Testing device for measuring and calculating rock mass mechanical damage based on energy evolution

Abstract

The invention relates to the technical field of test devices, in particular to a test device for measuring and calculating rock mass mechanical damage based on energy evolution. According to the technical scheme, the system comprises a multi-energy coupling monitoring module, a dynamic loading simulation module and a calculation and analysis module. Omnibearing real-time monitoring of changes of strain energy, acoustic emission energy and heat energy of the rock mass is achieved through the multi-energy coupling monitoring module, and a data basis is provided for measuring and calculating mechanical damage of the rock mass; the complex stress environment of the deep rock mass is highly simulated through the dynamic loading simulation module, and powerful support is provided for dealing with sudden dynamic loads in actual engineering; an innovative comprehensive energy damage variable and an optimized energy distribution proportionality coefficient are introduced through an energy-based damage algorithm model, rock mass damage is defined from the energy essential level, multiple factors such as the initial energy state of rock, energy conversion in the loading process and structural characteristics are comprehensively considered, the rock mass damage degree of each stage can be more accurately quantified, and the rock mass damage degree is more accurate. And the rock mass stability change trend is pre-judged in advance.

Description

Technical Field

[0001] The invention relates to the technical field of test devices, and in particular to a test device for measuring and calculating rock mass mechanical damage based on energy evolution. Background Art

[0002] In the field of geotechnical engineering, accurate calculation of rock mass mechanical damage characteristics plays a vital role in stability assessment, design optimization and disaster prediction of many engineering projects. As engineering construction continues to expand into deep strata and complex geological environments, such as deep mining, large underground cavern construction, and high and steep slope protection, there is a higher demand for the damage evolution law of rock mass under different stress and strain conditions.

[0003] Traditional rock mechanics damage testing methods have many limitations. On the one hand, most existing systems only focus on measuring one aspect of external force work or strain energy, ignoring the synchronous monitoring of other forms of energy such as thermal energy and acoustic emission energy in the process of internal energy dissipation of the rock, and cannot fully reflect the overall picture of energy evolution in the rock damage process, resulting in deviations in the assessment of the degree of damage; on the other hand, when simulating dynamic loading conditions such as earthquakes and impacts, it is difficult to accurately capture the rock mechanical response and rapid energy conversion characteristics under instantaneous high strain rates. Traditional sensors have insufficient response frequency and cannot track the complex distribution of energy in a very short time in real time, making the test data unable to accurately reflect the actual dynamic failure mechanism. Therefore, we propose a test device for measuring rock mechanical damage based on energy evolution. Summary of the invention

[0004] The purpose of the present invention is to propose a test device for measuring rock mechanical damage based on energy evolution in order to address the problem that the existing systems in the background technology ignore the synchronous monitoring of other forms of energy such as thermal energy and acoustic emission energy in the process of internal energy dissipation of rocks, and the existing systems are difficult to accurately capture the mechanical response of rock masses and the characteristics of rapid energy conversion under instantaneous high strain rates when simulating dynamic loading conditions such as earthquakes and impacts.

[0005] The technical solution of the present invention is: a test device for measuring and calculating rock mechanical damage based on energy evolution, comprising a multi-energy coupling monitoring module, a dynamic loading simulation module and a calculation and analysis module;

[0006] The multi-energy coupling monitoring module is used to collect strain energy, acoustic emission energy and thermal energy change data of the rock specimen during loading, and the multi-energy coupling monitoring module also includes a data acquisition submodule;

[0007] The dynamic loading simulation module is used to simulate the dynamic loading scenario;

[0008] The calculation and analysis module is used to convert test data into a basis for engineering decision-making, and the calculation and analysis module includes an energy-based damage algorithm model.

[0009] Optionally, the multi-energy coupling monitoring module further includes a foil strain gauge, a piezoelectric sensor and an infrared thermal imager;

[0010] The foil strain gauge is used to measure the strain of the rock specimen in different directions, and the foil strain gauge is symmetrically pasted on the axial and annular parts of the rock specimen;

[0011] The piezoelectric sensor is used to collect the acoustic emission signal generated by the expansion of microcracks inside the rock specimen. The piezoelectric sensor is buried on the surface of the rock specimen and in a preset borehole inside the rock specimen. The depth of the preset borehole is 1 / 3-1 / 2 of the radius of the rock specimen.

