116 results about "Axial strain" patented technology

The invention is suitable for the technical field of automobile fuel injection nozzle forging, and particularly relates to an automobile fuel injection nozzle forge piece forging method and equipment. The method comprises the steps that metal flow resistance, metal flow speed, forging vibration data and lateral force are obtained; determining a target flow velocity based on the metal flow resistance, the metal flow velocity and the forging vibration data; determining an axial strain coefficient and a radial strain coefficient based on the metal flow resistance, the metal flow velocity, the forging vibration data and the lateral force; based on the axial strain coefficient and the target flow velocity, generating a sliding block control instruction, and based on the radial strain coefficient, generating an ejector rod control instruction; and according to the sliding block control instruction and the ejector rod control instruction, a forging and pressing device and a hydraulic device are controlled to forge the automobile oil nozzle forge piece. According to the method, the forge piece forming precision, the production efficiency and the intelligence and automation level of the forging process can be remarkably improved.

The invention discloses an optical fiber three-dimensional shape sensor based on an optical frequency domain reflection technology and an application method of the optical fiber three-dimensional shape sensor, the optical fiber three-dimensional shape sensor comprises a base material and more than three optical fibers, and all the optical fibers are spirally wound and fixed on the surface of the base material at equal intervals and constant screw pitches to form distributed sensing units; according to the application method, measurement signals of all the optical fibers are obtained, and axial strain and strain are calculated; calculating the total curvature vector of the reconstruction curve of the measured object; calculating a bending direction angle and a curvature of the reconstruction curve of the measured object; performing differential calculation on the bending direction angle to obtain the torsion rate of the reconstructed curve of the measured object; and reconstructing the three-dimensional shape of the measured object according to the curvature and the torsion of the reconstructed curve of the measured object. The invention aims to realize synchronous measurement of bending, torsion and axial strain by using a distributed sensing unit formed by a multi-fiber structure which is spirally wound at the same interval and at a constant screw pitch.

The invention discloses a method and system for analyzing the rolling resistance of a concrete-filled steel tube combined pier column, and the method comprises the steps: applying an axial compression load to the concrete-filled steel tube combined pier column, and dividing the cross section of the concrete-filled steel tube combined pier column into three layers of regions along a radial material change part; according to corresponding total cross-section average axial strain generated by the steel pipe concrete combined pier column when different axial compression loads are applied, equivalent stress corresponding to each layer of area is calculated, total axial force corresponding to each total cross-section average axial strain is calculated, and a total cross-section average axial strain-total axial force curve is formed; searching a first total cross-section average axial strain corresponding to the maximum value of the total axial force in the total cross-section average axial strain-total axial force curve and a second total cross-section average axial strain corresponding to a first obvious inflection point of the total cross-section average axial strain-total axial force curve, and calculating a ductility coefficient, and judging whether the concrete-filled steel tube composite pier column meets the ductility design requirement or not.

The invention discloses a roadway roof damage time prediction method and system, and belongs to the technical field of mine rock mechanics and safety engineering. Comprising the following steps: recognizing a roof rock stratum structure and lithology of each layer through drilling peeping, and drilling a representative rock sample; determining the crack initiation strength and peak strength of the rock sample through a uniaxial compression test; selecting a plurality of stress levels between the axial strain and the acoustic emission signal to carry out a creep test, synchronously monitoring the axial strain and the acoustic emission signal, and determining an accelerated creep starting moment as the damage time under the stress according to the abrupt change characteristics of the axial strain and the acoustic emission signal; establishing a stress-failure time relation model of each lithology; finally, selecting a corresponding model to predict the damage time of rocks at different layers of the roof according to the actual rock stratum structure and ground stress state of the roadway; according to the method, accurate and reliable time prediction of the progressive damage process of the roadway roof is realized.

