Method and device for predicting stability of sliding type dangerous rock mass, medium and equipment

Abstract

The invention discloses a sliding type dangerous rock mass stability prediction method and device, a medium and equipment, and relates to the technical field of rock mass engineering disaster prediction.The method comprises the steps that a stress distribution model of a main control structural plane of a dangerous rock mass is constructed, loads borne by the main control structural plane are decomposed according to the stress distribution model, and the stress distribution model is obtained; the normal force and the tangential force of a main control structural plane are obtained, and the main control structural plane comprises a through section and a rock bridge section; the rock cohesion of the cut-through section and the rock cohesion of the rock bridge section are obtained, and the anti-sliding force of the main control structural surface is calculated based on the limit equilibrium theory according to the normal force, the tangential force, the rock cohesion of the cut-through section and the rock cohesion of the rock bridge section; and determining a stability coefficient of the dangerous rock mass according to the tangential force and the anti-sliding force, and predicting the stability of the dangerous rock mass according to the stability coefficient. According to the scheme, the stability of the sliding type dangerous rock body can be accurately predicted.

Description

Technical Field

[0001] The present invention relates to the technical field of prediction of rock mass engineering disasters, and particularly relates to a method, device, medium and equipment for predicting the stability of sliding dangerous rock masses. Background Art

[0002] With the advancement of more rock mass engineering projects into mountainous areas with strong geological structures and complex terrains, frequent blasting and excavation cause strong disturbances to the already fragile geological environment, easily leading to dynamic disturbance damage to adjacent dangerous rock masses, resulting in frequent occurrence of dangerous rock collapse disasters and seriously threatening the safety of transportation facilities along the line. For example, the stability of a dangerous rock mass in a certain place continuously deteriorated due to dynamic disturbance and finally collapsed, causing huge losses. Therefore, studying the damage and deterioration mechanism of dangerous rock masses under dynamic disturbance is of great significance for predicting their stability.

[0003] The core issue in evaluating the stability of dangerous rock masses is to establish a theoretical model that can reflect the current mechanical state and subsequent development law of dangerous rock masses. Many related scholars have conducted a lot of research on this. For example, according to the failure modes of dangerous rock masses, they are divided into three categories: sliding type, toppling type and falling type, and calculation methods for the stability of dangerous rock masses under different working conditions are given in combination with the limit equilibrium theory and the rock mass structure theory.

[0004] The existing methods for predicting the stability of sliding dangerous rock masses under blasting disturbance mainly consider the influence of blasting load on the tensile and shear stresses of structural planes, and pay less attention to the mesoscopic cumulative effect of blasting load on the rock bridges. However, the mechanical properties of the rock bridges are important factors for judging the stability of dangerous rock masses.

[0005] Therefore, the existing technology cannot accurately predict the stability of sliding dangerous rock masses. Summary of the Invention

[0006] Based on this, in view of the technical problem that the existing technology cannot accurately predict the stability of sliding dangerous rock masses, it is necessary to provide a method, device, medium and equipment for predicting the stability of sliding dangerous rock masses.

[0007] The present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides a method for predicting the stability of sliding dangerous rock masses, the method comprising:

[0009] Construct a force distribution model of the main control structural plane of the dangerous rock mass, decompose the load received by the main control structural plane according to the force distribution model to obtain the normal force and tangential force of the main control structural plane, the main control structural plane includes a through section and a rock bridge section, and the load is generated by the gravity of the dangerous rock mass and the stress generated by blasting disturbance;

[0010] Obtain the rock cohesion of the through - section and the rock cohesion of the rock - bridge section. Based on the limit equilibrium theory, calculate the anti - sliding force of the main control structural plane according to the normal force, the tangential force, the rock cohesion of the through - section and the rock cohesion of the rock - bridge section.

[0011] Determine the stability coefficient of the dangerous rock mass according to the tangential force and the anti - sliding force, and predict the stability of the dangerous rock mass according to the stability coefficient.

[0012] Furthermore, obtaining the rock cohesion of the through - section and the rock cohesion of the rock - bridge section, based on the limit equilibrium theory, calculating the anti - sliding force of the main control structural plane according to the normal force, the tangential force, the rock cohesion of the through - section and the rock cohesion of the rock - bridge section, specifically includes:

[0013] Obtain the rock cohesion of the through - section, the initial rock cohesion of the rock - bridge section and the initial damage variable of the dangerous rock mass.

[0014] Determine the cumulative damage variable of the dangerous rock mass after experiencing n blasting disturbances according to the initial damage variable, where n is a positive integer.

[0015] Determine the rock cohesion of the rock - bridge section after experiencing n blasting disturbances according to the initial rock cohesion, the initial damage variable and the cumulative damage variable.

[0016] Based on the limit equilibrium theory, calculate the anti - sliding force of the main control structural plane according to the normal force, the tangential force, the rock cohesion of the through - section and the rock cohesion of the rock - bridge section after experiencing n blasting disturbances.

[0017] Furthermore, determining the cumulative damage variable of the dangerous rock mass after experiencing n blasting disturbances according to the initial damage variable, specifically includes:

[0018] Divide the total area of the dangerous rock mass to obtain the undamaged rock area, the cumulative damage area after (n - 1) blasting disturbances, the load damage area under the nth blasting disturbance and the coupling damage area.

[0019] Determine the cumulative damage variable of the dangerous rock mass after experiencing (n - 1) blasting disturbances according to the cumulative damage area and the total area; determine the load damage variable under the action of the nth blasting disturbance according to the load damage area under the nth blasting disturbance, the coupling damage area, the total area and the cumulative damage area after (n - 1) blasting disturbances.

[0020] Determine the cumulative damage variable of the dangerous rock mass after n times of blasting disturbances based on the cumulative damage variable of the dangerous rock mass after n - 1 times of blasting disturbances, the load damage variable of the nth blasting disturbance, and the initial damage variable.

