Method for evaluating stability of slump type dangerous rock mass based on vibration frequency of locking section

Abstract

The invention discloses a slump type dangerous rock mass stability evaluation method based on the vibration frequency of a locking section and a heating device, and the method comprises the following steps: carrying out the geological exploration of a pre-analyzed dangerous rock mass, and obtaining a characteristic parameter set; the natural vibration frequency of the pre-analyzed dangerous rock body is obtained; according to the characteristic parameter set and the natural vibration frequency, the length of a locking section of the pre-analyzed dangerous rock body is calculated; according to the characteristic parameter set, the natural vibration frequency and the length of the locking section, the overall stability coefficient of the pre-analyzed dangerous rock body is calculated; and carrying out stability evaluation on the pre-analyzed dangerous rock mass according to the overall stability coefficient and the grading standard. The problem that the stability of the collapse type dangerous rock body with the locking section cannot be accurately and effectively evaluated can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of dangerous rock mass stability evaluation, and in particular to a method for evaluating the stability of a sliding dangerous rock mass based on the vibration frequency of a locking section. Background Art

[0002] The hydropower engineering sites in the southwest region are mostly deep river valleys, high and steep natural slopes, alternating shallow gullies and mountain ridges, developed fault structures and fissures, cut by structural surfaces, and many blocks that are unfavorable to slope stability are formed on specific slopes. The physical geological effects such as rock weathering and unloading are strong, and there are many dangerous rock masses developed on natural slopes, which are widely distributed. Rock rolling and collapse occur from time to time, especially the rock masses "hanging" on the upper slopes of the buildings in the hub area. Even if the "dangerous rock masses" in a small local area become unstable, forming high-level collapse and falling rocks, it will also pose a major threat to construction safety. It may also cause major damage to the buildings (structures) in the hub area during the operation period, and even catastrophic consequences. Therefore, rapid, accurate and scientific stability evaluation of dangerous rock masses is an important link that is indispensable to ensure the safe construction and operation of the project.

[0003] The deformation instability mode is the basis for the stability analysis and evaluation of dangerous rock masses. The Code for Engineering Geological Investigation and Prevention of Dangerous Rock Masses in Hydropower Projects (NB / T 10137-2019) divides the deformation instability mode of dangerous rock masses into four categories: landslide, dumping, falling, isolated rocks and isolated rock groups. For landslide-type dangerous rock masses, the stability calculation method proposed in the specification treats the unloading cracks at the rear edge as fully connected. However, in actual situations, the cracks at the rear edge are not necessarily fully connected, and there are often certain locking sections. In the southwest canyon area, due to the high mountains and steep slopes, it is difficult to get close to the dangerous rock mass through the traditional survey method to obtain relevant information on the locking section, so it is impossible to accurately and effectively evaluate the stability of the dangerous rock mass, and then it is impossible to take corresponding and targeted prevention, monitoring and early warning measures. Summary of the invention

[0004] The purpose of the present invention is to provide a method for evaluating the stability of a landslide-type dangerous rock mass based on the vibration frequency of a locking section, so as to solve the problem that the stability of a landslide-type dangerous rock mass with a locking section cannot be accurately and effectively evaluated.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for evaluating the stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section comprises the following steps:

[0007] Conduct geological survey on the pre-analyzed dangerous rock mass and obtain characteristic parameter sets;

[0008] Obtain the natural vibration frequency of the pre-analyzed dangerous rock mass;

[0009] Calculating the length of the locking section of the pre-analyzed dangerous rock mass according to the characteristic parameter set and the natural vibration frequency;

[0010] Calculating the overall stability coefficient of the pre-analyzed dangerous rock mass according to the characteristic parameter set, the natural vibration frequency and the length of the locking section;

[0011] The stability of the pre-analyzed dangerous rock mass is evaluated according to the overall stability coefficient and classification standard.

[0012] Optionally, the contents of the geological survey include: topography, stratum lithology, geological structure, distribution, occurrence and properties of structural surfaces that affect slope stability.

[0013] Optionally, the characteristic parameter set includes: the mass of the pre-analyzed dangerous rock body, the weight of the pre-analyzed dangerous rock body, the deformation modulus of the pre-analyzed dangerous rock body, the internal friction angle of the lower structural surface of the pre-analyzed dangerous rock body, the cohesion of the lower structural surface of the pre-analyzed dangerous rock body, the length of the lower structural surface of the pre-analyzed dangerous rock body and the inclination angle of the structural surface of the pre-analyzed dangerous rock body; as well as the internal friction angle of the locking section, the cohesion of the locking section and the thickness of the locking section.

