Method and system for determining main direction of rupture of hidden fault based on microseismic monitoring

Abstract

The application provides a method and system for determining the main rupture direction of a blind fault based on microseismic monitoring, wherein the method comprises the following steps: determining the three-dimensional positions of each microseismic point corresponding to microseismic activity based on microseismic signals, wherein the microseismic signals are obtained by monitoring the microseismic activity induced by the activation of the blind fault by a microseismic monitoring device; performing microseismic moment tensor inversion based on the three-dimensional positions of each microseismic point and the microseismic signals to obtain the focal mechanism of each microseismic point; determining the direction vector of the rupture surface corresponding to each microseismic point based on the focal mechanism of each microseismic point, and determining the main rupture direction of the blind fault based on the direction vector of the rupture surface corresponding to each microseismic point, thereby overcoming the defects of the traditional scheme, such as the difficulty and inconvenience in determining the main rupture direction of the blind fault, and realizing the rapid and convenient exploration of the main rupture direction of the blind fault. In addition, the internal blind fault activity of the rock mass is monitored in real time by using a non-destructive monitoring method, thereby avoiding the problems of difficult construction and high cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rock-soil mechanics, and in particular to a method and system for determining a main rupture direction of a concealed fault based on microseismic monitoring. BACKGROUND

[0002] Rock mass is a geological body with discontinuity, heterogeneity and anisotropy, which is composed of various rocks containing weak structural planes within a certain engineering range. In the long geological evolution process, a large number of concealed structural planes and concealed faults are present, which not only form the inflow path of underground water, but also may be activated, which undoubtedly brings great safety hazards to rock mass engineering construction.

[0003] At present, the method for exploring the main rupture direction of a concealed fault is mainly engineering geological investigation. However, the concealed fault is often deeply buried in rock mass and is not easy to find. Therefore, the method of engineering geology needs to consume a large amount of funds and is extremely difficult to construct under some conditions. Therefore, how to quickly and conveniently explore the main rupture direction of the concealed fault in the rock mass to ensure the safety of rock mass engineering construction has become a problem to be solved at present. SUMMARY

[0004] The present application provides a method and system for determining a main rupture direction of a concealed fault based on microseismic monitoring, which overcomes the defects that the determination of the main rupture direction of the concealed fault is very inconvenient, a large amount of funds are consumed and the construction is extremely difficult in the prior art, realizes the quick and accurate exploration of the main rupture direction of the concealed fault, and avoids the problems of difficult construction and large consumption through non-destructive monitoring means.

[0005] The present application provides a method for determining a main rupture direction of a concealed fault based on microseismic monitoring, characterized in that it comprises:

[0006] Obtaining a microseismic signal, wherein the microseismic signal is obtained by monitoring microseismic activity induced by activation of the concealed fault by a microseismic monitoring device;

[0007] Based on the microseismic signal, determining three-dimensional positions of each microseismic point corresponding to the microseismic activity, and based on the three-dimensional positions of each microseismic point and the microseismic signal, performing microseismic moment tensor inversion to obtain a focal mechanism of each microseismic point;

[0008] Based on the focal mechanism of each microseismic point, determining a direction vector of a rupture surface corresponding to each microseismic point, and based on the direction vector of the rupture surface corresponding to each microseismic point, determining a main rupture direction of the concealed fault.

[0009] According to the method for determining a main rupture direction of a concealed fault based on microseismic monitoring provided by the present application, the main rupture direction of the concealed fault is determined based on the direction vector of the rupture surface corresponding to each microseismic point, which comprises:

[0010] constructing a three-dimensional rose diagram based on the honeycomb sphere;

[0011] dividing the core of the three-dimensional rose diagram into a plurality of facets, and placing the direction vector of the rupture surface corresponding to each microseismic point at the core of the core of the three-dimensional rose diagram;

[0012] counting the number of direction vectors on each facet on the core, and determining the main rupture direction of the blind fault based on the number of direction vectors on each facet.

[0013] According to the method for determining the main rupture direction of a blind fault based on microseismic monitoring provided by the application, each facet on the core is extruded outward along the outward direction of the core based on the number of direction vectors on the corresponding facet;

[0014] The determination of the main rupture direction of the blind fault based on the number of direction vectors on each facet comprises:

[0015] determining the maximum extrusion facet from each facet based on the number of direction vectors on each facet;

[0016] determining the main rupture direction of the blind fault based on the extrusion direction corresponding to the maximum extrusion facet.

[0017] According to the method for determining the main rupture direction of a blind fault based on microseismic monitoring provided by the application, the determination of the direction vector of the rupture surface corresponding to each microseismic point based on the focal mechanism of each microseismic point comprises:

[0018] determining the source moment tensor of each microseismic point based on the focal mechanism of each microseismic point;

[0019] decomposing each source moment tensor, and determining the eigenvalue of each source moment tensor and the characteristic direction corresponding to the eigenvalue based on each component of each source moment tensor obtained by decomposition;

[0020] determining the direction vector of the rupture surface corresponding to each microseismic point based on the eigenvalue of each source moment tensor and the characteristic direction corresponding to the eigenvalue.