[0021] Further, the calculation expression of the anti-sliding force is:

[0022]

[0023] Wherein, is the internal friction angle of the rock, c w is the cohesion of the rock in the through section, c d is the cohesion of the rock in the rock bridge section, l w is the length of the through section, l d is the length of the rock bridge section, σ G is the gravity acting on the dangerous rock mass, is the normal stress of the blasting disturbance acting on the main control structural plane, and β is the dip angle of the main control structural plane.

[0024] Further, the calculation expression of the stability coefficient is:

[0025]

[0026] Wherein, is the internal friction angle of the rock, c w is the cohesion of the rock in the through section, c d is the cohesion of the rock in the rock bridge section, l w is the length of the through section, l d is the length of the rock bridge section, σ G is the gravity acting on the dangerous rock mass, is the normal stress of the blasting disturbance acting on the main control structural plane, β is the dip angle of the main control structural plane, is the tangential stress of the blasting disturbance acting on the main control structural plane, is the cohesion of the rock in the rock bridge section after experiencing the load generated by n times of blasting disturbances.

[0027] Further, the calculation expression of the cohesion of the rock in the rock bridge section after n times of blasting disturbances is:

[0028]

[0029] Wherein, c d is the cohesion of the rock in the rock bridge section, is the cohesion of the rock in the rock bridge section after experiencing the load generated by n times of blasting disturbances, D n-1$\omega_{n - 1}$ is the cumulative damage variable after the dangerous rock mass has experienced $n - 1$ times of blasting disturbances, $\xi$ is the influence coefficient of existing damage on new load damage, and $\kappa$ is the constitutive model parameter. $\varepsilon_{p}$ is the strain at the peak strength of the rock mass under the load of the $n$-th blasting disturbance of the dangerous rock mass.

[0030] Furthermore, the stability of the dangerous rock mass is predicted according to the stability coefficient, which specifically includes:

[0031] The stability of the dangerous rock mass is predicted according to the interval range where the stability coefficient is located.

[0032] In a second aspect, the present invention provides a prediction device for the stability of a sliding dangerous rock mass, including:

[0033] A construction module for constructing a force distribution model of the main control structural plane of the dangerous rock mass, decomposing the load received by the main control structural plane according to the force distribution model to obtain the normal force and tangential force of the main control structural plane. The main control structural plane includes a through section and a rock bridge section, and the load is generated by the gravity of the dangerous rock mass and the stress generated by blasting disturbances;

[0034] A calculation module for obtaining the rock cohesion of the through section and the rock cohesion of the rock bridge section, and calculating the anti-sliding force of the main control structural plane based on the limit equilibrium theory according to the normal force, the tangential force, the rock cohesion of the through section and the rock cohesion of the rock bridge section;

[0035] A prediction module for determining the stability coefficient of the dangerous rock mass according to the tangential force and the anti-sliding force, and predicting the stability of the dangerous rock mass according to the stability coefficient.

[0036] The present invention provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the method for predicting the stability of a sliding dangerous rock mass is implemented.

[0037] The present invention provides a computer device including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the method for predicting the stability of a sliding dangerous rock mass is implemented.

[0038] At least one technical solution adopted by the present invention can achieve the following beneficial effects: First, establish a force distribution model of the main control structural plane of the dangerous rock mass. Decompose the load on the main control structural plane according to the force distribution model to obtain the normal force and tangential force of the main control structural plane. The load is generated by the gravity of the dangerous rock mass and the stress generated by blasting disturbance. Then, obtain the rock cohesion of the through section and the rock cohesion of the rock bridge section. Based on the limit equilibrium theory, calculate the anti-sliding force of the main control structural plane according to the normal force, tangential force, rock cohesion of the through section and rock cohesion of the rock bridge section. Finally, determine the stability coefficient of the dangerous rock mass according to the tangential force and the anti-sliding force, and predict the stability of the dangerous rock mass according to the stability coefficient. Through the above solution, the gravity of the dangerous rock mass and the disturbance stress generated by blasting disturbance can be decomposed into the normal force and tangential force of the main control structural plane according to the force distribution model of the main control structural plane of the dangerous rock mass. Then, combined with the deterioration effect of blasting disturbance on the rock cohesion of the main control structural plane, the anti-sliding force of the main control structural plane can be accurately calculated. Finally, determine the stability coefficient of the dangerous rock mass according to the anti-sliding force of the main control structural plane and the tangential force of the main control structural plane, and then predict the stability of the dangerous rock mass according to the stability coefficient, realizing the accurate prediction of the stability of the dangerous rock mass, and providing a theoretical basis for the scientific disaster prevention and reduction work of the dangerous rock mass near frequent blasting excavation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 It is a flowchart of a method for predicting the stability of a sliding dangerous rock mass provided by the present invention;

[0041] Figure 2 It is a schematic diagram of the force model of a sliding dangerous rock mass provided by the present invention;

[0042] Figure 3 It is a schematic diagram of the stress distribution decomposition of the main control structural plane provided by the present invention;

[0043] Figure 4 It is an analysis diagram of the rock force of the rock bridge section provided by the present invention;

[0044] Figure 5 It is a schematic diagram of the composite dynamic damage model provided by the present invention;

[0045] Figure 6 It is a schematic diagram of the rock area division provided by the present invention;

[0046] Figure 7 It is a curve graph of the influence law of different parameters on the dynamic damage constitutive model of the dangerous rock mass provided by the present invention;

[0047] Figure 8 Curves showing the influence of different parameters provided by the present invention on the dynamic damage constitutive model of dangerous rock masses;

[0048] Figure 9 Curves showing the influence of different parameters provided by the present invention on the dynamic damage constitutive model of dangerous rock masses;

[0049] Figure 10 Curves showing the influence of different parameters provided by the present invention on the dynamic damage constitutive model of dangerous rock masses;

[0050] Figure 11 Comparison chart of the theoretical calculation results and experimental results of the cumulative damage of dangerous rock masses provided by the present invention;

[0051] Figure 12 Schematic diagram of a sliding dangerous rock mass at the exit of a certain tunnel provided by the present invention;

[0052] Figure 13 Curve showing the deterioration of the stability coefficient of dangerous rock masses provided by the present invention;

