Rock burst identification method and system and medium

Abstract

The invention relates to the technical field of geological exploration, and particularly discloses a rockburst identification method and system and a medium. According to the rockburst identification method provided on the basis of rock mass structural surface property ground stress characteristics and dynamic disturbance, the identification of the occurrence position and potential scale of strain type and structural surface type instant rockburst is realized by using mathematical space vector calculation from the nature of the strength of the rock mass and the stress state of the rock mass; according to the method, judgment is carried out through quantitative calculation, the accuracy is better, breakthrough of accurate position and potential scale calculation of rockburst in the tunnel cavern is achieved, meanwhile, the method is not limited by lithology and tunnel cavern types, accurate calculation can be achieved, calculation can be continuously carried out in the tunnel excavation process, limitation of monitoring equipment is avoided, and the method is suitable for popularization and application. The method is simple in calculation formula and wide in application range.

Description

Technical Field

[0001] The present invention relates to the field of geological exploration technology, and in particular to a rockburst identification method, system and medium. Background Art

[0002] Rockburst is a dynamic phenomenon in which the elastic deformation potential accumulated in deep or high tectonic stress rock mass is suddenly released under tunnel excavation or other external disturbances, resulting in the bursting and ejection of surrounding rock. Rockburst is a typical geological disaster in deep underground space engineering, which is highly sudden, random and harmful. The occurrence of rockburst often brings immeasurable losses to tunnel cavern construction personnel and equipment. Therefore, it is of great significance to propose a reasonable rockburst prediction method and accurately identify the location, scale and size of rockburst for rockburst disaster prevention and safety production in underground engineering.

[0003] At present, there are four methods for prediction and forecasting: ① Index judgment method: based on rock, ground stress characteristics, elastic strain energy and other indicators for judgment. The advantage is that this method is simple to use and can be directly measured on site. However, single-index rockburst judgment or multi-index rockburst judgment is affected by many factors and its prediction accuracy is limited; ② Numerical index method: based on the energy theory of rockburst generation, a numerical index judgment method is proposed, which can predict the potential rockburst location, but this method has made a series of simplifications to the on-site geological conditions and working conditions. The acquisition of ground stress and rock mass parameters may not be accurate, and the accuracy of the prediction results may be insufficient; ③ Applied mathematical methods: including artificial neural networks, support vector machines, distance discriminant analysis, Bayesian discriminant analysis, fuzzy mathematics, extenics, gray Color system theory, attribute mathematics, power coefficient method, ideal point method, approximate ideal solution method, evidence theory method, cloud model, etc. These methods reduce human intervention errors and improve prediction effects by considering multiple influencing factors, but their accuracy is seriously affected by training samples. The representativeness of training samples largely determines the accuracy of rockburst prediction; ④ On-site monitoring method: such as microseismic monitoring, acoustic emission monitoring, infrared monitoring, microgravity monitoring, etc., which can monitor rockburst risks in real time and are suitable for the construction stage. Among them, microseismic monitoring technology has been developed to maturity and can obtain microseismic information before rockburst occurs in real time 24 hours a day. By "interpreting" this information, rockburst can be predicted and warned in real time. However, the cost of using this on-site monitoring method is high and the monitoring range is small (only 100m before and after the face). Summary of the invention

[0004] In order to overcome the problems existing in the existing rockburst identification methods, such as limited prediction result accuracy, errors in training samples and small monitoring range, the present invention provides a rockburst identification method, system and medium.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a rockburst identification method, the method comprising:

[0007] Step 100: Obtain identification parameters of the target tunnel chamber, wherein the identification parameters include rock tensile strength, rock mass tensile strength, structural surface rock formation occurrence, and first stress parameters at the measuring point;

[0008] Step 200: judging the state of the rock mass of the target tunnel chamber, and when the rock mass of the target tunnel chamber is in a dry state, executing the identification process based on the identification parameters to obtain the rockburst parameters of the target tunnel chamber; otherwise, judging it as a rockburst-free area;

[0009] The identification process includes:

[0010] Step 201: determining that a strain-type immediate rock burst is about to occur in a target tunnel chamber based on the fact that the first stress parameter is greater than the rock tensile strength;

[0011] Step 202: Calculate the structural surface normal stress according to the first stress parameter and the occurrence of the structural surface rock layer, and determine that the target tunnel chamber is about to experience a structural surface type immediate rock burst based on the fact that the structural surface normal stress is greater than the rock mass tensile strength;

[0012] Step 203: Calculate the spatial normal vector of the free surface of the target tunnel chamber, obtain a first angle according to the spatial normal vector and the direction vector of the first stress parameter, determine the position of the strain-type instant rockburst according to the first angle, and determine the volume of the strain-type instant rockburst according to the first angle and a preset tensile rupture position;

[0013] Step 204: Obtain a second angle based on the spatial normal vector and the normal vector of the structural surface rock formation dip, determine the position of the structural surface type immediate rock burst based on the second angle, and determine the volume of the structural surface type immediate rock burst based on the intersection relationship of the structural surface rock formation dip and a connecting line of a preset tensile fracture position.

[0014] According to a specific implementation, in the above identification method, the first stress parameter includes a maximum principal stress, an intermediate principal stress, and a minimum principal stress; determining that a strain-type instantaneous rockburst occurs in a target tunnel chamber includes:

[0015] Compare the maximum principal stress with the rock tensile strength. If the maximum principal stress is greater than the rock tensile strength, determine that a strain-type instantaneous rock burst occurs in the target tunnel chamber, and substitute the maximum principal stress into the subsequent identification process. If it is less than;

[0016] Compare the intermediate principal stress with the rock tensile strength. If the intermediate principal stress is greater than the rock tensile strength, it is determined that a strain-type instantaneous rock burst occurs in the target tunnel chamber, and the intermediate principal stress is substituted into the subsequent identification process; if it is less than;

[0017] Compare the minimum principal stress with the rock tensile strength, and if the minimum principal stress is greater than the rock tensile strength, determine that a strain-type instantaneous rockburst occurs in the target tunnel chamber, and substitute the minimum principal stress into the subsequent identification process;

[0018] Among them, the maximum principal stress is greater than the intermediate principal stress, and the intermediate principal stress is greater than the minimum principal stress; when the maximum principal stress, the intermediate principal stress and the minimum principal stress are all less than the tensile strength of the rock, it is determined that strain-type immediate rock burst does not occur.

[0019] According to a specific implementation, in the above identification method, the free surface of the target tunnel chamber includes the heading surface, the arch top surface, the arch bottom surface and the arch waist side wall surface.

[0020] According to a specific implementation manner, in the above identification method, determining the position of the strain-type immediate rockburst according to the first angle includes: when the first angle is greater than When the first angle is less than or equal to When , the spatial normal vector corresponding to the minimum value of the first angle is selected as the normal vector of the rockburst position, and the position where the rockburst occurs is calculated according to the normal vector of the rockburst position; wherein, σ tys is the rock tensile strength, σ i is the first stress parameter, i is equal to 1 / 2 / 3, σ1 represents the maximum principal stress, σ2 represents the intermediate principal stress, and σ3 represents the minimum principal stress.

[0021] According to a specific implementation, in the above identification method, determining the location of the structural surface type immediate rockburst according to the second angle includes:

[0022] When the second angle is greater than When the instantaneous rockburst of the structural surface type occurs at the intersection angle of the side walls of the target tunnel chamber, the second angle is less than or equal to , the spatial normal vector corresponding to the second angle is used as the normal vector of the rockburst position, and the location where the rockburst occurs is calculated according to the normal vector of the rockburst position; wherein, σ tys is the rock tensile strength, σ i is the first stress parameter, i is equal to 1 / 2 / 3, σ1 represents the maximum principal stress, σ2 represents the intermediate principal stress, and σ3 represents the minimum principal stress.