[0021] According to the method for determining the main rupture direction of a blind fault based on microseismic monitoring provided by the application, the three-dimensional position of a microseismic point is an initial position solved by a least square method, and is obtained by iteration through the following formula:

[0022] AΔθ=B

[0023]

[0024] Wherein, x, y and z represent three-dimensional positions of the microseismic point, t represents a time when the microseismic activity occurs, Δx, Δy, Δz and Δt respectively represent increments of x, y, z and t, N represents a number of microseismic monitoring devices triggered by the microseismic signal, t N represents a p-wave arrival time on the Nth microseismic monitoring device, oN and t cN respectively represent an observed arrival time and a theoretical arrival time of the p-wave propagating from the microseismic point to the Nth microseismic monitoring device, Δθ represents a correction vector of the three-dimensional position θ solved by the least square method, Δθ=(A T A) -1 A T B, wherein T represents a matrix transpose, -1 represents a matrix inversion.

[0025] According to the method for determining a main direction of a hidden fault rupture based on microseismic monitoring provided in the application, the process of obtaining a focal mechanism of a microseismic point through microseismic moment tensor inversion can be represented by the following formula:

[0026]

[0027] Wherein, N represents a number of microseismic monitoring devices triggered by the microseismic signal, represents a displacement in the m direction generated at the Nth microseismic monitoring device under the action of a unit force in the k direction at the microseismic point, M represents a source moment tensor of the microseismic point, M ij is a component of M, u N represents a p-wave far-field displacement at the Nth microseismic monitoring device.

[0028] According to the method for determining a main direction of a hidden fault rupture based on microseismic monitoring provided in the application, a direction vector of a rupture surface corresponding to the microseismic point is determined based on the following formula:

[0029]

[0030] Wherein, l and n represent two direction vectors of a rupture surface corresponding to the microseismic point, M1, M2 and M3 are respectively three eigenvalues of the source moment tensor of the microseismic point, and M1>M2>M3, e1 and e3 are respectively three eigenvectors corresponding to M1 and M3, and e1 and e3 respectively represent eigen-directions corresponding to M1 and M3.

[0031] The application further provides a system for determining a main direction of a hidden fault rupture based on microseismic monitoring, comprising:

[0032] A signal acquisition unit is configured to acquire a microseismic signal, wherein the microseismic signal is obtained by monitoring microseismic activity induced by activation of a hidden fault through a microseismic monitoring device;

[0033] A moment tensor inversion unit is configured to determine three-dimensional positions of each microseismic point corresponding to the microseismic activity based on the microseismic signals, and perform microseismic moment tensor inversion based on the three-dimensional positions of each microseismic point and the microseismic signals to obtain a focal mechanism of each microseismic point.

[0034] A direction determination unit is configured to determine a direction vector of a rupture surface corresponding to each microseismic point based on the focal mechanism of each microseismic point, and determine a main rupture direction of the blind fault based on the direction vector of the rupture surface corresponding to each microseismic point.

[0035] The present application also provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for determining a main rupture direction of a blind fault based on microseismic monitoring according to any one of the above embodiments when executing the program.

[0036] The present application also provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program is executable on a processor to implement the method for determining a main rupture direction of a blind fault based on microseismic monitoring according to any one of the above embodiments.

[0037] The present application provides a method and system for determining a main rupture direction of a blind fault based on microseismic monitoring, which determines three-dimensional positions of each microseismic point corresponding to microseismic activity based on microseismic signals, and performs microseismic moment tensor inversion based on the three-dimensional positions of each microseismic point and the microseismic signals to obtain a focal mechanism of each microseismic point. The method and system overcome the difficulty and inconvenience of determining a main rupture direction of a blind fault in the prior art, and realize a quick and convenient determination of a main rupture direction of a blind fault, thereby providing data support for the safe construction of rock mass engineering. In addition, the method and system use non-destructive monitoring means to monitor the activity of a blind fault in a rock mass in real time, thereby avoiding the problems of difficult construction and high cost. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0039] Figure 1 is a flowchart of the method for determining a main rupture direction of a blind fault based on microseismic monitoring provided by the present application;

[0040] Figure 2 is the statistical analysis diagram of the direction vector of the rupture surface corresponding to the microseismic point in the three-dimensional rose diagram provided by the application;

[0041] Figure 3 is a structural schematic diagram of a system for determining a main rupture direction of a blind fault based on microseismic monitoring provided by the application;

[0042] Figure 4 is a structural schematic diagram of an electronic device provided by the application. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions in the present application will be described below in connection with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0044] Due to the hidden structural surface and the blind fault in the rock mass, not only the inflow path of underground water is formed, but also the activation is likely to occur, thereby threatening the safety of the rock mass engineering construction. Therefore, the activity of the fault in the rock mass needs to be monitored in real time, so as to quickly determine the main rupture direction of the blind fault in the rock mass, and thereby ensure the safety of the rock mass engineering construction.

[0045] However, the current method for determining the main rupture direction of the blind fault is mainly engineering geological investigation. However, the blind fault is often buried in the rock mass and is not easy to find. The method of engineering geological investigation needs to invest a large amount of funds, and in some conditions, the construction is extremely difficult. In short, the determination of the main rupture direction of the blind fault is difficult at present, and the process is inconvenient.