[0053] Figure 14 Curve showing the influence of different explosive charges on the cohesion of rock bridges provided by the present invention;

[0054] Figure 15 Curve showing the influence of different explosive charges on the stability coefficient of dangerous rock masses provided by the present invention;

[0055] Figure 16 Curve showing the influence of different horizontal blasting distances on the cohesion of rock bridges provided by the present invention;

[0056] Figure 17 Curve showing the influence of different horizontal blasting distances on the stability of dangerous rock masses provided by the present invention;

[0057] Figure 18 Curve showing the influence of different initial damages on the cohesion of rock bridges provided by the present invention;

[0058] Figure 19 Curve showing the influence of different elastic moduli on the stability of dangerous rock masses provided by the present invention;

[0059] Figure 20 Schematic diagram of the structure of a device for predicting the stability of a sliding dangerous rock mass provided by the present invention;

[0060] Figure 21 Schematic diagram of the structure of a computer device provided by the present invention. Detailed implementation manners

[0061] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0062] Currently, the server mentioned in the present invention can be a server set up on a service platform or a device such as a desktop computer or a laptop computer that can execute the solution of the present invention. For the convenience of description, only the server will be used as the execution subject for description below. The following will detail the technical solutions provided by each embodiment of the present invention with reference to the drawings.

[0063] Reference Figure 1 , shows a sliding type dangerous rock mass stability prediction method in the present invention, which specifically includes the following steps:

[0064] S10: Construct a force distribution model of the main control structural plane of the dangerous rock mass, decompose the load on the main control structural plane according to the force distribution model to obtain the normal force and tangential force of the main control structural plane. The main control structural plane includes a through section and a rock bridge section, and the load is generated by the gravity of the dangerous rock mass and the stress generated by blasting disturbance.

[0065] In this embodiment, the force distribution model of the main control structural plane is as Figure 2 shown, where σ B is the disturbance stress generated by blasting, M is the center of gravity of the dangerous rock mass, G is the gravity of the dangerous rock mass, AB is the main control structural plane of the dangerous rock mass, including the through section AO and the rock bridge section OB. β is the inclination angle of the main control structural plane of the dangerous rock mass, H, h w , h d are the height of the dangerous rock mass, the height of the through section, and the height of the rock bridge section respectively, and l w , l d are the lengths of the through section and the rock bridge section respectively.

[0066] Specifically, the present invention combines the disturbance stress generated by the blasting load on the main control structural plane, and equivalently translates the load on the dangerous rock mass to point O. Then, its normal stress is mainly composed of the compressive stress caused by self-weight and the blasting disturbance stress, and the shear stress is mainly composed of the shear force caused by self-weight stress and blasting disturbance stress. Decompose the force on the main control structural plane into Figure 3 the stress distribution shown.

[0067] According to Figure 3 the force analysis of the structural plane shown, the stress caused by the self-weight of the dangerous rock mass is calculated as a triangular distribution, and the self-weight stress σ G can be obtained:

[0068]

[0069] Among them, G is the gravity of the dangerous rock mass, β is the dip angle of the main control structural plane of the dangerous rock mass, and l w , l d are the lengths of the through section and the rock bridge section respectively, and H is the height of the dangerous rock mass.

[0070] According to Figure 2 the force model of the dangerous rock mass, decompose the load on the main control structural plane, and the normal force F N and the tangential force F T caused by self-weight stress and blasting disturbance stress can be obtained respectively as follows:

[0071]

[0072]

[0073] Among them, are the normal stress and tangential stress of the blasting disturbance stress decomposed onto the main control structural plane; lw and ld are the lengths of the rock in the through section and the rock in the rock bridge section respectively.

[0074] S20: Obtain the rock cohesion of the through section and the rock cohesion of the rock bridge section. Based on the limit equilibrium theory, calculate the anti-sliding force of the main control structural plane according to the normal force, tangential force, rock cohesion of the through section and rock cohesion of the rock bridge section.

[0075] In this embodiment, obtaining the rock cohesion of the through section and the rock cohesion of the rock bridge section, and calculating the anti-sliding force of the main control structural plane based on the limit equilibrium theory according to the normal force, tangential force, rock cohesion of the through section and rock cohesion of the rock bridge section specifically includes:

[0076] S201: Obtain the rock cohesion of the through section, the initial rock cohesion of the rock bridge section and the initial damage variable of the dangerous rock mass.

[0077] S202: Determine the cumulative damage variable of the dangerous rock mass after experiencing n times of blasting disturbance according to the initial damage variable, where n is a positive integer.

[0078] S203: Determine the rock cohesion of the rock bridge section after experiencing n times of blasting disturbance according to the initial rock cohesion, initial damage variable and cumulative damage variable.

[0079] S204: Based on the limit equilibrium theory, calculate the anti-sliding force of the main control structural plane according to the normal force, tangential force, rock cohesion of the through section and rock cohesion of the rock bridge section after experiencing n times of blasting disturbance.

[0080] In this embodiment, according to the limit equilibrium theory, the stability evaluation of the sliding dangerous rock mass is usually based on the ratio of the anti-sliding force to the sliding force on the main control structural plane as the stability coefficient. According to Equations (2) and (3), the anti-sliding force F on the main control structural plane of the dangerous rock mass can be obtained as follows: K is:

[0081]

[0082] where, is the internal friction angle of the rock, and c w is the cohesion of the rock in the through section, and c d is the cohesion of the rock in the rock bridge section.

[0083] S30: Determine the stability coefficient of the dangerous rock mass according to the tangential force and the anti-sliding force, and predict the stability of the dangerous rock mass according to the stability coefficient.

[0084] In this embodiment, for the sliding dangerous rock mass, its failure mode is mainly shear sliding failure along the main control structural plane. Therefore, the rock bridge section is defined as the extended section of the main control structural plane. The rock in the through section and the rock bridge section of the dangerous rock mass structure plane are subjected to the disturbance load generated after the attenuation of the explosion stress wave. The disturbance load generated after the attenuation of the stress wave usually has little influence on the through section of the structural plane and is not sufficient to cause the fracture and expansion of the main control structural plane. Otherwise, the dangerous rock mass is in an unstable state. Therefore, the focus is on exploring the deterioration effect of the disturbance load on the cohesion of the rock in the rock bridge section of the dangerous rock mass and its influence on the overall stability of the dangerous rock mass.