[0012] The infrared thermal imager is used to detect the distribution of the temperature field on the surface of the rock specimen. The infrared thermal imager is placed on a bracket with adjustable angle and distance and is equipped with a light shield.

[0013] Optionally, the data acquisition submodule includes a multi-channel synchronous acquisition card, each channel has an independent signal conditioning circuit, pre-processes the signal from the sensor, the sampling frequency is 2MHz, and the collected data is transmitted to the host computer through a high-speed data bus. The host computer software has real-time data display, storage and preliminary analysis functions.

[0014] Optionally, the dynamic loading simulation module includes an electro-hydraulic servo dynamic loading device and a transparent confining ballast tank;

[0015] The hydraulic system of the electro-hydraulic servo dynamic loading device adopts a proportional servo valve, the control accuracy of the servo valve is 0.1%-0.3%, the power source of the electro-hydraulic servo dynamic loading device adopts a motor and a hydraulic pump, the motor adopts a three-phase asynchronous motor with a rated power between 50-200kW, the hydraulic pump adopts an axial piston pump, the displacement range of the axial piston pump is 50-200mL / r, and the rated pressure is 30-35MPa;

[0016] The electro-hydraulic servo dynamic loading device also includes a loading head in contact with the rock specimen. A buffer material is provided at the contact end between the loading head and the rock specimen. The hardness range of the buffer material is Shore A60-90.

[0017] Optionally, the transparent confining ballast chamber is made of plexiglass material, the compressive strength of the transparent confining ballast chamber can meet the confining pressure requirement of more than 100MPa, the interior of the transparent confining ballast chamber is filled with silicone oil medium, and the transparent confining ballast chamber is provided with a plurality of micro pressure sensors for real-time monitoring of the uniformity of the confining pressure and its changes during the loading process.

[0018] Optionally, the energy-based damage algorithm model defines an improved comprehensive energy damage variable D E , the calculation formula is as follows:

[0019]

[0020] Among them, U0 is the initial total energy of the rock specimen, which includes the internal energy and elastic potential energy before loading, U res is the remaining recoverable energy after loading to a certain moment, ΔU ext The additional irreversible energy input by the external force during loading, ΔU ext The estimation is made by monitoring the power loss of the loading device and the friction heat between the specimen and the medium. ω is the weight coefficient considering the internal structural heterogeneity of the rock mass, and its value is 0.8-1.2.

[0021] Optionally, the U res It is obtained by integrating the area under the unloading curve. In the stress-strain curve, assuming the relationship between stress σ and strain ε, the unloading curve conforms to Hooke's law;

[0022] For the linear unloading process, U res The calculation formula is as follows:

[0023]

[0024] Among them, ε u is the strain at the end of unloading;

[0025] For the nonlinear unloading curve, a numerical integration method is used, which includes a trapezoidal method, and the unloading curve is divided into n small trapezoids, and the area of ​​each small trapezoid is:

[0026]

[0027] Secondly, U res The calculation formula is as follows:

[0028] Optionally, the ΔU ext The estimation methods include:

[0029] Estimation of power loss based on the loading device: Record the input power P of the loading device in And the output power P out , ΔU ext The calculation formula is as follows:

[0030]

[0031] Where t is the loading time, where the input power P inBy measuring voltage U, current I and power factor To calculate, the formula is: Output power P out According to the loading force F and the loading head speed v, the formula is: P out =Fv.

[0032] Estimation based on friction heat between the specimen and the surrounding medium: Assuming that the heat generated by friction is mainly dissipated through the surface of the specimen, measure the temperature rise ΔT on the surface of the specimen. Given the specific heat capacity c, mass m and heat dissipation coefficient h of the specimen, estimate the heat generated by friction. For a simple one-dimensional heat conduction case, Q = mcΔT;

[0033] Considering the heat dissipation, ΔU ext The calculation formula is as follows:

[0034]

[0035] Where A is the heat dissipation surface area of ​​the rock specimen.