Provided are a method and apparatus for calibrating contact parameters of electrode materials, and a computer storage medium. The method includes the following operations. A discrete element simulation test is performed on an electrode material based on a calibration model and calibration ranges of contact parameters of the electrode material when an axial force-displacement curve of a target pellet of the electrode material meets an adaption condition of the contact model; then a simulated axial pressure-axial strain relationship of the electrode material is acquired based on a target discrete element simulation parameter of the electrode material; whether the contact parameters are calibrated successfully is judged based on this relationship; and when the contact parameters are calibrated successfully, calibration results of the contact parameters are determined.

The invention relates to the technical field of nickel alloy pipe water pressure detection, and discloses a thin-wall nickel alloy pipe inner wall water pressure test detection system and method. The method comprises the steps that a closed water pressure environment is established in a pipe, a preset pressure gradient is applied, and pipe wall deformation response data are collected through a distributed sensing array; and generating a composite feature matrix containing axial strain, circumferential stress and radial displacement features through multi-dimensional feature extraction, inputting the composite feature matrix into a material performance degradation evaluation model, and simulating microstructure change to output a potential defect distribution map. Dynamically adjusting the water pressure gradient and the pressure maintaining time according to the map, executing a secondary water pressure test, and capturing a microscopic deformation sequence image through high-frequency imaging; comparing the image with a model prediction result identification deviation value, and iteratively updating a model parameter to optimize a detection threshold value; the test is completed by optimizing the threshold value, qualified pipe section marks and defective pipe section positioning coordinates are output, and the comprehensiveness and accuracy of thin-wall nickel alloy pipe inner wall defect detection are improved.

The invention provides a calculation method for the elastic modulus of a soil-rock mixture based on a mesoscopic structure model, relevant to the field of meso-numerical simulation of geotechnical materials. It includes the following steps: obtaining the gradation curve of soil-rock mixture particles through a screening test and constructing a two-dimensional random meso-structure model of the mixture with varying stone contents. Using the finite element method, a biaxial compression numerical test is conducted on the model under different stone contents and confining pressures. The equivalent elastic modulus of the mixture is determined by the corresponding secant elastic modulus at an axial strain of 1%. This macro-equivalent elastic modulus, considering stone content and confining pressure, is then fitted. This method effectively addresses the challenge of presenting accurate physical and mechanical parameters in engineering design and construction, making it directly applicable to practical engineering involving soil-rock mixture materials.

This application relates to the field of automotive fuel injector forging technology, and particularly to a forging method and equipment for automotive fuel injector forgings. The method includes: acquiring metal flow resistance, metal flow velocity, forging vibration data, and lateral force; determining a target flow velocity based on the metal flow resistance, metal flow velocity, and forging vibration data; determining axial strain coefficient and radial strain coefficient based on the metal flow resistance, metal flow velocity, forging vibration data, and lateral force; generating a slider control command based on the axial strain coefficient and the target flow velocity, and generating a push rod control command based on the radial strain coefficient; and controlling a forging device and a hydraulic device to forge the automotive fuel injector forging according to the slider control command and the push rod control command, respectively. This method can significantly improve the forging accuracy, production efficiency, and the level of intelligence and automation in the forging process.

The invention provides a rock strain softening constitutive model construction method, and relates to the field of rock mechanics, the method comprises the following steps: determining an actually measured rock axial stress-axial strain curve to be fitted; dividing a post-peak strain softening curve of the axial stress-axial strain curve of the rock into j sections according to engineering requirements; the axial stress and the axial strain of the peak intensity are recorded as the sum, and the axial stress and the axial strain at the right end point of each segment divided into the j segments are recorded as the sum; calculating to obtain axial cumulative plastic strain corresponding to each point; calculating cohesion corresponding to each point; and importing the axial cumulative plastic strain corresponding to each point and the cohesive force corresponding to each point into FLAC3D software in a table form to complete the construction of the rock strain softening constitutive model. According to the method, the problems that a conventional strain softening model is complex in parameter, poor in fitting with an actual test result and difficult to construct in numerical software are solved to a certain extent.