[0023] According to a specific implementation, in the above identification method, the method further includes performing time-lag rockburst identification on the target tunnel chamber, and the time-lag rockburst identification includes:

[0024] By monitoring the ground stress of the target tunnel chamber, the newly added maximum principal stress, newly added intermediate principal stress and newly added minimum principal stress after time t are obtained;

[0025] The newly added maximum principal stress, the newly added intermediate principal stress, the newly added minimum principal stress and the first stress parameter decomposition are summed in the X, Y and Z axis directions to obtain the sum stress in the X, Y and Z axis directions;

[0026] A second stress parameter is generated according to the magnitude of the sum of the stresses in the X, Y, and Z axis directions, and the second stress parameter is substituted into the identification process to obtain the rockburst parameter after time t, and determine the occurrence of a time-delayed rockburst.

[0027] According to a specific implementation, in the above-mentioned identification method, the time-lag rockburst identification also includes: monitoring the dynamic disturbance of the target tunnel chamber to obtain the vibration frequency, testing the rock mass of the target tunnel chamber to obtain the natural frequency, and judging whether a time-lag rockburst occurs in the target tunnel chamber at the location where a strain-type immediate rockburst and / or a structural surface-type immediate rockburst occurs based on the vibration frequency and the natural frequency.

[0028] A rockburst identification method according to claim 1, characterized in that the structural surface rock formation attitude includes n groups of structural surfaces; determining the volume of the structural surface type immediate rockburst includes: selecting a structural surface with a structural surface extension length greater than or equal to 1m in the structural surface rock formation attitude as a dominant structural surface, and connecting the lines according to the intersection relationship of the dominant structural surface rock formation attitude and the preset tensile fracture position; wherein n is a positive integer, and for the dominant structural surface, n is less than or equal to 3.

[0029] In a second aspect, the present invention provides a rockburst identification system, the system comprising:

[0030] The acquisition module is used to obtain the identification parameters of the target tunnel chamber;

[0031] The identification module is used to execute a rockburst identification method as described in any one of the above items, perform rockburst identification on the target tunnel chamber, and obtain rockburst parameters.

[0032] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the computer executes any of the methods described above.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention proposes a rockburst identification method based on the properties of rock mass structural surfaces and ground stress characteristics. Starting from the essence of the rock mass's own strength and the stress state it is in, the mathematical space vector calculation is used to realize the identification of the occurrence location and potential scale of strain-type immediate rockburst and structural surface type immediate rockburst. The present invention improves the accuracy of rockburst identification through quantitative calculation, and achieves a breakthrough in the calculation of the accurate location and potential scale of rockburst in tunnel caverns. At the same time, the present invention is not limited by rock types and tunnel cavern types, and can realize accurate calculation, and can continuously perform calculations during tunnel excavation, and is not limited by monitoring equipment. The method has a simple calculation formula and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a flow chart of a rockburst identification method provided by an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of calculating the scale of rock burst at a tunnel face provided by an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of calculating the rockburst volume of a flat floor of a tunnel chamber provided in an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of calculating the rockburst volume of a tunnel chamber arch provided by an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of a rockburst volume calculation model for an arc-shaped tunnel chamber provided in an embodiment of the present invention;

[0040] Figure 6 A schematic diagram of a rockburst volume calculation model for a group of advantageous structural surfaces of an arc-shaped tunnel chamber provided in an embodiment of the present invention;

[0041] Figure 7 A schematic diagram of a rockburst volume calculation model for two groups of advantageous structural surfaces of an arc-shaped tunnel chamber provided in an embodiment of the present invention;

[0042] Figure 8 A schematic diagram of a rockburst volume calculation model for two groups of advantageous structural surfaces on the arch haunch of a tunnel chamber provided in an embodiment of the present invention;

[0043] Fig. 9 A schematic diagram of a rockburst volume calculation model for two groups of advantageous structural surfaces of a flat floor of a tunnel chamber provided in an embodiment of the present invention;

[0044] Fig.10 A schematic diagram of the calculation results of the free surface direction and stress angle of a tunnel chamber provided by an embodiment of the present invention;

[0045] Fig.11A schematic diagram of the direction and radius of the open surface of an excavated tunnel chamber provided in an embodiment of the present invention;

[0046] Fig.12 A schematic diagram of calculating the rockburst volume of an arc-shaped tunnel chamber provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0048] The terms "first", "second", etc. in the embodiments of the specification, claims, and drawings of the present invention are used only for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, including a series of steps or units. The method, system, product, or device is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0049] Please refer to Figure 1 , which shows a schematic flow chart of a rockburst identification method provided by an embodiment of the present invention, the method comprising:

[0050] Step 100: Obtain identification parameters of the target tunnel chamber, wherein the identification parameters include rock tensile strength, rock mass tensile strength, structural surface rock formation occurrence, and first stress parameters at the measuring point.

[0051] Among them, the three-dimensional ground stress state of the rock mass is measured in the borehole near the potential rock burst tunnel chamber by using ground stress testing methods such as hydraulic fracturing, anelastic method, and stress relief method to obtain the ground stress component σ at the measuring point x , σ y , σ z , τ xy , τ yz , τ zx And the maximum principal stress, intermediate principal stress, minimum principal stress σ1, σ2, σ3 (where: σ1>σ2>σ3), and the corresponding principal stress azimuth and inclination angles β1°∠α1°, β2°∠α2°, β3°∠α3°, the normal vectors of the maximum principal stress, intermediate principal stress, minimum principal stress σ1, σ2, σ3 directions are calculated as follows:

[0052]

[0053]

[0054]

[0055] Preferably, the spacing between geostress measurement points in areas with little terrain undulation is no more than 1 km; when the tunnel chamber passes through mountains or valleys, geostress tests should preferably be carried out on both sides of the mountains or valleys and the spacing between measurement points should not be more than 500 m.

[0056] Furthermore, the rock formation occurrence θ of n groups of structural surfaces (the structural surfaces in the embodiment of the present invention refer to relatively weak structural surfaces such as faults, rock formation layers, quasi-bedding, veins, micro-cracks, etc.) of the potential rock burst tunnel chamber are measured by means of on-site compass tape measurement, three-dimensional laser scanning, and downhole television. i °∠φ i °(i=1,2,3…,i≤n), obtain the structure surface spacing d, extension length s, where, θ i ° is the dip of the rock formation, φ i ° is the inclination of the rock layer; then the normal vector of the rock layer attitude of the i-th group of structural planes can be calculated:

[0057]

[0058] Furthermore, the tensile strength of the rock σ is measured by hydraulic fracturing, disc radial fracturing, bending test and other methods through the core collected from the drilling or tunnel cavern construction site. tys Or the tensile strength value of the rock mass structural surface σ ti , or through the compressive strength value of the rock mass σ c And simply converted into the tensile strength of rock σ tys Or the tensile strength value of the rock mass structural surface σ ti (i=1,2,3…,i≤n) for quick determination:

[0059] σ tys =σ ti =λσ c ,in

[0060] Step 200: judging the state of the rock mass of the target tunnel chamber. When the rock mass of the target tunnel chamber is in a dry state, executing a judgment process based on the judgment parameters to obtain rockburst parameters of the target tunnel chamber; otherwise, judging that the target tunnel chamber is in a rockburst-free area; wherein the judgment process includes:

[0061] Step 201: Based on the first stress parameter being greater than the rock tensile strength, it is determined that a strain-type instantaneous rockburst occurs in the target tunnel chamber, wherein the specific determination process is as follows:

[0062] The first stress parameter σ iThe maximum principal stress σ1, the intermediate principal stress σ2 and the minimum principal stress σ3 in are compared with the rock tensile strength. tys When σ<1, the tunnel chamber is about to experience strain-type immediate rockburst; when σ tys When σ<1, we should also judge tys With σ 2、 σ3; if σ tys <σ2, then σ2 should be substituted into the subsequent identification process for calculation with reference to σ1; if σ tys <σ2 and σ tys <σ3, then σ3 should be substituted into the subsequent identification process for calculation with reference to σ1. tys >σ1>σ2>σ3, no strain-type instantaneous rock burst will occur in the tunnel chamber. It can be understood that the maximum principal stress is greater than the intermediate principal stress, and the intermediate principal stress is greater than the minimum principal stress.

