testing technology, and in particular to a cylindrical rock core direct shear test device. The cylindrical rock core direct shear test device includes a base plate, two sets of support plates, a support beam, and two sets of linear guide rails; a control box, installed on the outer wall of the support plates; two sets of guide rods, each set installed in a through slot in one of the two support plates, with a lifting plate slidably mounted on each set of guide rods. An upper shear sleeve is fixedly mounted on the lifting plate, and a positive pressure mechanism is installed on the support beam directly above the upper shear sleeve; a sliding frame, slidably mounted on the two sets of linear guide rails, with a connecting column fixedly mounted at the top of the sliding frame, and a lower shear sleeve fixedly mounted at the top of the connecting column. A clamping assembly for holding the cylindrical rock core is mounted on the lower shear sleeve. The cylindrical rock core direct shear test device provided by this utility model has the advantages of convenient loading and unloading and accurate testing.

The invention discloses an in-situ drilling vertical direct shear test device suitable for a soft soil area. The in-situ drilling vertical direct shear test device comprises a counter-force bracket, a soil sample in-situ shear cylinder, a worm gear elevator and a data acquisition and transmission control device, a hollow steel cylinder is arranged at the lower end of the soil sample in-situ shearing cylinder, and the diameter of the steel cylinder is the same as that of a reconnaissance drill hole; two soil body vertical direct shear boxes capable of extending out of the hollow steel cylinder are symmetrically arranged in the hollow steel cylinder; the hydraulic ejector rod is used for pushing outwards; strain gauges are arranged on the back surfaces of a bottom plate and a side plate of the soil body vertical direct shear box and are connected with a data acquisition and transmission control device; a rod piece is arranged at the upper part of the soil sample in-situ shearing cylinder, the upper end of the rod piece is connected with a worm gear elevator, and the worm gear elevator is fixed on a counter-force bracket. According to the device, the natural state of a soil body structure is kept to the maximum extent, it is guaranteed that the stress state of a soil body is not changed, mechanical parameters of a current reconnaissance soil layer are tested in situ, reconnaissance design work of geotechnical engineering can be guided, and the device has the advantages of being convenient to carry and easy to operate.

The invention relates to a rock high-frequency multi-surface direct shear test system and a rock high-frequency multi-surface direct shear test method considering fluid-solid coupling, and relates to the field of rock mechanics and seepage mechanics. Comprising a true triaxial loading frame which is used as a supporting frame of a test system and is used for clamping a sample and realizing a true triaxial stress state; the shear loading device is arranged in the true triaxial loading frame and is used for independently applying a horizontal shear load; the seepage module is connected with the true triaxial loading frame and is used for feeding fluid into the surface of the sample; the high-frequency dynamic disturbance device is arranged in the true triaxial loading frame and is used for applying a disturbance load; the data acquisition system is used for monitoring and recording stress, strain, displacement, acoustic emission signals and seepage parameters in the test process in real time; and the servo control system is used for coordinating and controlling static loading, shear loading, seepage and high-frequency dynamic disturbance processes. The invention provides a test system and method capable of comprehensively considering a fluid-structure interaction effect, high-frequency disturbance and multi-surface direct shear loading so as to overcome the defects in the prior art.

The invention provides a method for determining shear strength parameters of cemented coarse-grained soil with oversized particle size, which belongs to the technical field of engineering investigation and measurement, and comprises the following steps: taking an undisturbed sample; carrying out an indoor flat pushing method direct shear test on the undisturbed sample to obtain a plurality of cohesive force data; performing data processing on the multiple pieces of cohesion data to obtain an undisturbed sample cohesion standard value; a disturbance sample is adopted; performing an indoor vertical pressurization direct shear test on the disturbance sample to obtain a plurality of internal friction angle data; performing data processing on the plurality of internal friction angle data to obtain a disturbance sample internal friction angle standard value; and determining the cohesive force standard value of the undisturbed sample and the internal friction angle standard value of the disturbance sample as shear strength parameters of the cemented coarse-grained soil with the ultra-large particle size, wherein the maximum particle size of soil particles of the cemented coarse-grained soil with the ultra-large particle size exceeds 200mm. According to the method, the obtained result is accurate, the test cost can be saved by 90% or above, the test period is greatly shortened, and meanwhile potential safety hazards of on-site in-situ tests can be avoided.