[0014] Optionally, obtaining the natural vibration frequency of the pre-analyzed dangerous rock body includes the following steps: using a vibrometer to measure the pre-analyzed dangerous rock body under artificial excitation or environmental vibration conditions, and recording a vibration curve; and according to the vibration curve, obtaining the natural vibration frequency of the pre-analyzed dangerous rock body through Fourier transform.

[0015] Optionally, the calculation formula of the natural vibration frequency of the pre-analyzed dangerous rock mass is:

[0016]

[0017] in:

[0018] f is the natural vibration frequency;

[0019] K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass;

[0020] m is the mass of the pre-analyzed dangerous rock mass.

[0021] Optionally, when P n When <0, take P n =0.

[0022] Optionally, the calculation formula of the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass is:

[0023]

[0024] in:

[0025] K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass;

[0026] E is the deformation modulus of the pre-analyzed dangerous rock mass;

[0027] A s is the bonding area of ​​the locking section;

[0028] d is the thickness of the locking section.

[0029] Optionally, when the width of the locking section is 1 m, the calculation formula of the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass is:

[0030]

[0031] in:

[0032] K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass;

[0033] E is the deformation modulus of the pre-analyzed dangerous rock mass;

[0034] L2 is the length of the locking section;

[0035] d is the thickness of the locking section.

[0036] Optionally, the length of the locking section is calculated as follows:

[0037]

[0038] in:

[0039] L2 is the length of the locking section;

[0040] f is the natural vibration frequency;

[0041] m is the mass of the pre-analyzed dangerous rock mass;

[0042] d is the thickness of the locking section;

[0043] E is the deformation modulus of the pre-analyzed dangerous rock mass.

[0044] Optionally, calculating the overall stability coefficient of the pre-analyzed dangerous rock mass comprises the following steps:

[0045] Taking the bottom end of the locking section as a base point, the pre-analyzed dangerous rock mass is divided vertically upward to obtain a first block and a second block;

[0046] According to the characteristic parameter set, the natural vibration frequency and the length of the locking section, respectively calculating the stability coefficients of the first block and the second block to obtain a first stability coefficient and a second stability coefficient;

[0047] Assuming that the first stability coefficient is equal to the second stability coefficient, then the first stability coefficient=the second stability coefficient=the overall stability coefficient.

[0048] Optionally, the performing stability evaluation on the pre-analyzed dangerous rock mass according to the overall stability coefficient and the classification standard refers to:

[0049] When F s When <1, the pre-analyzed dangerous rock mass is in an unstable state;

[0050] When 1≤F s When <1.05, the pre-analyzed dangerous rock mass is in a state of poor stability;

[0051] When 1.05≤F s When <1.15, the pre-analyzed dangerous rock mass is in a basically stable state;

[0052] When 1.15≤F s When , the pre-analyzed dangerous rock mass is in a stable state;

[0053] in:

[0054] F s is the overall stability coefficient of the pre-analyzed dangerous rock mass.

[0055] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0056] The present invention provides a method for evaluating the stability of a collapsing dangerous rock mass based on the vibration frequency of a locking section. The method performs geological survey on the pre-analyzed dangerous rock mass to obtain various geological conditions of the pre-analyzed dangerous rock mass and successfully obtains a characteristic parameter set of the pre-analyzed dangerous rock mass. On this basis, the natural vibration frequency of the pre-analyzed dangerous rock mass can be obtained through the above-mentioned geological survey and the collection of the characteristic parameter set, and then the locking section length of the natural vibration frequency can be calculated according to the characteristic parameter set and the natural vibration frequency, and then the overall stability coefficient of the pre-analyzed dangerous rock mass can be further accurately calculated, and finally the stability can be evaluated according to the overall stability coefficient. Through the mutual coordination of the above-mentioned steps, the method for evaluating the stability of a collapsing dangerous rock mass based on the vibration frequency of a locking section can effectively solve the problem that the stability of a collapsing dangerous rock mass with a locking section cannot be accurately and effectively evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0058] Figure 1A flow chart of a method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section provided in an embodiment of the present invention;

[0059] Figure 2 A schematic diagram of a dangerous rock mass model according to a method for evaluating stability of a sliding dangerous rock mass based on the vibration frequency of a locking section provided in an embodiment of the present invention;

[0060] Figure 3 A division model of dangerous rock masses and a schematic diagram of force analysis of a method for evaluating the stability of a sliding dangerous rock mass based on the vibration frequency of a locking section provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0061] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0062] Please refer to Figures 1 to 3 This embodiment provides a method for evaluating the stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section, comprising the following steps:

[0063] S1. Conduct geological survey on the pre-analyzed dangerous rock mass and obtain a set of characteristic parameters;

[0064] S2. Obtain the natural vibration frequency of the pre-analyzed dangerous rock mass;

[0065] S3. Calculating the length of the locking section of the pre-analyzed dangerous rock mass according to the characteristic parameter set and the natural vibration frequency;

[0066] S4. Calculating the overall stability coefficient of the pre-analyzed dangerous rock mass according to the characteristic parameter set, the natural vibration frequency and the length of the locking section;

[0067] S5. Evaluate the stability of the pre-analyzed dangerous rock mass according to the overall stability coefficient and classification standard.

