A multi-field coupling geotechnical shear strength test method and system

Abstract

The present application relates to the technical field of geotechnical mechanics test, in particular to a multi-field coupling geotechnical shear strength test method and system. The method comprises the following steps: synchronously applying coupling effects of rainfall, temperature change and freeze-thaw cycle to a geotechnical sample according to a preset test path, collecting temperature data and complex impedance data of multiple sampling nodes along the axial direction of the sample in real time during the coupling process; based on the temperature data and complex impedance data, analyzing the coupling relationship and topological persistence of spatial mutation strength through the axial temperature gradient and the phase transition complex impedance gradient, and determining the real-time position of the freezing front; calculating the migration speed of the freezing front using the freezing front position, and determining whether the freezing front enters the stable phase transition stage according to the stability of the freezing depth ratio and the migration speed; after determining that the freezing front enters the stable phase transition stage, applying a perturbation horizontal displacement to the sample and measuring the corresponding shear resistance to obtain the real-time shear strength under the coupling effect.

Description

Technical Field

[0001] This invention relates to the field of geotechnical mechanics testing technology, specifically to a multi-field coupled method and system for testing the shear strength of soil and rock masses. Background Technology

[0002] In cold-region engineering projects, seasonally frozen soil areas, and regions with complex climate conditions, the stability of soil and rock structures such as roadbeds, slopes, and foundations is constantly affected by the coupled effects of multiple environmental factors, including rainfall, temperature changes, and freeze-thaw cycles. These factors do not act independently but interact and couple with each other, forming a complex multi-physical field environment of water, heat, and force (including salinity), which together cause the soil and rock mass to weaken, deform, or even suffer catastrophic damage.

[0003] Rainfall infiltration alters soil moisture content, freezing temperatures trigger frost heave, and thawing leads to thaw settlement. The soil strength at the freeze-thaw interface is significantly reduced, making it highly susceptible to engineering disasters such as slope slippage and roadbed instability. Shear strength of soil and rock is a core parameter for stability assessment and design in geotechnical engineering. Accurately determining the dynamic evolution of shear strength under multi-field coupling is of significant theoretical and engineering value for revealing the disaster mechanisms in cold-region engineering and guiding disaster prevention and mitigation design.

[0004] Existing methods for testing the shear strength of soil and rock masses can only simulate the effects of a single environmental factor or can only measure static strength indicators after the test. They cannot simultaneously simulate the multi-field coupling process of rainfall, temperature, and freeze-thaw cycles, nor can they identify freeze-thaw fronts, track phase change evolution, and measure instantaneous shear strength in real time during the coupling process. As a result, they cannot truly reflect the dynamic changes in soil and rock strength under multi-field coupling, leading to significant deviations between test results and actual engineering environments. Summary of the Invention

[0005] To address the shortcomings of existing methods and the needs of practical applications, this invention provides a multi-field coupled method for testing the shear strength of soil and rock masses, comprising the following steps: Following a pre-set test path, rainfall, temperature changes, and freeze-thaw cycles are simultaneously applied to soil and rock samples. During this coupling process, temperature and complex impedance data are collected in real time at multiple sampling nodes along the sample axis. Based on these temperature and complex impedance data, the coupling relationship and topological persistence of spatial abrupt change intensity are analyzed using the axial temperature gradient and phase transition complex impedance gradient to determine the real-time location of the freezing front. The freezing front migration velocity is calculated using the location of the freezing front, and the stability of the migration velocity relative to the freezing depth is used to determine whether the freezing front has entered the stable phase transition stage. After determining that it has entered the stable phase transition stage, a micro-perturbation horizontal displacement is applied to the sample, and the corresponding shear resistance is measured to obtain the real-time shear strength under the coupling effect.