[0063] It should be noted that the rock has a stress state before tunnel excavation. After tunnel excavation, the original stress state changes. The rock mass on the surface of the tunnel surrounding rock changes from the original state of being subjected to the maximum principal stress σ1 to 0. Then the rock mass on the surface of the tunnel surrounding rock is subjected to an instantaneous tensile stress. When the tensile stress is greater than the tensile strength, damage will occur. Generally, in the process of identifying rock bursts based on the maximum principal stress and the strength-stress ratio of the rock, only the maximum principal stress σ1 is considered. However, when the intermediate principal stress σ2 and the minimum principal stress σ3 are consistent with the free surface of the tunnel and are greater than the tensile strength, rock bursts can also occur on the rock surface. The embodiment of the present invention can avoid the problem of inaccurate identification of rock bursts by considering multiple parameters.

[0064] Step 202: Calculate the structural surface normal stress according to the first stress parameter and the occurrence of the structural surface rock formation, and determine that a structural surface type immediate rock burst occurs in the target tunnel chamber based on the fact that the structural surface normal stress is greater than the rock mass tensile strength.

[0065] The specific determination process is as follows:

[0066] The ground stress component σ measured in the borehole near the rockburst tunnel chamber x , σ y , σ z , τ xy , τ yz , τ zx , the normal stress magnitude σ on the i-th group of structural surfaces is calculated using the Mohr stress circle i :

[0067]

[0068] When σ ti <σ BiWhen , the i-th group of tunnel structural surfaces is about to experience structural surface type immediate rock burst, and the number of structural surface type immediate rock burst groups k and the normal vector corresponding to the i-th group of structural surfaces are determined. (a i 、b i 、c i )(i=1,2,3...,i≤n). When σ ti >σ Bi , no immediate structural surface rock burst will occur in the tunnel chamber.

[0069] It should be noted that when it is determined that the tunnel chamber will not experience strain-type immediate rockburst and structural surface-type immediate rockburst, it is determined that the tunnel will not experience rockburst, and the above-mentioned identification process is terminated.

[0070] Step 203: Calculate the spatial normal vector of the free surface of the target tunnel chamber, obtain a first angle according to the spatial normal vector and the direction vector of the first stress parameter, determine the position of the strain-type instant rockburst according to the first angle, and determine the volume of the strain-type instant rockburst according to the first angle and a preset tensile rupture position.

[0071] Specifically, according to the design drawings, select any section of the tunnel chamber to determine the inclination and inclination angle ψ of any point perpendicular to the tunnel chamber face, arch top surface, arch bottom surface, and arch waist side wall surface. j °∠ω j °(j=1,2,3…), calculate its spatial normal vector (l j 、m j 、n j )(j=1,2,3…) is:

[0072]

[0073] Then calculate the principal stress direction vector (i=1,2,3) and vector The first angle γ j ; When the first angle When the first angle When (i=1,2,3) is the stress normal vector of rock burst in tunnel chamber. j Select the minimum value γ min The corresponding vector (l min 、m min 、n min) is the normal vector of the free surface of the cavern where the rockburst occurs. The spatial position of the tunnel chamber corresponding to the spatial normal vector is the location where the rockburst occurs, and the tensile stress on the vertical tunnel chamber side wall is σ b =σ1cos(γ min ),

[0074]

[0075] If the plane where the rockburst occurs in the tunnel chamber is not the tunnel face, it is necessary to determine the location where the rockburst occurs on the side wall of the tunnel chamber; assuming that the inclination and dip angle of the excavated tunnel face are ψ1°∠ω1° and pass through a point O1(0,0,0) in space, then its spatial normal vector is Then the plane equation and normal vector of the tunnel chamber face are l1X+m1Y+n1Z=0.

[0076] The plane normal vector due to the rock burst in the tunnel chamber The coordinates are (x k1 ,y k1 ,z k1 ), and is from the origin to the point (x k1 ,y k1 ,z k1 ), then the distance d1 from point A1 to the tunnel face plane is

[0077]

[0078] Let A'1(x k1 ',y k1 ',z k1 ') is point A1(x k1 ,y k1 ,z k1 ) to the tunnel face plane, For vector (x k1 ,y k1 ,z k1 ) to the tunnel chamber face plane projection vector (x k1 ',y k1 ',z k1 '),but:

[0079]

[0080] Since the tunnel face plane is perpendicular to the XY horizontal plane, the vector is converted into a two-dimensional vector coordinate on the plane of the tunnel face. k1 When '>0, the two-dimensional vector of the rockburst location in the tunnel chamber is When k1 When '=0, the two-dimensional vector of the rockburst location in the tunnel chamber is When k1 When '<0, the two-dimensional vector of the rockburst location in the tunnel chamber is Will After the vector is normalized, the normalized unit vector is obtained When k1 When '>0, the two-dimensional vector of the rockburst location in the tunnel chamber is When k1 When '=0, the two-dimensional vector of the rockburst location in the tunnel chamber is When k1 When '<0, the two-dimensional vector of the rockburst location in the tunnel chamber is By adding the unit vector By multiplying it by the cavity radius r1, we can obtain the coordinates of the occurrence position of strain-type instantaneous rockburst at the tunnel cavity interface.

[0081] Furthermore, when the tunnel is excavated, the stress field changes. According to the above calculation, when the original rock stress is released, the tensile strength of a small rock unit on the free surface of the tunnel chamber is tys When σ1 is less than σ1, strain-type rock burst will occur in the tunnel chamber; when the original rock stress is released, when the tensile strength of a small rock unit on the free surface of the tunnel chamber is σ1*cos(γ)≤σ tys When the original rock stress is released, the tensile strength of a small rock unit on the free surface of the tunnel chamber is σ tys When <σ1*cos(γ), a minor or more severe rockburst will occur.

[0082] ① Calculation of rockburst volume at tunnel face

[0083] When the direction of the maximum principal stress is consistent with the tunnel axis, the area of ​​the lower rectangular surface of the tunnel face where the rock burst occurs is S1, the area of ​​the upper semicircle is S2, and the total area of ​​the tunnel face is S 合 ; Assume that the tensile stress on the rock mass at a certain section outside the tunnel face is equal to the tensile strength σ of the rock mass tys , which is the preset tensile fracture position, the area of ​​the lower rectangular surface of the tunnel face is S2', the area of ​​the upper semicircle is S4', and the total area of ​​the projected tunnel face is S 合 '. Please refer to Figure 2 , which shows a schematic diagram of the calculation of the rockburst scale of the tunnel face provided by an embodiment of the present invention. Since the intersection angle between the tunnel face and the tunnel side wall bottom plate is a right angle, with the rotation of the free face, the tensile stress of the rock mass at a certain point is:

[0084] σ1*cos(γ)*cos(ε / 2)=σ tys .

