A method for quantifying geological strength index of filling fissure rock mass under influence of freeze-thaw environment at different depths

Abstract

The present application relates to geotechnical test technical field, especially to a kind of filling type fissure rock mass geological strength index quantification method under the influence of different buried depth freeze-thaw environment, including obtaining different buried depth temperature data, the fissure filling material taken from mine is prepared to be consistent with the actual dry density, moisture content of sample in situ, carry out freeze-thaw cycle test, calculate the cohesion and internal friction angle of fissure filling material;Filling type fissure rock mass numerical model is constructed and numerical simulation under triaxial compression condition is carried out, the volume of characterization unit is determined, and the degradation process of the mechanical parameters of filling type fissure rock mass under the influence of different buried depth freeze-thaw environment is quantified;Freeze-thaw correction coefficient of fissure filling material is introduced in structural plane grade parameter SCR, and the correction of filling type fissure rock mass geological strength index under the influence of different buried depth freeze-thaw environment is realized;The present application significantly improves the accuracy and application range of strength prediction, and overcomes the limitations of traditional method ignoring freeze-thaw damage.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering testing technology, and in particular to a method for quantifying the geological strength index of filled fractured rock masses considering the effects of freeze-thaw environments at different burial depths. Background Technology

[0002] Against the backdrop of global warming and accelerated resource development in cold regions, the stability of open-pit mine slopes in high-altitude and cold areas is becoming increasingly prominent. my country's high-altitude and cold regions are rich in mineral resources; however, frequent freeze-thaw disasters severely restrict construction efficiency and resource development. The widely present fissure infill material in rock masses is a sensitive factor in freeze-thaw degradation, and its physical and mechanical properties change significantly at different burial depths, directly affecting rock mass strength. Current research mostly focuses on single freeze-thaw factors, lacking a systematic understanding of the evolution of fissure infill material and fissure rock masses under the coupled effects of freeze-thaw cycles and temperature gradients, thus limiting the accuracy of stability assessment for infilled fissure rock masses. Therefore, this invention provides a calculation method that considers the impact of fissure infill material on rock mass strength and quality indicators under freeze-thaw conditions at different burial depths, which has significant engineering implications for the quality evaluation of rock masses and slope stability assessment in high-altitude and cold regions. Summary of the Invention

[0003] This invention provides a quantitative method for the geological strength index of filled fractured rock masses considering the effects of freeze-thaw environments at different burial depths. It can dynamically reflect the evolution process of the mechanical properties of rock masses at different depths in cold regions, significantly improving the accuracy and applicability of strength prediction. It overcomes the limitation of traditional methods that ignore the effects of freeze-thaw damage and can more realistically depict the shear degradation behavior of infilled structural surfaces in fractured rock masses.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A method for quantifying the geological strength index of filled fractured rock masses considering the effects of freeze-thaw environments at different burial depths includes the following steps:

[0006] S1. Use the temperature monitoring device inside the mine slope to obtain temperature data at different burial depths, and set the freeze-thaw cycle test parameters corresponding to different burial depths accordingly.

[0007] S2. Prepare samples of the fracture filling material taken from the mine with the same dry density and moisture content as the actual site, carry out freeze-thaw cycle tests, and conduct shear tests after reaching the predetermined number of freeze-thaw cycles to calculate the cohesion and internal friction angle of the fracture filling material.

[0008] S3. Construct a numerical model of the filled fractured rock mass and perform numerical simulation under triaxial compression conditions to determine the volume of the characterizing unit and quantify the deterioration process of the mechanical parameters of the filled fractured rock mass under the influence of freeze-thaw environments at different burial depths.

[0009] S4. Introduce a freeze-thaw correction coefficient for fracture filling material into the structural plane grade parameter SCR. Calculate the optimal value of the correction coefficient using the ergonomic solution method. This ensures that the rock mechanics parameters estimated by combining this coefficient and the Hawke-Brown strength criterion are closest to the numerical simulation results in S3, thereby correcting the geological strength index of filled fracture rock masses under the influence of freeze-thaw environments at different burial depths.

[0010] Furthermore, the preparation of the fracture filling material obtained from the mine specifically includes the following steps:

[0011] (1) Calculate the amount of wet soil sample to prepare the sample based on the required dry density and moisture content;

[0012] The formula for calculating the total required soil mass is as follows:

[0013]

[0014] in, The required dry density for preparing the sample, in g / cm³; The moisture content is measured on-site, %; V is the calculated volume of the compacted soil sample or the volume of the ring cutter used in the compactor, cm³.

[0015] The formula for calculating the additional water required to prepare soil samples is as follows:

[0016]

[0017] in, The amount of water to be added to prepare the sample, in g; The target moisture content required during sample preparation, % .