The present disclosure discloses a test method for reducing test error in shear strength of a root-soil composite, belonging to the field of agricultural engineering testing methods. The method includes: sampling with a ring knife perpendicular to an actual shear surface to ensure consistency between a direction of the actual shear surface of the root-soil composite and a shear surface direction in a direct shear test; determining a shear strength of soil in each layer within an actual shear depth range by stratifying with a minimum thickness of the ring knife; and planning an annular sampling area and performing sampling in various directions along the annular area, thereby reducing test error in determining shear characteristics of the root-soil composite from three aspects.

The invention belongs to the technical field of outdoor field in-situ direct shear tests, and discloses in-situ direct shear test equipment, a test system and a use method, the equipment comprises a base, and a shear clamp is arranged at the top of a fixed clamp; through holes are formed in four corners of the fixing clamp and the shearing clamp; a clamp sliding groove is formed in the bottom face of the shearing clamp. A clamp rolling ball is arranged in the clamp sliding groove. A first pressing plate is arranged at the top of the shearing clamp, a second pressing plate is arranged at the top of the first pressing plate, and a pressure plate sliding groove is formed in the bottom of the second pressing plate; a pressure plate rolling ball is arranged in the pressure plate sliding groove. Supporting frames are arranged on the base on the outer sides of four corners of the fixing clamp; a vertical load simulation loading mechanism is arranged at the top of the support frame; a shearing force load simulation loading mechanism is arranged on a supporting body on the right side of the fixing clamp and the shearing clamp. The device is small in occupied space, convenient to carry and transfer and capable of adapting to field direct shearing in various geological environments.

A constant-speed dynamic direct-shear test system and a test method for a rock mass structural plane are provided; the system includes a bearing frame, a loading frame, a horizontal loading device, a normal loading device, an oil supply device and a digital controller, a shear box is arranged in the loading frame, and the loading frame is fixedly connected with a top surface of one end of the bearing frame; the oil supply device and the horizontal loading device are controlled by the digital controller and output shearing force, the normal loading device is arranged on the loading frame and provides normal force to the shear box.

The invention discloses a coal rock unilateral free surface plane strain compression test device and method, and relates to the technical field of rock mechanics and mine engineering.The coal rock unilateral free surface plane strain compression test device comprises a main base and supporting legs, a limiting column is fixedly installed on the main base, a pressing plate body driven by a hydraulic push rod is arranged on the limiting column, and a linear guide rail is further installed on the main base; a linear guide rail is arranged on the main base, the linear guide rail is provided with a displacement seat driven by a driving mechanism, a lateral baffle is further connected to the main base in a sliding mode, an observation frame driven by an adjusting mechanism is further arranged on the main base, and an experiment area used for containing a coal rock mass is jointly formed between the pressing plate body and the lateral baffle. During use, the hydraulic push rod drives the pressing plate main body to vertically apply pressure to simulate uniaxial compression, and meanwhile, the displacement seat is matched to drive the lateral baffles to extrude the two sides of a sample to simulate a direct shear test; the two stress states are combined to accurately simulate the actual stress condition of the coal and rock mass under the condition of a single-side free surface.

The application belongs to the technical field of frozen soil engineering, and particularly relates to a concrete-frozen soil contact surface direct shear test sample manufacturing device and method, which comprises a box body, a counterforce frame, a heating plate and a refrigeration plate. The top of the counterforce frame is provided with a walking device, the bottom of the walking device is provided with a pressurizing device, and the pressurizing device is provided with a pressure gauge. The bottom of the counterforce frame is provided with a concrete pouring chamber and a soil sample chamber, and a partition plate is arranged between the concrete pouring chamber and the soil sample chamber. The device has the advantages that the problem of excessive water content of the concrete-frozen soil interface caused by water migration due to gravity is solved.

The invention provides a CT scanning device for a direct shear test of a large rock-soil body and a test method of the CT scanning device, and relates to the technical field of rock-soil mechanics, and the CT scanning device comprises a box body which comprises a groove body, a top plate and a bottom plate, an upper slot horizontally penetrating through one side face is formed in an upper port of the groove body, two middle slots horizontally penetrating through the two opposite side faces of the groove body are formed in the middle of the groove body, a lower slot horizontally penetrating through one side face is formed in a lower port of the groove body, the top plate is detachably inserted into the upper slot, and the bottom plate is detachably inserted into the lower slot. And the bearing cloth strip penetrates through the two middle slots. The method has the beneficial effects that a sample reloading process after CT scanning in a test process can be avoided, so that test steps are simplified, and the consistency between a CT scanning result and a real microstructure of a soil sample at a shearing surface in an actual shearing process is ensured; further, the influence of the microstructure of the soil sample on the shear strength index of the shear surface can be more accurately researched.