The invention relates to the technical field of combined machining, in particular to a special-shaped ring rolling process method for tooth blank die forging forming, which comprises the following steps: circularly adjusting the rotating speed of a main roller and the feeding speed of a core roller of a ring rolling device in real time according to the actual rotating angle of an annular blank, and correcting the eccentric degree of the annular blank; reflecting the matching condition of the radial strain rate and the axial strain rate according to the change of the convex part of the annular blank, adjusting a correction parameter for correcting the eccentricity degree of the annular blank, and adjusting the holding roller compression rate of the rolling ring device to make up the change of the length of the convex part; estimating the required torque of the main roller and the maximum static friction, and judging whether the eccentricity of the corrected annular blank can cause the required torque of the main roller to exceed the limit or not; when the required torque of the main roller exceeds the limit, the adjusting amplitude of the rotating speed of the main roller and the feeding speed of the core roller is reduced, and the judgment standard for judging whether the eccentricity degree of the annular blank can be corrected or not is called back. The forming uniformity of the non-standard annular special-shaped tooth blank is improved by combining die forging with ring rolling.

The application relates to a kind of high strain rate under fiber concrete material dynamic axial tensile performance test method, comprising: setting Hopkinson tensile rod device, using the verified Hopkinson tensile rod device to pulse wave is applied to test piece, and the deformation of resistance strain gauge is collected;The deformation is converted into voltage signal, for calculating the strain of resistance strain gauge and the average compressive stress of test piece;Based on strain and average compressive stress, determine the dynamic tensile stress-strain relationship of test piece, according to the dynamic tensile stress-strain relationship of test piece, the dynamic tensile stress time history and dynamic axial strain time history are point by point corresponding pairing on time axis, and the dynamic tensile stress-strain curve of test piece under high strain rate is obtained.The application can make the performance test of fiber concrete and other materials under high strain rate more easily realized, provide the basis for the dynamic performance characterization of material, help the application and popularization of high-performance materials under extreme working conditions such as explosion impact.

The present invention discloses a pipeline leakage prediction method and system, belonging to the technical field of pipeline leakage monitoring. The present invention predicts leakage for buried pipelines that have not yet leaked. By establishing a corresponding relationship between the depth of the corrosion pit and the axial strain of the pipeline outer wall, and with the monitoring cooperation of an optical fiber measurement system, the present invention can effectively predict the leakage location and the time when a leak will occur in the buried pipeline that has not yet leaked, thereby preventing problems before they occur, eliminating the need to wait until the pipeline leaks before taking measures, greatly reducing the risk of explosions and the like caused by pipeline leakage, and facilitating its application in pipeline transportation in the fields of oil and natural gas.

The present invention provides a state monitoring method for an ultra-high pressure cylinder, comprising monitoring the ultra-high pressure cylinder through finite strain monitoring, temperature monitoring, key phase monitoring and plunger strain test calibration; polishing the symmetrical outer surface of a pipeline near the inlet and exhaust ports of the ultra-high pressure cylinder and pasting a temperature self-compensating strain gauge to test the axial strain and axial strain of the pipeline respectively; pasting a resistive temperature sensor near the strain gauge to test the temperature change of the inlet and exhaust pipelines, calculating the increased axial strain of the pipeline after the pipeline is heated and expanded according to the temperature change of the inlet and exhaust pipelines and the equivalent material linear expansion coefficient of the ultra-high pressure pipeline, thereby obtaining the pressure change in the inlet and exhaust pipelines; pasting a temperature self-compensating strain gauge on the symmetrical outer surface of the plunger tail end to test the axial strain of the plunger when the ultra-high pressure cylinder is working; accurately identifying the PV diagram of the working process of the ultra-high pressure cylinder, and realizing online monitoring of the ultra-high pressure compressor.