[0018] (2) Take a certain amount of crack filling material sample using the four-point method, place it on a rubber plate and crush it with a wooden roller or a soil roller, put it in a soil tray and dry it at 100℃~105℃ for 24 hours until constant weight; take out the dried soil sample and cool it to room temperature, then spread it flat in a non-absorbent soil tray, spray the required amount of water evenly onto the soil sample according to the predetermined moisture content using a water spraying device, mix it well and put it into a plastic bag or seal it in a soil container and let it stand for later use.

[0019] (3) Place the compactor stably on a rigid foundation, apply a layer of lubricating oil to the inner wall and bottom plate of the compaction cylinder, connect the compaction cylinder and the bottom plate, install the protective casing, weigh a certain amount of soil from a prepared sample, pour it into the compaction cylinder in 3 or 5 layers and level the soil surface, compact in layers, cut along the wall of the protective casing with a soil trimming knife, twist and remove the protective casing, carefully trim the sample along the top of the compaction cylinder, remove the bottom plate, trim the bottom surface of the sample when it extends beyond the cylinder, and finally push the sample out of the compaction cylinder with a bulldozer.

[0020] Furthermore, the step of conducting a shear test after reaching the predetermined number of freeze-thaw cycles to calculate the cohesion and internal friction angle of the crack filler specifically includes the following steps:

[0021] (1) Take 3 to 5 specimens for each test group and conduct shear tests under 3 to 5 different vertical pressures. Apply vertical pressures of various levels according to the actual engineering situation and the hardness of the soil. The differences between the various levels of vertical pressure should be equal or nearly equal. Alternatively, several levels of pressure can be selected in the range of 100 to 400 kPa for testing. (2) The shear stress of the specimen is calculated by the following formula:

[0022]

[0023] Where τ is the shear stress (kPa); C is the calibrator coefficient (N / 0.01mm); R is the calibrator reading (0.01mm); and A0 is the initial area of ​​the sample (cm²). 2 ;

[0024] (3) Plot the shear stress and shear displacement on the vertical axis. Relationship curve; select shear stress With shear displacement The peak point or stable value on the relationship curve is taken as the shear strength. When there is no obvious peak point, the shear displacement is taken. The corresponding shear stress is taken as the shear strength; plot the relationship curve between shear strength and vertical pressure with shear strength as the ordinate and vertical pressure as the abscissa. Based on the points on the graph, draw an observational straight line, and the inclination angle of the straight line is the internal friction angle of the soil. The intercept of the straight line on the ordinate axis is the cohesion of the soil. .

[0025] Furthermore, the construction of a numerical model of a filled fractured rock mass and the performance of numerical simulations under triaxial compression conditions to determine the volume of the characterizing unit cell specifically include the following steps:

[0026] (1) Based on the probability distribution parameters of the number of joint groups, dip angle, trace length, fault distance and spacing of the structural surface, the structural surface trace is generated by the Monte Carlo method. Finally, the data is imported into the finite element software COMSOL, and the cracks are thickened to change the generated structural surface trace from a "boundary" object to a "domain" object, so that a two-dimensional structural surface rock mass containing a certain thickness of filling material is generated. Then, the rock mass model is analyzed and solved.

[0027] (2) When the rock blocks and fissure filling materials that make up the rock mass are both continuous media, the Mohr-Coulomb model is adopted, and the mechanical parameters of the rock blocks and fissure filling materials in the rock mass containing the fissure filling material are assigned based on the mechanical test results of the rock blocks and fissure filling materials under different freeze-thaw cycles in the laboratory.

[0028] (3) The experimental conditions of the triaxial compression test were simulated by setting boundary conditions for the model. A constant confining pressure was applied to the side of the two-dimensional jointed rock mass model using boundary loads. Fixed displacement constraints were set on the bottom surface, and the vertical displacement was gradually increased on the top surface by setting a specified displacement through parametric scanning to simulate the loading process. The displacement of each loading step under compression conditions was ΔS = 0.001. 0.003mm, in 1 The size effect of the rock mass containing fractured infill structure under the condition of side length within 10m is calculated and analyzed.

[0029] Furthermore, the numerical simulation under triaxial compression conditions refers to the indoor test process of triaxial compression, and physical simulation is performed in COMSOL to realize the construction of a triaxial compression numerical test model.

[0030] Furthermore, the specific process of quantifying the deterioration process of mechanical parameters of filled fractured rock masses under the influence of freeze-thaw environments at different burial depths is as follows: based on the minimum characterization unit model obtained from the REV simulation results of fractured rock masses with infill material under triaxial compression tests, numerical simulations of triaxial compression tests under different confining pressures are carried out to calculate its cohesion and internal friction angle; the decay law of cohesion and internal friction angle of rock masses with infill material structural surfaces at different freeze-thaw cycles and different burial depths is analyzed.

