215 results about "Triaxial compression" patented technology

The invention relates to a device and a method for measurement, in particular to the method for calculating the mechanical properties of a series of rock sample materials by recording relationships between testing forces/loads and indentation depths/displacements at different moments. The device comprises a rack, a DC motor, displacement measurers, a rigid flat-bottom pressure head and a sample fixing station, wherein the rack is divided into two layers; the upper layer of the rack is provided with the DC motor of which one end is connected with the rigid flat-bottom pressure head; the displacement measurers are distributed about the rigid flat-bottom pressure head; and the sample fixing station is fixed on a base of the lower layer of the rack. The reliability and effectiveness of the method can be evaluated by comparing basic rock mechanical property measurement results with those obtained by other conventional testing means. In addition, compared with conventional mechanical test methods such as single-pressing tests, single-pulling tests, triaxial compression tests and the like in laboratories, the method has the advantages of short test process, simplicity and convenience of operation, low requirements on samples, economy and the like.

The invention relates to a dynamically-disturbed low-temperature rock triaxial loading and unloading rheometer and test method. The rheometer comprises a dynamic disturbance system, a frame, a guide rail, a lifting mechanism, a pressure chamber, a trolley, a temperature control system, an axial loading system, a confining pressure loading system, a measuring system, a control system and a computer and software system, a loading cylinder in the axial loading system can switch between a lead screw booster and a servo valve through a switching valve, a servo oil source, a servo valve and a loading cylinder are communicated through the switching valve when a conventional triaxial compression test is performed, the lead screw booster is communicated with the loading cylinder through the switching valve when a triaxial rheological test is performed, and rock samples are subjected to dynamic disturbance by the aid of a weight dynamic disturbance system or an impacting cylinder disturbance system. The rheometer effectively achieves rock triaxial loading and unloading rheological tests and conventional triaxial compression tests under the conditions of negative temperature and dynamic disturbance and is simple in integral structure principle, variable in function and high in applicability.

The invention provides a triaxial compression rheological test system capable of simulating an engineering geological environment, belonging to rock material compression experimental facilities. The remarkable characteristics of the invention are as follows: a test chamber in the triaxial compression rheological test system capable of simulating the engineering geological environment can depend on a normal rheological compression test device to realize the analogue simulation of the variations of a temperature field, a humidity field and a chemical field in the engineering geological environment by utilizing a humidifier, a heater and a fluid tank. The device fundamentally solves the problems of larger deviation of rock mechanics parameters obtained by a laboratory test and a field in-situ test and analogue simulation of a geotechnical wall-rock multi-field coupling environment. The test system has compact structure and low cost, is rather easy to install and dismount test pieces, detectors, pipelines and lead wires, and has stronger adaptability on the test pieces with different lithologies and sizes, thereby providing a set of complete technology and means for the study on the mechanical behavior of the wall-rock stability under a complex engineering geological condition.

The invention discloses a multifunctional true triaxial rock creepmeter, comprising a base, a test piece mounting base arranged on the base, two groups of horizontal direction stress loading systems with the same structure, a vertical direction stress loading system and a creep data measuring system. The multifunctional true triaxial rock creepmeter disclosed by the invention can carry out a single-axis pulling and pressing creep test and also can carry out a true triaxial compression, pulling and pressing combined creep and unloading-creep test which simulates three-dimensional stress state and loading and unloading stress path of a natural geological rock mass and an engineering rock mass and maintain tension stress states in one or two directions unloaded to the rock; and test function is more comprehensive, practicability is stronger, and a pulling and pressing combined creep and stable pressing and pulling stress conversion unloading-creep test is realized; a pull pressure loading system can provide a pressure which is high enough to meet creep test requirements of most rock materials, and a long-term constant load can be provided; and the multifunctional true triaxial rock creepmeter disclosed by the invention has the characteristics of having a simpler structure, hardly consuming energy source in a test process and having low test cost.

The invention discloses a design method for property parameters of anti-collapse drilling fluid for fractured formations. According to sequence, the design method includes the following steps: core samples are prepared; four of the core samples are chosen for a triaxial compression test and an acoustic emission test, and the crustal stress of a formation owning the core samples is determined; two of the core samples are chosen for the triaxial compression test, and the cohesion and internal friction angle of the weak planes of the rocks are tested; eight of the core samples are chosen to be put into the drilling fluid, the triaxial compression test is carried out after the core samples are soaked for different times, and the cohesion and internal friction angle of the weak planes of the rocks are tested; the cohesion and internal friction angle of the weak planes of the rocks are respectively linearly fitted to soaking times; the fluid-solid coupling theory is utilized to create a fractured formation well surrounding rock stress distribution model; the elastic mechanics coordinate transformation theory is utilized to create a fractured formation weak plane destruction model; a relation chart between the property parameters of the drilling fluid is determined. The design method disclosed by the invention can quantitatively optimize the key property parameters of the drilling fluid according the requirement of a site for well wall stability.