The invention relates to the technical field of marine flexible riser monitoring, in particular to a marine flexible riser axial strain monitoring and verification method. The strain monitoring device comprises a corrosion-resistant pipe clamp and a stepped shaft type strain rod, a fiber bragg grating sensor is packaged on the strain rod and is fixed on a vertical pipe through a metal pipe clamp, and the strain value of the vertical pipe is calculated through the change of the central wavelength of the fiber bragg grating sensor. The strain relation between the strain of the vertical pipe and the strain rod is obtained; finite element models of the riser and the strain monitoring device are established by adopting Ansys finite element analysis software, theoretical values of riser strain are calculated, the theoretical values are compared with simulation values, the strain monitoring device shows high accuracy, the actual monitoring accuracy is as high as 90%, the actual monitoring accuracy is remarkably improved compared with a traditional mode, and the reliability of monitoring data is ensured.

The present application provides a kind of microwave rock volume change measurement system and method thereof, including test cavity, microwave control device, strain measurement device, measurement circuit and resistance strain gauge;Test cavity is sealed cavity structure, and rock test piece is placed in test cavity;Microwave control device is set to the inside of test cavity;Strain measurement device includes hoop strain gauge and axial strain gauge, and strain measurement device is attached to rock test piece surface;Measurement circuit is connected with multiple strain measurement devices by lead, and resistance strain gauge is connected with measurement circuit.In the microwave emitted by microwave control device acts on rock test piece, data acquisition is carried out to rock test piece by multiple hoop strain gauges and axial strain gauges attached to rock test piece surface, and the volume change of rock test piece can be obtained by combining measurement circuit and resistance strain gauge, so as to exclude the volume change of liquid or gas caused by temperature change, and more accurately measure the size of the influence of microwave on rock volume.

A medical probe is presented including an expandable basket assembly coupled to a distal end of a tubular shaft. The basket assembly includes a cloverleaf cutout structure at its distal end and spines extending proximally from the cloverleaf structure and coupling to the tubular shaft. The cloverleaf structure includes a sinusoidal-like member extending from one spine to an adjacent spine in a direction around the longitudinal axis. Dimensions of the sinusoidal-like member can be configured to provide a lateral stiffness of the expandable basket assembly within a predetermined range and a maximum peak stress during retraction of the expandable basket assembly into an intermediate catheter such that the maximum peak stress is less than a predetermined threshold.

The application particularly relates to a cast stainless steel multiaxial low-cycle fatigue prediction method, which comprises the following steps: measuring or calculating the axial strain amplitude and the corresponding axial stress, the shear strain amplitude and the corresponding shear stress, and the phase difference between the axial strain amplitude and the shear strain amplitude of a cast stainless steel concerned part; calculating the equivalent axial strain amplitude and the equivalent shear strain amplitude of the cast stainless steel concerned part after correction and containing the influence of thermal aging; and substituting the equivalent axial strain amplitude and the equivalent shear strain amplitude of the cast stainless steel concerned part after correction and containing the influence of thermal aging and the phase difference therebetween into a cast stainless steel multiaxial low-cycle fatigue prediction model containing the influence of thermal aging to calculate the multiaxial low-cycle fatigue life and the fatigue crack direction of the cast stainless steel after thermal aging. The cast stainless steel multiaxial low-cycle fatigue prediction method can accurately predict the fatigue life of the cast stainless steel under multiaxial low-cycle fatigue loading and the direction of fatigue crack initiation and initial propagation.

The application discloses a kind of cavity-containing bolt pre-tightening force and temperature compound sensing optical fiber sensor and method, including bolt, glue and fiber grating, the cavity, longitudinal hole and transverse through hole are equipped in bolt, two transverse through holes are arranged in the cavity both sides, longitudinal hole sequentially passes through transverse through hole and internal cavity along bolt length direction, longitudinal hole is used to lay optical fiber, one half grating area of fiber grating is suspended and arranged at the cavity, the other half grating area surface is attached with metal plating layer and then is pasted in longitudinal hole by glue, since the cavity and longitudinal hole are different in bolt cross-sectional area, when bolt is subjected to axial stretching, two sections grating area will have different axial strain;Simultaneously after metal plating layer, there will be no chirp phenomenon, and metal plating layer can change the response coefficient of grating area to temperature.The application realizes the simultaneous monitoring of bolt temperature and force signal, and obtains accurate bolt temperature and force signal according to the different sensing coefficients of two parts of fiber grating to temperature and force.