[0046] Further, due to the symmetry of the elastic wave radiation of the double coupling mechanism, it is often difficult to determine the real fault surface from the two sections of the focal mechanism solution. Therefore, the present application provides a method for determining the main rupture direction of a blind fault based on microseismic monitoring, which aims to use non-destructive monitoring means to monitor the activity of the blind fault in the rock mass in real time, avoids the problems of difficult construction and huge cost, and can quickly and accurately determine the main rupture direction of the blind fault, thereby ensuring the safety of the rock mass engineering construction. Figure 1 is a flowchart of the method for determining the main rupture direction of a blind fault based on microseismic monitoring provided by the application, as shown in Figure 1 The method comprises the following steps:

[0047] In step 110, a microseismic signal is obtained, which is obtained by monitoring the microseismic activity induced by the activation of the blind fault by a microseismic monitoring device;

[0048] In step 120, based on the microseismic signal, the three-dimensional positions of each microseismic point corresponding to the microseismic activity are determined, and based on the three-dimensional positions of each microseismic point and the microseismic signal, a microseismic moment tensor inversion is performed to obtain the focal mechanism of each microseismic point.

[0049] In step 130, based on the focal mechanism of each microseismic point, the direction vector of the rupture surface corresponding to each microseismic point is determined, and based on the direction vector of the rupture surface corresponding to each microseismic point, the main rupture direction of the blind fault is determined.

[0050] Specifically, before determining the main rupture direction of the blind fault, the microseismic signal needs to be obtained first, i.e., the microseismic signal released by the activity of the blind fault inside the rock mass is obtained, which can be monitored based on the microseismic monitoring equipment. Specifically, the microseismic monitoring equipment can be installed near the blind fault to monitor the microseismic activity induced by the activation of the blind fault in real time, thereby obtaining the microseismic signal. The microseismic monitoring equipment here can be a microseismic monitor, a microseismic monitoring system, a microseismic sensor, etc.

[0051] Here, the microseismic monitoring equipment can be used to realize non-destructive monitoring of the activity of the blind fault inside the rock mass, which well avoids the problem of huge capital demand and difficult construction in the traditional scheme due to the limitation of the geographical location and environmental conditions of the blind fault, and realizes convenient, real-time and non-destructive microseismic activity monitoring.

[0052] Then, the microseismic signal can be used to determine the focal position corresponding to the microseismic activity. It can be understood that the focal position here is the three-dimensional position of the microseismic point, i.e., the three-dimensional positions of each microseismic point corresponding to the microseismic activity can be located based on the microseismic signal. Specifically, each microseismic point corresponding to the microseismic activity can be located based on the microseismic activity monitored by the microseismic monitoring equipment, thereby obtaining the three-dimensional positions of each microseismic point.

[0053] Here, the positioning of each microseismic point corresponding to the microseismic activity can be realized by using relevant positioning algorithms, such as the Gage algorithm, the least squares method, the p-wave arrival time algorithm, etc. As a preferred embodiment, in order to more accurately locate each microseismic point and obtain high-precision three-dimensional positions, in the present embodiment, the Gage algorithm can be used to locate the three-dimensional positions of each microseismic point corresponding to the microseismic activity based on the microseismic signal.

[0054] Then, the focal mechanism of each microseismic point can be obtained by using the moment tensor inversion method based on the three-dimensional positions of each microseismic point and the microseismic signal, i.e., the focal mechanism of each microseismic point can be inverted by using the moment tensor inversion technology based on the three-dimensional positions of each microseismic point and the microseismic signal. Specifically, the microseismic moment tensor inversion can be performed based on the three-dimensional positions of each microseismic point and the microseismic signal, and the focal mechanism of each microseismic point can be obtained by using the standard form of the microseismic moment tensor inversion.

[0055] Then, the direction vector of the rupture surface corresponding to each microseismic point can be determined according to the focal mechanism of each microseismic point, that is, the occurrence of the secondary rupture surface can be inverted by the focal mechanism of each microseismic point, and specifically, the rupture direction of each microseismic point, that is, the direction vector of the rupture surface corresponding to each microseismic point, can be determined by using the eigenvalue and eigen direction reflected by the focal mechanism of each microseismic point.

[0056] In addition, the rupture mechanism of each microseismic point near the blind fault is affected by the activity of the blind fault, so the rupture direction of each microseismic point should be similar to the main rupture direction of the blind fault. Therefore, after determining the direction vector of the rupture surface corresponding to each microseismic point, the main rupture direction of the blind fault can be determined according to the direction vector of the rupture surface, and specifically, the main rupture direction of the blind fault can be obtained by statistically analyzing the rupture direction of each microseismic point and analyzing the direction vector in each direction.