[0036] Optionally, the energy-based damage algorithm model also includes optimizing the energy allocation ratio coefficient α i , the calculation formula is as follows:

[0037]

[0038] Among them, U i Different energy forms, including strain energy U s , acoustic emission energy U AE 、Heat Energy U T , β i is the correction factor of the corresponding energy form, strain energy U s The value is 0.9-1.1, the acoustic emission energy U AE The value is 0.8-1.2 according to the sensor calibration, thermal energy U T According to the heat conduction model and the environment, the value is 0.7-1.3, α i Indicates the energy ratio.

[0039] In summary, the present application includes at least one of the following beneficial technical effects:

[0040] 1. The present invention realizes all-round real-time monitoring of rock strain energy, acoustic emission energy and thermal energy changes through a multi-energy coupling monitoring module, which can completely capture the energy evolution of the rock during stress, avoid the damage assessment deviation caused by the lack of energy monitoring, and provide a data basis for measuring rock mechanical damage;

[0041] 2. The present invention applies impact forces of different frequencies and amplitudes to rock specimens through a dynamic loading simulation module, and can also highly simulate the complex stress environment of deep rock mass, overcoming the problems of delayed response and poor waveform control accuracy of traditional dynamic loading devices, so that the test data can truly reflect the mechanical properties and damage mechanism of the rock mass under dynamic conditions, providing strong support for coping with sudden dynamic loads in actual engineering;

[0042] 3. The present invention introduces an innovative comprehensive energy damage variable and an optimized energy distribution ratio coefficient through an energy-based damage algorithm model to define rock damage from the energy essence level. Different from the traditional single damage variable based on macro cracks or simple stress-strain reduction, the model comprehensively considers multiple factors such as the initial energy state of the rock, energy conversion during the loading process, and structural characteristics. It can more accurately quantify the degree of rock damage at each stage and predict the trend of rock stability changes in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A principle block diagram of a test device for measuring and calculating rock mass mechanical damage based on energy evolution is given in the present invention. DETAILED DESCRIPTION

[0044] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0045] The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0046] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0047] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0048] It should be noted that the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0049] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] Example

[0051] The present invention proposes a test device for measuring rock mechanical damage based on energy evolution, such as Figure 1 As shown, it includes a multi-energy coupling monitoring module, a dynamic loading simulation module and a calculation and analysis module.

[0052] The multi-energy coupling monitoring module is used to collect the strain energy, acoustic emission energy and thermal energy change data of the rock specimen during the loading process. The multi-energy coupling monitoring module also includes a data acquisition submodule;

[0053] Among them, the multi-energy coupling monitoring module also includes foil strain gauges, piezoelectric sensors and infrared thermal imagers. The foil strain gauges are used to measure the strains of rock specimens in different directions. The foil strain gauges are symmetrically pasted on the axial and annular parts of the rock specimens. The piezoelectric sensors are used to collect acoustic emission signals generated by the expansion of microcracks inside the rock specimens. The piezoelectric sensors are buried on the surface of the rock specimens and in preset boreholes inside. The depth of the preset boreholes is preferably 1 / 3 of the radius of the rock specimens. The infrared thermal imager is used to detect the distribution of the temperature field on the surface of the rock specimens.

[0054] The data acquisition submodule includes a multi-channel synchronous acquisition card. Each channel has an independent signal conditioning circuit to pre-process the signal from the sensor. The sampling frequency is 2MHz. The collected data is transmitted to the host computer through a high-speed data bus. The host computer software has real-time data display, storage and preliminary analysis functions;

[0055] The present invention realizes all-round real-time monitoring of rock strain energy, acoustic emission energy and thermal energy changes through a multi-energy coupling monitoring module, which can completely capture the energy evolution of the rock during the stress process, avoid damage assessment deviations caused by the lack of energy monitoring, and provide a data basis for measuring rock mechanical damage.