[0006] Optionally, the step of determining the real-time location of the freezing front by analyzing the coupling relationship and topological persistence of the spatial abrupt change intensity based on the temperature data and complex impedance data through the axial temperature gradient and phase transition complex impedance gradient includes the following steps: Based on the complex impedance data, calculate the phase transition complex impedance factor for each sampling node; Based on the temperature data and the phase transition complex impedance factor, the axial temperature gradient and the phase transition complex impedance gradient are calculated respectively to obtain the corresponding spatial abrupt intensity of the temperature gradient and the spatial abrupt intensity of the complex impedance gradient. The initial phase transition coupling gradient function is obtained by synchronously harmonic coupling the spatial abrupt change intensity of the temperature gradient and the spatial abrupt change intensity of the complex resistance gradient. Calculate the topological durability of the local peaks in the initial phase transition coupling gradient function, and use the topological durability to optimize the initial phase transition coupling gradient function to obtain the optimized phase transition coupling function; The location of the freezing front is determined based on the location of the maximum value of the optimized phase transition coupling function.

[0007] Optionally, the phase transition complex impedance factor satisfies:

[0008] in, This represents the phase transition complex impedance factor. Represents the real part of the resistance. Indicates the imaginary reactance. Indicates the prevention of zero constant, Indicates the sampling node index. Indicates time.

[0009] Optionally, the intensity of the spatial abrupt change in the temperature gradient satisfies:

[0010] in, Indicates the intensity of the spatial abrupt change in the temperature gradient. Indicates the axial temperature gradient. Represents temperature data. Indicates the distance between sampling nodes. Indicates the sampling node index; The intensity of the spatial abrupt change in the complex resistive gradient satisfies:

[0011] in, Indicates the spatial abrupt change strength of the complex resistive gradient. For phase transition complex impedance gradient, This represents the phase transition complex impedance factor.

[0012] Optionally, the simultaneous harmonic coupling of the spatial abrupt change intensity of the temperature gradient and the spatial abrupt change intensity of the complex impedance gradient yields an initial phase transition coupling gradient function that satisfies:

[0013] in, This represents the initial phase transition coupling gradient function. Indicates the sampling node index. Indicates time, , , Indicates the intensity of the spatial abrupt change in the temperature gradient. This represents the intensity of the spatial abrupt change in the complex resistive gradient.

[0014] Optionally, the topology persistence satisfies:

[0015] in, Indicates topological durability. This represents the initial phase transition coupling gradient function. Indicates the sampling node index. Indicates time, This indicates the lowest value in the interval traversed before the local peak extends to the left and encounters a higher peak. This indicates the lowest value in the interval through which the local peak extends to the right until it encounters a higher peak.

[0016] Optionally, the initial phase transition coupling gradient function is optimized using the topological persistence to obtain an optimized phase transition coupling function that satisfies:

[0017] in, This represents the optimized phase transition coupling function. This represents the initial phase transition coupling gradient function. Indicates topological durability. Indicates the sampling node index. Indicates time.

[0018] Optionally, determining the real-time location of the frozen front further includes: For a given sequence of freezing front locations, a Kalman dynamic smoothing model is used to process the data to obtain a smoothed continuous freezing migration trajectory.

[0019] Optionally, the determination of whether the freezing front has entered the stable phase transition stage satisfies: Freezing depth ratio Freezing stability , in, To freeze the position of the front, The height of the sample. To freeze the speed of frontal migration, and This is a preset threshold.

[0020] Secondly, to efficiently execute the multi-field coupled shear strength testing method for soil and rock provided by this invention, this invention also provides a multi-field coupled shear strength testing system for soil and rock, comprising: an input device, an output device, a processor, and a memory, wherein the input device, output device, processor, and memory are interconnected, and the memory stores program instructions for the multi-field coupled shear strength testing method for soil and rock. The multi-field coupled shear strength testing system for soil and rock of this invention has a compact structure and stable performance, and can stably execute the multi-field coupled shear strength testing method for soil and rock provided by this invention, further improving the overall applicability and practical application capability of this invention.