[0057] The method for determining the main rupture direction of the blind fault based on microseismic monitoring provided by the present application determines the three-dimensional position of each microseismic point corresponding to the microseismic activity by microseismic signals, which are obtained by monitoring the microseismic activity induced by the activation of the blind fault by a microseismic monitoring device; based on the three-dimensional position of each microseismic point and the microseismic signals, the microseismic moment tensor inversion is performed to obtain the focal mechanism of each microseismic point; based on the focal mechanism of each microseismic point, the direction vector of the rupture surface corresponding to each microseismic point is determined, and based on the direction vector of the rupture surface corresponding to each microseismic point, the main rupture direction of the blind fault is determined, which overcomes the difficulty and inconvenience of determining the main rupture direction of the blind fault in the traditional scheme, realizes the rapid and convenient exploration of the main rupture direction of the blind fault, and provides data support for the safe construction of rock mass engineering; in addition, the activity of the blind fault inside the rock mass is monitored in real time by using non-destructive monitoring means, which avoids the problems of difficult construction and high cost.

[0058] Based on the above embodiment, the main rupture direction of the blind fault is determined based on the direction vector of the rupture surface corresponding to each microseismic point, which includes:

[0059] A three-dimensional rose diagram is constructed based on the honeycomb sphere;

[0060] The core of the three-dimensional rose diagram is divided into a plurality of patches, and the direction vector of the rupture surface corresponding to each microseismic point is placed at the center of the core of the three-dimensional rose diagram;

[0061] The number of direction vectors on each patch on the core is counted, and the main rupture direction of the blind fault is determined based on the number of direction vectors on each patch.

[0062] Specifically, the process of determining the main rupture direction of the blind fault according to the direction vectors of the rupture surfaces corresponding to the microseismic points can be realized by means of a three-dimensional rose diagram, that is, a three-dimensional rose diagram can be established first, and then the rupture directions of the microseismic points are statistically analyzed by means of the three-dimensional rose diagram, so as to determine the main rupture direction of the blind fault according to the direction vectors on each surface patch in the three-dimensional rose diagram, and the specific process includes the following steps:

[0063] Firstly, a three-dimensional rose diagram can be established, and in order to facilitate the statistical analysis of the direction vectors of the rupture surfaces corresponding to the microseismic points, the three-dimensional rose diagram here can be a honeycomb shape that can cover multiple different directions, and since the core of the three-dimensional rose diagram is spherical, the three-dimensional rose diagram can be constructed by a honeycomb-shaped sphere.

[0064] Then, the spherical core of the three-dimensional rose diagram can be divided into surface patches, and specifically, since the uniformity and rationality of the surface patch division will affect the statistical analysis process and results, in the embodiment of the present application, when the spherical core of the three-dimensional rose diagram is decomposed, a hexagonal grid with good uniformity can be used to cover the spherical core, and after covering, the grid lines of the spherical core are in a honeycomb shape, and the natural degree is higher.

[0065] Here, for the spherical core with a honeycomb-shaped grid structure, the three-dimensional rose diagram can be represented in different resolutions according to the number of surface patches thereon.

[0066] Subsequently, the rupture direction of each microseismic point can be placed at the center of the spherical core of the three-dimensional rose diagram, that is, the direction vector of the rupture surface to be analyzed can be placed at the center of the three-dimensional rose diagram, so as to be analyzed by means of the three-dimensional rose diagram, so as to obtain the dominant direction on the three-dimensional rose diagram, and then the main rupture direction of the blind fault can be determined.

[0067] After that, the direction vectors on each surface patch of the spherical core of the three-dimensional rose diagram can be counted to obtain the number of direction vectors on each surface patch, and specifically, the intersection of the direction vector placed at the center of the spherical core with each surface patch can be determined, and if the direction vector intersects with the surface patch, the direction vector is the direction vector on the corresponding surface patch, and the number of direction vectors on each surface patch is counted.

[0068] Finally, the main rupture direction of the blind fault can be determined according to the number of direction vectors on each surface patch, that is, the dominant direction on the three-dimensional rose diagram can be determined by referring to the number of direction vectors on each surface patch of the spherical core, so as to obtain the main rupture direction of the blind fault, for example, the surface patch with the largest number of direction vectors can be determined, and the main rupture direction of the blind fault can be determined according to the extrusion direction of the surface patch along the center of the three-dimensional rose diagram.

[0069] Based on the above embodiment, each face sheet on the core of the sphere is extruded outward along the outward direction of the sphere center based on the number of direction vectors on the corresponding face sheet;

[0070] Based on the number of direction vectors on each face sheet, the main rupture direction of the blind fault is determined, comprising:

[0071] Based on the number of direction vectors on each face sheet, the maximum extrusion face sheet is determined from each face sheet;

[0072] Based on the extrusion direction corresponding to the maximum extrusion face sheet, the main rupture direction of the blind fault is determined.

[0073] Specifically, the process of determining the main rupture direction of the blind fault according to the number of direction vectors on each face sheet comprises the following steps:

[0074] Figure 2 The statistical analysis diagram of the direction vector of the rupture surface corresponding to the microseismic point in the three-dimensional rose diagram provided by the application is shown in FIG. 1. Figure 2 As shown in FIG. 1, each face sheet on the core of the three-dimensional rose diagram is extruded outward along the outward direction of the sphere center according to the number of direction vectors thereon, so that the maximum extrusion face sheet can be determined from each face sheet by the number of direction vectors on each face sheet, and the maximum extrusion face sheet is the face sheet with the largest extrusion degree in each face sheet.