[0031] Furthermore, the calculation of its cohesion and internal friction angle specifically includes the following:

[0032] Based on theory and practice, in the triaxial test data analysis method Law as independent variable σ1 is the dependent variable The regression equation is obtained by using the least squares method. ,constant , and , The relationship is shown in the following formula:

[0033]

[0034]

[0035] Under low confining pressure, the strength curve is simplified to a straight line, i.e., a linear strength curve; all scattered points ( , Linear regression yields regression coefficients b and a, which are calculated using the following formula:

[0036]

[0037]

[0038] in, x-axis data The average value, Data on the vertical axis The average value;

[0039] The correlation coefficient r is calculated using the following formula:

[0040]

[0041] internal friction angle and cohesion Calculate according to the following formulas:

[0042]

[0043]

[0044] In the formula, Angle of internal friction in rock, °; The cohesive force of a rock, in MPa; The lateral stress at failure of the i-th specimen, in MPa; Let be the failure axial stress of the i-th specimen, in MPa.

[0045] Furthermore, the structural plane level parameter SCR is... One of the scoring indicators, the The calculation formula is as follows:

[0046]

[0047] in, For structural levels.

[0048] Furthermore, the structural hierarchy is determined by the number of volume joints. Determine the number of volume joints. Unit is items / structural level The calculation formula is as follows:

[0049]

[0050] Structural level A comprehensive score is introduced here, based on roughness, weathering degree, and filling state. A correction factor for the fracture infill material characterizes the freeze-thaw degradation of the fracture infill material's strength. This correction factor is then normalized to map to the 0-1 range, ensuring the scoring results are compatible with the base system, which is [base system information missing]. Scores from 0 to 100 are shown in the following formula:

[0051]

[0052] in, It is a volume joint; For roughness; Degree of weathering; It is in the filling state; The coefficient of the fracture filling material.

[0053] Furthermore, the fracture filling coefficient characterizes the weakening effect of the fracture filling on the rock mass quality, and the calculation formula is as follows:

[0054]

[0055] in, The cohesion and internal friction angle of the rock mass containing fractured infill; The initial cohesion and internal friction angle of the fractured rock mass; , , These are the weighting coefficients for cohesion and internal friction angle, respectively. Their values ​​are determined by iterative solving, so that the rock mechanics parameters estimated by combining these coefficients and the Hawke-Brown strength criterion are closest to the numerical simulation results in S3.

[0056] Compared with the prior art, the beneficial effects of the present invention are:

[0057] 1) Enhanced model adaptability and accuracy: By introducing coupled parameters of multiple factors such as burial depth, number of freeze-thaw cycles, and properties of fracture filling material, this method can dynamically reflect the evolution of rock mechanical properties at different depths in cold regions, significantly improving the accuracy and applicability of strength prediction and overcoming the limitation of traditional methods that ignore the influence of freeze-thaw damage. When the electric shovel encounters an unknown object during excavation, causing the shovel to shake when the steel cable retracts and lifts the bucket, the bucket will be buffered by the buffer rod between the bucket and the support arm to reduce the shaking of the bucket. This reduces the shaking of the electric shovel bucket caused by the unknown or changing characteristics of the object being excavated during the excavation process, thereby improving the stability of electric shovel operation.

[0058] 2) Improve the reliability of engineering applications: This method can more realistically depict the shear degradation behavior of the infilled structural surface in fractured rock mass, providing more targeted and scientific mechanical parameter support for the stability evaluation and support design of open-pit mine slopes in cold regions, which helps to reduce disaster risks and optimize construction schemes. Attached Figure Description

[0059] Figure 1 This is a schematic diagram illustrating the temperature variation at different depths over time according to the present invention.

[0060] Figure 2 This is a schematic diagram of the internal temperature change process of the open-pit mine slope according to the present invention.

[0061] Figure 3 This is a schematic diagram of the crack filling sample after compaction according to the present invention.

[0062] Figure 4 This is a schematic diagram of the displacement-stress variation curve of the fault mud direct shear test under two freeze-thaw cycles according to the present invention.

[0063] Figure 5 This is a schematic diagram of the displacement-stress variation curve of the fault mud direct shear test under 5 freeze-thaw cycles according to the present invention.

[0064] Figure 6 This is a schematic diagram of the displacement-stress variation curve of the fault mud direct shear test after 10 freeze-thaw cycles according to the present invention.

[0065] Figure 7 This is a schematic diagram of the displacement-stress variation curve of the fault gouge under 20 freeze-thaw cycles according to the present invention.

