A surrounding rock grading correction method considering thermal, water and force coupling

Abstract

The application discloses a surrounding rock grading correction method considering thermal, water and force coupling, which comprises the following steps: drilling rock mass at an engineering site to be studied to prepare a plurality of standard samples, vacuum saturating all the standard samples, and then wiping off surface moisture of the standard samples after vacuum saturation; carrying out saturated granite uniaxial test and thermal-water-force coupling orthogonal test on the plurality of saturated standard samples to obtain rock saturated uniaxial strength and multi-field coupling rock theoretical uniaxial strength; using a quotient of the multi-field coupling rock theoretical uniaxial strength and the rock saturated uniaxial strength as a surrounding rock grading correction coefficient; and correcting multi-field coupling environment surrounding rock grading based on BQ grading, Q system and / or Rmi rock mass quality according to the surrounding rock grading correction coefficient.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel and underground engineering surrounding rock classification, and particularly relates to a surrounding rock classification correction method considering thermal, water and force coupling. BACKGROUND

[0002] The energy and space demands brought by economic and social development force more and more projects to go deep, such as the Sichuan-Tibet Railway and the hydropower projects in the lower reaches of the Yarlung Zangbo River. The engineering rock mass under deep environment is greatly affected by the coupling environment of high geothermal, high ground stress and high permeation pressure, and the mechanical response of the engineering rock mass is complex and variable, which greatly affects the fine classification of deep rock mass quality during the construction stage, and the problem of identifying the deterioration of related mechanical parameters of engineering rock mass under the multi-field coupling environment needs to be solved urgently.

[0003] Generally speaking, the thermal expansion of rock minerals and thermal cracking between minerals caused by high temperature will lead to significant changes in the mechanical properties of rocks. Meanwhile, the continuous influence of the coupling of the pore pressure of the underground seepage field and the water-rock material reaction, the initiation, expansion and penetration of microcracks in the surrounding rock mass under the condition of thermal-water-force multi-field coupling are strengthened, which leads to the reduction of rock mass strength and the weakening of stability, and causes the destruction and instability of surrounding rock. Although the existing rock mass classification methods such as the modified BQ rock mass classification, Q system and RMi have realized the influence of underground water, geological structure and ground stress on the evaluation results of surrounding rock quality, and further evaluated the classification results considering the ground stress and underground water, they do not fully consider the influence of temperature and coupling environment on the mechanical properties of rock mass, resulting in low classification accuracy, and further causing the improper construction method or support method of the rock mass at the project site, which has certain safety hazards.

[0004] Therefore, it is urgent to propose a surrounding rock classification correction method considering the deterioration of high geothermal and multi-field coupling environment on the mechanical properties of engineering rock mass. SUMMARY

[0005] In view of the above shortcomings in the prior art, the surrounding rock classification correction method considering thermal, water and force coupling provided by the application solves the problem that the existing rock mass quality classification method does not consider the deterioration of high geothermal and multi-field coupling environment on the mechanical properties of engineering rock mass, resulting in inaccurate rock mass quality classification.

[0006] In order to achieve the above-mentioned purposes, the technical scheme adopted by the application is as follows:

[0007] A surrounding rock classification correction method considering thermal, water and force coupling is provided, which comprises the following steps:

[0008] S1, drilling the rock mass at the project site to be studied to prepare a plurality of standard samples, and vacuum saturating all the standard samples, and then wiping the surface moisture of the vacuum saturated standard samples;

[0009] S2, carrying out saturated granite uniaxial test and thermal-water-force coupling orthogonal test on a plurality of saturated standard samples to obtain rock saturated uniaxial strength and multi-field coupling rock theoretical uniaxial strength;

[0010] S3, using a quotient of the multi-field coupling rock theoretical uniaxial strength and the rock saturated uniaxial strength as a surrounding rock classification correction coefficient;

[0011] S4, according to the surrounding rock classification correction coefficient, correcting the surrounding rock classification in a multi-field coupling environment based on BQ classification, Q system and / or Rmi rock mass quality:

[0012] [BQ] THM =100+3αR c +250K v -100(K1+K2+K3)

[0013]

[0014] Wherein, [BQ] THM , Q THM and RMi THM are rock mass basic quality indexes BQ, Q and RMi respectively; α is the surrounding rock classification correction coefficient; R c is the rock saturated uniaxial strength; K1 is a groundwater influence correction coefficient of underground engineering; K2 is a main structural plane occurrence influence correction coefficient of underground engineering; K3 is an initial stress state influence correction coefficient; K v is a classification factor quantitative index; RQD is a rock quality index; J n is a grade of joint sets; J r is a grade of joint surface roughness; J a is a grade of alteration degree or clay filling joint sets; J w is a grade of groundwater inflow and pressure influence; SRF is a stress reduction coefficient; J c is a structural plane condition coefficient; V b is a volume of a block cut by a structural plane; D is a transition parameter, D=0.37J c -0.2 .

[0015] Further, the method for carrying out saturated granite uniaxial test to obtain rock saturated uniaxial strength comprises:

[0016] S21, placing the standard sample on a testing machine loading table of a GCTS system, and respectively installing an axial displacement sensor, a ring displacement sensor and an acoustic emission probe on a heat shrink film surface of the standard sample;

[0017] S22, testing the sample at a preset axial deformation rate, and recording rock mass basic mechanical parameters in the testing process.

[0018] S23, when all standard samples are executed to complete step S21 and step S22, according to the cross-sectional area of the standard sample, the stress of the standard sample under each load is calculated:

[0019]

[0020] Wherein, σ is stress; P is load; A is the cross-sectional area of the standard sample;

[0021] S24, according to the stress under each load, the stress evolution curve of the standard sample in the loading process is obtained, and the maximum value in the stress evolution curve is selected as the saturated uniaxial strength of the rock.

[0022] Further, the method for obtaining the theoretical uniaxial strength of the multi-field coupled rock includes:

[0023] A1, the standard sample after being saturated is subjected to confining pressure, when the set confining pressure is reached, the permeation pressure is applied, then the target temperature is maintained for a preset time, and the loading test is carried out until the standard sample is destroyed;

[0024] A2, when a plurality of standard samples after being saturated are completed in step A1, the confining pressure and the rock compressive strength under the corresponding confining pressure recorded in the test process of step A1 are used to calculate the effective confining pressure and the effective peak strength:

[0025]

[0026] Wherein, the variable i=1 and 3, σ3 is the recorded confining pressure; σ1 is the rock compressive strength corresponding to σ3; And The effective peak strength and the effective confining pressure are respectively P w The void water pressure;

[0027] A3, the effective confining pressure and the effective peak strength of the plurality of standard samples are fitted to obtain the fitting formula:

[0028]

[0029] A4, according to the slope and intercept of the fitting formula, the internal friction angle And the cohesion c of the rock are calculated:

[0030]

[0031] Wherein, m and b are the slope and intercept respectively;

[0032] A5, according to the internal friction angle And the cohesion c of the rock, the theoretical uniaxial strength of the multi-field coupled rock is calculated:

[0033]

[0034] wherein, is the theoretical uniaxial strength of the multi-field coupled rock.

[0035] Further, the method for obtaining the theoretical uniaxial strength of the multi-field coupled rock includes:

[0036] B1, applying confining pressure to the standard sample after saturation, applying permeation pressure when the set confining pressure is reached, then maintaining the target temperature for a preset time, and performing a loading test until the standard sample is destroyed;

[0037] B2, using the temperature increment and the rock elastic modulus obtained in the multi-field coupled test stage to calculate the theoretical uniaxial strength of the multi-field coupled rock:

[0038]

[0039] wherein, is the theoretical uniaxial strength of the multi-field coupled rock; C v is the specific heat at constant volume of the rock material; ΔT and E are the temperature increment and the rock elastic modulus in the multi-field coupled test stage, respectively; R c is the saturated uniaxial strength of the rock; k is the first fitting parameter; E0 is the elastic modulus of the rock under uniaxial conditions.