[0085] Due to the simplified assumption that a point at the location of the rockburst on the free face of the tunnel chamber is a rod extending along the tunnel excavation direction to the stress limit equilibrium point outside the cavern, according to Saint-Venant's principle, F1 = F2, s1 = ah, Therefore, σ1cos(γ)S 合 =σ1cos(γ)(S1+S2)=σ tys S' 合 , so

[0086] because: but:

[0087] The depth of rock burst at the tunnel face is: The volume of the rockburst is:

[0088] ② Calculation of rockburst volume of straight floor of tunnel chamber

[0089] For a straight tunnel floor, when the maximum principal stress direction is perpendicular to the tunnel floor, let the tunnel floor width be a, the tunnel floor length of the rock burst section be b, and the tunnel floor area of ​​the rock burst section be S. 合 ; Assume that the tensile stress on the rock mass at a certain section outside the tunnel floor is equal to the tensile strength σ of the rock mass tys , which is the preset tensile rupture position, the width of the bottom plate is a', the length of the bottom plate of the rock burst section tunnel is b', and the floor area of ​​the rock burst section tunnel is S 合 ', please refer to Figure 3 , which shows a schematic diagram of the rockburst volume calculation of the flat floor of the tunnel chamber provided by the embodiment of the present invention. Since the intersection angle between the tunnel chamber floor and the tunnel chamber side wall bottom plate is a right angle, with the rotation of the free surface, the tensile stress of the rock mass at a certain point is: σ1*cos(γ)*cos(ε / 2)=σ tys

[0090] Due to the simplification, it is assumed that the point where the rock burst occurs on the tunnel chamber floor is a rod along the outer side of the tunnel chamber floor. According to Saint-Venant's principle, F1 = F2, S 合 = ab,σ1cos(γ)S 合 =σ tys S' 合 , so because: but: The depth of rock burst at the tunnel face is: The volume of the rockburst is:

[0091] ③ Calculation of rockburst volume of tunnel chamber arch side wall

[0092] For the tunnel chamber arch side wall, when the maximum principal stress direction is perpendicular to the tunnel chamber arch side wall, the tunnel chamber radius is r1, the arch side wall height is h, and the area of ​​the tunnel chamber arch side wall in the rock burst section is S. 合 ; Assume that the tensile stress on the rock mass at a certain section outside the tunnel floor is equal to the tensile strength σ of the rock mass tys , which is the preset tensile rupture position, the distance between this section and the tunnel centerline is l, and the floor area of ​​the rockburst section is S 合 ', please refer to Figure 4 , which shows a schematic diagram of the calculation of the rockburst volume of the tunnel chamber arch waist provided by an embodiment of the present invention.

[0093] Simplified assumption: A point at the free surface of the tunnel chamber arch side wall where the rock burst occurs extends radially and horizontally to the stress limit equilibrium point outside the tunnel chamber as a rod. According to Saint-Venant's principle, F1 = F2. σ1cos(γ)S 合 =σ tys S' 合 ,

[0094] The volume of the rockburst is

[0095] ④ Calculation of rockburst volume of arc-shaped tunnel chamber

[0096] Assume that the center of the arc-shaped tunnel chamber is A, the radius of the tunnel chamber is r1, the location of the rock burst on the free surface is B, and The direction is consistent with the principal stress σ1*cos(γ); let the stress limit equilibrium points extending from the center A of the tunnel chamber surface to the outer side of the tunnel chamber along the radial direction be C, D, and F. The tensile stresses at these three points are approximately equal to the tensile strength σ of the rock mass. tys , which is the preset tensile rupture position, the distance from the center of the circle to point C is l; let the vector The first angle between the vector and the X axis is ω1. and The first angle between them is ε; according to the three points C, D, and F on the circumscribed circle, a small circle with a radius of r2 can be drawn, and its center is O(x6,y6), the vector The first angle between is ω2, please refer to Figure 5 , which shows a schematic diagram of a rockburst volume calculation model for an arc-shaped tunnel chamber provided in an embodiment of the present invention.

[0097] Simplified assumption is that a point at the location of the rock burst on the free face of the tunnel chamber extends radially to the stress limit equilibrium point on the outer side of the cavern as a rod. According to Saint-Venant's principle: the different ways in which the force acts on the rod end will only affect the range within the distance from the rod end that is not greater than the lateral dimension of the rod. Assume that the axial force and area of ​​points B and C at the tiny rock unit are F1, F2, A1, and A2 respectively, and the first angle of the fan is ε1 (°), so According to Saint-Venant's principle, F1=F2, so we can calculate:

[0098]

[0099]

[0100]

[0101] Taking the rockburst location in the first quadrant of the coordinate system as an example, according to the determination of the strain-type instantaneous rockburst location, the unit vector of the rockburst location is

[0102]

[0103]

[0104] Then the vector The first angle between the X-axis and vector The first angle between the X-axis and Then the coordinates of points F and D can be obtained as follows:

[0105]

[0106]

[0107] Based on the coordinates of the three points C(x3,y3), D(x4,y4), and F(x5,y5) on the small circle, the center of the small circle can be calculated to be O(x6,y6).

[0108] Then the vector They are: (x5-x6, y5-y6), (x4-x6, y4-y6)

[0109]

[0110] Find the shadow area of ​​the rockburst region:

[0111] S 阴影 =S 扇OFCD -S 扇OFBD =S 扇OFCD -(S 扇AFBD -S AFO -SADO )

[0112] Due to S AFO =S ADO ,so:

[0113]

[0114] The volume of the rockburst is

[0115] In addition to the manual calculation method mentioned above, the rockburst area can also be drawn in the CAD software according to the design parameters and rock mass parameters, and the rockburst shadow area can be obtained through the query function, and finally the rockburst volume can be calculated.

[0116] Step 204: Obtain a second angle based on the spatial normal vector and the normal vector of the structural surface rock formation dip, determine the position of the structural surface type immediate rock burst based on the second angle, and determine the volume of the structural surface type immediate rock burst based on the intersection relationship of the structural surface rock formation dip and a connecting line of a preset tensile fracture position.

[0117] Specifically, the spatial normal vectors of the tunnel face, arch top, arch bottom, and arch waist side walls perpendicular to the tunnel chamber are determined according to the design drawings. (l j 、m j 、n j )(j=1,2,3…), calculate the normal vector (a i 、b i 、c i ) and vector (l j 、m j 、n j ) between the second angle γ; when the second angle When the second angle When (l j 、m j 、n j ) is the normal vector of the plane where the rockburst occurs in the tunnel chamber. The spatial position of the tunnel chamber corresponding to the spatial normal vector is the location where the rockburst occurs, and the tensile stress perpendicular to the structural surface is σ j =σ i cos(γ).

[0118]

[0119] If the plane where the rockburst occurs in the tunnel chamber is not the tunnel face, it is necessary to determine the location where the rockburst occurs on the side wall of the tunnel chamber; assuming that the inclination and dip angle of the excavated tunnel face are ψ1°∠ω1° and pass through a point O1(0,0,0) in space, then its spatial normal vector is Then the plane equation and normal vector of the tunnel chamber face are:

[0120] l1X+m1Y+n1Z=0,

[0121] The normal vector of the plane where the rock burst occurs in the tunnel chamber is: (l j 、m j 、n j ),because and are vectors on the same tunnel chamber section and are perpendicular to the XY horizontal plane. is converted into two-dimensional vector coordinates on the plane of the tunnel face. j When >0, the two-dimensional vector of the rockburst location in the tunnel chamber is When m j = 0, the two-dimensional vector of the location where the rock burst occurs in the tunnel chamber is When m j When <0, the two-dimensional vector of the location where the rock burst occurs in the tunnel chamber is Will After the vector is normalized, the normalized unit vector is obtained When k1 When '>0, the two-dimensional vector of the rockburst location in the tunnel chamber is When k1 When '=0, the two-dimensional vector of the rockburst location in the tunnel chamber is When k1 When '<0, the two-dimensional vector of the rockburst location in the tunnel chamber is By adding the unit vector Multiplying by the cavity radius r1 can obtain the coordinates of the occurrence position of the rockburst at the tunnel cavity interface.

[0122] Furthermore, for the volume of the structural surface type instant rock burst, in the embodiment of the present invention, the structural surface with an extension length of greater than or equal to 1m in the structural surface rock formation dip is selected as the dominant structural surface, and there are usually only 3 groups of dominant structural surfaces. The structural surface is a general term for various geological interfaces that cut the rock mass. Since the spatial state of the dominant structural surface cutting of the natural rock mass is very diverse, if there are more than 3 groups of joint cutting, the three groups of structural surfaces with the longest extension length are selected as the dominant structural surfaces to carry out the calculation of the volume of the structural surface instant rock burst. The following is a detailed description of the volume of the scale of the structural surface type instant rock burst determined based on the 3 groups of dominant structural surfaces.