[0085] According to the stress distribution of the main control structural plane of the dangerous rock mass, the cohesion of the rock in the rock bridge section and the stability coefficient Fn after n times of dynamic disturbance are respectively:

[0086]

[0087] where, is the cohesion of the rock in the rock bridge section after n times of dynamic disturbance loads, D n is the cumulative damage variable of the rock mass after n times of dynamic disturbance loads, and D0 is the initial damage variable of the rock.

[0088] It can be seen from Equation (5) that under the action of the disturbance load, the disturbance stress on the main control structural plane and the cohesion of the rock in the rock bridge section, the internal friction angle and other parameter changes will all change the anti-sliding performance of the main control plane, and thus affect the overall stability of the dangerous rock mass.

[0089] Specifically, and The solution process is as follows:

[0090] During the propagation of blast stress waves in rock masses, they face a complex geological environment. Medium factors such as rock types, pores, and water will all affect the propagation characteristics of stress waves. At the same time, when stress waves propagate to the structural plane of dangerous rock masses, repeated reflection, transmission, and other superposition effects will occur. However, the wavelength of the stress wave after attenuation is quite different from the scale of the structural plane of the dangerous rock mass, and this superposition effect has little impact on the stability of the dangerous rock mass. Therefore, in this paper, it is assumed that both the dangerous rock mass and the bedrock are homogeneous bodies, and at the same time, the stress superposition effect caused by the reflection and transmission of blast stress waves at the structural plane is not considered. Research shows that the particle vibration velocity is closely related to factors such as the amount of explosive and the distance from the blast center. Based on this, the peak velocity of the explosion wave reaching the dangerous rock mass can be determined. Based on the one-dimensional stress wave theory, according to the Sadovskii formula, the peak velocity and peak stress are as follows:

[0091]

[0092] Among them, σ max is the peak stress at any point of the dangerous rock mass, ρ is the medium density, c is the stress wave velocity, V max is the peak vibration velocity at any point of the dangerous rock mass, Q is the amount of explosive, R is the distance from the blast center, which is the distance from this point to the blasting point, and K and α are the correlation coefficient and attenuation index respectively, which are related to topographic and geological conditions, rock properties, blasting conditions, etc. The values can be seen in Table 1.

[0093] Table 1 Value table of different lithology parameters

[0094]

[0095]

[0096] Frequent blasting may cause damage to dangerous rock masses with structural planes in the non-excavation area, and then deteriorate the rock mechanical properties of the rock bridge section. When the disturbance stress exceeds the damage threshold of the rock mass, the mesoscopic defects of the rock will continuously accumulate, expand, and even form macroscopic cracks with the increase of the impact times. The construction blasting source is usually far from the main control structural plane of the dangerous rock mass. According to the positional relationship between the blasting source and the main control structural plane, when the stress wave attenuates and propagates to the main control structural plane, the rock bridge section of the structural plane satisfies Figure 4 the force relationship shown.

[0097] As Figure 4 shown, the OB section is the rock bridge section of the main control surface of the dangerous rock mass. The horizontal distance and vertical distance from the blasting source to the top O point of the rock bridge section are L0 and h0 respectively, and the horizontal distance from the blasting source to the bottom B point of the rock bridge section is R; θ is the horizontal angle between the line connecting any point on the rock bridge section of the rock and the blasting source. Assuming the attenuation distance l from the blasting source to any point on the main control surface, it satisfies:

[0098]

[0099] Combining equations (6) and (7), the peak stress σ of the stress wave propagation attenuation to the rock mass in the rock bridge section can be obtained as follows: max That is:

[0100]

[0101] Since the magnitudes and directions of the disturbance stresses at each position on the main control structural plane due to the propagation and attenuation of the explosion stress wave are different. Combining equations (7) and (8), the tangential stress and the normal stress of the disturbance stress on the main control structural plane are respectively:

[0102]

[0103] where θ1 and θ2 are respectively the horizontal angles between the connecting lines from point O and point B of the rock mass in the rock bridge section to the explosion source.

[0104] Based on Figure 1 a slip-type dangerous rock mass stability prediction method shown, first construct a force distribution model of the main control structural plane of the dangerous rock mass, decompose the load on the main control structural plane according to the force distribution model to obtain the normal force and tangential force of the main control structural plane. The load is generated by the gravity of the dangerous rock mass and the stress generated by blasting disturbance; then obtain the rock cohesion of the through section and the rock cohesion of the rock bridge section. Based on the limit equilibrium theory, calculate the anti-sliding force of the main control structural plane according to the normal force, tangential force, rock cohesion of the through section and rock cohesion of the rock bridge section; finally, determine the stability coefficient of the dangerous rock mass according to the tangential force and the anti-sliding force, and predict the stability of the dangerous rock mass according to the stability coefficient. Through the above solution, the gravity of the dangerous rock mass and the disturbance stress generated by blasting disturbance can be decomposed into the normal force and tangential force of the main control structural plane according to the force distribution model of the main control structural plane of the dangerous rock mass, and then combined with the deterioration effect of blasting disturbance on the rock cohesion of the main control structural plane, the anti-sliding force of the main control structural plane can be accurately calculated. Finally, determine the stability coefficient of the dangerous rock mass according to the anti-sliding force of the main control structural plane and the tangential force of the main control structural plane, and then predict the stability of the dangerous rock mass according to the stability coefficient, realizing the accurate prediction of the stability of the dangerous rock mass, and providing a theoretical basis for the scientific disaster prevention and mitigation work of the dangerous rock mass near frequent blasting excavation.

[0105] When applying a slip-type dangerous rock mass stability prediction method provided by the present invention, it is not necessary to execute according to the order of the steps shown Figure 1 The specific execution order of each step can be determined according to needs, and the present invention does not limit this.