[0068] The present embodiment provides a method for evaluating the stability of a collapsing dangerous rock mass based on the vibration frequency of a locking section. Through step S1, a geological survey is conducted on the pre-analyzed dangerous rock mass to obtain various geological conditions of the pre-analyzed dangerous rock mass, and a characteristic parameter set of the pre-analyzed dangerous rock mass is successfully obtained. On this basis, the natural vibration frequency of the pre-analyzed dangerous rock mass can be obtained through the geological survey obtained in step S1 and the collection of the characteristic parameter set and step S2, and then through step S3, the length of the locking section of the natural vibration frequency can be calculated according to the characteristic parameter set and the natural vibration frequency, and then according to step S4, the overall stability coefficient of the pre-analyzed dangerous rock mass is further accurately calculated, and finally, according to step S5, the stability can be evaluated according to the overall stability coefficient. Through the mutual coordination of the above steps, the method for evaluating the stability of a collapsing dangerous rock mass based on the vibration frequency of a locking section can effectively solve the problem that the stability of a collapsing dangerous rock mass with a locking section cannot be accurately and effectively evaluated.

[0069] Furthermore, the contents of the geological survey include: topography, stratum lithology, geological structure, distribution, occurrence and properties of structural surfaces that affect slope stability.

[0070] For further explanation of the specific contents of the feature parameter set, please refer to Figure 2 and Figure 3 The characteristic parameter set includes: the mass m of the pre-analyzed dangerous rock mass, the weight W of the pre-analyzed dangerous rock mass, the deformation modulus E of the pre-analyzed dangerous rock mass, the internal friction angle of the lower structure surface of the pre-analyzed dangerous rock mass The cohesion of the lower structural surface of the pre-analyzed dangerous rock mass c j , the length L1 of the lower structural surface of the pre-analyzed dangerous rock mass and the inclination angles α and β of the structural surface of the pre-analyzed dangerous rock mass; and the internal friction angle of the locking section The cohesion of the locking section c s And the thickness d of the locking section.

[0071] Optionally, the step of obtaining the natural vibration frequency of the pre-analyzed dangerous rock mass comprises the following steps:

[0072] S2.1. Use a vibration meter to measure the pre-analyzed dangerous rock mass under artificial excitation or environmental vibration conditions, and record the vibration curve;

[0073] S2.2. According to the vibration curve, obtain the natural vibration frequency f of the pre-analyzed dangerous rock mass through Fourier transformation.

[0074] There are generally two ways to obtain the natural vibration frequency. One is to measure the natural frequency of the dangerous rock mass under the influence of environmental vibration without artificial excitation, and the other is to measure the corresponding natural frequency under artificial excitation. In theory, the natural frequency measured under artificial excitation is closer to its true frequency, but the natural frequencies of the dangerous rock mass measured under artificial excitation and environmental vibration are generally very close. Therefore, in the case of unconditional excitation of the dangerous rock mass, the natural frequency can be measured by the response of the dangerous rock mass under environmental vibration.

[0075] It should be noted that the present invention regards the pre-analyzed dangerous rock mass as a particle vibration model and ignores the system damping. Then the calculation formula of the natural vibration frequency of the pre-analyzed dangerous rock mass is:

[0076]

[0077] Wherein: f is the natural vibration frequency; K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass; and m is the mass of the pre-analyzed dangerous rock mass.

[0078] It should be noted that the present invention mainly considers the contribution of the locking section to the system stiffness, and the mechanical strength of the lower structural surface is mainly considered. Therefore, the calculation formula of the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass is:

[0079]

[0080] Where: K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass; E is the deformation modulus of the pre-analyzed dangerous rock mass; A s is the bonding area of ​​the locking section; d is the thickness of the locking section.

[0081] Further preferably, when the width of the locking section is 1 m, the calculation formula of the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass is:

[0082]

[0083] Wherein: K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass; E is the deformation modulus of the pre-analyzed dangerous rock mass; L2 is the length of the locking section; d is the thickness of the locking section.