[0123] ① Cut by 1 group of advantageous structural surfaces

[0124] When there is a set of dominant structural surfaces (the extension length of the structural surface is greater than 1m), and according to the above calculation, it can be known that the second angle between the normal vector of the tunnel chamber free surface and the tunnel chamber free surface is The normal vector of the dominant structural surface when (a1, b1, c1), according to the measured structural surface spacing d and extension length s, the structural surface is drawn on the strain-type instant rockburst calculation model diagram, please refer to Figure 6 , which shows a schematic diagram of a rockburst volume calculation model for a group of advantageous structural surfaces of an arc-shaped tunnel chamber provided by an embodiment of the present invention; by drawing a rockburst volume calculation model diagram in a CAD diagram, the area of ​​the tunnel section S is obtained by querying the area function. 阴影 area.

[0125] The volume of the rockburst is: V 岩爆 =bS 阴影 .

[0126] ② Cut by 2 groups of advantageous structural surfaces

[0127] When there are two sets of dominant structural surfaces (when the extension length of the structural surface is greater than 1m), and according to the above calculation, the second angle γ1 and the normal vector of the free surface of the tunnel chamber are obtained. When or and The normal vector of the dominant structural surface (a1, b1, c1), (a2, b2, c2), according to the measured structural surface spacing d and extension length s, the structural surface is drawn on the strain-type instant rockburst calculation model diagram; by drawing the rockburst volume calculation model diagram in the CAD diagram, the area function is used to obtain the S on the tunnel section. 阴影 area.

[0128] When it is an arc-shaped tunnel chamber, such as Figure 7 As shown, the volume of the rockburst is V 岩爆 =bS 阴影 ; When it is a tunnel chamber arch, Figure 8 As shown, the volume of the rockburst is When it is a flat floor of a tunnel chamber, such as Fig. 9 As shown, the volume of the rockburst is

[0129] ③ Cut by 3 groups of advantageous structural surfaces

[0130] When there are three sets of dominant structural surfaces (when the extension length of the structural surface is greater than 1m), and according to the above calculation, the normal vector to the free surface of the tunnel chamber is obtained: (l1, m1, n1) the second angle γ1, γ2, When or and and The normal vector of the dominant structural surface (a1, b1, c1), (a2, b2, c2), (a3, b3, c3), and obtain a point P1(x1, y1, z1), P2(x2, y2, z2), and P3(x3, y3, z3) on the three sets of structural surfaces respectively, and the plane equations S of the three sets of structural surfaces can be calculated J1 , S J2 , S J3 :

[0131] S J1 :a1x+b1y+c1z+d1=0;S J2 :a2x+b2y+c2z+d2=0;S J3 :a3x+b3y+c3z+d3=0.

[0132] Get a point on the tunnel's free surface, that is, the preset tensile fracture position, and calculate the tunnel's free surface vector The plane equation S of (l1, m1, n1) c :

[0133] Solve for S separately J1 , S J2 , S J3 The intersection coordinates p(x1,y1,z1), the structural surface S J1 , S J2 , S c The intersection coordinates c(x2,y2,z2), the structural surface S J1 , S J3 , S c The intersection coordinates b(x3,y3,z3), the structural surface S J2 , S J3 , S c The intersection coordinates are a(x4,y4,z4). Cramer's rule is used to solve the non-homogeneous linear equations to obtain the three plane intersection points.

[0134] Structural surface S J1 , S J2 , S J3 Taking the intersection coordinates p(x1,y1,z1) as an example, the specific calculation process is as follows:

[0135] SP=D,where

[0136] Then P=S -1D. Since S and D are known, the coordinates p(x1, y1, z1) can be obtained. Similarly, c(x2, y2, z2), b(x3, y3, z3), and a(x4, y4, z4) can be obtained, and we get: Therefore, the volume of rockburst cut by the three groups of structures is:

[0137]

[0138] According to a specific implementation, the above identification method further includes performing time-lag rockburst identification on the target tunnel chamber, and the time-lag rockburst identification includes:

[0139] By monitoring the ground stress of the target tunnel chamber, the newly added maximum principal stress, newly added intermediate principal stress and newly added minimum principal stress after time t are obtained;

[0140] The newly added maximum principal stress, the newly added intermediate principal stress, the newly added minimum principal stress and the first stress parameter decomposition are summed in the X, Y and Z axis directions to obtain the sum stress in the X, Y and Z axis directions;

[0141] A second stress parameter is generated according to the magnitude of the sum of the stresses in the X, Y, and Z axis directions, and the second stress parameter is substituted into the identification process to obtain the rockburst parameter after time t, and determine the occurrence of a time-delayed rockburst.

[0142] Specifically, in tectonic active areas, the maximum principal stress σ that increases with time is obtained by monitoring the ground stress. 1z , intermediate principal stress σ 2z , minimum principal stress σ 3z (Where: σ z1 >σ z2 >σ z3 ), the corresponding principal stress azimuth and inclination are β 1z °∠α 1z °, β 2z °∠α 2z °, β 3z °∠α 3z °; based on the initial maximum principal stress σ1, intermediate principal stress σ2, and minimum principal stress σ3 (where: σ1>σ2>σ3), the corresponding principal stress azimuth and inclination angles are β1°∠α1°, β2°∠α2°, and β3°∠α3°.

[0143]

[0144]

[0145]

[0146] Assume that the direction vectors of the X, Y, and Z axes are (1, 0, 0), (0, 1, 0), (0, 0, 1), then the initial maximum principal stress σ1, the initial intermediate principal stress σ2, the initial minimum principal stress σ3, the additional maximum principal stress σ z1 , the additional intermediate principal stress σ z2 , and the additional minimum principal stress σ z3 (where: σ1 > σ2 > σ3, σ z1 > σ z2 > σ z3 ) are decomposed in the X, Y, and Z axis directions and the stress is summed:

[0147] σ x合 = σ1cos(η x1 ) + σ2cos(η x2 ) + σ3cos(η x3 ) + σ 1z cos(η x1z ) + σ 2z cos(η x2z ) + σ 3z cos(η x3z ),

[0148] σ y合 = σ1cos(η y1 ) + σ2cos(η y2 ) + σ3cos(η y3 ) + σ 1z cos(η y1z ) + σ z2 cos(η y2z ) + σ z3 cos(η y3z ),

[0149] σ z合 = σ1cos(η z1 ) + σ2cos(η z2 ) + σ3cos(η z3 ) + σ 1z cos(η z1z ) + σ 2z cos(η z2z ) + σ 3z cos(η z3z ),

[0150] where

[0151]

[0152]

[0153]

[0154]

[0155]

[0156] Finally, the sum stress σ in the X, Y, and Z axis directions is obtained x合 , σ y合 , σ z合 , and τ xy合 , τ yz合 , τ zx合 is 0. Compare σ x合 , σ y合 , σ z合 The maximum value among the three is set as the maximum principal stress value σ 1合 , the minimum value among the three is set as the minimum principal stress σ 3合 , the intermediate value between the three is set as the intermediate principal stress σ 2合 . The σ 1合 , σ 2合 , σ 3合 The second stress parameter is substituted into the identification process for calculation and judgment. If the requirement is met, it indicates that a time-delayed rockburst will occur at time t without support.

[0157] Furthermore, the time-lag rockburst identification also includes: monitoring the dynamic disturbance of the target tunnel chamber to obtain the vibration frequency, testing the rock mass of the target tunnel chamber to obtain the natural frequency, and judging whether a time-lag rockburst occurs in the target tunnel chamber at a location where a strain-type instant rockburst and / or a structural surface-type instant rockburst occurs based on the vibration frequency and the natural frequency.

[0158] Preferably, when the vibration frequency of low-frequency vibration (<40HZ) or dynamic disturbance is close to or basically consistent with the natural frequency of the rock mass of the target tunnel chamber, a time-delay rockburst will occur at the location where strain-type instant rockburst and / or structural surface-type instant rockburst has occurred.