[0056] In addition, the dynamic loading simulation module is used to simulate the dynamic loading scene. The dynamic loading simulation module includes an electro-hydraulic servo dynamic loading device and a transparent confining ballast tank. The hydraulic system of the electro-hydraulic servo dynamic loading device adopts a proportional servo valve. The servo valve control accuracy is preferably 0.1%. The power source of the electro-hydraulic servo dynamic loading device adopts a motor and a hydraulic pump. The motor adopts a three-phase asynchronous motor with a rated power of 100kW. The hydraulic pump adopts an axial piston pump. The displacement range of the axial piston pump is 100mL / r and the rated pressure is 32MPa. The electro-hydraulic servo dynamic loading device also includes a loading head in contact with the rock specimen, and a buffer material is provided at the contact end between the loading head and the rock specimen;

[0057] The transparent confining ballast tank is made of organic glass material. The compressive strength of the transparent confining ballast tank can meet the confining pressure requirement of more than 100MPa. The transparent confining ballast tank is filled with silicone oil medium. The transparent confining ballast tank is equipped with multiple micro pressure sensors for real-time monitoring of the uniformity of the confining pressure and the changes during the loading process.

[0058] The present invention applies impact forces of different frequencies and amplitudes to rock specimens through a dynamic loading simulation module, and can also simulate the complex stress environment of deep rock mass, overcoming the problems of delayed response and poor waveform control accuracy of traditional dynamic loading devices, so that the test data can truly reflect the mechanical properties and damage mechanism of the rock mass under dynamic conditions, providing strong support for coping with sudden dynamic loads in actual engineering.

[0059] Energy-based damage algorithm model definition Improved comprehensive energy damage variable D E , the calculation formula is as follows:

[0060]

[0061] Among them, U0 is the initial total energy of the rock specimen, which includes the internal energy and elastic potential energy before loading, U res is the remaining recoverable energy after loading to a certain moment, ΔU ext The additional irreversible energy input by the external force during loading, ΔU ext The estimation is made by monitoring the power loss of the loading device and the friction heat between the specimen and the medium. ω is the weight coefficient considering the internal structural heterogeneity of the rock mass, and its value is 0.8-1.2.

[0062] Among them, U resIt is obtained by integrating the area under the unloading curve. In the stress-strain curve, assuming that the relationship between stress σ and strain ε, the unloading curve conforms to Hooke's law. For the linear unloading process, U res The calculation formula is as follows: Among them, ε u is the strain at the end of unloading;

[0063] For the nonlinear unloading curve, the numerical integration method is used, which includes the trapezoidal method. The unloading curve is divided into n small trapezoids, and the area of ​​each small trapezoid is: Among them, U res The calculation formula is as follows:

[0064] In addition, ΔU ext Estimation is made by monitoring the power loss of the loading device and the friction heat between the specimen and the medium;

[0065] Estimation of power loss based on the loading device: Record the input power P of the loading device in And the output power P out , ΔU ext The calculation formula is Where t is the loading time, where the input power P in By measuring voltage U, current I and power factor To calculate, the formula is: Output power P out According to the loading force F and the loading head speed v, the formula is: P out =Fv.

[0066] Estimation based on friction heat between the specimen and the surrounding medium: Assuming that the heat generated by friction is mainly dissipated through the surface of the specimen, measure the temperature rise ΔT on the surface of the specimen. Given the specific heat capacity c, mass m and heat dissipation coefficient h of the specimen, estimate the heat generated by friction. For a simple one-dimensional heat conduction case, Q = mcΔT;

[0067] Considering the heat dissipation, ΔU ext The calculation formula is Where A is the heat dissipation surface area of ​​the rock specimen.

[0068] The energy-based damage algorithm model also includes optimizing the energy distribution ratio coefficient α i , the calculation formula is Among them, U i Different energy forms, including strain energy U s , acoustic emission energy U AE 、Heat Energy U T , β iis the correction factor of the corresponding energy form, strain energy U s The value is 0.9-1.1, the acoustic emission energy U AE The value is 0.8-1.2 according to the sensor calibration, thermal energy U T According to the heat conduction model and the environment, the value is 0.7-1.3, α i Indicates the energy ratio.

[0069] In the present invention, an innovative comprehensive energy damage variable and an optimized energy distribution ratio coefficient are introduced through an energy-based damage algorithm model to define rock damage from the energy essence level. Different from the traditional single damage variable based on macro cracks or simple stress-strain reduction, the model comprehensively considers multiple factors such as the initial energy state of the rock, energy conversion during the loading process, and structural characteristics. It can more accurately quantify the degree of rock damage at each stage and predict the trend of rock stability changes in advance.