[0106] In addition, in one or more embodiments of the present invention, determining the cumulative damage variable of the dangerous rock mass after experiencing n times of blasting disturbance according to the initial damage variable specifically includes:

[0107] Divide the total area of the dangerous rock mass to obtain the undamaged rock area, the cumulative damage area after n - 1 times of blasting disturbance, the load damage area and the coupling damage area under the nth blasting disturbance.

[0108] In this embodiment, the process from local failure to overall instability of the rock mass is a process of damage accumulation and fracture occurrence, and it has significant time-dependent characteristics. The experimental results of impact loading on the rock mass using a split Hopkinson pressure bar device show that: the macroscopic damage of the rock mass has a softening effect on the mechanical properties of the rock mass, while the strain rate has an obvious hardening effect, that is, the dynamic failure of the rock mass has composite damage, static elastic characteristics and dynamic viscous characteristics. In order to be able to represent the damage characteristics and viscosity of the rock mass, based on the strain equivalence principle, the cumulative damage Dn - 1 of the rock mass in the previous n - 1 times and the dynamic disturbance load damage D n d are connected in parallel to form the composite damage Dn, and then connected in parallel with the Maxwell body to form the dynamic damage model of the rock mass, as Figure 5 shown.

[0109] According to Figure 5 the series-parallel relationship of the composite damage model shown:

[0110]

[0111] Among them, is the stress of the damaged body during the nth cyclic impact, is the strain of the damaged body during the nth cyclic impact, σ M is the stress of the Maxwell body, ε M is the strain of the Maxwell body.

[0112] The Maxwell body does not play a role under static load. Only when the loading rate reaches a certain value can the viscous characteristics of the rock mass be reflected. The constitutive relationship followed in the main loading direction is:

[0113]

[0114] Among them, ε is the strain rate, σ M is the loading rate, and η is the viscosity coefficient.

[0115] Perform Laplace transform on Equation (11) to eliminate the loading rate σ M and use the boundary conditions ε(0) = 0 and σ M (0) = 0 to obtain:

[0116]

[0117] According to Equation (12), it can be seen that the stress σ M (t) changes dynamically with time. For the convenience of calculation, among them, the dynamic parameters and ε(t) are respectively replaced by the average strain rate ε and the strain ε n respectively.

[0118] Now, the macro-meso damage of the rock mass is regarded as the weakening of the area of undamaged rock. The total area of the rock in the loading direction is divided into four parts, namely undamaged rock, cumulative damage of n - 1 times, damage of the nth load, and coupling damage. All damages are regarded as the weakening of the area of undamaged rock due to the existence of macro-meso defects.

[0119] Refer to Figure 6 , and the areas of each part satisfy:[[]]

[0120]

[0121] where A is the total area of the rock, Au is the area of undamaged rock, An - 1 is the area of cumulative damage of the previous n - 1 times, is the area of damage of the nth load, is the area of coupling damage between the cumulative damage of the previous n - 1 times and the damage of the nth load.

[0122] For the analysis of the nth dynamic impact action, the cumulative damage variable of the rock mass before the load action is defined as D n-1 , and the load damage variable of the nth load action is defined as The composite damage variable of the rock mass after the nth load action is defined as D n . According to Figure 6 the regional division method shown, the damage variables are respectively:[[]]

[0123]

[0124] According to Eqs. (13) and (14), the composite damage variable D of the rock mass can be obtained n :[[]]

[0125]

[0126] According to the strain equivalence principle, the damage evolution of the damaged rock mass under the load depends on the initial damage, and its axial strain satisfies:[[]]

[0127]

[0128] where ε is the axial strain and ξ is the influence coefficient of the existing damage on the new load damage.

[0129] Integrating Eq. (16) gives:[[]]

[0130]

[0131] where κ is the constitutive model parameter.

[0132] Combining equations (15) and (17) gives the composite damage variable D n :

[0133]

[0134] Assume that the biaxial stress σ3 = γσ1 = γσ, and the damage evolution equation of the damaged rock mass under quasi-static load is:

[0135]

[0136] where is the axial stress, Er is the elastic modulus of the completely undamaged rock, and v is the Poisson's ratio of the rock.

[0137] Substituting equation (18) into equation (19) gives the damage evolution equation of the rock mass under quasi-static load:

[0138]

[0139] For an ideal undamaged rock mass without any cracks and pores, i.e., D n-1 = 0, when the stress reaches the peak value σ m under the load, at this time there is ε n = ε m , Taking the derivative of equation (20) gives:

[0140] 1 - exp(κ - ζε m ) - ζε m = 0 (21)

[0141] where ε m is the strain corresponding to the peak stress of the ideal undamaged rock mass.

[0142] For the ideal undamaged rock mass, substituting the boundary conditions ε n = ε m , into equation (21) gives:

[0143]

[0144] where σ m is the peak stress of the ideal undamaged rock mass.

[0145] Combining equations (21) and (22) gives the values of the parameters κ and ζ as:

[0146]

[0147] Combining equations (13), (21), and (23) gives the constitutive equation of the composite damage of the rock mass under dynamic disturbance as:

[0148]

[0149] From Equation (24), the strain corresponding to the peak strength of the rock mass under the nth load can be obtained. Substituting it into Equation (18), the composite damage variable Dn can be obtained:

[0150]

[0151] According to the cumulative damage area and the total area, the cumulative damage variable of the dangerous rock mass after (n - 1) blasting disturbances is determined; according to the load damage area, coupled damage area, total area under the nth blasting disturbance and the cumulative damage area after (n - 1) blasting disturbances, the load damage variable under the action of the nth blasting disturbance is determined.

[0152] According to the cumulative damage variable of the dangerous rock mass after (n - 1) blasting disturbances, the load damage variable under the action of the nth blasting disturbance and the initial damage variable, the cumulative damage variable of the dangerous rock mass after n blasting disturbances is determined.

[0153] The following combines Appendices Figure 7 to Appendices Figure 19 to verify the dynamic damage constitutive equation of the dangerous rock mass.