[0159] In summary, the present invention proposes a rockburst identification method based on the properties of rock mass structural surfaces and ground stress characteristics. Starting from the essence of the rock mass's own strength and the stress state it is in, the mathematical space vector calculation is used to realize the identification of the occurrence location and potential scale of strain-type immediate rockburst and structural surface type immediate rockburst; the present invention improves the accuracy of rockburst identification through quantitative calculation, and achieves a breakthrough in the calculation of the exact location and potential scale of rockburst in tunnel caverns. At the same time, the present invention is not limited by rock types and tunnel cavern types, and can realize accurate calculation, and can continuously perform calculations during tunnel excavation, without being limited by monitoring equipment, and the method has a simple calculation formula and a wide range of applications.

[0160] The present invention is further introduced and illustrated below in conjunction with specific implementation modes.

[0161] For a specific target tunnel chamber, as described in step 100 above, the three-dimensional ground stress state of the rock mass in the borehole of the potential rock burst tunnel chamber section is measured by the stress relief method to obtain the ground stress component σ at the measuring point x , σ y , σ z , τ xy , τ yz , τ zx They are 14.21MPa, 13.31MPa, 11.07MPa, 1.99MPa, 0.62MPa, and -1.09MPa respectively; the maximum principal stress σ1, intermediate principal stress σ2, and minimum principal stress σ3 are 16.11MPa, 11.76MPa, and 10.73MPa respectively, and the corresponding principal stress azimuth and inclination angles are 52°∠13.9°, 324.6°∠10.4°, and 90.2°∠72.5° respectively. The normal vectors of the maximum principal stress, intermediate principal stress, and minimum principal stress σ1, σ2, and σ3 directions are calculated as follows:

[0162]

[0163]

[0164]

[0165] Furthermore, by measuring with a compass and a tape measure, five groups of rock formations in the potential rock burst tunnel chamber section were obtained: 299°∠86°, 312°∠82°, 96°∠82°, 279°∠73°, and 259°∠80°. The normal vectors of the rock formations of the five structural surfaces can be calculated as follows:

[0166]

[0167]

[0168]

[0169]

[0170]

[0171] Furthermore, the tensile strength of rock measured by Brazilian disc radial fracturing method is tys The uniaxial compressive strength of the rock is 7.45-9.46 MPa. The uniaxial compressive strength of the rock is 91.7-139.38 MPa as measured by the uniaxial compression test. c And simply converted into the tensile strength value σ of the rock mass structural surface ti (i=1,2,3…,i≤n) can be quickly judged to obtain the tensile strength characteristic value σ t1 ≈4.59MPa,σ t2 ≈6.97MPa,σ t3 ≈9.17MPa,σ t4 ≈13.94MPa.

[0172] Further, as described in the above step 200, the rock mass of the tunnel is in a dry state after tunnel excavation, so the identification process is executed based on the above identification parameters.

[0173] Specifically, as described in step 201 above, the rock tensile strength σ obtained by the Brazilian disc radial fracturing method is tys and σ estimated from the uniaxial compressive strength of rock t1 , σ t2 , σ t3 , σ t4 , and compared with the maximum principal stress σ1, the intermediate principal stress σ2, and the minimum principal stress σ3. t4 In addition, they are all smaller than the maximum principal stress σ1, the intermediate principal stress σ2, and the minimum principal stress σ3, which determines that strain-type immediate rockburst will occur in the tunnel chamber, and the maximum principal stress σ1, the intermediate principal stress σ2, and the minimum principal stress σ3 are substituted into the subsequent identification process for calculation.

[0174] As described in step 202 above, the ground stress component σ measured in the borehole near the rockburst tunnel chamber x , σ y , σ z , τ xy , τ yz , τ zx They are 14.21MPa, 13.31MPa, 11.07MPa, 1.99MPa, 0.62MPa, and -1.09MPa respectively. The normal stresses of the five groups of structural surfaces are calculated using Mohr stress circles, which are:

[0175] σB1 =11.15Mpa,σ B2 =11.25MPa,σ B3 =10.99MPa,σ B4 =11.66MPa,σ B5 =11.34MPa.

[0176] The normal stress on all structural surfaces is greater than the tensile strength σ tys (7.45~9.46MPa), which is also greater than σ t4 Based on the estimated tensile strength values, it is determined that all five rock formations will experience structural surface instant rock bursts.

[0177] As described in step 203 above, specifically, according to the design drawings, any cross section of the tunnel chamber is selected to determine the inclination and inclination angle ψ of 13 free-facing surfaces perpendicular to the tunnel chamber face, arch top face, arch bottom face, and arch waist side wall face. j °∠ω j °(j=1,2,3…12,13), calculate the space normal vectors corresponding to the inclination and dip angle of the 13 free-facing surfaces and the first angle γ between the maximum principal stress σ1, the intermediate principal stress σ2, and the minimum principal stress σ3 ij (where i = 1, 2, 3, j = 1, 2, 3…12, 13), the specific calculation results are as follows Fig.10 As shown in the figure, the direction of the open face of the excavated tunnel chamber and the radius of the tunnel are shown in the figure below. Fig.11 shown.

[0178] In order to ensure the accuracy of rockburst location calculation, this embodiment selects the rock tensile strength σ measured by the Brazilian disc radial fracturing method tys The minimum and maximum values ​​of 7.45MPa and 9.46MPa are used as the tensile strength calculation parameters. The maximum principal stress σ1 = 16.11MPa, the intermediate principal stress σ2 = 11.76MPa, and the minimum principal stress σ3 = 10.73MPa obtained by the stress relief method are used as stress parameters for calculating the range value of the stress circle. It can be obtained that:

[0179] according to Fig.10 The calculation results shown in the figure are as follows: the left arch waist inclination angle of 262°∠-70°~10° all meet the rock burst conditions and are controlled by the maximum principal stress σ1. Among them, the first angle between the tunnel free surface and the maximum principal stress direction when the left arch waist inclination angle is -16° and the right arch waist inclination angle is 16° is the smallest, and the direction vector is determined is the normal vector of the free surface of the rockburst cavern controlled by the maximum principal stress, σ1*cos(γ 1min)=16.11*cos(29.04°)=14.08MPa; When the inclination angle of the tunnel face is 352°∠3°, the rock burst condition is met and it is controlled by the intermediate principal stress σ2. Among them, only the first angle between the tunnel face and the intermediate principal stress direction is the smallest, and the direction vector is determined. is the normal vector of the free surface of the rockburst cavern controlled by the intermediate principal stress, σ2*cos(γ 2min )=11.76*cos(28.18°)=10.37MPa; when the inclination angle of the arch top surface is 252°∠-87°, the inclination angle of the arch bottom surface is 252°∠87°, and the inclination angle of the left arch waist is 262°∠-72.7°~50°, the rock burst conditions are met and it is controlled by the minimum principal stress σ3. When the inclination angle of the left arch waist is -72.7°, the first angle with the minimum principal stress direction is the smallest, and the direction vector is determined is the normal vector of the free surface of the rockburst cavern controlled by the intermediate principal stress, σ3*cos(γ 3min )=10.73*cos(2.46°)=10.72MPa. Therefore, rock burst will occur in the tunnel chamber from the arch to the bottom of the left arch waist and the face.

[0180] If the plane where the rockburst occurs in the tunnel chamber is not the tunnel face, it is necessary to determine the location where the rockburst occurs on the side wall of the tunnel chamber; assuming that the inclination and dip angle of the excavated tunnel face are 352°∠3° and pass through a point O1(0,0,0) in space, then its spatial normal vector is (l1, m1, n1) = (-0.138982473, -0.988910926, 0.052335955), then the plane equation and normal vector of the tunnel chamber face are: -0.138982473X-0.988910926Y+0.052335955Z = 0.