[0040] Further, the expression construction method of the theoretical uniaxial strength of the multi-field coupled rock in step B2 includes:

[0041] B21, constructing a releasable elastic energy model under the condition of thermal-hydraulic coupling:

[0042]

[0043] wherein, U e is the releasable elastic energy of the rock; and are the effective peak strength, the effective principal stress and the effective confining pressure, respectively; μ is the Poisson's ratio;

[0044] B22, constructing the critical value G c of the maximum energy release rate according to the saturated uniaxial strength of the rock:

[0045]

[0046] wherein, K3 is a material constant;

[0047] B23, determining the strength criterion of the rock as a whole when it is destroyed under the condition of thermal-hydraulic coupling:

[0048]

[0049] B24, the strength criterion of the whole rock failure is substituted into the releasable elastic energy model, and an expression is obtained:

[0050]

[0051] B25, the expression in step B24 is modified by using a strain energy dispersion coefficient, and a rock energy type strength criterion under the condition of thermo-hydraulic coupling is obtained:

[0052]

[0053] wherein N is a strain energy dispersion coefficient, n is a second fitting parameter;

[0054] B26, the rock energy type strength criterion is set as Let a uniaxial strength expression of the multi-field coupling rock theory is obtained:

[0055]

[0056] Further, when the BQ classification is corrected, the saturated uniaxial strength R c of the rock and the classification factor quantitative index K v satisfy the conditions: when R c >90K v +30, R c =90K v +30; when K v >0.04R c ,

[0057] K v =0.04R c +0.4.

[0058] Further, the standard sample is a granite sample.

[0059] Further, after obtaining the rock mass basic quality index BQ, Q and RMi, the rock mass quality grade of the rock mass at the engineering site to be studied is obtained according to the classification standard of the rock mass quality grade corresponding to the rock mass basic quality index BQ, Q and RMi.

[0060] The beneficial effects of the present application are: the present scheme starts from the description of the multi-field coupling environment and the groundwater in the surrounding rock classification method commonly faced in deep engineering, obtains the mechanical parameters of the rock through the uniaxial test and the multi-field coupling test, then obtains the multi-field coupling rock theoretical uniaxial strength and the rock saturated uniaxial strength based on the mechanical parameters, and further determines the surrounding rock classification correction coefficient. Compared with the existing surrounding rock classification method, the present scheme combines the laboratory test results, obtains the multi-field coupling theoretical uniaxial strength, considers the degradation effect of the thermal-water-force multi-field coupling on the mechanical properties of the surrounding rock mass, makes the surrounding rock classification result more accurate, provides more reliable guarantee for the reasonable design and safe construction of the tunnel and underground engineering, and can reduce the existing safety hidden danger to a certain extent. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 The flowchart of the surrounding rock classification correction method considering the coupling effects of heat, water and force.

[0062] Figure 2 The compressive strength of granite under the multi-field coupling condition according to one embodiment of the present application.

[0063] Figure 3 The linear relationship between the effective confining pressure and the effective peak stress of granite under the multi-field coupling condition according to one embodiment of the present application. DETAILED DESCRIPTION

[0064] The specific embodiments of the present application are described below to facilitate the understanding of the present application by those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.

[0065] The present scheme mainly modifies the domestic and foreign mainstream surrounding rock classification methods (BQ classification, RMR classification and Q system three methods), and for this embodiment, the groundwater state involved in the domestic and foreign mainstream surrounding rock classification methods is described first, as shown in Tables 1-3.

[0066] Table 1 Groundwater outflow state of BQ classification

[0067]

[0068] Table 2 Index description of RMR classification

[0069]

[0070]

[0071] Table 3 Parameter description of Q system

[0072]

[0073] In Table 1, p is the fissure water pressure of underground engineering surrounding rock (MPa), and Q is the water inflow per 10 m of tunnel length (L / min·10 m). In the Q system, the values of C-F terms are all rough estimates, and 10 kg / cm 2 = 1 MPa fissure water pressure of underground engineering surrounding rock.