The invention relates to a method for simulating mud cake removal of a shield cutter head, a device for simulating mud cake removal of the shield cutter head, a storage medium and electronic equipment. The method for simulating the mud cake removal of the shield cutter head belongs to the technical field of tunnel excavation, and comprises the following steps: acquiring a first contact parameter between mud cake particles and a second contact parameter between a mud cake and an interface through a direct shear test or a pull-out test; on a simulation platform based on the first contact parameter and the second contact parameter, constructing a mud cake microcosmic particle system in which a mud cake is attached to a shield cutter head; the jet flow model and the mud cake microcosmic particle system are subjected to water flow jet coupling on the simulation platform, the stress, the motion trail and the falling process of mud cake particles under jet flow scouring are simulated, and the most reasonable water flow jet scouring scheme can be simulated on the simulation platform when mud cakes are attached in various different states. Therefore, unreasonable flushing conditions such as blind water pressure increase or overlong spraying time can be reduced.

The invention discloses an in-situ drilling horizontal direct shear test device suitable for a soft soil area and a use method. The in-situ drilling horizontal direct shear test device comprises a soil sample protection and consolidation cylinder, a cutting and dumping hollow drill bit, a soil sample in-situ shear cylinder, various sensors and a data acquisition and transmission control device, during the exploration operation, an exploration drill hole is directly used for testing, and when a soil layer to be tested is drilled during the exploration operation, the cutting and dumping hollow drill bit and the soil sample protection and consolidation cylinder are embedded and sleeved together and then are inserted into the center of the bottom of the exploration hole, and due to the fact that the annular baffle is arranged at the tail end of the cutting and dumping hollow drill bit, the cutting and dumping hollow drill bit and the soil sample protection and consolidation cylinder are inserted into the center of the bottom of the exploration hole. A hollow needle bearing on the upper surface of the soil sample protection and consolidation cylinder is synchronously downward in the drilling process; then the cutting and soil discharging hollow drill bit is lifted out of the drill hole, the soil sample protecting and consolidating cylinder is left in the drill hole, and a pressing rod of the soil sample protecting and consolidating cylinder is connected with a drill rod of a reconnaissance drilling machine through threads so as to maintain the in-situ state of the test soil body; the device has the advantage that the mechanical parameters of the current reconnaissance soil layer can be tested in situ.

The embodiment of the application provides a non-uniform load rough structure surface direct shear test method and system, and belongs to the technical field of rock mass mechanics test. The method comprises the following steps: obtaining a joint structure surface grayscale image, and extracting joint profile coordinate data of a joint structure surface profile based on the joint structure surface grayscale image; constructing a three-dimensional entity model of the joint structure surface based on the joint profile coordinate data; placing a rock-like joint structure surface sample constructed based on the three-dimensional entity model of the joint structure surface into a direct shear loading device, and executing shear loading after non-uniform normal load is applied to the rock-like joint structure surface sample, so as to obtain shear response data of the rock-like joint structure surface sample; and analyzing the shear response data to obtain the shear resistance characteristic result of the rock-like joint structure surface sample. According to the application scheme, the shear behavior of the rough joint structure surface under the non-uniform load condition can be quantified, reconstructed and mechanically characterized with spatial resolution.

The utility model discloses a combined large direct shear test device for a reinforced hot melt pile-soil interface under a curing condition, and relates to a direct shear device. The utility model aims to solve the technical problem that the influence of the lime curing age on the mechanical property of the reinforced hot melt pile-rib-soil interface is difficult to research at present. Through the design of the shear box and the inner sleeve box, the test piece can be molded and cured in the inner sleeve box, so that the shear test piece does not need to be demolded and cured after being molded, and disturbance damage to an interface in the demolding and remold processes of the test piece is prevented; the maintenance test piece is independently stored and maintained in the inner sleeve box to the target maintenance time and then assembled with the shear box, maintenance of a large batch of direct shear test pieces can be carried out at the same time, the number of needed shear boxes is reduced, meanwhile, the inner sleeve box is made of organic glass materials, the weight of a maintenance test piece mold is greatly reduced, operation is easy and convenient, and cost is low. During loading, the inner sleeve box and the shear box are spliced and then integrally shear, so that the strength requirement of the shear box can be met.