[0066] Figure 8 This is a scatter plot showing the change in cohesion of fault gouge at different burial depths with the number of freeze-thaw cycles.

[0067] Figure 9 This is a surface fitting diagram showing the variation of the cohesion of fault gouge at different burial depths with the number of freeze-thaw cycles according to the present invention.

[0068] Figure 10 This is a geometric schematic diagram of the triaxial compression calculation model of a jointed rock mass with a side length of 1m according to the present invention.

[0069] Figure 11 This is a schematic diagram of the mesh division of the triaxial compression calculation model for a jointed rock mass with a side length of 1m according to the present invention.

[0070] Figure 12 This is the equivalent plastic strain cloud map of the rock mass containing fault mudstone structure in the 1m rock stratum of the present invention.

[0071] Figure 13 This is the equivalent plastic strain cloud map of the rock mass containing fault mudstone structure in the 3m rock stratum of this invention.

[0072] Figure 14 This is the equivalent plastic strain cloud map of the rock mass containing fault mudstone structure in the 5m rock stratum of this invention.

[0073] Figure 15 This is the equivalent plastic strain cloud map of the rock mass containing fault mudstone structure in the 7m rock stratum of this invention.

[0074] Figure 16 This is a cloud map showing the error analysis of the internal friction angle correction value of the rock mass mechanical parameters containing filling material according to the present invention.

[0075] Figure 17 This is a cloud map showing the error analysis of the cohesion correction value of the mechanical parameters of the rock mass containing infill material according to the present invention. Detailed Implementation

[0076] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0077] This invention provides a method for quantifying the geological strength index of filled fractured rock masses considering the influence of freeze-thaw environments at different burial depths, comprising the following steps:

[0078] S1. Temperature data at different burial depths are obtained using a temperature monitoring device inside the mine slope, see... Figure 1-2 Based on this, the test parameters for freeze-thaw cycles at different burial depths were set, as shown in Table 1.

[0079] Table 1

[0080]

[0081] S2. Prepare samples of the fracture filling material taken from the mine into samples with the same dry density and moisture content as the actual site conditions, conduct freeze-thaw cycle tests, and perform shear tests after reaching the predetermined number of freeze-thaw cycles to calculate the cohesion and internal friction angle of the fracture filling material.

[0082] The preparation of the fracture filling material obtained from the mine specifically includes the following steps, and the sample is as follows: Figure 3 As shown, the diameter is 60mm and the height is 25mm:

[0083] (1) Calculate the amount of wet soil sample to prepare the sample based on the required dry density and moisture content;

[0084] The formula for calculating the total required soil mass is as follows:

[0085]

[0086] in, The required dry density for preparing the sample, in g / cm³; The moisture content is measured on-site, %; V is the calculated volume of the compacted soil sample or the volume of the ring cutter used in the compactor, cm³.

[0087] The formula for calculating the additional water required to prepare soil samples is as follows:

[0088]

[0089] in, The amount of water to be added to prepare the sample, in g; The target moisture content required during sample preparation, % .

[0090] (2) Take a certain amount of crack filling material sample using the four-point method, place it on a rubber plate and crush it with a wooden roller or a soil roller; put it in a soil tray and dry it at 104℃ for 24 hours; take out the dried soil sample and cool it to room temperature, then spread it flat in a non-absorbent soil tray, spray the required amount of water evenly onto the soil sample according to the predetermined moisture content using a water spraying device, mix it well and put it into a plastic bag or seal it in a soil container and let it stand for later use.

[0091] (3) Place the compactor stably on a rigid foundation. Apply a thin layer of lubricating oil to the inner wall and bottom plate of the compaction cylinder. Connect the compaction cylinder to the bottom plate and install the protective casing. Weigh a certain amount of soil from a prepared sample and pour it into the compaction cylinder in 3 or 5 layers. Level the soil surface and compact it in layers. After cutting along the wall of the protective casing with a soil trimming knife, twist and remove the protective casing. Carefully trim the sample along the top of the compaction cylinder and remove the bottom plate. If the bottom surface of the sample extends beyond the cylinder, it should be trimmed. Finally, use a bulldozer to push the sample out of the compaction cylinder.

[0092] Prepare samples for various working conditions according to the above steps, with at least four samples prepared for each working condition. Do not reuse soil samples. The moisture content should be the actual data measured on-site to better reflect the engineering site. After reaching the predetermined number of freeze-thaw cycles, conduct a shear test to calculate the cohesion and internal friction angle of the crack filling material. The specific steps include the following:

[0093] (1) Four specimens should be taken for each group of tests and shear tests should be carried out under four different vertical pressures. Vertical pressures of different levels can be applied according to the actual engineering situation and the hardness of the soil. The difference between each level of vertical pressure should be approximately equal. Vertical pressures of 100 kPa, 200 kPa, 300 kPa and 400 kPa can also be used.