[0021] This invention employs programmed control to achieve automatic operation of multi-field coupling time sequence of rainfall, temperature change, and freeze-thaw cycles. It relies on synchronous acquisition of multi-point temperature and complex impedance data from the sample to construct a phase transition complex impedance factor. Combined with temperature and impedance gradient abrupt change parameters, a phase transition coupling function is formed through normalized coupling and topological durability optimization. Kalman filtering is used to smooth and eliminate data noise, accurately locating the freezing front and calculating its migration rate. The stable phase transition state of the soil is determined by dual thresholds of freezing depth ratio and front movement stability. Once the thresholds are met, low-speed micro-perturbation shearing is automatically initiated. Instantaneous shear strength is measured in real time under the premise of minimal disturbance to the original soil structure, establishing a dynamic mapping relationship between strength parameters and freeze-thaw front evolution. At the end of the experiment, a traditional destructive direct shear test is performed to complete the dynamic and static strength calibration. Compared to conventional tests that only measure static strength under single environmental conditions and after the test is completed, this invention offers multi-field testing that closely matches the actual service environment of soil and rock in cold regions. The dual-field coupling for judging the freeze-thaw interface is more resistant to interference than a single temperature criterion. It can track the dynamic evolution of soil strength during the freeze-thaw phase change process, forming an integrated closed-loop testing system that combines environmental parameters, freeze-thaw evolution, and shear strength. The data is highly accurate and can provide refined test data for the analysis of disaster prevention mechanisms and engineering design of slopes and roadbeds in cold regions. Attached Figure Description

[0022] Figure 1 A flowchart of a multi-field coupled shear strength testing method for soil and rock masses provided in this embodiment of the invention; Figure 2 A framework diagram of a multi-field coupled soil and rock shear strength testing system provided for an embodiment of the present invention. Detailed Implementation

[0023] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, software, or methods have not been specifically described to avoid obscuring the invention.

[0024] Throughout this specification, references to "an embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "in an embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale.

[0025] Please see Figure 1 This invention provides a method for testing the shear strength of soil and rock masses using multi-field coupling, comprising the following steps: S1. Apply the coupling effects of rainfall, temperature change and freeze-thaw cycle to the soil sample simultaneously according to the preset test path. During the coupling process, collect temperature data and complex impedance data of multiple sampling nodes along the sample axis in real time.

[0026] In this embodiment, standard soil and rock samples are prepared, temperature sensors and complex impedance sensors are installed, and after sealing, they are placed in the test chamber and connected to a rainfall, temperature control, and shear loading system. Then, a complex test path is programmed and set, for example: first, continuous rainfall is simulated for 12 hours until the water content is saturated, then the temperature is lowered and frozen at a rate of -0.5°C / h, while the rainfall is stopped, and the temperature is maintained at -10°C for 24 hours, and then the temperature is raised at a rate of +0.3°C / h to melt, during which intermittent light rain is simulated. The entire path is executed automatically, and temperature data and complex impedance data of multiple sampling nodes are collected in real time along the sample axis during the process.

[0027] S2. Based on the temperature data and complex impedance data, the coupling relationship and topological persistence of spatial abrupt change intensity are analyzed through the axial temperature gradient and phase change complex impedance gradient to determine the real-time freezing front position.

[0028] First, calculate the phase transition complex impedance factor of each sampling node based on the complex impedance data.

[0029] The phase transition complex impedance factor satisfies:

[0030] in, Represents the phase transition complex impedance factor. Represents the real part of the resistance. Indicates the imaginary reactance. Indicates the prevention of zero constant, Indicates the sampling node index. Indicates time.

[0031] Then, based on the temperature data and the phase transition complex impedance factor, the axial temperature gradient and the phase transition complex impedance gradient are calculated respectively to obtain the corresponding spatial abrupt change intensity of the temperature gradient and the spatial abrupt change intensity of the complex impedance gradient.

[0032] The intensity of the spatial abrupt change in the temperature gradient satisfies:

[0033] in, Indicates the intensity of the spatial abrupt change in the temperature gradient. Indicates the axial temperature gradient. Represents temperature data. Indicates the distance between sampling nodes. Indicates the sampling node index; The intensity of the spatial abrupt change in the complex resistive gradient satisfies:

[0034] in, Indicates the spatial abrupt change strength of the complex resistive gradient. For phase transition complex impedance gradient, This represents the phase transition complex impedance factor.

[0035] Next, the spatial abrupt change intensity of the temperature gradient and the spatial abrupt change intensity of the complex resistance gradient are synchronously harmonicly coupled to obtain the initial phase transition coupling gradient function.