[0154] From the dynamic damage constitutive equation of the rock mass, it can be seen that the parameters σ m , ε m , E M , and η need to be obtained by fitting experimental parameters, and their values all have important influences on the mechanical properties of the rock mass. In order to discuss the influence degree of the values of each parameter on the constitutive model, a single parameter analysis is used to study the influence on the dynamic damage constitutive of the rock mass.

[0155] Referring to Figure 7 , the change of the parameter ε m has little influence on the peak strength of the rock mass, but has a significant influence on the strain at the peak strength and the post-peak stage. With the increase of ε m , the strain at the peak strength increases significantly, and there is more internal damage in the yield stage of the rock mass, which indicates that the parameter ε m reflects the degree of internal damage concentration of the load on the rock mass.

[0156] Referring to Figure 8 , the change of the parameter σ m mainly affects the peak strength and yield stage of the rock mass, but has little influence on the strain at the peak strength. With the increase of σ m , the peak strength of the rock mass also increases, and the influence of σ m on the constitutive relationship is mainly in the stage of internal pore development and fracture. This indicates that σ m is an average reflection of the overall strength of the rock mass.

[0157] Reference Figure 9 The change of the parameter η has a great influence on the peak strength and yield stage of the rock, but has a certain influence on the strain at the peak strength and the elastic stage. As η increases, the peak strength of the rock mass and the curvature of the inelastic deformation stage become larger, and the dynamic viscosity effect is also stronger. This shows that η reflects the correlation degree of the strain rate effect of the rock mass.

[0158] Reference Figure 10 The change of the parameter E M has a certain influence on both the peak strength and the deformation modulus, but has little influence on the strain at the peak strength . As E M increases, the peak strength of the rock becomes larger accordingly but the growth rate decreases, reflecting the concentration degree of the viscosity effect, indicating that E M is a comprehensive reflection of the correlation degree and concentration degree of the strain rate effect of the rock mass.

[0159] Based on the above theoretical analysis, the influence law of each fitting parameter on the constitutive relationship can be known. Using rock-like materials, loading is carried out on a split Hopkinson pressure bar device. The specimens are processed into cylinders with dimensions of Ф50mm×25mm. The two ends and the side surfaces are polished with sandpaper until there are no protrusions and the flatness is less than 0.02mm, and the incident peak stress is 90MPa. Among them, ε m , σ m , E M , and η parameters are obtained by fitting based on the test results and the sensitivity analysis of the model parameters , and \(\dot{\varepsilon}\) is the average strain rate of the test. The model parameters are shown in Table 2.

[0160] Table 2 Constitutive model parameters

[0161]

[0162] Substituting the rock mechanics parameters in Table 2 into Equation (25), the comparison diagram of the theoretical calculation results and test results of the cumulative damage of the rock mass under cyclic impact can be obtained, as shown in Figure 11 .

[0163] Reference Figure 11, the theoretical calculation results and experimental results using the method in this paper have good consistency. After 5 cyclic load impacts, the damage degree of the rock mass changes from 0.294 to 0.712. As the number of impacts increases, the internal damage degree of the rock mass will increase rapidly, and microcracks will develop and expand rapidly until the bearing capacity is lost. Since the influence of the compaction elastic stage of the rock mass is not considered in the model in this paper, there are still some deviations between the model and the measured results. Generally speaking, the model can better reflect the relationship between rock strength and the number of cyclic impacts, indicating that the calculation model of the present invention has good applicability to the cumulative damage of the rock mass in this environment.

[0164] To study the evolution law and damage characteristics of the stability of sliding dangerous rock masses under blasting disturbance, a sliding dangerous rock mass at the exit of a certain tunnel is taken as an engineering example, as shown in Figure 12 . The dangerous rock mass is composed of argillaceous sandstone, the dip angle of the structural plane is 40.6°, the horizontal included angle from the blasting source to point B is 59.3°, the height of the dangerous rock mass is 3.7 m, the height of the through section is 1.8 m, the height of the rock bridge section is 1.9 m, and the other parameters are shown in Table 3.

[0165] Table 3 Model parameters of the dangerous rock mass

[0166]

[0167] Substitute the parameters of the dangerous rock mass in Table 3 into equations (5), (12), and (27) to obtain the curve of the stability coefficient of the sliding dangerous rock mass varying with the number of blasting impacts. The results are as shown in Figure 13 .

[0168] It can be seen from Figure 13 that blasting disturbance has an important impact on the stability of the dangerous rock mass. After 8 blasting stress wave actions, the stability coefficient of the dangerous rock mass at the moment of blasting decreases from 1.142 to 1.051; after blasting, only considering the deterioration effect of the blasting stress wave on the cohesion of the rock in the rock bridge section, the long-term stability decreases from 1.159 to 1.092. Under the frequent disturbance of the stress wave, the cohesion of the rock in the rock bridge section continues to deteriorate, and the stability of the dangerous rock mass further decreases, and the sensitivity of the blasting load to the stability of the dangerous rock mass is higher than the deterioration of the cohesion. Thus, it can be seen that the impact of the blasting load on the stability of the dangerous rock mass is significant.

[0169] To study the influence of blasting environment parameters on the deterioration law of the dangerous rock mass. Using the rock physical and mechanical parameters in Table 3, by changing a single factor, analyze the sensitivity of parameters such as explosive charge and horizontal blasting distance to the cohesion of the rock in the rock bridge section

[0170] Figure 14 and 15The influence laws of the cohesion of rock in the rock bridge section and the stability coefficient of rock mass with the number of blasting disturbances when the explosive charges are 30 kg, 40 kg, and 50 kg respectively. As shown in the figure, with the increase of the explosive charge, the deterioration of the cohesion of the rock mass in the rock bridge section becomes more obvious, and the stability of the dangerous rock mass is lower; with the increase of the number of disturbances, the decreasing rates of the cohesion of the rock in the rock bridge section and the stability of the dangerous rock mass become slower. Taking 5 impact times as an example, under 3 different explosive charges, the cohesion of the rock in the rock bridge section deteriorates by 14.94%, 18.81%, and 23.79% respectively, and the stability of the rock mass decreases by 4.97%, 6.03%, and 8.77% respectively. The high-intensity explosion stress wave exacerbates the deterioration degree of the cohesion of the rock in the rock bridge section in the early and late stages, but still shows a trend of slower attenuation in the later stage. Therefore, the explosive charge is an important factor affecting the stability of dangerous rocks.