[0094] (2) The shear stress of the specimen is calculated using the following formula:

[0095]

[0096] Where τ is the shear stress (kPa); C is the force gauge calibration coefficient (N / 0.01mm); R is the force gauge reading (0.01mm); and A0 is the initial area of ​​the sample (cm²). 2 ;

[0097] (3) Plot the shear stress and shear displacement on the vertical axis. Relationship curve. Select shear stress. With shear displacement The peak point or stable value on the relationship curve is taken as the shear strength; when there is no obvious peak point, the shear displacement is taken. The corresponding shear stress is taken as the shear strength. Plot the shear strength versus vertical pressure curve with shear strength as the ordinate and vertical pressure as the abscissa; based on the points on the graph, draw an apparent straight line; the inclination angle of the straight line is the internal friction angle of the soil. The intercept of the straight line on the ordinate axis is the cohesion of the soil. ;

[0098] The displacement-stress variation curves of fault gouge under different freeze-thaw cycles are shown below. Figure 4-7 As shown, the variation of fault gouge cohesion at different burial depths with the number of freeze-thaw cycles is as follows: Figure 8-9 As shown.

[0099] S3. Construct a numerical model of the filled fractured rock mass and conduct numerical simulations under triaxial compression conditions to determine the volume of the characterizing unit. This includes the following steps:

[0100] (1) Based on the probability distribution parameters of the number of joint groups, dip angle, trace length, fault displacement and spacing of the structural surface, the Monte Carlo method is used to generate the structural surface traces. Finally, the data is imported into the finite element software COMSOL, and the cracks are thickened by 10mm to change the generated structural surface traces from "boundary" objects to "domain" objects, so as to generate a two-dimensional structural surface rock mass containing a 10mm thick filling material. Then, the rock mass model is analyzed and solved. The triaxial compression calculation model of the jointed rock mass with a side length of 1m is as follows: Figure 10-11 As shown;

[0101] (2) When the rock blocks and fissure filling materials that make up the rock mass are both continuous media, the Mohr-Coulomb model is adopted, and the mechanical parameters of the rock blocks and fissure filling materials in the rock mass containing the fissure filling material are assigned based on the mechanical test results of the rock blocks and fissure filling materials under different freeze-thaw cycles in the laboratory.

[0102] (3) The experimental conditions of triaxial compression test were simulated by setting the boundary conditions of the model. A constant confining pressure was applied to the side of the two-dimensional jointed rock mass model by the boundary load. The bottom surface was set with a fixed constraint on the displacement. The top surface was set with a specified displacement by parametric scanning to slowly increase the vertical displacement and simulate the loading process. The displacement of each loading step under compression conditions was ΔS=0.002mm. The rock mass with fractured filling structure under the conditions of side lengths of 1m, 3m, 5m, 7m and 9m was calculated to study the size effect.

[0103] Step S3 utilizes the cohesion and internal friction angle obtained from the shear test of the fractured rock mass containing the fractured filling material under the influence of freeze-thaw cycles to conduct REV simulation of the fractured rock mass containing the fractured filling material under triaxial compression test. The size effect of triaxial compression of the rock mass containing the filling material structural plane is studied and discussed using numerical simulation method, and the characterization unit of its triaxial compression strength is determined. The numerical simulation refers to the laboratory test process of triaxial compression, and physical simulation is carried out in COMSOL to realize the construction of the triaxial compression numerical test model.

[0104] Step S3, based on the REV simulation results of fractured rock mass with fracture infill material under triaxial compression tests, includes equivalent plastic strain contour maps of rock masses with fault-gouge structural planes of different sizes, as shown in the figure. Figure 12-15 As shown in Table 2, the rate of change in peak intensity under a confining pressure of 1 MPa is as follows:

[0105] Table 2

[0106]

[0107] The degradation process of mechanical parameters of filled fractured rock masses under the influence of freeze-thaw environments at different burial depths was further quantified. Specifically, based on the REV simulation results of fractured rock masses with infilled structures under triaxial compression tests, the smallest characterization unit model was obtained. The variation rate of peak strength under a confining pressure of 1 MPa is shown in Table 2. According to the REV size quantification index of variation rate less than 10%, the REV size of the peak strength of rock masses with fault gouge structures under a confining pressure of 1 MPa can be determined to be 9m×9m×9m. Numerical simulations of triaxial compression tests under different confining pressures were carried out to calculate its cohesion and internal friction angle. The decay law of cohesion and internal friction angle of rock masses with infilled structures under different freeze-thaw cycles and different burial depths was analyzed. The specific calculation of its cohesion and internal friction angle is as follows:

[0108] Based on theory and practice, in the triaxial test data analysis method Law as independent variable σ1 is the dependent variable The regression equation is obtained by using the least squares method. ,constant , and , The relationship is shown in the following formula:

[0109]

[0110]

[0111] Under low confining pressure, the strength curve is simplified to a straight line, i.e., a linear strength curve; all scattered points ( , Linear regression yields regression coefficients b and a, which are calculated using the following formula:

[0112]

[0113]

[0114] in, x-axis data The average value, Data on the vertical axis The average value;

[0115] The correlation coefficient r is calculated using the following formula:

[0116]

[0117] internal friction angle and cohesion Calculate according to the following formulas:

[0118]

[0119]

[0120] In the formula, Angle of internal friction in rock, °; The cohesive force of a rock, in MPa; The lateral stress at failure of the i-th specimen, in MPa; Let be the axial stress at failure of the i-th specimen, in MPa;

[0121] The calculation results of cohesion and internal friction angle of rock masses with fault gouge structure at different freeze-thaw cycles and different burial depths are shown in Table 3.

[0122] Table 3

[0123]

[0124] S4. Introduce a freeze-thaw correction coefficient for fracture filling material into the structural plane grade parameters, and use the ergonomic solution method to calculate the optimal value of the correction coefficient so that the rock mass mechanical parameters estimated by combining this coefficient and the Hawke-Brown strength criterion are closest to the numerical simulation results in S3, thereby realizing the correction of the geological strength index of filled fracture rock mass under the influence of freeze-thaw environment at different burial depths.

[0125] The structural plane level parameter SCR is: One of the scoring indicators, the The calculation formula is as follows:

[0126]

[0127] in, For structural hierarchy;

[0128] Structural grade SR is determined by the number of volume joints. (strip / The calculation formula is as follows:

[0129]

[0130] Structural level A comprehensive score is introduced here, based on roughness, weathering degree, and filling state. The crack filling material correction factor characterizes the freeze-thaw degradation of the crack filling material strength. This correction factor is then normalized to map it to the 0-1 range, ensuring the scoring results are consistent with the baseline system. (0~100 points) compatible, as shown in the following formula:

[0131]

[0132] in, It is a volume joint; For roughness; Degree of weathering; It is in the filling state; The coefficient of the crack filling material;

[0133] The fracture filling coefficient The correction factor characterizes the weakening effect of fracture filling on rock mass quality. The greater the thickness of the weak interlayer, the lower the correction factor. This is combined with the test results of the fault-gouge-containing structural surface. Figure 12-15 Table 3;

[0134] This indicates that a 10mm thick fault gouge can reduce cohesion by 30%, as shown in Table 4.

[0135] Table 4

[0136]

[0137] Its specific expression is shown in the following formula:

[0138]

[0139] in, The cohesion and internal friction angle of the rock mass containing fractured infill; The initial cohesion and internal friction angle of the fractured rock mass; , , These are the weighting coefficients for cohesion and internal friction angle, respectively. Their values ​​are determined by iterative solving, so that the rock mechanics parameters estimated by combining these coefficients and the Hawke-Brown strength criterion are closest to the numerical simulation results in S3.

[0140] The filling state of infilled rock masses under freeze-thaw cycles and The product is used for correction, thereby correcting the Structural Surface Grade (SCR) and subsequently the Geological Strength Index (GSI). The corrected GSI value is then substituted into the generalized Hoek-Brown strength criterion to calculate the cohesion of the mechanical parameters of the rock mass at different freeze-thaw cycles and depths. internal friction angle This is compared with the cohesion of the rock mass mechanical parameters obtained from numerical simulation. internal friction angle A comparison is performed, the error between the two is calculated, and verification is conducted. This includes adjusting the correction coefficient. Weighting coefficients for cohesion and internal friction angle , The value of is calculated iteratively within the range (0, 0.1, 1) to obtain the mechanical parameter cohesion. internal friction angle The value at which the sum of errors is minimized is the contribution coefficient; this can be obtained through iterative calculation. , .

[0141] Table 4 shows the freeze-thaw correction results and error analysis of the mechanical parameters of the rock mass containing infill material. The error analysis cloud diagram of the freeze-thaw correction results is shown below. Figure 16-17 As shown, the average correction errors for the internal friction angle and cohesion of the infilled rock mass are 7.36% and 9.59%, respectively, indicating that the method for quantifying the geological strength index of infilled fractured rock mass considering the effects of freeze-thaw environments at different burial depths has high reliability.

[0142] The above embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the above embodiments. Unless otherwise specified, the methods used in the above embodiments are conventional methods.