[0074] As can be seen from Table 1, the division of the fissure water pressure p of underground water surrounding rock is usually bounded by 0.1 MPa, 0.5 MPa and 1 MPa, and the corresponding water inflow per 10 m of tunnel length Q is 25 L / min·10 m, 125 L / min·10 m and 250 L / min·10 m, respectively.

[0075] At the same time, in Table 4, the consideration of underground water in the surrounding rock classification specification methods such as Railway Tunnel Design Specification TB10003-2016, Hydraulic Tunnel Design Specification SL279, Water Resources and Hydropower Engineering Geological Exploration Specification GB50487 and Rock Mass Structure Evaluation Classification (RSR) is fully investigated.

[0076] Table 4

[0077]

[0078] As can be seen from Table 4, the maximum underground water fissure water pressure p threshold considered in the existing surrounding rock classification specification and method is 1 MPa, and the maximum water inflow Q is 125 L / min·10 m. Therefore, the maximum seepage pressure condition in the multi-field coupled intact rock test can be limited to 1 MPa, and the simulation seepage pressure conditions are set to 0.1 MPa, 0.5 MPa and 1 MPa, respectively, by referring to the grade division of the fissure water pressure p of underground water surrounding rock in the specification.

[0079] At the same time, the setting of the test temperature condition is determined by referring to the high-temperature environment faced in the existing deep tunnel engineering construction. The existing research predicts that the maximum tunnel body temperature of Baima Tunnel can exceed 60℃, and the maximum ground temperature in Sangzhuling Tunnel, which has been completed, reaches nearly 90℃.

[0080] Therefore, combined with the high-temperature environment faced in the actual deep engineering, the simulation temperatures of 60℃ and 100℃ are set at an equal gradient based on the room temperature of 25℃. At the same time, considering that the subsequent surrounding rock classification correction needs to obtain the theoretical uniaxial strength by combining the Mohr-Coulomb criterion, the confining pressure can be set at a lower level, for example, 2, 5 and 10 MPa, and the multi-field coupled intact rock test conditions are obtained as shown in Table 5.

[0081] Table 5

[0082] Surrounding pressure condition setting (MPa): 2 5 10 Osmotic pressure condition setting (MPa): 0.1 0.5 1 Temperature condition setting (°C): 25 60 100

[0083] The parameters selected in Tables 1-5 are combined below to carry out saturated granite uniaxial tests and thermal-water-force coupling orthogonal tests to modify the surrounding rock classification:

[0084] Reference Figure 1 , Figure 1 A surrounding rock classification modification method considering thermal, water and force coupling is shown; the method S includes steps S1-S4.

[0085] In step S1, a rock mass at a project to be studied is drilled to prepare a plurality of standard samples, and all the standard samples are vacuum saturated, and then the surface moisture of the vacuum saturated standard samples is wiped dry; the standard sample is preferably a granite sample.

[0086] The detailed implementation process of step S1 is as follows:

[0087] The granite rock mass taken from a certain tunnel excavation is processed into a standard sample with a diameter of 50 mm and a height of 100 mm according to the provisions in the national standard "Coal and Rock Physical and Mechanical Property Determination Method", and the non-parallelism of the two ends of the sample is not greater than 0.05 mm; the diameter deviation of the upper and lower ends of the sample should not be greater than 0.3 mm, the surface of the sample should be smooth, and stress concentration phenomena caused by irregular surfaces should be avoided. Then the granite is vacuum saturated for 48 hours using a vacuum saturation device to ensure that the sample is in a saturated state.

[0088] In step S2, saturated granite uniaxial tests and thermal-water-force coupling orthogonal tests are carried out on the plurality of saturated standard samples to obtain the saturated uniaxial strength of the rock and the theoretical uniaxial strength of the multi-field coupled rock; the saturated granite uniaxial tests and thermal-water-force coupling orthogonal tests are carried out by relying on the GCTS high-temperature rock mechanics test system.