[0171] Figure 16 and Figure 17 They are respectively the influence laws of different horizontal blasting distances on the cohesion of the rock in the rock bridge section and the stability of the dangerous rock mass. As shown in the figure, when the blasting distance is 70 m, the initial cohesion of the rock in the rock bridge section is 8.1 MPa, and the stability of the dangerous rock mass is 1.35. With the disturbance effect of multiple-frequency blasting, it causes the deterioration of the cohesion of the rock in the rock bridge section and then leads to the gradual attenuation of the stability. When experiencing 8 times of blasting disturbances, the cohesion of the rock in the rock bridge section of the dangerous rock mass and the overall stability decrease to 6.02 MPa and 1.23 respectively, and the attenuation amplitudes are 25.6% and 8.89% respectively. Different blasting distances will cause different amplitudes of deterioration of the cohesion of the rock in the rock bridge section, and with the increase of the blasting distance, the deterioration amplitude of the cohesion gradually decreases. It is because the increase of the attenuation distance of the stress wave makes the energy consumed in the propagation in the rock mass increase, resulting in the decrease of the energy of the stress wave when it propagates to the rock in the rock bridge section, and different degrees of initiation and development of microcracks occur in the rock in the rock bridge section.

[0172] Combined with Figure 16 and Figure 17 , with the increase of the horizontal blasting distance, the attenuation amplitude of the cohesion of the rock in the rock bridge section weakens, but the stability of the dangerous rock mass does not increase but decreases. It is because with the decrease of the horizontal blasting distance, the disturbance stress on the rock in the rock bridge section continuously increases, but at this time the disturbance stress does not completely play a negative role in the stability of the dangerous rock mass, and the tangential stress decomposed on its structural plane is the anti-sliding force resisting the gravity action, which is instead beneficial to the stability of the rock mass. It can be seen from Equation (12) that when the included angle between the propagation direction of the stress wave and the structural plane is greater than 90°, the disturbance tangential stress plays a positive role in the stability of the dangerous rock mass. The impact load generated by blasting is more sensitive to the influence on the stability of the dangerous rock mass than the deterioration of the cohesion. Therefore, in blasting excavation, the stability of the dangerous rock mass is not only affected by the blasting distance, but also closely related to the blasting position.

[0173] To study the influence of rock properties on the deterioration law of dangerous rock masses, using the rock physical and mechanical parameters in Table 3, analyze parameters such as the initial damage D0 of the rock mass and the rock elastic modulus Er, and the sensitivity of the cohesion of the rock bridge section and the stability coefficient Fn of the dangerous rock mass.

[0174] Figure 18 It is the influence law of different initial damages on the deterioration of the cohesion of the rock bridge section. The deterioration amplitude of the cohesion of the rock bridge section increases with the increase of the initial damage of the rock mass, and the deterioration rate shows a law of first accelerating and then decelerating. Taking the initial damage D0 = 0.15 as an example, after the first 2 disturbance actions, the cohesion of the rock bridge section deteriorates from 8.1 to 6.58, and the deterioration amplitude is 18.76%. After the next 6 disturbances, the cohesion drops from 6.58 to 6.04, and the deterioration amplitude is 6.67%. The greater the initial damage of the rock mass, the more obvious the initiation and development degree of the mesoscopic damage inside the rock, which is more conducive to the fracture and expansion of the mesoscopic pores of the rock, thereby accelerating the deterioration of the cohesion of the rock bridge section.

[0175] Figure 19 It is the influence law of the rock elastic modulus on the stability of the dangerous rock mass. The greater the rock elastic modulus, the faster the rock disturbance damage rate with the increase of the number of disturbance times. When Er = 1.4 GPa, after 5 disturbances, the rock mass directly breaks and loses the ability to withstand impacts. The main reason is that the greater the rock elastic modulus, the greater the cumulative absorbed stress wave energy, causing greater damage. Generally speaking, the change of the elastic modulus of the rock mass has a very significant impact on the stability and high sensitivity.

[0176] The above is a method for predicting the stability of a sliding dangerous rock mass provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding device for predicting the stability of a sliding dangerous rock mass, such as Figure 20 shown, including:

[0177] A construction module for constructing a force distribution model of the main control structural plane of the dangerous rock mass, decomposing the load received by the main control structural plane according to the force distribution model to obtain the normal force and tangential force of the main control structural plane. The main control structural plane includes a through section and a rock bridge section, and the load is generated by the gravity of the dangerous rock mass and the stress generated by blasting disturbance.

[0178] A calculation module for obtaining the cohesion of the through section and the cohesion of the rock bridge section of the rock, and calculating the anti-sliding force of the main control structural plane based on the limit equilibrium theory according to the normal force, tangential force, the cohesion of the through section and the cohesion of the rock bridge section.

[0179] A prediction module for determining the stability coefficient of the dangerous rock mass according to the tangential force and the anti-sliding force, and predicting the stability of the dangerous rock mass according to the stability coefficient.

[0180] Specific limitations on a sliding dangerous rock mass stability prediction device can be referred to the limitations on a sliding dangerous rock mass stability prediction method in the above text, which will not be elaborated here. Each module in the sliding dangerous rock mass stability prediction device can be implemented in whole or in part by software, hardware, and their combination. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or stored in a memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0181] The present invention also provides a computer-readable storage medium storing a computer program, which can be used to execute the Figure 1 sliding dangerous rock mass stability prediction method provided.

[0182] The present invention also provides Figure 21 a schematic structural diagram of the computer device shown, as Figure 21 shown. At the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for other services. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the Figure 1 sliding dangerous rock mass stability prediction method provided.