[0036] The initial phase transition coupling gradient function satisfies:

[0037] in, This represents the initial phase transition coupling gradient function. Indicates the sampling node index. Indicates time, , , Indicates the intensity of the spatial abrupt change in the temperature gradient. This represents the intensity of the spatial abrupt change in the complex resistive gradient.

[0038] Then, the topological durability of the local peaks in the initial phase transition coupling gradient function is calculated, and the initial phase transition coupling gradient function is optimized using the topological durability to obtain the optimized phase transition coupling function.

[0039] For every moment The sequence is analyzed to find all local peaks and to calculate the topological durability of each peak. ,satisfy:

[0040] in, This indicates that the peak extends to the left to the lowest value in the interval it passes through before encountering a higher peak. This indicates that the peak extends to the right to the lowest value in the interval it passes through before encountering a higher peak.

[0041] Furthermore, multiplying the topological durability by the initial phase transition coupling gradient function yields the optimized phase transition coupling function, which satisfies:

[0042] in, This represents the optimized phase transition coupling function. This represents the initial phase transition coupling gradient function. Indicates topological durability. Indicates the sampling node index. Indicates time.

[0043] Finally, the location of the freezing front is determined based on the location of the maximum value of the optimized phase transition coupling function.

[0044] exist Select the location where the maximum value is located and define that location as the real-time frozen front location.

[0045] After identifying a single-moment freezing front, the location of the freezing front is defined as... Calculate the migration velocity of the freezing front. .

[0046] Instead of simply determining where the value is the largest, we determine where thermal abrupt changes, electrical abrupt changes, and spatial structural stability protrusions are present simultaneously. This effectively eliminates local noise peaks, single-field disturbance peaks, and instantaneous abnormal peaks, thus elevating freeze-thaw front identification from judging the point of maximum value to identifying synchronous phase change structures.

[0047] In actual experiments, due to the random formation of local ice crystals, the freezing front will exhibit jump noise. Therefore, a Kalman dynamic smoothing model is further introduced. The position of the freezing front is smoothed by the prediction equation and update equation of the Kalman dynamic smoothing model to obtain a continuous freezing migration trajectory.

[0048] S3. Calculate the migration velocity of the frozen front using the location of the frozen front, and determine whether the frozen front has entered the stable phase transition stage based on the ratio of freezing depth to migration velocity.

[0049] The freezing depth ratio is defined based on the location and migration speed of the freezing front. and freezing stability Set depth ratio threshold and stability threshold, when the following conditions are met: , , in, To freeze the position of the front, The height of the sample. To freeze the speed of frontal migration, and A preset threshold is used to determine whether the frozen front has entered the stable phase transition stage.

[0050] S4. After determining that the sample has entered the stable phase transition stage, apply a micro-perturbation horizontal displacement to the sample and measure the corresponding shear resistance to obtain the real-time shear strength under the coupling effect.

[0051] After identifying the location of the freeze-thaw front and determining that the freeze front has entered the stable phase transition stage, the instantaneous shear resistance is measured by applying a very small and slow horizontal displacement increment (e.g., 0.001-0.01 mm / min) in the perturbation shear test mode, without disturbing the current structure and stress state of the specimen.

[0052] Through multiple perturbation tests, the real-time mapping relationship between shear strength, freezing front position, and migration velocity is plotted, thereby reversing the influence of freeze-thaw interface evolution on shear strength and realizing a complete closed loop of perception-identification-tracking-judgment-triggering-testing-feedback.

[0053] It should be noted that the specific implementation methods described above, such as image processing, numerical simulation, and the construction and training of machine learning models, can all be accomplished by the processor by calling the corresponding computer program instructions stored in memory. Those skilled in the art can implement the above functions using algorithms and tools known in the prior art, according to actual needs.