The invention provides an optical fiber shape sensing system, method, medium and equipment, in the system, a sensing unit comprises a multi-core optical fiber, the multi-core optical fiber is provided with at least three eccentrically distributed sensing cores and a central core, each sensing core is inscribed with a fiber bragg grating used for sensing axial strain caused by bending and torsion, and the central core is provided with a fiber bragg grating used for sensing the axial strain caused by bending and torsion. The central core is used for providing temperature compensation reference; the signal processing unit is used for receiving the original wavelength and strain data acquired by the sensing unit and executing filtering, temperature compensation and curvature and torsion calculation processing; and the shape reconstruction and display unit reconstructs a three-dimensional space curve through numerical integration based on the geometric parameters output by the signal processing unit, and realizes real-time visual display of a three-dimensional shape. According to the invention, high-precision and high-stability optical fiber shape sensing can be realized in a complex dynamic scene, and application requirements of complex scenes such as medical catheter navigation and flexible robot control can be met.

The invention provides a multi-source data fusion prestressed structure health monitoring and early warning method, and relates to the technical field of constructional engineering structure health monitoring, and the method comprises the steps: carrying out the processing of a self-adaptive weighted data fusion model based on monitoring data obtained by a sensor, so as to output a prestressed comprehensive loss rate, the monitoring data comprises axial strain field data of the steel strand, and displacement and tensioning force of an anchorage device clamping piece; based on the historical sequence, an LSTM prediction model is improved to output a future trend prediction value; based on the future trend prediction value, the prestress comprehensive loss rate, the anchorage device clamping piece displacement and the tensioning force, performing evaluation through a failure probability model based on a fuzzy Petr network to obtain a real-time failure probability; and comparing and judging the future trend prediction value and the real-time failure probability with a preset threshold value to generate early warning information.

The invention relates to the technical field of rail shape monitoring, in particular to a rail deformation sensing method and device based on a flat-ribbon optical cable. The device is characterized by comprising a bandlet optical cable, a conduction optical fiber, a demodulator and a computer, a fiber bragg grating array which is weak in reflectivity, determined in grating distance and capable of being calibrated in position is accurately inscribed in two optical fibers in the flat-ribbon optical cable, interference of temperature fluctuation and axial strain is effectively eliminated through double-optical-fiber cooperative measurement and differential calculation, and when a rail is subjected to sedimentation or bending deformation under the action of train loads and environmental factors, the fiber bragg grating array is accurately inscribed in the flat-ribbon optical cable. Deformation is synchronously transmitted to the bandlet optical cable and causes the wavelength change of the reflection center of each fiber bragg grating, a wavelength change signal is transmitted to the demodulator through the conduction optical fiber to be demodulated in real time and output to the computer, and the computer is based on a wavelength-strain-curvature mapping relation and combines a Freen-Serret shape reconstruction and vertex error correction algorithm. The spatial shape reconstruction of the rail is realized, and the settlement height change is output, so that the real-time, continuous and visual monitoring of the settlement process of the rail is realized. The method is suitable for the technical field of rail deformation and settlement monitoring.

The present application relates to the technical field of tunnel construction, and particularly relates to a pile foundation response test method under a double-line tunnel shield side-penetration working condition. Residual strain is obtained after the first tunneling body passes and rests until the end, and the stiffness attenuation rate at each depth is calculated according to the attenuation linkage ratio; when the second tunneling body passes from the other side, the cumulative axial strain and the cumulative hoop strain are obtained by merging the stiffness attenuation rate as the weight, the real-time axial and hoop strain and the residual strain at each depth, and the cumulative plastic strain, the cumulative settlement and the bottom interface stiffness are calculated accordingly, so that the quantitative characterization of the pile body deformation and the internal force distribution evolution law in the whole double-line construction process is realized.