Claims

1. A method for quantifying the geological strength index of filled fractured rock masses considering the effects of freeze-thaw environments at different burial depths, characterized in that, Includes the following steps: S1. Use the temperature monitoring device inside the mine slope to obtain temperature data at different burial depths, and set the freeze-thaw cycle test parameters corresponding to different burial depths accordingly. S2. Prepare samples of the fracture filling material taken from the mine with the same dry density and moisture content as the actual site, carry out freeze-thaw cycle tests, and conduct shear tests after reaching the predetermined number of freeze-thaw cycles to calculate the cohesion and internal friction angle of the fracture filling material. S3. Construct a numerical model of the filled fractured rock mass and perform numerical simulation under triaxial compression conditions to determine the volume of the characterizing unit and quantify the deterioration process of the mechanical parameters of the filled fractured rock mass under the influence of freeze-thaw environments at different burial depths. S4. Introduce the freeze-thaw correction coefficient for fracture filling material in the structural plane grade parameter SCR, and use the ergonomic solution method to calculate the optimal value of the correction coefficient so that the rock mass mechanical parameters estimated by combining the coefficient and the Hawke-Brown strength criterion are closest to the numerical simulation results in S3, thereby realizing the correction of the geological strength index of filled fracture rock mass under the influence of freeze-thaw environment at different burial depths. The structural plane level parameter SCR is: One of the scoring indicators, the The calculation formula is as follows: in, For structural hierarchy; The structural hierarchy is determined by the number of volume joints. Determine the number of volume joints. Unit is items / structural level The calculation formula is as follows: Structural level A comprehensive score is introduced here, taking into account roughness, weathering degree, and filling state. A correction factor for the fracture infill material characterizes the freeze-thaw degradation of the fracture infill material's strength. This correction factor is then normalized to map to the 0-1 range, ensuring the scoring results are compatible with the base system, which is [base system information missing]. Scores from 0 to 100 are shown in the following formula: in, It is a volume joint; For roughness; Degree of weathering; It is in the filling state; The coefficient of the crack filling material; The fracture filling coefficient characterizes the weakening effect of the fracture filling on the rock mass quality, and the calculation formula is as follows: in, The cohesion and internal friction angle of the rock mass containing fractured infill; The initial cohesion and internal friction angle of the fractured rock mass; , , These are the weighting coefficients for cohesion and internal friction angle, respectively. Their values ​​are determined by iterative solving, so that the rock mechanics parameters estimated by combining these coefficients and the Hawke-Brown strength criterion are closest to the numerical simulation results in S3.

2. The method for quantifying the geological strength index of filled fractured rock masses considering the effects of freeze-thaw environments at different burial depths, as described in claim 1, is characterized in that... The preparation of the fracture filling material obtained from the mine specifically includes the following steps: (1) Calculate the amount of wet soil sample to prepare the sample based on the required dry density and moisture content; The formula for calculating the total required soil mass is as follows: in, The required dry density for preparing the sample, in g / cm³; The moisture content is measured on-site, %; V is the calculated volume of the compacted soil sample or the volume of the ring cutter used in the compactor, cm³. The formula for calculating the additional water required to prepare soil samples is as follows: in, The amount of water to be added to prepare the sample, in g; The target moisture content required during sample preparation, % . (2) Take a certain amount of crack filling material sample using the four-point method, place it on a rubber plate and crush it with a wooden roller or a soil roller, put it in a soil tray and dry it at 100℃~105℃ for 24 hours until constant weight; take out the dried soil sample and cool it to room temperature, then spread it flat in a non-absorbent soil tray, spray the required amount of water evenly onto the soil sample according to the predetermined moisture content using a water spraying device, mix it well and put it into a plastic bag or seal it in a soil container and let it stand for later use. (3) Place the compactor stably on a rigid foundation, apply a layer of lubricating oil to the inner wall and bottom plate of the compaction cylinder, connect the compaction cylinder and the bottom plate, install the protective casing, weigh a certain amount of soil from a prepared sample, pour it into the compaction cylinder in 3 or 5 layers and level the soil surface, compact in layers, cut along the wall of the protective casing with a soil trimming knife, twist and remove the protective casing, carefully trim the sample along the top of the compaction cylinder, remove the bottom plate, trim the bottom surface of the sample when it extends beyond the cylinder, and finally push the sample out of the compaction cylinder with a bulldozer.