[0070] The test using the test device for calculating rock mass mechanical damage based on energy evolution includes the following steps:

[0071] 1. Test Preparation

[0072] Sample selection and processing: Granite cores are selected from the target mining area as samples. The core diameter is preferably 50mm and the height is 100mm. High-precision grinders are used to grind both ends of the core to a flatness error of To ensure that the rock specimen is evenly stressed during loading.

[0073] Sensor installation and calibration: including foil strain gauges, piezoelectric sensors and infrared thermal imagers;

[0074] Foil strain gauge: 8 axial strain gauges and 4 circumferential strain gauges were selected and pasted according to the principle of symmetrical distribution on the key axial and circumferential parts of the rock specimen. A strain simulator was used to apply known strain signals to the strain gauges. The measured values ​​were compared with the theoretical values. After repeated debugging, the error was controlled within ±0.5%, ensuring that the foil strain gauges could accurately measure strains in different directions to accurately calculate strain energy.

[0075] Piezoelectric sensor: The piezoelectric sensor is preferably a PZT piezoelectric ceramic sensor. The piezoelectric sensor is embedded in the surface of the specimen and in the preset drilled holes inside. The drilling depth is 17 mm, which is about 1 / 3 of the radius of the specimen. According to the acoustic emission calibration standard, the sensitivity is calibrated within the specific frequency range of 100kHz-1 MHz using a standard acoustic emission source so that its deviation does not exceed ±1dB, ensuring that the acoustic emission signal generated by the expansion of microcracks inside the rock can be accurately captured and the stereo positioning of the acoustic emission source and the monitoring of the acoustic emission energy at different depths can be achieved.

[0076] Infrared thermal imager: An uncooled focal plane array infrared thermal imager with a resolution of 640×480 pixels and an accuracy of ±0.05°C is installed on a bracket with adjustable angle and distance, and is equipped with a sunshade. The temperature measurement accuracy is calibrated using a blackbody radiation source to ensure that the temperature measurement error is within ±0.05°C, enabling it to monitor the surface temperature field distribution of the rock specimen in real time to accurately calculate the heat energy dissipation.

[0077] Loading device debugging: selection and debugging of electro-hydraulic servo dynamic loading device and transparent confining ballast tank;

[0078] Electro-hydraulic servo dynamic loading device: Its hydraulic system adopts a proportional servo valve with a flow control accuracy of 0.1%. The power source is equipped with a three-phase asynchronous motor with a rated power of 100kW and an axial piston pump with a displacement of 100mL / r and a rated pressure of 32MPa to ensure the stability of the hydraulic oil pressure during high-frequency loading. The contact part between the loading head and the specimen adopts Shaw A75 polyurethane elastomer material as a buffer material, and combines the adaptive structure composed of a ball hinge structure and an elastic floating plate. The ball hinge structure is installed at the connection between the loading head and the loading device, and can rotate freely within the range of ±5° to automatically adapt to the unevenness of the specimen surface in the horizontal direction. The elastic floating plate adopts a 0.5mm thick spring steel sheet radially fixed on the end face of the loading head, which can produce corresponding elastic deformation according to the vertical concave and convex conditions of the specimen surface to ensure that the loading force is evenly distributed on the specimen.

[0079] Transparent confining pressure chamber: It is made of high-strength organic glass material with a compressive strength of 120MPa, and is filled with precisely formulated silicone oil medium with a viscosity of 50cP to simulate the confining pressure environment of about 20MPa deep in the mine. Four micro pressure sensors are installed on the confining pressure chamber and calibrated with a standard pressure source to ensure that the pressure measurement accuracy is within ±0.01MPa. It is used to monitor the uniformity of the confining pressure and its changes during the loading process in real time, and to conduct collaborative analysis with the external loading force and specimen deformation data.

[0080] 2. Experimental Implementation Phase

[0081] Preload calibration: Apply static preload of 0-10% of the estimated peak load. The estimated peak load is 500kN, that is, 0-50kN load, and the loading rate is 0.1kN / s. During this process, calibrate the sensor zero point, record the initial energy state, and detect the sealing of the confining ballast tank and the stability of the loading device. Use a helium mass spectrometer leak detector to check that the leakage rate of the confining ballast tank is less than 1×10 - 6 Pa·m 3 / s, ensuring that the initial state of the entire test system is normal.