The invention discloses a method for forecasting a weak plane formation collapse pressure equal yield density window. The method sequentially includes the steps: dividing a weak plane formation into a compact section and a crack section according to characteristics of the weak plane formation; testing the strength of a rock body and the strength of a weak plane of a rock by the aid of the triaxial compression test of the rock; inverting stress distribution and pore pressure distribution of surrounding rocks of a compact formation well by the aid of a fluid-solid coupling model, and determining the lower limit of the collapse pressure equal yield density of a compact formation according to Mohr-coulomb failure criteria; analyzing the failure state of the surrounding rocks of the weak plane formation well according to the rock weak plane failure criteria, and determining the lower limit and the upper limit of the collapse pressure equal yield density window of a crack formation; building a weak plane formation collapse pressure equal yield density window calculation model, substituting parameter values into the model and then determining the weak plane formation collapse pressure equal yield density window. The weak plane formation collapse pressure equal yield density window can be forecasted before drilling, so that drilling fluid density is reasonably selected, and wellbore instability is effectively stopped.

The invention belongs to the technical field of rock and soil mechanics, and relates to a true triaxial test device for combustible ice sediments. According to the true triaxial test device, the formation process of the combustible ice sediments in a deep sea reservoir stratum can be simulated in a laboratory, a true triaxial compression test is carried out on the combustible ice sediments, and therefore a technical guarantee and support are provided for accurately predicting the strength characteristics of the reservoir stratum and researching the constitutive relation of the reservoir stratum; and in the true triaxial compression test, main stress in three directions can be applied independently, the real stress characteristics of the combustible ice sediments in a bottom layer can be better reflected, but the boundary loading condition problem can be easily caused in the loading process, composite loading plates of rigid plates and deformation plates are adopted in the front-and-back pressurization direction, so that the pressure can be uniformly loaded on a sample through the composite loading plates in the front-back pressurization process, and therefore the problems that mutual interference of loading plates in three-directional loading is caused in the loading process, and loading is not uniform due to the fact that the sample is deformed in the loading expansion processcan be solved.

The invention discloses a construction method for a rock freeze-thaw damage constitutive model under the action of constant confining pressure. Based on a popularized strain equivalence principle, taking the joint action of two damage factors (freeze-thaw cycle and load) into consideration, the invention proposes an expression of a total damage variable. If the strength of a rock element body is subject to Weibull distribution, on the basis of a D-P failure criterion and geometrical conditions at peak points of a rock stress-strain curve, an expression of a random distribution variable F, a distribution parameter m and F0 is obtained, and a rock freeze-thaw damage constitutive model under the action of constant confining pressure is created. A triaxial compression experiment is carried out on a rock under the action of freeze-thaw cycle, and the experiment verifies the rationality of the model. The method disclosed by the invention is a method combined with theoretical derivation and experimental verification. The theoretical curve of the rock damage constitutive model created by the method is identical with the experimental curve, the mechanical behaviors of a rock under various confining pressures and freeze-thaw cycle numbers can be perfectly reflected, and a theoretical guidance is provided for designs and construction of cold-region projects.

The invention discloses a numerical simulation analysis method for the deformation of a soft soil deep foundation pit. The numerical simulation analysis method comprises the following steps: firstly taking soft soil to carry out a triaxial compression creep experiment in a laboratory before the excavation of the foundation pit, obtaining time hardening model creep parameters of the soft soil through STATISTIC software fitting, in the design stage of the foundation pit, applying large finite element software ABAQUS to build a finite element model, building the influence at the simulation infinity of an infinite element on the excavation of the foundation pit around the model, and obtaining the earth excavation manner and the excavation time of the foundation pit as well as the influence rule of a construction gap for stress and deformation of the foundation pit through analog computation. In the design stage, the construction parameters of the foundation pit, particularly the three important parameters such as earth excavation manner, earth excavation time and construction gap, can be optimally designed. Through the optimization of the three parameters, the deformation and support shaft force of the foundation pit can be effectively reduced, and then the safety coefficient of the foundation pit is increased.

The invention discloses an improved method for carrying out rock shearing test by using a rock triaxial compression apparatus. An assembled die adopted for test of the rock triaxial compression apparatus comprises a jack pressure head (1), a pressure chamber (2), a pair of rigid stepped cylindrical base plates (5) and a pair of flexible semi-cylinder base plates (6). The assembled die adopted by the invention inherits the advantages of rock triaxial compression test, and steady confining pressure is provided for a rock sample (3) by the pressure chamber (2); according to axial force exerted when a rock sample is damaged and in combination with the elasticity modulus E1 of the rigid stepped cylindrical base plates and the elasticity modulus E2 of the flexible semi-cylinder base plates, pressures F1 and F4 applied by the two rigid stepped cylindrical base plates to the rock sample and pressures F2 and F3 applied by the two flexible semi-cylinder base plates to the rock sample can be computed, so as to further determine the shearing force delta F on the shearing surface of the rock; the shear strength of the rock can be obtained according to the relation between the shearing force and the shearing area on the shearing surface, so that a triaxial tester can be directly used for measuring the shear strength of the rock.