[0084] It should be further explained that the calculation formula for the length of the locking section is:

[0085]

[0086] Wherein: L2 is the length of the locking section; f is the natural vibration frequency; m is the mass of the pre-analyzed dangerous rock mass; d is the thickness of the locking section; and E is the deformation modulus of the pre-analyzed dangerous rock mass.

[0087] Optionally, see Figure 3 , calculating the overall stability coefficient of the pre-analyzed dangerous rock mass comprises the following steps:

[0088] S4.1. Taking the bottom end of the locking section as the base point, divide the pre-analyzed dangerous rock mass in the vertical upward direction to obtain a first block ① and a second block ②;

[0089] S4.2, according to the characteristic parameter set, the natural vibration frequency f and the length L2 of the locking section, respectively calculating the stability coefficients of the first block ① and the second block ② to obtain a first stability coefficient F1 and a second stability coefficient F2;

[0090] S4.3, let the first stability coefficient F1 and the second stability coefficient F2 be equal, then the first stability coefficient F1 = the second stability coefficient F2 = the overall stability coefficient F s .

[0091] The calculation formula for the collapse-type dangerous rock mass proposed in the specification does not take the locking section into consideration. After considering the locking section based on the vibration frequency, in order to improve the stability calculation formula, the calculation section of the dangerous rock mass is processed as described in S4.1 above, and the dangerous rock mass is divided into two parts, blocks ① and ②. Since the instability of this type of dangerous rock mass mainly comes from the expansion and extension of the rear edge cracks, that is, block ① loses stability first, in general, the stability coefficient F1 of block ① is smaller than the stability coefficient F2 of block ②, which also means that block ① will give block ② a thrust. Assuming that the force T direction of block ① on block ② is parallel to the locking section, based on the above analysis, combined with the limit equilibrium theory, the stability coefficients corresponding to blocks ① and ② are calculated respectively. The specific calculation formula is as follows:

[0092]

[0093] Where: W1 and W2 are the rock masses of block ① and block ② respectively.

[0094] The overall stability factor F of the pre-analyzed dangerous rock mass s When F1 and F2 are equal, we can obtain s =F1=F2.

[0095] It should be noted that the stability evaluation of the pre-analyzed dangerous rock mass according to the overall stability coefficient and classification standard refers to:

[0096] When F s When <1, the pre-analyzed dangerous rock mass is in an unstable state, the structural surface is generally open and has obvious deformation, the rock mass is loose, and the structural surface is unfavorable for complete combination;

[0097] When 1≤F sWhen <1.05, the pre-analyzed dangerous rock mass is in a state of poor stability, the structural plane is open, and the unfavorable combination is relatively complete;

[0098] When 1.05≤F s When <1.15, the pre-analyzed dangerous rock mass is in a basically stable state, the structural surface is partially open or closed, and the unfavorable combination is relatively complete or incomplete;

[0099] When 1.15≤F s When , the pre-analyzed dangerous rock mass is in a stable state;

[0100] Among them: F s is the overall stability coefficient of the pre-analyzed dangerous rock mass.

[0101] Example

[0102] In order to provide a better explanation of the implementation of the present invention, a high-level dangerous rock mass on the slope of a hydropower station hub area in the southwest canyon area is taken as an example for detailed explanation.

[0103] First, a detailed geological survey was conducted on the dangerous rock mass. The survey showed that the dangerous rock mass was granodiorite, with steep unloading cracks along the slope at the rear edge, with an inclination of 65°, and a structural surface along the slope outside the gentle slope at the lower part, with an inclination of 28°. It was determined that the instability mode was a landslide, so it met the requirements of the present invention.

[0104] Based on the on-site geological survey work and in combination with the "Code for Engineering Geological Survey and Prevention of Dangerous Rock Masses in Hydropower Projects" (NB / T10137-2019), the stability of the dangerous rock mass was evaluated using qualitative and semi-quantitative methods, and the overall evaluation was stable.

[0105] The main parameters obtained are as follows: rock density is 2.5g / cm 3 , deformation modulus 1.2GPa, internal friction angle of the locking section 35°, cohesion 300kPa, inclination angle 65°, internal friction angle of the lower structure surface 32°, cohesion 150kPa, inclination angle 28°, and locking section thickness 10mm.

[0106] Second, obtain the vibration frequency of the dangerous rock mass. Use a vibration meter to measure the dangerous rock mass under the influence of environmental vibration and collect the vibration curve. Use Fourier transform to calculate its natural vibration frequency of 88.16Hz.

[0107] Third, calculate the length of the locking section of the dangerous rock mass. Substitute the vibration frequency, locking section thickness, deformation modulus and other data into formula (4) to calculate the locking section length L2 as 6.83m.