[0082] Gradual loading test: A static step-by-step loading system was used. The load was first loaded from 50 kN to 200 kN at a loading rate of 0.2 kN / s, and then maintained for 10 seconds. Energy data was collected synchronously. At this time, the multi-channel synchronous acquisition card collected data from various sensors at a sampling frequency of 2 MHz. The host computer software displayed, stored, and preliminarily analyzed the data in real time, associated the data of different sensors at the same time, and plotted the strain energy U s , acoustic emission energy U AE 、Heat Energy U T Comparison curves over time;

[0083] Continue loading at a loading rate of 0.3 kN / s to 350 kN, hold for 20 s, and collect analysis data again. As the load increases, the strain energy U s The proportion gradually decreases, and the acoustic emission energy U AE The proportion begins to rise, indicating the initiation of microcracks inside the rock;

[0084] Finally, the specimen was loaded at a loading rate of 0.4 kN / s to 500 kN until failure. During this period, the comprehensive energy damage variable D in the energy-based damage algorithm model was calculated in real time. E and energy distribution proportional coefficient α i When the acoustic emission energy distribution coefficient rises sharply to more than 0.3, it is judged that the rock mass has entered the rapid damage stage, which is consistent with the actual observation of a large number of microcracks on the surface of the specimen, and accurately captures the rock mass damage threshold and failure precursors.

[0085] 3. Post-test processing stage

[0086] Data summary and analysis: After unloading, the data collected during the entire test process are summarized, including strain, stress, various energy change values, and energy damage variable D at different stages. E and energy distribution proportional coefficient α i Combined with the rock microstructure scanning results, the energy damage model calculation results and the microstructure change characteristics were compared and analyzed, and it was found that D E The growth trend of the value is highly correlated with microscopic phenomena such as the increase in microcrack density and the breakage of mineral particles, which verifies the accuracy of the energy damage model.

[0087] Model optimization and application: According to the comparison results of test data and microstructure, the parameters in the energy-based damage algorithm model are further optimized. The weight coefficient considering the internal structural heterogeneity of the rock mass can be adjusted. The optimized model is applied to the rock stability assessment of the mining project. Combined with the on-site monitoring data, the mining sequence, support timing and strength are reasonably adjusted, which effectively reduces the risk of rock burst and ensures the smooth progress of the project.

[0088] The above specific embodiments are only several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant inspirations of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A test device for measuring rock mechanical damage based on energy evolution, characterized in that: It includes multi-energy coupling monitoring module, dynamic loading simulation module and calculation and analysis module; The multi-energy coupling monitoring module is used to collect strain energy, acoustic emission energy and thermal energy change data of the rock specimen during loading, and the multi-energy coupling monitoring module also includes a data acquisition submodule; The dynamic loading simulation module is used to simulate the dynamic loading scenario; The calculation and analysis module is used to convert test data into a basis for engineering decision-making, and the calculation and analysis module includes an energy-based damage algorithm model.

2. The test device for measuring rock mechanical damage based on energy evolution according to claim 1 is characterized in that: The multi-energy coupling monitoring module also includes a foil strain gauge, a piezoelectric sensor and an infrared thermal imager; The foil strain gauge is used to measure the strain of the rock specimen in different directions, and the foil strain gauge is symmetrically pasted on the axial and annular parts of the rock specimen; The piezoelectric sensor is used to collect the acoustic emission signal generated by the expansion of microcracks inside the rock specimen. The piezoelectric sensor is buried on the surface of the rock specimen and in a preset borehole inside the rock specimen. The depth of the preset borehole is 1 / 3-1 / 2 of the radius of the rock specimen. The infrared thermal imager is used to detect the distribution of the temperature field on the surface of the rock specimen. The infrared thermal imager is placed on a bracket with adjustable angle and distance and is equipped with a light shield.

3. The test device for measuring rock mechanical damage based on energy evolution according to claim 2 is characterized in that: The data acquisition submodule includes a multi-channel synchronous acquisition card, each channel has an independent signal conditioning circuit, and pre-processes the signal from the sensor. The sampling frequency is 2MHz, and the collected data is transmitted to the host computer through a high-speed data bus. The host computer software has real-time data display, storage and preliminary analysis functions.