The invention provides a nondestructive testing system and method for the bearing capacity of an uplift pile, and the system comprises a strain sensing unit which comprises a distributed annular fiber grating array disposed on a target uplift pile and is used for detecting the strain information of the target uplift pile on the whole pile length; the displacement monitoring unit comprises an MEMS inclinometer and a laser range finder which are arranged at the top of the pile, and an LVDT displacement meter pre-embedded in a pile-soil interface, and is used for synchronously monitoring absolute displacement and relative slippage of the target uplift pile; and the processor unit is used for carrying out inversion calculation on the bearing capacity of the target uplift pile by adopting an FPGA accelerated LSTM-GRU hybrid neural network based on the strain information, the absolute displacement and the relative slippage. According to the method, the differential coupling model of the axial strain of the pile body, the relative displacement of the pile soil and the side friction resistance is established, accurate mapping from the distributed optical fiber strain to the bearing capacity subitem index is achieved, therefore, the nondestructive testing target is achieved, the detection cost is low, and the detection accuracy and reliability are high.

The present application relates to the technical field of nickel alloy pipe water pressure detection, and discloses a thin-walled nickel alloy pipe inner wall hydraulic test detection system and method. The method comprises establishing a closed water pressure environment in the pipe and applying a preset pressure gradient, collecting pipe wall deformation response data through a distributed sensing array; generating a composite feature matrix containing axial strain, circumferential stress and radial displacement features through multi-dimensional feature extraction, inputting a material performance degradation evaluation model, simulating microstructure changes to output a potential defect distribution map. The water pressure gradient and pressure holding time are dynamically adjusted according to the map, a second hydraulic test is performed, and micro-deformation sequence images are captured through high-frequency imaging; the deviation amount is identified by comparing the images with the model prediction results, the model parameters are iteratively updated to optimize the detection threshold; the test is completed using the optimized threshold, and the qualified pipe section marker and defect pipe section positioning coordinates are output, thereby improving the comprehensiveness and accuracy of thin-walled nickel alloy pipe inner wall defect detection.

The invention discloses an axial strain rate field simulation method of a distributed optical fiber DAS-VSP based on strain tensor projection under a non-vertical well layout condition, and belongs to the field of exploration. Aiming at the problem that a traditional vertical well simulation method is difficult to accurately simulate wave field propagation characteristics in a curved well trajectory, high-precision wave field simulation under a non-vertical well type condition is realized by establishing a parameterized well trajectory model based on a curvilinear function and combining a first-order speed-stress elastic wave equation and a finite difference algorithm. A tangential direction projection algorithm is introduced to convert a velocity field into optical fiber axial strain rate response, and a dynamic scale distance segmentation method is adopted to truly simulate the spatial sampling characteristics of an actual DAS system. By constructing PML absorption boundary conditions and a stability control mechanism, the numerical stability of highly-deviated well section wave field simulation is ensured. According to the method, a reliable numerical experiment method is provided for DAS-VSP data interpretation and forward modeling under the non-straight well type condition, and important technical support is provided for non-straight well optical fiber earthquake monitoring in oil-gas exploration.

The invention relates to the technical field of tunnel monitoring, and discloses a device and method for monitoring deformation of an existing subway interval tunnel caused by pipe-jacking construction, and the device comprises an optical fiber which is laid on the arc surface of the inner wall of the tunnel in a snake-shaped wave shape, and the optical fiber is spread towards the two sides with the top of the tunnel as the center. And bending back and forth between the left and right side walls while extending longitudinally along the tunnel, so that the crest part is positioned on one side wall of the tunnel, the trough part is positioned on the other side wall of the tunnel, and the crest part and the trough part are flush in height in the cross section of the tunnel. The optical fiber is laid on the arc surface of the inner wall of the tunnel in a snakelike wave shape, radial deformation of the section of the tunnel is converted into axial strain of the optical fiber through wave geometry, and meanwhile the optical fiber extends in the longitudinal direction and can also sense longitudinal differential settlement.