3. The method for quantifying the geological strength index of filled fractured rock masses considering the effects of freeze-thaw environments at different burial depths, as described in claim 1, is characterized in that... The step of conducting a shear test after reaching a predetermined number of freeze-thaw cycles to calculate the cohesion and internal friction angle of the crack filler includes the following steps: (1) Take 3 to 5 specimens for each test group and conduct shear tests under 3 to 5 different vertical pressures. Apply vertical pressures of various levels according to the actual engineering situation and the hardness of the soil. The differences between the various levels of vertical pressure should be equal or nearly equal; or select several levels of pressure within the range of 100 to 400 kPa for testing. (2) The shear stress of the specimen is calculated according to the following formula: Where τ is the shear stress (kPa); C is the force gauge calibration coefficient (N / 0.01mm); R is the force gauge reading (0.01mm); and A0 is the initial area of ​​the sample (cm²). 2 ; (3) Plot the shear stress and shear displacement on the vertical axis. Relationship curve; select shear stress With shear displacement The peak point or stable value on the relationship curve is taken as the shear strength. When there is no obvious peak point, the shear displacement is taken. The corresponding shear stress is taken as the shear strength; plot the relationship curve between shear strength and vertical pressure with shear strength as the ordinate and vertical pressure as the abscissa. Based on the points on the graph, draw an observational straight line, and the inclination angle of the straight line is the internal friction angle of the soil. The intercept of the straight line on the ordinate axis is the cohesion of the soil. .

4. The method for quantifying the geological strength index of filled fractured rock mass considering the effects of freeze-thaw environments at different burial depths, as described in claim 1, is characterized in that... The construction of a numerical model of a filled fractured rock mass and the performance of numerical simulations under triaxial compression conditions to determine the volume of the characterizing unit cell specifically include the following steps: (1) Based on the probability distribution parameters of the number of joint groups, dip angle, trace length, fault distance and spacing of the structural surface, the structural surface trace is generated by the Monte Carlo method. Finally, the data is imported into the finite element software COMSOL, and the cracks are thickened to change the generated structural surface trace from a "boundary" object to a "domain" object, so that a two-dimensional structural surface rock mass containing a certain thickness of filling material is generated. Then, the rock mass model is analyzed and solved. (2) When the rock blocks and fissure filling materials that make up the rock mass are both continuous media, the Mohr-Coulomb model is adopted, and the mechanical parameters of the rock blocks and fissure filling materials in the rock mass containing the fissure filling material are assigned based on the mechanical test results of the rock blocks and fissure filling materials under different freeze-thaw cycles in the laboratory. (3) The experimental conditions of the triaxial compression test were simulated by setting boundary conditions for the model. A constant confining pressure was applied to the side of the two-dimensional jointed rock mass model using boundary loads. Fixed displacement constraints were set on the bottom surface, and the vertical displacement was gradually increased on the top surface by setting a specified displacement through parametric scanning to simulate the loading process. The displacement of each loading step under compression conditions was ΔS = 0.

001. 0.003mm, in 1 The size effect of the rock mass containing fractured infill structure under the condition of side length within 10m is calculated and analyzed.

5. The method for quantifying the geological strength index of filled fractured rock masses considering the effects of freeze-thaw environments at different burial depths, as described in claim 1, is characterized in that... The numerical simulation under triaxial compression conditions refers to the indoor test process of triaxial compression. Physical simulation is performed in COMSOL to realize the construction of a triaxial compression numerical test model.

6. The method for quantifying the geological strength index of filled fractured rock mass considering the effects of freeze-thaw environments at different burial depths, as described in claim 1, is characterized in that... The specific process of quantifying the deterioration process of mechanical parameters of filled fractured rock masses under the influence of freeze-thaw environments at different burial depths is as follows: Based on the minimum characterization unit model obtained from the REV simulation results of fractured rock masses with infill material under triaxial compression tests, numerical simulations of triaxial compression tests under different confining pressures are carried out to calculate its cohesion and internal friction angle; the decay law of cohesion and internal friction angle of rock masses with infill material structural surfaces at different freeze-thaw cycles and different burial depths is analyzed.

7. The method for quantifying the geological strength index of filled fractured rock mass considering the effects of freeze-thaw environments at different burial depths, as described in claim 6, is characterized in that... The calculation of its cohesive force and internal friction angle specifically includes the following: Based on theory and practice, in the triaxial test data analysis method Law as independent variable σ1 is the dependent variable The regression equation is obtained by using the least squares method. ,constant , and , The relationship is shown in the following formula: Under low confining pressure, the strength curve is simplified to a straight line, i.e., a linear strength curve; all scattered points ( , Linear regression yields regression coefficients b and a, which are calculated using the following formula: in, x-axis data The average value, Data on the vertical axis The average value; The correlation coefficient r is calculated using the following formula: internal friction angle and cohesion Calculate according to the following formulas: In the formula, Angle of internal friction in rock, °; The cohesive force of a rock, in MPa; The lateral stress at failure of the i-th specimen, in MPa; Let be the failure axial stress of the i-th specimen, in MPa.

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