[0089] The GCTS high-temperature rock mechanics test system has a confining pressure and axial loading system, a permeable water pressure loading and temperature control system, can apply a maximum confining pressure of 140 MPa, a maximum pore water pressure of 140 MPa and a maximum axial load of 4600 kN, and can heat the standard sample to a maximum temperature of 150℃. During the test, the temperature control, loading rate, load and deformation measurement are all controlled by computer programs and measured by high-precision sensors, and data acquisition and recording are automatically performed. An axial displacement sensor with a range of ±2.5 mm and a hoop displacement sensor with a range of ±2.5 mm are used to measure the axial strain and hoop strain of the loaded sample, respectively. The axial displacement sensor, hoop displacement sensor and acoustic emission probe are installed on the surface of the sample heat shrink film, and vaseline is applied between the probe and the heat shrink film. Adjust the travel of the axial and hoop displacement sensors to ensure that the displacement sensors are always within the effective range during the test.

[0090] In implementation, the method for obtaining the saturated uniaxial strength of the rock by carrying out the saturated granite uniaxial test preferably comprises the following steps:

[0091] S21, placing the standard sample on the testing machine loading table of the GCTS system, and respectively installing the axial displacement sensor, the ring displacement sensor and the acoustic emission probe on the surface of the heat shrink film of the standard sample;

[0092] S22, testing the sample at a preset axial deformation rate, and recording the basic mechanical parameters of the rock mass in the testing process; the preset axial deformation rate is 0.04 mm / min;

[0093] S23, after all the standard samples are executed to complete the steps S21 and S22, calculating the stress of the standard sample under each load according to the cross-sectional area of the standard sample:

[0094]

[0095] wherein, σ is the stress; P is the load; A is the cross-sectional area of the standard sample;

[0096] S24, obtaining the stress evolution curve of the standard sample in the loading process according to the stress under each load, and selecting the maximum value in the stress evolution curve as the saturated uniaxial strength of the rock;

[0097] The mechanical parameters of the plurality of standard samples obtained by using the test parameters given above can be referred to Table 6.

[0098] Table 6

[0099]

[0100] In step S3, the quotient of the uniaxial strength of the rock mass by the saturated uniaxial strength of the rock is used as the surrounding rock classification correction coefficient:

[0101]

[0102] In step S4, the surrounding rock classification based on the multi-field coupling environment of the BQ classification, the Q system and / or the Rmi rock mass quality is corrected according to the surrounding rock classification correction coefficient:

[0103] [BQ] THM = 100 + 3aR c + 250K v - 100(K1 + K2 + K3)

[0104]

[0105] wherein, [BQ] THM , Q THM and Rmi THMBQ, Q and RMi are basic quality indexes of rock mass, respectively; a is the correction coefficient of surrounding rock classification; R c R is the saturated uniaxial strength of rock; K1 is the correction coefficient of groundwater influence of underground engineering; K2 is the correction coefficient of occurrence influence of main structural plane of underground engineering; K v K is the quantitative index of classification factor; RQD is the rock quality index; J n J is the grade of the number of joint sets; r J is the grade of joint surface roughness; a J is the grade of alteration degree or clay filling joint sets; w J is the grade of groundwater inflow and pressure influence; SRF is the stress reduction coefficient; c J is the condition coefficient of structural plane; V b V is the volume of the block cut by the structural plane; D is a transition parameter, D = 0.37J c -0.2 .

[0106] In step S4, when the BQ classification is corrected, the saturated uniaxial strength R c of rock and the quantitative index K v of classification factor meet the conditions as follows: when R c >90K v +30, R c =90K v +30; when K v >0.04R c , K v =0.04R c +0.4.

[0107] The scheme gives two methods for carrying out thermal-water-force coupling orthogonal test to obtain the theoretical uniaxial strength of multi-field coupling rock, the first method is:

[0108] A1, a standard sample after being saturated with water is subjected to confining pressure, when the set confining pressure is reached, a permeation pressure is applied, then the target temperature is reached and maintained for a preset time, and a loading test is carried out until the standard sample is destroyed;

[0109] The detailed implementation process of step A1 is as follows:

[0110] (1) Apply confining pressure: increase the confining pressure to the target value (2 MPa, 5 MPa, 10 MPa) at a rate of 3 MPa / min

[0111] (2) Apply permeation pressure: set the permeation pressure of this test to 0.1, 0.5, 1 MPa. After reaching the set confining pressure, increase the water pressure at the inlet end of the granite sample to the set value, and set the water pressure at the outlet end to 0.