[0054] Please see Figure 2In an embodiment, to efficiently execute the multi-field coupled shear strength testing method for soil and rock provided by the present invention, the present invention also provides a multi-field coupled shear strength testing system for soil and rock, comprising: an input device 1, an output device 2, a processor 3, and a memory 4, wherein the input device 1, output device 2, processor 3, and memory 4 are interconnected, and the memory 4 stores program instructions for executing the steps of the multi-field coupled shear strength testing method for soil and rock. The multi-field coupled shear strength testing system for soil and rock of the present invention has a compact structure and stable performance, and can stably execute the multi-field coupled shear strength testing method for soil and rock of the present invention, further improving the overall applicability and practical application capability of the present invention.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A multi-field coupled method for testing the shear strength of soil and rock masses, characterized in that, Includes the following steps: According to the preset test path, the soil and rock samples were simultaneously subjected to the coupling effect of rainfall and freeze-thaw cycle. During the coupling process, temperature data and complex impedance data of multiple sampling nodes were collected in real time along the sample axis. Based on the complex impedance data, calculate the phase transition complex impedance factor for each sampling node; Based on the temperature data and the phase transition complex impedance factor, the axial temperature gradient and the phase transition complex impedance gradient are calculated respectively to obtain the corresponding spatial abrupt intensity of the temperature gradient and the spatial abrupt intensity of the complex impedance gradient. The spatial abrupt change intensity of the temperature gradient and the spatial abrupt change intensity of the complex impedance gradient are synchronously harmonicly coupled to obtain the initial phase transition coupling gradient function; Calculate the topological durability of the local peaks in the initial phase transition coupling gradient function, and use the topological durability to optimize the initial phase transition coupling gradient function to obtain the optimized phase transition coupling function; The location of the freezing front is determined based on the location of the maximum value of the optimized phase transition coupling function; The migration velocity of the frozen front is calculated using the location of the frozen front. Based on the stability of the migration velocity in relation to the freezing depth ratio, it is determined whether the frozen front has entered a stable phase transition stage. After determining that the sample has entered the stable phase transition stage, a horizontal displacement increment of 0.001-0.01 mm / min is applied to the sample and the corresponding shear resistance is measured to obtain the real-time shear strength under the coupling action. The phase transition complex impedance factor satisfies: in, Represents the phase transition complex impedance factor. Represents the real part of the resistance. Indicates the imaginary reactance. Indicates the prevention of zero constant, Indicates the sampling node index. Indicates time; The intensity of the spatial abrupt change in the temperature gradient satisfies: in, Indicates the intensity of the spatial abrupt change in the temperature gradient. Indicates the axial temperature gradient. Represents temperature data. Indicates the spacing between sampling nodes; The intensity of the spatial abrupt change in the complex impedance gradient satisfies: in, This represents the intensity of the spatial abrupt change in the complex impedance gradient. The phase transition complex impedance gradient; The spatial abrupt intensity of the temperature gradient and the spatial abrupt intensity of the complex impedance gradient are synchronously harmonicly coupled to obtain an initial phase transition coupling gradient function, which satisfies: in, This represents the initial phase transition coupling gradient function. Indicates the sampling node index. Indicates time, , , To achieve a dummy index; The topology persistence satisfies: in, Indicates topological durability. This represents the initial phase transition coupling gradient function. This indicates the lowest value in the interval traversed before the local peak extends to the left and encounters a higher peak. This indicates the lowest value in the interval through which the local peak extends to the right until it encounters a higher peak. The initial phase transition coupling gradient function is optimized using the topological durability to obtain the optimized phase transition coupling function, which satisfies: in, This represents the optimized phase transition coupling function.

2. The multi-field coupled shear strength testing method for soil and rock mass according to claim 1, characterized in that, The determination of the real-time location of the frozen front also includes: For a given sequence of freezing front locations, a Kalman dynamic smoothing model is used to process the data to obtain a smoothed continuous freezing migration trajectory.

3. The multi-field coupled shear strength testing method for soil and rock mass according to claim 1, characterized in that, The determination of whether a frozen front has entered a stable phase transition stage is based on the following: Freezing depth ratio Freezing stability , in, To freeze the position of the front, The height of the sample. To freeze the speed of frontal migration, and This is a preset threshold.

4. A multi-field coupled shear strength testing system for soil and rock masses, characterized in that, The multi-field coupled soil and rock shear strength testing system includes: an input device, an output device, a processor, and a memory, wherein the input device, output device, processor, and memory are interconnected, and the memory stores program instructions for executing the multi-field coupled soil and rock shear strength testing method according to any one of claims 1-3.

Images