[0075] Here, each face sheet is extruded outward along the outward direction of the sphere center according to the number of direction vectors thereon, which can also be understood as each face sheet is extruded outward according to the number of direction vectors intersecting therewith, and specifically, the more the number of direction vectors thereon, the larger the extrusion degree of the corresponding face sheet; otherwise, the extrusion degree of the corresponding face sheet is smaller.

[0076] Then, the main rupture direction of the blind fault can be determined according to the extrusion direction corresponding to the maximum extrusion face sheet, that is, the extrusion direction when the maximum extrusion face sheet is extruded outward along the outward direction of the sphere center, which is the dominant direction on the three-dimensional rose diagram, and can also be called the dominant direction of the fracture network or rock mass rupture, so that the main rupture direction of the blind fault can be determined.

[0077] Based on the above embodiment, the direction vector of the rupture surface corresponding to each microseismic point is determined based on the focal mechanism of each microseismic point, comprising:

[0078] The focal moment tensor of each microseismic point is determined based on the focal mechanism of each microseismic point;

[0079] Each focal moment tensor is decomposed, and based on each component of each focal moment tensor obtained by decomposition, the eigenvalue of each focal moment tensor and the characteristic direction corresponding to the eigenvalue are determined;

[0080] Based on the eigenvalue of each source moment tensor and the characteristic direction corresponding to the eigenvalue, the direction vector of the rupture surface corresponding to each microseismic point is determined.

[0081] Specifically, the process of determining the direction vector of the rupture surface corresponding to each microseismic point according to the focal mechanism of each microseismic point can specifically include:

[0082] Firstly, the source moment tensor of each microseismic point can be determined through the focal mechanism of each microseismic point, that is, the standard form in the process of determining the focal mechanism of each microseismic point can be inverted by using the moment tensor inversion technology to solve the source moment tensor of each microseismic point.

[0083] Then, the source moment tensor of each microseismic point can be decomposed to decompose the source moment tensor of each microseismic point into different components, such as isotropic (ISO) component, double couple (DC) component, compensated linear vector dipole (CLVD) component, etc., so as to obtain each component corresponding to the source moment tensor of each microseismic point, and the eigenvalue of the corresponding source moment tensor and the characteristic direction corresponding to the eigenvalue can be determined according to each component. Here, the characteristic direction can be the maximum couple direction represented by the eigenvector corresponding to the eigenvalue.

[0084] After that, the rupture direction of each microseismic point can be determined according to the eigenvalue of each source moment tensor and the characteristic direction corresponding to the eigenvalue, that is, the rupture direction of the source rupture surface is solved on the basis of the eigenvalue of each source moment tensor in combination with the characteristic direction corresponding to the eigenvalue, so as to obtain the direction vector of the rupture surface corresponding to each microseismic point.

[0085] Based on the above embodiment, the three-dimensional position of the microseismic point is the three-dimensional position solved by the least square method as the initial position, which is obtained by iteration through the formula, and the specific process includes:

[0086] Wherein, the relationship between the three-dimensional position (x i , y i , z i , t i ) of the microseismic monitoring device and the three-dimensional position (x, y, z, t) of the microseismic point can be represented by the following formula:

[0087] [(x i -x) 2 +(y i -y) 2 +(z i -z) 2 ] 1 / 2 =v p (t i -t)

[0088] where i represents the i-th microseismic monitoring device triggered by the microseismic signal, x i , y i and z i are the horizontal coordinate, vertical coordinate and vertical coordinate of the i-th microseismic monitoring device respectively, t i represents the p-wave arrival time on the sensor of the i-th microseismic monitoring device, x, y and z are the horizontal coordinate, vertical coordinate and vertical coordinate of the microseismic point respectively, t represents the time when the microseismic activity occurs, and v p is the wave velocity of the p-wave.

[0089] The above formula can be linearized by using Taylor formula to obtain the following formula:

[0090]

[0091]

[0092] where t oi and t ci respectively represent the observed arrival time and the theoretical arrival time of the p-wave propagating from the microseismic point to the i-th microseismic monitoring device, Δx, Δy, Δz and Δt are the increments of x, y, z and t respectively, and R represents the distance between the microseismic monitoring device and the microseismic point.

[0093] At this time, the N microseismic monitoring devices triggered by the microseismic signal are solved simultaneously, and the above formula can be rewritten to obtain the following formula:

[0094] AΔθ=B

[0095]

[0096] where N represents the number of microseismic monitoring devices triggered by the microseismic signal, t N represents the p-wave arrival time on the N-th microseismic monitoring device, t oN and t cN respectively represent the observed arrival time and the theoretical arrival time of the p-wave propagating from the microseismic point to the N-th microseismic monitoring device.

[0097] At this time, the three-dimensional position of the microseismic point Δθ can be solved by the least square method:

[0098] Δθ=(A T A) -1 A T B

[0099] where T represents the matrix transpose, and -1 represents the matrix inversion.

[0100] Here, the three-dimensional position solved by the least square method is taken as the initial position / iteration initial value, the above formula is repeated for iteration, and the three-dimensional position of the microseismic point is changed to θ=θ+Δθ, until the convergence condition is met, that is, Δθ is less than a preset threshold, and the three-dimensional position θ obtained at this time is the three-dimensional position of the microseismic point.