[0112] (3) Loading test: after heating to the target temperature (60℃, 100℃) and maintaining for 30 minutes, the granite is subjected to loading test at a loading rate of 0.04 mm / min until the sample is destroyed, and the mechanical parameters of the granite under different conditions are recorded. For example, Figure 2 The granite strength degradation characteristics under different temperatures and different osmotic pressure conditions are obtained under a confining pressure of 2 MPa.

[0113] A2, when a plurality of standard samples after being saturated with water are all completed in step A1, the confining pressure and the rock compressive strength under the corresponding confining pressure recorded in the test process in step A1 are used to calculate the effective confining pressure and the effective peak strength:

[0114]

[0115] wherein the variables i=1 and 3, σ3 is the recorded confining pressure; σ1 is the rock compressive strength under σ3; σ1 e and are the effective peak strength and the effective confining pressure respectively; P w is the pore water pressure.

[0116] A3, the effective confining pressure and the effective peak strength of a plurality of standard samples are fitted to obtain a fitting formula:

[0117]

[0118] The fitting formula can refer to Figure 3 , and the values of m and b are preferably 13.32 and 156.78.

[0119] A4, according to the slope and intercept of the fitting formula, the internal friction angle and the cohesion c of the rock are calculated:

[0120]

[0121] wherein m and b are the slope and the intercept respectively;

[0122] A5, according to the internal friction angle and the cohesion c of the rock, the theoretical uniaxial strength of the multi-field coupled rock is calculated:

[0123]

[0124] wherein, is the theoretical uniaxial strength of the multi-field coupled rock.

[0125] The second method for obtaining the theoretical uniaxial strength of the multi-field coupled rock provided by the scheme includes:

[0126] B1, the confining pressure is applied to the standard sample after being saturated, the osmotic pressure is applied when the set confining pressure is reached, then the target temperature is maintained for a preset time period, and the loading test is carried out until the standard sample is damaged;

[0127] B2, the temperature increment and the rock elastic modulus obtained in the multi-field coupling test stage are used to calculate the multi-field coupling rock theoretical uniaxial strength:

[0128]

[0129] Wherein, The multi-field coupling rock theoretical uniaxial strength; C v The specific heat capacity of the rock material; ΔT and E are the temperature increment and the rock elastic modulus in the multi-field coupling test stage respectively; R c The saturated uniaxial strength of the rock; k is the first fitting parameter; E0 is the elastic modulus of the rock under uniaxial condition.

[0130] In an embodiment of the present application, the expression construction method of the multi-field coupling rock theoretical uniaxial strength in step B2 comprises:

[0131] B21, the releasable elastic energy model under the thermal-hydraulic coupling condition is constructed:

[0132]

[0133] Wherein, U e The releasable elastic energy of the rock; And The effective peak strength, the effective principal stress and the effective confining pressure respectively; μ is the Poisson's ratio;

[0134] B22, according to the saturated uniaxial strength of the rock, the critical value G c of the maximum energy release rate is constructed:

[0135]

[0136] Wherein, K3 is a material constant;

[0137] B23, the strength criterion when the rock as a whole is damaged under the thermal-hydraulic coupling condition is determined:

[0138]

[0139] B24, the releasable elastic energy model is substituted into the strength criterion when the rock as a whole is damaged, and the expression is obtained:

[0140]

[0141] B25, the strain energy dispersion coefficient is used to modify the expression in step B24 to obtain the rock energy type strength criterion under thermal-hydraulic coupling conditions:

[0142]

[0143] wherein N is a strain energy dispersion coefficient, n is a first fitting parameter;

[0144] B26, let the rock energy type strength criterion be Let obtain the uniaxial strength expression of the multi-field coupling rock theory:

[0145]

[0146] After obtaining the rock mass basic quality index BQ, Q and RMi, the rock mass quality grade of the rock mass at the engineering site to be studied is obtained according to the classification standard of the rock mass basic quality index BQ, Q and RMi and the corresponding rock mass quality grade.