[0181] The plane normal vector due to the rock burst in the tunnel chamber The coordinates are (0.764935018,-0.597632754,0.240228038) and (0.300703988,0.001049651,0.953716944), and they are vectors from the origin to the point (0.764935018,-0.597632754,0.240228038). The distances d1 and d2 from points A1 and A2 to the plane of the tunnel face are:

[0182]

[0183] Let A'1(x k1 ',y k1 ',z k1 '), A'3(x k3 ',yk3 ',z k3 ') is point A1(x k1 ,y k1 ,z k1 )、A3(x k3 ,y k3 ,z k3 ) to the tunnel face plane, For vector (0.764935018,-0.597632754,0.240228038), (0.300703988, 0.001049651, 0.953716944) to the tunnel chamber face plane projection vector (x k1 ',y k1 ',z k1 ')、(x k3 ',y k3 ',z k3 '),but:

[0184]

[0185]

[0186] Available,

[0187] Due to the tunnel section The corresponding radius r 1、 r3 is 7.29m and 4.38m respectively, and the corresponding coordinates of the rockburst position relative to the center point of the arc on the tunnel wall are (-7.00, 2.00) and (-4.18, 1.32).

[0188] Furthermore, based on the fact that strain-type rockbursts may occur in tunnel chambers, according to the test results, due to σ tys The value is between 7.45 and 9.46 MPa, and its average value is σ1*cos(γ 1min )>σ3*cos(γ 3min )>σ2*cos(γ 2min )>σ tys , this section of the tunnel chamber will experience slight or severe rock bursts from the arch crown to the bottom of the left arch waist and the heading face.

[0189] ① Calculation of rockburst volume at tunnel face

[0190] Since the direction of the intermediate principal stress σ2 is consistent with the direction of the tunnel axis, the tensile stress on the rock mass at a certain section outside the tunnel face is equal to the tensile strength σ tys=8.18MPa, which is the preset tensile fracture position. By checking the design drawings, the tunnel chamber rock burst face area is S1 = 62.6438m 2 Since the intersection angle between the tunnel face and the tunnel diameter is a right angle, as the free face rotates, the tensile stress on the rock mass at a certain point is σ2*cos(γ)*cos(ε / 2)=σ tys ,

[0191] Due to the simplified assumption, a point at the location of the rockburst on the free face of the tunnel chamber is a bar extending along the tunnel excavation direction to the stress limit equilibrium point outside the tunnel chamber. According to Saint-Venant's principle, F1 = F2, so σ2cos(γ)S1 = σ tys S'1,

[0192] Since the tunnel chamber in this embodiment is an irregular section composed of multiple arcs, the offset command is used in CAD. When the tunnel chamber area is 79.415m 2 .

[0193] The depth of rock burst at the tunnel face is: The volume of the rockburst is:

[0194] ② Calculation of rockburst volume of straight floor of tunnel chamber

[0195] For a straight tunnel floor, since the direction of the minimum principal stress σ3 is consistent with the tunnel axis, the tensile stress on the rock mass on a certain section outside the floor is equal to the tensile strength σ tys =8.18MPa. By consulting the design drawings, the width of the tunnel chamber floor a is 9m. Taking the tunnel floor with a length b of 3m along the tunnel axis as an example, the area S1 is 27m 2 The intersection angle between the tunnel face and the tunnel chamber diameter is a right angle. As the free face rotates, the tensile stress on the rock mass at a certain point is σ3*cos(γ 3min )*cos(ε / 2)=σ tys ,

[0196] Due to the simplified assumption, a point at the location of the rockburst on the free face of the tunnel chamber is a bar extending along the tunnel excavation direction to the stress limit equilibrium point outside the tunnel chamber. According to Saint-Venant's principle, F1 = F2, so σ3cos(γ)S1 = σ tys S'1, because: but The depth of rock burst at the tunnel face is:

[0197] The volume of the rockburst is:

[0198] ④ Calculation of rockburst volume of arc-shaped tunnel chamber

[0199] According to the calculation results of the strain-type instantaneous rockburst occurrence location, rockburst will occur in the curved side walls of the tunnel chamber from the bottom of the left arch waist to the arch top, among which the rockburst on the left arch waist of the tunnel chamber is controlled by the maximum principal stress, and the rockburst on the arch top is controlled by the minimum principal stress. According to the above calculation, σ1*cos(γ 1min )=16.11*cos(29.04°)=14.08MPa、σ3*cos(γ 3min )=10.73*cos(2.46°)=10.72MPa, so it is assumed that the rock burst occurs at the free surface at B and E respectively. Through the design drawing query, it can be known that the design radius r1 of the left arch waist of the tunnel and the design radius r3 of the arch cavern are 7.29m and 4.38m respectively, and the centers are O1 and O3 respectively; it is assumed that the stress limit equilibrium points extending from the center O1 of the left arch waist surface of the tunnel cavern to the outer side of the cavern are C, D, and F along the radial direction. The tensile stresses of these three points are approximately equal to the tensile strength σ of the rock mass. tys ; Assume that the stress limit equilibrium points extending from the center of the circle O3 of the tunnel vault surface to the outer side of the tunnel are G, H, and I. The tensile stresses at these three points are equal to the tensile strength σ of the rock mass. tys ;like Fig.12 As shown. Let the distance from the center O1 to point C be l σ1 , let the distance from the center O2 to point H be l σ3 ; Let vector The first angle between the X axis and the σ1 , let the vector The first angle between the X axis and the σ3 ; Let vector and The first angle between σ1 , let the vector and The first angle between σ3 .

[0200] Simplified assumption is that a point at the location of the rockburst on the free face of the tunnel chamber extends radially to the stress limit equilibrium point on the outer side of the cavern as a rod. According to Saint-Venant's principle: the different ways in which the force acts on the rod end will only affect the range within the distance from the rod end that is not greater than the lateral dimension of the rod. Let the axial force and area of ​​points B and C at the tiny rock unit be F1, F2, A1, and A2 respectively, and let the axial force and area of ​​points H and E at the tiny rock unit be F3, F4, A3, and A4 respectively.

[0201] Therefore, for the rock burst on the left side of the tunnel chamber:

[0202]

[0203] According to Saint-Venant's principle, F1 = F2, so we can calculate

[0204] Therefore, for tunnel chamber vault rock burst According to Saint-Venant's principle, F1 = F2, so we can calculate

[0205] The rockburst location is in the second quadrant. According to the determination of the strain-type immediate rockburst location, the unit vectors of the rockburst at the left haunch of the tunnel chamber and the arch of the tunnel chamber are:

[0206]

[0207]

[0208] Due to the tunnel section The corresponding radius r 1、 r3 is 7.29m and 4.38m respectively, and the corresponding coordinates of the rockburst position relative to the center point of the arc on the tunnel wall are (-7.00, 2.00) and (-4.18, 1.32).

[0209] Then the vector The first angle with the X axis is: vector The first angle with the X axis is: vector The first angle with the X axis is: vector The first angle with the X axis is:

[0210] Then the coordinates of points D(x4,y4), F(x5,y5), G(x6,y6), and I(x7,y7) can be obtained respectively:

[0211]

[0212]

[0213]

[0214]

[0215] Since the vector The angular deviation range has exceeded the tunnel design arc with center O1 as the center and radius r1. To determine the scale of rock burst, it is necessary to calculate the stress limit equilibrium point extending from the center O1 of the left arch waist surface of the tunnel chamber along the radial direction to the outer side of the cavern.

[0216] According to the design drawings, the inclination angle from the bottom of the left arch waist of the tunnel to the center O1 is 262°∠16°, and the normal vector is The first angle γ between it and the direction of the maximum principal stress 拱腰底 =42.10°, then

[0217] With O1 as the center, Extend in the direction l 拱腰底 Length to point K, determine point K as the critical point of rock burst boundary. Suppose there is a point J on the arc with center O3 as the center and radius r3 such that σ tys =σ1cos(γ 1min )cos(γ J ),but The coordinate position of point J relative to the center O3 can be calculated as I(2.54,3.57).