The invention discloses a submarine cable temperature stress state simulation experiment device and method. The device integrates an optical fiber coil assembly, a temperature displacement simulation box, a stretching mechanism, a wave making circulation cavity and a distributed optical fiber sensing system. The same submarine cable sample is subjected to adjustable temperature in a temperature control bath, axial strain is applied and measured by a stretching mechanism, a wave making circulation cavity reproduces periodic / aperiodic ocean current impact through a wave making plate, a driving paddle and a wave suppression grid, temperature, strain and flow field multivariable synchronous or independent loading is achieved, a distributed optical fiber sensing system obtains Brillouin frequency shift of the same section, and the Brillouin frequency shift is subjected to temperature control. And calibrating temperature and strain coefficients. The problem of signal aliasing errors caused by the fact that an existing experimental device can only test in a single-variable and segmented mode is solved, and the reliability and precision of submarine cable temperature stress monitoring by the BOTDR are improved.

This invention discloses a uniaxial acceleration sensing chip based on a pure axial strain beam and its operating method. Each sensitive beam has a force-sensitive resistor. The inner frame of the fixed frame is rectangular, and all vibration units are identical and sequentially arranged at the four corners of the inner frame. A groove is provided on the mass block for the movement of the support beam. One end of the support beam is fixedly connected to a corner of the inner frame, and the other end is connected to the bottom of the groove on the mass block. Sensitive beams are arranged between the two adjacent sides of the mass blocks of the first and second vibration units; sensitive beams are also arranged between the two adjacent sides of the mass blocks of the third and fourth vibration units; all sensitive beams are parallel to each other. This invention can produce the effect of pure axial tension or compression of the sensitive beam. Furthermore, this significantly reduces the overall stiffness of the movable structure of the chip in a small size, allowing the sensitive core to still have good sensitivity and high bandwidth characteristics even in a small size.

This invention relates to a time-varying evolution inversion method for fracture morphology, net pressure, and minimum geostress, belonging to the field of petroleum technology. The method includes: acquiring on-site bottomhole pressure data, monitoring well information, and LF-DAS data during fracturing operations; discretizing the fracture along its length into several units based on the three-dimensional displacement discontinuity method and constructing a net pressure distribution matrix; using a pre-constructed mechanical response relationship between net pressure and fracture width distribution to solve for the fracture width distribution corresponding to the current net pressure distribution; calculating the axial strain response of the fracture at the monitoring well based on the fracture width distribution to form a forward model for pressure-fracture width-strain solution; iteratively updating the fracture half-length and net pressure using the least squares method, constructing a residual between the inverted strain and the on-site strain to minimize the residual, and obtaining the time-varying inversion results for the fracture half-length and net pressure. The time-varying evolution process of minimum geostress can be characterized by the difference between the on-site bottomhole pressure and the inverted net pressure.

The present invention proposes a method and system for predicting the loading deformation of overburden foundation sand and gravel materials. The method includes conducting triaxial shear tests on graded, formed sand and gravel samples to obtain axial strain, volumetric strain, and deviatoric stress; establishing a tangent elastic modulus relationship for material strain softening based on the deviatoric stress and axial strain; calculating lateral strain based on the axial strain and volumetric strain, and establishing a Poisson's ratio relationship for the material's dilatancy properties based on the lateral strain and axial strain; constructing a constitutive model based on the tangent elastic modulus relationship and the Poisson's ratio relationship; and using the constitutive model to predict simulated data of the overburden foundation sand and gravel material, predicting how the deviatoric stress and volumetric strain change with the axial strain during loading, to obtain prediction results. This method effectively predicts the loading deformation characteristics of overburden foundation sand and gravel materials, minimizing the deviation between the predicted and actual results.