[0183] Those of ordinary skill in the art can understand that all or part of the processes in the method of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memories. The non-volatile memory can include a read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical memory, etc. The volatile memory can include a random access memory (RAM) or an external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), etc.

[0184] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope recorded by the present invention.

Claims

1. A method for predicting the stability of sliding dangerous rock mass, characterized in that: include: Constructing a force distribution model of the main control structure surface of the dangerous rock mass, decomposing the load on the main control structure surface according to the force distribution model, and obtaining the normal force and tangential force of the main control structure surface, wherein the main control structure surface includes a through section and a rock bridge section, and the load is generated by the gravity of the dangerous rock mass and the stress generated by the blasting disturbance; Obtaining the rock cohesion of the through section and the rock cohesion of the rock bridge section, and calculating the anti-sliding force of the main control structure surface based on the limit equilibrium theory according to the normal force, the tangential force, the rock cohesion of the through section and the rock cohesion of the rock bridge section; The stability coefficient of the dangerous rock mass is determined according to the tangential force and the anti-sliding force, and the stability of the dangerous rock mass is predicted according to the stability coefficient.

2. A method for predicting stability of sliding dangerous rock mass according to claim 1, characterized in that: Obtaining the rock cohesion of the through section and the rock cohesion of the rock bridge section, and calculating the anti-sliding force of the main control structure surface based on the limit equilibrium theory according to the normal force, the tangential force, the rock cohesion of the through section and the rock cohesion of the rock bridge section, specifically including: Obtaining the rock cohesion of the through section, the initial rock cohesion of the rock bridge section, and the initial damage variable of the dangerous rock mass; Determine the cumulative damage variable of the dangerous rock mass after experiencing n blasting disturbances according to the initial damage variable, where n is a positive integer; Determine the rock cohesion of the rock bridge section after experiencing n blasting disturbances according to the initial rock cohesion, the initial damage variable and the cumulative damage variable; Based on the limit equilibrium theory, the anti-sliding force of the main control structure surface is calculated according to the normal force, the tangential force, the rock cohesion of the through section and the rock cohesion of the rock bridge section after n blasting disturbances.

3. A method for predicting stability of sliding dangerous rock mass according to claim 2, characterized in that: Determining the cumulative damage variable of the dangerous rock mass after experiencing n blasting disturbances according to the initial damage variable specifically includes: The total area of ​​the dangerous rock mass is divided to obtain the undamaged rock area, the cumulative damage area after n-1 blasting disturbances, the load damage area under the nth blasting disturbance, and the coupled damage area; Determine the cumulative damage variable of the dangerous rock mass after n-1 blasting disturbances according to the cumulative damage area and the total area; determine the load damage variable of the n-th blasting disturbance according to the load damage area under the n-th blasting disturbance, the coupled damage area, the total area and the cumulative damage area after n-1 blasting disturbances; The cumulative damage variable of the dangerous rock mass after experiencing n-1 blasting disturbances, the load damage variable of the nth blasting disturbance and the initial damage variable are determined.

4. A method for predicting stability of sliding dangerous rock mass according to claim 1, characterized in that: The calculation expression of the anti-slip force is: in, is the internal friction angle of rock, c w is the rock cohesion of the through section, c d is the rock cohesion of the rock bridge section, l w is the length of the through section, l d is the length of the rock bridge section, σ G is the gravity exerted on the dangerous rock mass, is the normal stress of the blasting disturbance acting on the main control structure surface, and β is the inclination angle of the main control structure surface.

5. A method for predicting stability of sliding dangerous rock mass according to claim 1, characterized in that: The calculation expression of the stability coefficient is: in, is the internal friction angle of rock, c w is the rock cohesion of the through section, c d is the rock cohesion of the rock bridge section, l w is the length of the through section, l d is the length of the rock bridge section, σ G is the gravity exerted on the dangerous rock mass, is the normal stress of the blasting disturbance acting on the main control structure surface, β is the inclination angle of the main control structure surface, is the tangential stress of the main control structure surface caused by the blasting disturbance, is the cohesion of the rock in the rock bridge section after experiencing the load generated by n blasting disturbances.

6. A method for predicting stability of sliding dangerous rock mass according to claim 2, characterized in that: The calculation expression of the rock cohesion after the rock bridge section has been disturbed by n blastings is: Among them, c d is the rock cohesion of the rock bridge section, is the cohesion of the rock in the rock bridge section after experiencing the load generated by n blasting disturbances, D n-1 is the cumulative damage variable of the dangerous rock mass after n-1 blasting disturbances, ξ is the influence coefficient of the existing damage on the new load damage, κ is the constitutive model parameter, It is the strain of the peak strength of the dangerous rock mass under the load of the nth blasting disturbance.

7. A method for predicting stability of sliding dangerous rock mass according to claim 1, characterized in that: Predicting the stability of the dangerous rock mass according to the stability coefficient specifically includes: The stability of the dangerous rock mass is predicted according to the interval range of the stability coefficient.

8. A device for predicting the stability of a sliding dangerous rock mass, characterized in that: include: A construction module is used to construct a force distribution model of the main control structure surface of the dangerous rock mass, and decompose the load on the main control structure surface according to the force distribution model to obtain the normal force and tangential force of the main control structure surface. The main control structure surface includes a through section and a rock bridge section. The load is generated by the gravity of the dangerous rock mass and the stress generated by the blasting disturbance; a calculation module, for obtaining the rock cohesion of the through section and the rock cohesion of the rock bridge section, and calculating the anti-sliding force of the main control structure surface based on the limit equilibrium theory according to the normal force, the tangential force, the rock cohesion of the through section and the rock cohesion of the rock bridge section; The prediction module is used to determine the stability coefficient of the dangerous rock mass according to the tangential force and the anti-sliding force, and predict the stability of the dangerous rock mass according to the stability coefficient.

9. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the method for predicting stability of a sliding dangerous rock mass according to any one of claims 1 to 7 is implemented.

10. A computer device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the program, a method for predicting stability of a sliding dangerous rock mass as claimed in any one of claims 1 to 7 is implemented.

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