[0108] Fourth, the calculated locking section length, structural surface cohesion, internal friction angle and other parameters are substituted into the above formula. When F1 = F2, the force T between blocks ① and ② is 6.41×10 6 N, and finally the stability coefficient F of the dangerous rock mass is obtained s =1.24, the dangerous rock mass is in a stable state at this time, and the calculation results are consistent with the qualitative and semi-quantitative evaluation results.

[0109] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for evaluating the stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section, characterized in that: The steps include: Conduct geological survey on the pre-analyzed dangerous rock mass and obtain characteristic parameter sets; Obtain the natural vibration frequency of the pre-analyzed dangerous rock mass; Calculating the length of the locking section of the pre-analyzed dangerous rock mass according to the characteristic parameter set and the natural vibration frequency; Calculating the overall stability coefficient of the pre-analyzed dangerous rock mass according to the characteristic parameter set, the natural vibration frequency and the length of the locking section; The stability of the pre-analyzed dangerous rock mass is evaluated according to the overall stability coefficient and classification standard.

2. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 1 is characterized in that: The contents of the geological survey include: topography, stratum lithology, geological structure, distribution, occurrence and properties of structural surfaces that affect slope stability.

3. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 2 is characterized in that: The characteristic parameter set includes: The mass of the pre-analyzed dangerous rock mass, the weight of the pre-analyzed dangerous rock mass, the deformation modulus of the pre-analyzed dangerous rock mass, the internal friction angle of the lower structural surface of the pre-analyzed dangerous rock mass, the cohesion of the lower structural surface of the pre-analyzed dangerous rock mass, the length of the lower structural surface of the pre-analyzed dangerous rock mass and the inclination angle of the structural surface of the pre-analyzed dangerous rock mass; and, The internal friction angle of the locking section, the cohesion of the locking section and the thickness of the locking section.

4. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 1 is characterized in that: The step of obtaining the natural vibration frequency of the pre-analyzed dangerous rock mass comprises the following steps: Use a vibration meter to measure the pre-analyzed dangerous rock mass under artificial excitation or environmental vibration conditions, and record the vibration curve; According to the vibration curve, the natural vibration frequency of the pre-analyzed dangerous rock mass is obtained through Fourier transformation.

5. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 1 is characterized in that: The calculation formula of the natural vibration frequency of the pre-analyzed dangerous rock mass is: in: f is the natural vibration frequency; K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass; m is the mass of the pre-analyzed dangerous rock mass.

6. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 5 is characterized in that: The calculation formula of the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass is: in: K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass; E is the deformation modulus of the pre-analyzed dangerous rock mass; A s is the bonding area of ​​the locking section; d is the thickness of the locking section.

7. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 6 is characterized in that: When the width of the locking section is 1 m, the calculation formula of the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass is: in: K is the equivalent stiffness coefficient of the pre-analyzed dangerous rock mass; E is the deformation modulus of the pre-analyzed dangerous rock mass; L2 is the length of the locking section; d is the thickness of the locking section.

8. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 7 is characterized in that: The calculation formula of the length of the locking section is: in: L2 is the length of the locking section; f is the natural vibration frequency; m is the mass of the pre-analyzed dangerous rock mass; d is the thickness of the locking section; E is the deformation modulus of the pre-analyzed dangerous rock mass.

9. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 1, characterized in that: Calculating the overall stability coefficient of the pre-analyzed dangerous rock mass includes the following steps: Taking the bottom end of the locking section as a base point, the pre-analyzed dangerous rock mass is divided vertically upward to obtain a first block and a second block; According to the characteristic parameter set, the natural vibration frequency and the length of the locking section, respectively calculating the stability coefficients of the first block and the second block to obtain a first stability coefficient and a second stability coefficient; Assuming that the first stability coefficient is equal to the second stability coefficient, then the first stability coefficient=the second stability coefficient=the overall stability coefficient.

10. The method for evaluating stability of a sliding and dangerous rock mass based on the vibration frequency of a locking section according to claim 1, characterized in that: The stability evaluation of the pre-analyzed dangerous rock mass according to the overall stability coefficient and classification standard refers to: When F s When <1, the pre-analyzed dangerous rock mass is in an unstable state; When 1≤F s When <1.05, the pre-analyzed dangerous rock mass is in a state of poor stability; When 1.05≤F s When <1.15, the pre-analyzed dangerous rock mass is in a basically stable state; When 1.15≤F s When , the pre-analyzed dangerous rock mass is in a stable state; in: F s is the overall stability coefficient of the pre-analyzed dangerous rock mass.

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