[0101] Based on the above embodiment, the process of obtaining the focal mechanism of the microseismic point by microseismic moment tensor inversion can specifically include:

[0102] If the microseismic signal triggers N microseismic monitoring devices at the same time, the standard form of microseismic moment tensor inversion can be represented as GM=u, wherein u is the p-wave far-field displacement at the microseismic monitoring device, which can be equivalent to the p-wave initial motion amplitude of the received signal of each microseismic monitoring device, and is an N*1 vector. The standard form can be expanded as:

[0103]

[0104] In the formula, represents the displacement along the m direction generated by the Nth microseismic monitoring device under the action of the unit force along the k direction at the microseismic point, M represents the source moment tensor of the microseismic point, and M ij is a component of M, u N represents the p-wave far-field displacement at the Nth microseismic monitoring device.

[0105] Based on the above embodiment, the process of determining the direction vector of the rupture surface corresponding to the microseismic point can specifically include:

[0106] The source moment tensor is decomposed into isotropic component, double force couple component and compensated linear vector doublet component, as shown in the following formula:

[0107]

[0108] In the formula, M 11 , M 12 , M 13 , M 21 , M 22 , M 23 , M 31 , M 32 and M 33 are nine components of the source moment tensor M pq , and M 12 and M 21 , M 32 and M 23 , and M 31 and M 13 are symmetric tensors, and two tensors symmetric to each other are equal.

[0109] M1, M2 and M3 are the source moment tensor Mpq three eigenvalues of M1, M2 and M3 respectively, and M1>M2>M3, e1, e2 and e3 are three eigenvectors corresponding to M1, M2 and M3 respectively, and e1, e2 and e3 represent the maximum couple direction of M1, M2 and M3 respectively, i.e. the characteristic direction.

[0110] At this time, the direction vector of the rupture surface corresponding to the microseismic point has two possibilities, which are represented as n and l respectively, and can be calculated by the following formula:

[0111]

[0112] In the formula, l and n represent two direction vectors of the rupture surface corresponding to the microseismic point.

[0113] The system for determining the main rupture direction of a blind fault based on microseismic monitoring provided by the present application is described below, and the system for determining the main rupture direction of a blind fault based on microseismic monitoring described below can be correspondingly referred to the method for determining the main rupture direction of a blind fault based on microseismic monitoring described above.

[0114] Figure 3 is a structural schematic diagram of the system for determining the main rupture direction of a blind fault based on microseismic monitoring, as shown in Figure 3 The system comprises:

[0115] A signal acquisition unit 310 is configured to acquire a microseismic signal, wherein the microseismic signal is obtained by monitoring microseismic activity induced by activation of a blind fault by a microseismic monitoring device.

[0116] A moment tensor inversion unit 320 is configured to determine three-dimensional positions of each microseismic point corresponding to the microseismic activity based on the microseismic signal, and perform microseismic moment tensor inversion based on the three-dimensional positions of each microseismic point and the microseismic signal to obtain a focal mechanism of each microseismic point.

[0117] A direction determination unit 330 is configured to determine direction vectors of a rupture surface corresponding to each microseismic point based on the focal mechanism of each microseismic point, and determine the main rupture direction of the blind fault based on the direction vectors of the rupture surface corresponding to each microseismic point.

[0118] The application provides a system for determining a main rupture direction of a blind fault based on microseismic monitoring, which determines three-dimensional positions of each microseismic point corresponding to microseismic activity by microseismic signals, wherein the microseismic signals are obtained by monitoring microseismic activity induced by activation of the blind fault by microseismic monitoring equipment; based on the three-dimensional positions of each microseismic point and the microseismic signals, microseismic moment tensor inversion is performed to obtain a focal mechanism of each microseismic point; based on the focal mechanism of each microseismic point, a direction vector of a rupture surface corresponding to each microseismic point is determined, and based on the direction vector of the rupture surface corresponding to each microseismic point, the main rupture direction of the blind fault is determined, thus overcoming the difficulty and inconvenience of determining the main rupture direction of the blind fault in the prior art, achieving rapid and convenient exploration of the main rupture direction of the blind fault, and providing data support for safe construction of rock mass engineering; in addition, real-time monitoring of the activity of the blind fault in the rock mass is achieved by using a non-destructive monitoring method, thus avoiding the problems of difficult construction and high cost.

[0119] Based on the above embodiment, the direction determination unit 330 is configured to:

[0120] construct a three-dimensional rose diagram based on the honeycomb sphere;

[0121] divide a spherical core of the three-dimensional rose diagram into a plurality of surface patches, and place the direction vector of the rupture surface corresponding to each microseismic point at a spherical center of the spherical core of the three-dimensional rose diagram;

[0122] count the number of direction vectors on each surface patch on the spherical core, and determine the main rupture direction of the blind fault based on the number of direction vectors on each surface patch.

[0123] Based on the above embodiment, each surface patch on the spherical core is extruded outward along the outward direction of the spherical center based on the number of direction vectors on the corresponding surface patch;

[0124] The direction determination unit 330 is configured to:

[0125] determine a maximum extrusion surface patch from the plurality of surface patches based on the number of direction vectors on each surface patch;

[0126] determine the main rupture direction of the blind fault based on an extrusion direction corresponding to the maximum extrusion surface patch.