[0147] Based on the uniaxial test and the multi-field coupling orthogonal test in this embodiment, the detailed test parameters are given, and the part of the multi-field coupling surrounding rock classification correction coefficient obtained by combining the surrounding rock classification correction method of the scheme is shown in Table 7.

[0148] Table 7

[0149]

[0150] In this embodiment, the granite used in the uniaxial test and the multi-field coupling test is a representative of igneous rock, and the multi-field coupling environment can cause a strength degradation of up to 12%. This result can provide a reference for the surrounding rock classification correction under the multi-field coupling environment.

Claims

1. A method for classifying and correcting surrounding rock considering the coupling effects of heat, water, and force, characterized in that, Including the following steps: S1. Drill the rock mass at the site of the project to be studied to prepare multiple standard samples, and vacuum saturate all the standard samples with water, and then wipe the surface moisture of the vacuum saturated standard samples dry. S2. Saturated granite uniaxial tests and thermo-hydraulic-mechanical coupled orthogonal tests were carried out on multiple saturated standard samples to obtain the saturated uniaxial strength of the rock and the theoretical uniaxial strength of the multi-field coupled rock. S3. The quotient of the uniaxial strength of the multi-field coupled rock theory and the saturated uniaxial strength of the rock is used as the correction coefficient for the classification of surrounding rock. S4. Correct the surrounding rock classification in a multi-field coupled environment based on BQ classification, Q system, and / or RMi rock mass quality according to the surrounding rock classification correction coefficient: [BQ] THM =100+3αR c +250K v -100(K1+K2+K3) Among them, [BQ] THM Q THM and RMi THM These are the basic quality indicators of the rock mass: BQ, Q, and RMi; α is the surrounding rock classification correction coefficient; R c K1 is the saturated uniaxial strength of the rock; K2 is the correction factor for the influence of groundwater on underground engineering; K3 is the correction factor for the influence of the attitude of the main structural planes of underground engineering; K4 is the correction factor for the influence of the initial stress state; K5 is the saturated uniaxial strength of the rock; K6 is the correction factor for the influence of groundwater on underground engineering; K7 is the correction factor for the influence of the initial stress state; K8 is the saturated uniaxial v RQD is a quantitative indicator for grading factors; J is a rock quality indicator. n The order of the number of joint groups; J r The grade of joint surface roughness; J a The degree of alteration or the grade of clay-filled joint groups; J w The level of groundwater inflow and pressure impact; SRF is the stress reduction factor; J c V represents the structural surface condition coefficient; b Let be the volume of the block divided by the structural plane; D is the transition parameter, D = 0.37 J. c -0.2 .

2. The method for classifying and correcting surrounding rock considering the coupling effects of heat, water, and force according to claim 1, characterized in that, Methods for obtaining the saturated uniaxial strength of rock by conducting uniaxial tests on saturated granite include: S21. Place the standard sample on the loading table of the GCTS system testing machine, and install the axial displacement sensor, circumferential displacement sensor and acoustic emission probe on the heat shrink film surface of the standard sample respectively. S22. Test the sample at a preset axial deformation rate and record the basic mechanical parameters of the rock mass during the test. S23. After all standard specimens have completed steps S21 and S22, calculate the stress of the standard specimens under each load based on the cross-sectional area of ​​the standard specimens: Where σ is stress; P is load; and A is the cross-sectional area of ​​the standard specimen. S24. Based on the stress under each load, obtain the stress evolution curve of the standard specimen during the loading process, and select the maximum value in the stress evolution curve as the saturated uniaxial strength of the rock.