4. The test device for measuring rock mechanical damage based on energy evolution according to claim 1 is characterized in that: The dynamic loading simulation module includes an electro-hydraulic servo dynamic loading device and a transparent confining ballast tank; The hydraulic system of the electro-hydraulic servo dynamic loading device adopts a proportional servo valve, the control accuracy of the servo valve is 0.1%-0.3%, the power source of the electro-hydraulic servo dynamic loading device adopts a motor and a hydraulic pump, the motor adopts a three-phase asynchronous motor with a rated power between 50-200kW, the hydraulic pump adopts an axial piston pump, the displacement range of the axial piston pump is 50-200mL / r, and the rated pressure is 30-35MPa; The electro-hydraulic servo dynamic loading device also includes a loading head in contact with the rock specimen. A buffer material is provided at the contact end between the loading head and the rock specimen. The hardness range of the buffer material is Shore A60-90.

5. The test device for measuring rock mechanical damage based on energy evolution according to claim 4 is characterized in that: The transparent confining ballast chamber is made of organic glass material, the interior of the transparent confining ballast chamber is filled with silicone oil medium, and the transparent confining ballast chamber is provided with a plurality of micro pressure sensors for real-time monitoring of the uniformity of the confining pressure and the changes during the loading process.

6. The test device for measuring rock mechanical damage based on energy evolution according to claim 1 is characterized in that: The energy-based damage algorithm model defines an improved comprehensive energy damage variable D E , the calculation formula is as follows: Among them, U0 is the initial total energy of the rock specimen, which includes the internal energy and elastic potential energy before loading, U res is the remaining recoverable energy after loading to a certain moment, ΔU ext The additional irreversible energy input by the external force during loading, ΔU ext The estimation is made by monitoring the power loss of the loading device and the friction heat between the specimen and the medium. ω is the weight coefficient considering the internal structural heterogeneity of the rock mass, and its value is 0.8-1.

2.

7. The test device for measuring rock mechanical damage based on energy evolution according to claim 6 is characterized in that: The U res It is obtained by integrating the area under the unloading curve. In the stress-strain curve, assuming the relationship between stress σ and strain ε, the unloading curve conforms to Hooke's law; For the linear unloading process, U res The calculation formula is as follows: Among them, ε u is the strain at the end of unloading; For the nonlinear unloading curve, a numerical integration method is used, which includes a trapezoidal method, and the unloading curve is divided into n small trapezoids, and the area of ​​each small trapezoid is: Secondly, U res The calculation formula is as follows:

8. The test device for measuring rock mass mechanical damage based on energy evolution according to claim 6 is characterized in that: The ΔU ext The calculation formula includes: Estimation of power loss based on the loading device: Record the input power P of the loading device in And the output power P out , ΔU ext The calculation formula is as follows: Where t is the loading time, where the input power P in By measuring voltage U, current I and power factor To calculate, the formula is: Output power P out According to the loading force F and the loading head speed v, the formula is: P out =Fv. Estimation based on friction heat between the specimen and the surrounding medium: Assuming that the heat generated by friction is mainly dissipated through the surface of the specimen, measure the temperature rise ΔT on the surface of the specimen. Given the specific heat capacity c, mass m and heat dissipation coefficient h of the specimen, estimate the heat generated by friction. For a simple one-dimensional heat conduction case, Q = mcΔT; Considering the heat dissipation, ΔU ext The calculation formula is as follows: Where A is the heat dissipation surface area of ​​the rock specimen.

9. The test device for measuring rock mechanical damage based on energy evolution according to claim 8 is characterized in that: The energy-based damage algorithm model also includes optimizing the energy distribution ratio coefficient α i , the calculation formula is as follows: Among them, U i Different energy forms, including strain energy U s , acoustic emission energy U AE 、Heat Energy U T , β i is the correction factor of the corresponding energy form, strain energy U s The value is 0.9-1.1, the acoustic emission energy U AE The value is 0.8-1.2 according to the sensor calibration, thermal energy U T According to the heat conduction model and the environment, the value is 0.7-1.3, α i Indicates the energy ratio.

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