[0127] Based on the above embodiment, the direction determination unit 330 is configured to:

[0128] determine a focal moment tensor of each microseismic point based on the focal mechanism of each microseismic point;

[0129] decompose each focal moment tensor, and determine eigenvalues of each focal moment tensor and characteristic directions corresponding to the eigenvalues based on each component of each focal moment tensor obtained by the decomposition;

[0130] Determine the direction vector of the rupture surface corresponding to each microseismic point based on the eigenvalue of each source moment tensor and the characteristic direction corresponding to the eigenvalue.

[0131] Based on the above embodiment, the three-dimensional position of the microseismic point is taken as the initial position by solving the three-dimensional position by the least square method, and is obtained by iteration through the following formula:

[0132] AΔθ=B

[0133]

[0134] Wherein, x, y and z represent the three-dimensional position of the microseismic point, t represents the time when the microseismic activity occurs, Δx, Δy, Δz and Δt represent the increments of x, y, z and t respectively, N represents the number of microseismic monitoring devices triggered by the microseismic signal, t N represents the p-wave arrival time on the Nth microseismic monitoring device, t oN and t cN respectively represent the observed and theoretical arrival times of the p-wave propagating from the microseismic point to the Nth microseismic monitoring device, Δθ represents the correction vector of the three-dimensional position θ solved by the least square method, Δθ=(A T A) -1 A T B, wherein T represents the matrix transpose, -1 represents the matrix inversion.

[0135] Based on the above embodiment, the process of obtaining the source mechanism of the microseismic point by microseismic moment tensor inversion can be represented by the following formula:

[0136]

[0137] Wherein, N represents the number of microseismic monitoring devices triggered by the microseismic signal, represents the displacement along the m direction generated at the Nth microseismic monitoring device under the action of the unit force along the k direction at the microseismic point, M represents the source moment tensor of the microseismic point, M ij is the component of M, u N represents the p-wave far-field displacement at the Nth microseismic monitoring device.

[0138] Based on the above embodiment, the direction vector of the rupture surface corresponding to the microseismic point is determined based on the following formula:

[0139]

[0140] Wherein, l and n represent two direction vectors of the rupture surface corresponding to the microseismic point, M1, M2 and M3 are respectively three eigenvalues of the source moment tensor of the microseismic point, and M1>M2>M3, e1 and e3 are respectively three eigenvectors corresponding to M1 and M3, and e1 and e3 represent respectively the characteristic direction corresponding to M1 and M3.

[0141] Figure 4 An example of a schematic diagram of a physical structure of an electronic device is shown in Figure 4 The electronic device can include a processor 410, a communications interface 420, a memory 430, and a communications bus 440, wherein the processor 410, the communications interface 420, and the memory 430 communicate with each other through the communications bus 440. The processor 410 can invoke a logical instruction in the memory 430 to execute a method for determining a main rupture direction of a blind fault based on microseismic monitoring, which includes: obtaining a microseismic signal, the microseismic signal being obtained by a microseismic monitoring device monitoring microseismic activity induced by activation of the blind fault; determining three-dimensional positions of each microseismic point corresponding to the microseismic activity based on the microseismic signal, and performing microseismic moment tensor inversion based on the three-dimensional positions of each microseismic point and the microseismic signal to obtain a focal mechanism of each microseismic point; determining a direction vector of a rupture surface corresponding to each microseismic point based on the focal mechanism of each microseismic point, and determining the main rupture direction of the blind fault based on the direction vector of the rupture surface corresponding to each microseismic point.

[0142] In addition, the logical instruction in the memory 430 described above can be implemented in the form of a software functional unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in the embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0143] In another aspect, the present application also provides a computer program product, which comprises a computer program stored on a non-transitory computer-readable storage medium, and the computer program comprises program instructions, and when the program instructions are executed by a computer, the computer can execute the method for determining a main rupture direction of a blind fault based on microseismic monitoring, which comprises: obtaining a microseismic signal, wherein the microseismic signal is obtained by a microseismic monitoring device monitoring microseismic activity induced by activation of the blind fault; determining three-dimensional positions of microseismic points corresponding to the microseismic activity based on the microseismic signal, and performing microseismic moment tensor inversion based on the three-dimensional positions of the microseismic points and the microseismic signal to obtain focal mechanisms of the microseismic points; determining direction vectors of rupture surfaces corresponding to the microseismic points based on the focal mechanisms of the microseismic points, and determining the main rupture direction of the blind fault based on the direction vectors of the rupture surfaces corresponding to the microseismic points.

[0144] In yet another aspect, the present application also provides a non-transitory computer-readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method for determining a main rupture direction of a blind fault based on microseismic monitoring, which comprises: obtaining a microseismic signal, wherein the microseismic signal is obtained by a microseismic monitoring device monitoring microseismic activity induced by activation of the blind fault; determining three-dimensional positions of microseismic points corresponding to the microseismic activity based on the microseismic signal, and performing microseismic moment tensor inversion based on the three-dimensional positions of the microseismic points and the microseismic signal to obtain focal mechanisms of the microseismic points; determining direction vectors of rupture surfaces corresponding to the microseismic points based on the focal mechanisms of the microseismic points, and determining the main rupture direction of the blind fault based on the direction vectors of the rupture surfaces corresponding to the microseismic points.