The invention discloses a shear test and simulation analysis method for a jointed rock mass containing a weak intercalated layer, relates to the technical field of underground engineering tests, and realizes accurate and efficient characterization of shear deformation and failure mechanisms of the jointed rock mass containing the weak intercalated layer. The method comprises the following steps: calibrating mesoscopic parameters of a fault mud geometric model according to a standard fault mud test shear stress displacement curve of a standard fault mud material in a direct shear test, determining mesoscopic parameters of a split rock geometric model according to a rock test shear stress displacement curve obtained by carrying out a variable-angle shear test on a complete rock, and calculating a split rock geometric model according to the mesoscopic parameters of the split rock geometric model. On the basis of the microscopic parameters calibrated by the two, according to a test shear stress displacement curve of the mud-clamping sample obtained by carrying out a variable-angle shear test on the jointed rock mass sample containing the weak intercalated layer, the microscopic parameters of the structural surface model in the geometric model of the mud-clamping sample are calibrated, and a mud-clamping sample model is obtained; and representing the shear deformation and failure mechanism of the jointed rock mass containing the weak intercalated layer according to the mud sample model.

This invention discloses a direct shear device and method for geotechnical testing. The direct shear device for geotechnical testing includes: a lower shear box with a groove on its top corresponding to the soil sample; an upper shear box placed on top of the lower shear box, with a first through hole on the upper shear box corresponding to the soil sample and engaging with the groove, the first through hole and the groove forming a top opening for accommodating the soil sample; and a limiting structure disposed between the lower and upper shear boxes, the limiting structure only restricting the upward movement of the upper shear box relative to the lower shear box and capable of releasing the restriction on the upper shear box. The above-mentioned direct shear device for geotechnical testing can selectively restrict the upward movement of the upper shear box relative to the lower shear box, thereby enabling selective direct shear tests with or without a fixed shear surface, which is beneficial for increasing the experimental data obtained during the direct shear test.

This invention relates to the field of building material testing equipment technology, specifically disclosing a direct shear test device for contact between surrounding rock and cylindrical concrete. The device includes a pull-out machine, a test platform, and a rigid cylinder. The rigid cylinder is fixedly mounted on the test platform. A pressure gauge is installed outside the rigid cylinder. Inside the rigid cylinder, from the outside in, are arranged an annular airbag, a surrounding rock placement chamber, and a concrete specimen placement chamber. The annular airbag has inflation and deflation holes for adjusting the air pressure. Surrounding rock, composed of two semi-annular rock units joined together with a gap between them, is placed in the surrounding rock placement chamber. A cylindrical concrete specimen is placed in the concrete specimen placement chamber, forming a full-surface contact between the concrete specimen and the surrounding rock. The top of the cylindrical concrete specimen is connected to the pull-out machine via a universal joint. Using this device for full-surface contact testing can visually demonstrate the changing trend of frictional resistance.

The invention discloses a soil-diaphragm wall contact surface direct shear test sample preparation device and a direct shear test method.According to the sample preparation device, a lower sample box, water-permeable geotextile and a water-permeable plate are combined to form a soil sample saturation assembly, and a base, a pressure chamber and a top plate are combined to form a closed space for soil sample saturation; a water inlet / outlet channel between the second through hole in the side surface of the pressure chamber and the lower sample box is formed by the water guide bracket; a top plate, a lower sample box, a shearing lamination and an upper sample box are combined to form a pressurizing assembly, and a third through hole in the top plate is used for vacuumizing in a soil sample saturation stage and pressurizing in slurry permeation and solidification and concrete pressurizing; and the top plate is dismounted during concrete pouring and is mounted back after pouring. According to the invention, the flow of diaphragm wall construction by the slurry protection wall grooving construction process can be truly reproduced, the influence of the construction process on contact surface mud cake formation is finely simulated, and the mud cake formation process under different pressures and the influence of the mud cake formation process on the contact surface mechanical properties are accurately simulated.