[0218] According to the coordinates of the three points C, K, and J on the big circle, a big circle O1' can be drawn in the CAD drawing; according to the points G, H, and I on the small circle, a small circle O3' can be drawn in the CAD drawing; finally, the shadow area S of the overlap of the big circle O1' and the small circle O3' 合 is the rockburst area S on the cross section 合 =48.09m 2 .

[0219] According to the on-site situation, the length of the rockburst b is 10m, and the volume of the rockburst is V 岩爆 =bS 合 =480.9m 3 .

[0220] In summary, the present invention proposes a rockburst identification method based on the geostress characteristics and dynamic disturbance of the rock mass structural surface. Starting from the essence of the rock mass's own strength and the stress state it is in, the mathematical vector calculation is used to realize the identification of the location and potential scale of various rockbursts. The present invention uses quantitative calculation to make identification, with better accuracy, and achieves a breakthrough in the calculation of the accurate location and potential scale of rockbursts in tunnel chambers. At the same time, the present invention is not limited by the rock type and tunnel chamber type, and can achieve accurate calculation, and can continuously perform calculations during tunnel excavation, without being limited by monitoring equipment, and the calculation formula of this method is simple and has a wide range of applications.

[0221] On the other hand, an embodiment of the present invention further provides a rockburst identification system, the system comprising:

[0222] The acquisition module is used to obtain the identification parameters of the target tunnel chamber;

[0223] The identification module is used to execute a rockburst identification method as described in any one of the above items, perform rockburst identification on the target tunnel chamber, and obtain rockburst parameters.

[0224] In addition, an embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the computer executes any of the rockburst identification methods described above.

[0225] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A rockburst identification method, characterized in that: The method comprises: Step 100: Obtain identification parameters of the target tunnel chamber, wherein the identification parameters include rock tensile strength, rock mass tensile strength, structural surface rock formation occurrence, and first stress parameters at the measuring point; Step 200: judging the state of the rock mass of the target tunnel chamber, and when the rock mass of the target tunnel chamber is in a dry state, executing the identification process based on the identification parameters to obtain the rockburst parameters of the target tunnel chamber; otherwise, judging it as a rockburst-free area; The identification process includes: Step 201: determining that a strain-type immediate rock burst is about to occur in a target tunnel chamber based on the fact that the first stress parameter is greater than the rock tensile strength; Step 202: Calculate the structural surface normal stress according to the first stress parameter and the occurrence of the structural surface rock layer, and determine that the target tunnel chamber is about to experience a structural surface type immediate rock burst based on the fact that the structural surface normal stress is greater than the rock mass tensile strength; Step 203: Calculate the spatial normal vector of the free surface of the target tunnel chamber, obtain a first angle according to the spatial normal vector and the direction vector of the first stress parameter, determine the position of the strain-type instant rockburst according to the first angle, and determine the volume of the strain-type instant rockburst according to the first angle and a preset tensile rupture position; Step 204: Obtain a second angle based on the spatial normal vector and the normal vector of the structural surface rock formation dip, determine the position of the structural surface type immediate rock burst based on the second angle, and determine the volume of the structural surface type immediate rock burst based on the intersection relationship of the structural surface rock formation dip and a connecting line of a preset tensile fracture position.

2. A rockburst identification method according to claim 1, characterized in that: The first stress parameters include maximum principal stress, intermediate principal stress and minimum principal stress; Determine the occurrence of strain-type immediate rockburst in the target tunnel chamber, including: Compare the maximum principal stress with the rock tensile strength, and if the maximum principal stress is greater than the rock tensile strength, determine that a strain-type instantaneous rockburst occurs in the target tunnel chamber, and substitute the maximum principal stress into the subsequent identification process; Compare the intermediate principal stress with the rock tensile strength, and if the intermediate principal stress is greater than the rock tensile strength, determine that a strain-type instantaneous rock burst occurs in the target tunnel chamber, and substitute the intermediate principal stress into the subsequent identification process; Compare the minimum principal stress with the rock tensile strength, and if the minimum principal stress is greater than the rock tensile strength, determine that a strain-type instantaneous rockburst occurs in the target tunnel chamber, and substitute the minimum principal stress into the subsequent identification process; Among them, the maximum principal stress is greater than the intermediate principal stress, and the intermediate principal stress is greater than the minimum principal stress; when the maximum principal stress, the intermediate principal stress and the minimum principal stress are all less than the tensile strength of the rock, it is determined that strain-type immediate rock burst does not occur.

3. A rockburst identification method according to claim 2, characterized in that: The open surfaces of the target tunnel chamber include the heading face, arch top face, arch bottom face and arch waist side wall face.

4. A rockburst identification method according to claim 3, characterized in that: Determining the position of the strain-type instantaneous rockburst according to the first angle includes: when the first angle is greater than When the first angle is less than or equal to When , the spatial normal vector corresponding to the minimum value of the first angle is selected as the normal vector of the rockburst position, and the position where the rockburst occurs is calculated according to the normal vector of the rockburst position; wherein, σ tys is the rock tensile strength, σ i is the first stress parameter, i is equal to 1 / 2 / 3, σ1 represents the maximum principal stress, σ2 represents the intermediate principal stress, and σ3 represents the minimum principal stress.

5. A rockburst identification method according to claim 3, characterized in that: Determining the location of the structural surface type instant rockburst according to the second angle includes: When the second angle is greater than When the instantaneous rockburst of the structural surface type occurs at the intersection angle of the side walls of the target tunnel chamber, the second angle is less than or equal to , the spatial normal vector corresponding to the second angle is used as the normal vector of the rockburst position, and the location where the rockburst occurs is calculated according to the normal vector of the rockburst position; wherein, σ tys is the rock tensile strength, σ i is the first stress parameter, i is equal to 1 / 2 / 3, σ1 represents the maximum principal stress, σ2 represents the intermediate principal stress, and σ3 represents the minimum principal stress.

6. A rockburst identification method according to claim 2, characterized in that: The method further includes performing time-lag rockburst identification on the target tunnel chamber, wherein the time-lag rockburst identification includes: By monitoring the ground stress of the target tunnel chamber, the newly added maximum principal stress, newly added intermediate principal stress and newly added minimum principal stress after time t are obtained; The newly added maximum principal stress, the newly added intermediate principal stress, the newly added minimum principal stress and the first stress parameter decomposition are summed in the X, Y and Z axis directions to obtain the sum stress in the X, Y and Z axis directions; A second stress parameter is generated according to the magnitude of the sum of the stresses in the X, Y, and Z axis directions, and the second stress parameter is substituted into the identification process to obtain the rockburst parameter after time t, and determine the occurrence of a time-delayed rockburst.

7. A rockburst identification method according to claim 6, characterized in that: The time-lag rockburst identification also includes: monitoring the dynamic disturbance of the target tunnel chamber to obtain the vibration frequency, testing the rock mass of the target tunnel chamber to obtain the natural frequency, and judging whether a time-lag rockburst occurs in the target tunnel chamber at a location where a strain-type instant rockburst and / or a structural surface-type instant rockburst occurs based on the vibration frequency and the natural frequency.

8. A rockburst identification method according to claim 1, characterized in that: The structural surface rock formation occurrence includes n groups of structural surfaces; Determining the volume of the structural surface type instant rock burst includes: selecting a structural surface with an extension length greater than or equal to 1 m in the structural surface rock stratum dip as a dominant structural surface, and connecting a line based on the intersection relationship of the dominant structural surface rock stratum dip and a preset tensile fracture position; wherein n is a positive integer, and for the dominant structural surface, n is less than or equal to 3.

9. A rockburst identification system, characterized in that: The system comprises: The acquisition module is used to obtain the identification parameters of the target tunnel chamber; The identification module is used to execute a rockburst identification method as described in any one of claims 1 to 8, perform rockburst identification on a target tunnel chamber, and obtain rockburst parameters.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the computer is caused to perform the method according to any one of claims 1 to 8.

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