The invention provides a rock brittleness evaluation method based on a stress strain curve and a scratch test. The method comprises the following steps that: evaluating rock from a crustal stress environment where the rock is positioned, and pore pressure, and obtaining the stratum condition of the rock; selecting a rock mechanical experiment of the environment where a rock sample to be tested ispositioned, wherein the experiment includes a conventional triaxial compression test or a triaxial compression test which considers pore pressure, and a scratch test; obtaining a pre-peak strain energy density value, a crack initiation stress value, a peak value stress value, a residual stress value as well as corresponding strain size and crack linear density; and determining the value range of an effective stress coefficient [Alpha] from the pore pressure of a tested rock sample, and substituting the pre-peak strain energy density value, the crack initiation stress value, the peak value stress value, the residual stress value as well as the corresponding strain size and crack linear density into a brittleness index calculation formula to obtain the brittleness index of the rock to be tested. By use of the brittleness evaluation method, the accuracy and the applicability of the rock brittleness evaluation can be improved.

The invention provides a rock damage prediction method based on acoustic emission source dominant frequency uniqueness. The rock damage prediction method comprises the steps of preparation of a standard rock test piece, acoustic emission source positioning, acoustic emission source type identification, calculation of acoustic emission dominant frequencies corresponding to different types of sources and rock damage prediction. According to the method, the defects of wide acoustic emission main frequency band and non-obvious acoustic emission main frequency characteristics of an existing rock damage prediction method based on acoustic emission main frequency characteristics are overcome. The method is suitable for predicting rock damage in Brazilian splitting tests, shearing tests and creeptests under uniaxial and triaxial compression conditions.

The invention relates to a squeeze head used for a rock conventional triaxial test acoustic emission test and belongs to the technical field of geotechnical engineering. The squeeze head comprises an upper squeeze head and a lower squeeze head, wherein the upper squeeze head and the lower squeeze head are arranged on a rock message delivery system (MTS) conventional triaxial compression test machine. Round grooves are formed in the lower end face of the upper squeeze head and the upper end face of the lower squeeze head. Two perpendicular installation holes are symmetrically formed in the bottom of each round groove. Perpendicular conductor holes are formed in bottoms of the installation holes. Horizontal conductor holes are formed in side walls of the upper squeeze head and the lower squeeze head, and the perpendicular conductor holes are communicated with the horizontal conductor holes. Springs are arranged at the bottoms of the installation holes. Cover plates are arranged on the round grooves and shapes and sizes of the cover plates are identical to shapes and sizes of the round grooves. By means of the squeeze head used for the rock conventional triaxial acoustic emission test, attenuation and distortion of emission signals can be reduced to the maximum extent, the situation that an acoustic emission sensor is immersed in hydraulic oil is avoided, the acoustic emission test of high confining pressure can be carried out and the facture surface of rock can be positioned.

The invention discloses a multifunctional unsaturated soil consolidation apparatus and a test method, belonging to the field of geotechnical testing instruments. A thrust bearing, a linear bearing, a self-aligning assembly and an axial pressure sensor are arranged on a loading rod of a consolidation apparatus test platform in a built-in mode, so that the influence of friction force is eliminated during loading; and unnecessary pre-compression on a sample is reduced due to the design of a rotary rigid connection assembly, and the problem that the loading rod and the sample are eccentric due to machining and mounting is solved by virtue of the design of the self-aligning assembly. Meanwhile, according to the optimization design of the structure, the apparatus can be adaptive to multiple loading platforms, and the test can be performed on a conventional saturated soil consolidation apparatus and also can be performed on a triaxial compression tester.

The invention provides an elastoplastic constitutive model of steel fiber reinforced concrete considering fiber slippage. The elastoplastic constitutive model of the steel fiber reinforced concrete is characterized in that the model is as shown in the following formula. According to the elastoplastic constitutive model of the steel fiber reinforced concrete considering fiber slippage disclosed by the invention, composite material mixing theories are used, and steel fiber and matrix concrete constitutive equations are respectively obtained based on a thermodynamic dissipation inequation. Matrix concrete is the elastoplastic constitutive model, and steel fibers are one-dimensional elastic constitutive models considering fiber interface slippage. The plasticity of the matrix concrete adopts Hsieh-Ting-Chen four-parameter yield criteria and Drucker-Prager classic plastic flow rules, and plastic hardening/softening criteria adopt a modified Guo Zhenhai model. The parameters of the steel fiber one-dimensional elastic constitutive model considering an interface are determined through a steel fiber pullout test. The parameters of the concrete elastoplastic constitutive model can be calibrated by uniaxial and true three-axial compression tests. The model considers a steel fiber slip mechanism in the meso-scale, and combines elastic constitutive structures of the ordinary concrete and the steel fibers to construct the elastoplastic constitutive model of the steel fiber reinforced concrete, thereby being simple and feasible, and having important promoting significance to basic theoretical research of the fiber reinforced concrete.