3. The method for classifying and correcting surrounding rock considering the coupling effects of heat, water, and force according to claim 1, characterized in that, Methods for obtaining the theoretical uniaxial strength of rocks through multi-field coupled orthogonal tests involving thermo-hydraulic-mechanical coupling include: A1. Apply confining pressure to the standard sample after it is saturated with water. When the set confining pressure is reached, apply osmotic pressure. Then heat it to the target temperature and maintain it for a preset time. Perform a loading test until the standard sample is destroyed. A2. When multiple saturated standard specimens have all completed step A1, use the confining pressure and the corresponding rock compressive strength recorded during the test in step A1 to calculate the effective confining pressure and effective peak strength: Where, variables i = 1 and 3, σ3 is the recorded confining pressure, and σ1 is the rock compressive strength corresponding to σ3; and These are the effective peak strength and effective confining pressure, respectively; P w It is the pore water pressure; A3. By fitting the effective confining pressure and effective peak intensity of multiple standard specimens, the fitting formula is obtained: A4. Calculate the internal friction angle of the rock based on the slope and intercept of the fitted equation. And cohesion c: Where m and b are the slope and intercept of the line, respectively; A5. Based on the internal friction angle of the rock And cohesion c, calculate the uniaxial strength of multi-field coupled rock theory: in, This is the uniaxial strength of rock based on multi-field coupled rock theory.

4. The method for classifying and correcting surrounding rock considering the coupling effects of heat, water, and force according to claim 1, characterized in that, Methods for obtaining the theoretical uniaxial strength of rocks through multi-field coupled orthogonal tests involving thermo-hydraulic-mechanical coupling include: B1. Apply confining pressure to the standard sample after it is saturated with water. When the set confining pressure is reached, apply osmotic pressure. Then heat it to the target temperature and maintain it for a preset time. Perform a loading test until the standard sample is destroyed. B2. Using the temperature increment and rock elastic modulus obtained during the multi-field coupling test phase, calculate the theoretical uniaxial strength of the multi-field coupled rock: in, For multi-field coupled rock theory uniaxial strength; C v R represents the isochoric specific heat of the rock material; ΔT and E represent the temperature increment and rock elastic modulus during the multi-field coupling test, respectively; c denoted as saturated uniaxial strength of rock; k is the first fitting parameter; E0 is the elastic modulus of rock under uniaxial conditions.

5. The surrounding rock classification correction method considering the coupling effects of heat, water, and force according to claim 4, characterized in that, The method for constructing the expression for the uniaxial strength of multi-field coupled rock theory in step B2 includes: B21. Construct a model for releaseable elastic energy under hydrodynamic coupling conditions: Among them, U e Rocks can release elastic energy; and These represent the effective peak strength, effective principal stress, and effective confining pressure, respectively; μ is Poisson's ratio. B22. Based on the saturated uniaxial strength of rock, construct the critical value G for the maximum energy release rate. c : Where K3 is a material constant; B23. Determine the strength criterion for overall rock failure under hydrodynamic coupling conditions: B24. Substituting the releasable elastic energy model into the strength criterion for overall rock failure, we obtain the following expression: B25. The expression in step B24 is corrected using the strain energy dispersion coefficient to obtain the rock energy-type strength criterion under hydrodynamic coupling conditions: Where N is the strain energy dispersion coefficient. n is the second fitting parameter; B26, the rock energy type intensity criterion make The uniaxial strength expression for multi-field coupled rock theory is obtained as follows:

6. The method for classifying and correcting surrounding rock considering the coupling effects of heat, water, and force according to any one of claims 1-5, characterized in that, When correcting for BQ classification, the saturated uniaxial strength R of the rock c And the quantitative index K of the hierarchical factors v The condition that must be satisfied is: when R c >90K v At +30, R c =90K v +30; when K v >0.04R c At that time, K v =0.04R c +0.

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7. The method for classifying and correcting surrounding rock considering the coupling effects of heat, water, and force according to any one of claims 1-5, characterized in that, The standard specimen is a granite specimen.

8. The method for classifying and correcting surrounding rock considering the coupling effects of heat, water, and force according to any one of claims 1-5, characterized in that, After obtaining the basic quality indicators of the rock mass, BQ, Q, and RMi, the following are also included: Based on the basic rock mass quality indicators BQ, Q, and RMi and their corresponding rock mass quality grade classification standards, the rock mass quality grade of the rock mass at the project site under study is obtained.

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