[0145] The device embodiments described above are only schematic, wherein the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment scheme. Those skilled in the art can understand and implement without creative labor.

[0146] Those skilled in the art can clearly understand the technical solutions of the various embodiments from the above description of the embodiments, and the various embodiments can be implemented by means of software with the necessary general hardware platforms, and of course, can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that makes a contribution, can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, and the like, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0147] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for some technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for determining a main direction of a concealed fault rupture based on microseismic monitoring, characterized in that, The method comprises the following steps: acquiring a microseismic signal, the microseismic signal being obtained by a microseismic monitoring device monitoring microseismic activity induced by activation of a blind fault; determining three-dimensional positions of each microseismic point corresponding to the microseismic activity based on the microseismic signal, and performing microseismic moment tensor inversion based on the three-dimensional positions of each microseismic point and the microseismic signal to obtain a focal mechanism of each microseismic point; determining a direction vector of a rupture surface corresponding to each microseismic point based on the focal mechanism of each microseismic point, and constructing a three-dimensional rose diagram based on a honeycomb sphere; dividing a spherical core of the three-dimensional rose diagram into a plurality of surface patches, and placing the direction vector of the rupture surface corresponding to each microseismic point at a spherical center of the spherical core of the three-dimensional rose diagram; each surface patch on the spherical core is extruded outward along a direction away from the spherical center based on a number of direction vectors on the corresponding surface patch; counting the number of direction vectors on each surface patch on the spherical core, and determining a maximum extrusion surface patch from the each surface patch based on the number of direction vectors on the each surface patch; determining a main rupture direction of the blind fault based on an extrusion direction corresponding to the maximum extrusion surface patch.

2. The method according to claim 1, wherein, The method for determining the direction vector of the rupture surface corresponding to each microseismic point based on the focal mechanism of each microseismic point comprises the following steps: determining a source moment tensor of each microseismic point based on the focal mechanism of each microseismic point; decomposing each source moment tensor, and determining eigenvalues of each source moment tensor and characteristic directions corresponding to the eigenvalues based on each component of each source moment tensor obtained by the decomposition; determining the direction vector of the rupture surface corresponding to each microseismic point based on the eigenvalues of each source moment tensor and the characteristic directions corresponding to the eigenvalues.

3. The method according to claim 1 or 2, characterized in that, The three-dimensional position of each microseismic point is obtained by iteration based on an initial position of the three-dimensional position solved by a least square method through the following formula: AΔθ=B wherein x, y and z represent three-dimensional positions of the microseismic point, t represents a time when the microseismic activity occurs, Δx, Δy, Δz and Δt respectively represent increments of x, y, z and t, N represents a number of microseismic monitoring devices triggered by the microseismic signal, t N represents a p-wave arrival time on the Nth microseismic monitoring device, t oN and t cN respectively represent an observed arrival time and a theoretical arrival time of the p-wave propagating from the microseismic point to the Nth microseismic monitoring device, Δθ represents a correction vector of the three-dimensional position θ solved by the least square method, Δθ = (A T A) -1 A T B, wherein T represents a matrix transpose, -1 represents a matrix inversion.

4. The method according to claim 1 or 2, characterized in that, The process of obtaining the focal mechanism of each microseismic point through microseismic moment tensor inversion can be represented by the following formula: wherein N represents the number of microseismic monitoring devices triggered by the microseismic signal, represents the displacement along the m direction at the Nth microseismic monitoring device under the unit force along the k direction at the microseismic point, M represents the moment tensor of the microseismic point, M ij is a component of M, u N represents the p-wave far-field displacement at the Nth microseismic monitoring device.

5. The method according to claim 2, wherein, The direction vector of the rupture surface corresponding to each microseismic point is determined based on the following formula: wherein, l and n represent two direction vectors of the rupture surface corresponding to each microseismic point, M1, M2 and M3 are three eigenvalues of the source moment tensor of each microseismic point, and M1>M2>M3, e1 and e3 are three eigenvectors corresponding to M1 and M3, and e1 and e3 represent the characteristic directions corresponding to M1 and M3, respectively.

6. A system for determining a main direction of rupture of a blind fault based on microseismic monitoring, characterized in that, The method comprises the following steps: a signal acquisition unit is configured to acquire a microseismic signal, the microseismic signal being obtained by a microseismic monitoring device monitoring microseismic activity induced by activation of a blind fault; a moment tensor inversion unit is configured to determine three-dimensional positions of each microseismic point corresponding to the microseismic activity based on the microseismic signal, and perform microseismic moment tensor inversion based on the three-dimensional positions of each microseismic point and the microseismic signal to obtain a focal mechanism of each microseismic point; The direction determining unit is configured to determine a direction vector of a rupture surface corresponding to each microseismic point based on a focal mechanism of the microseismic point, and construct a three-dimensional rose diagram based on a honeycomb sphere; divide a spherical core of the three-dimensional rose diagram into a plurality of surface patches, and place the direction vector of the rupture surface corresponding to each microseismic point at a spherical center of the spherical core of the three-dimensional rose diagram; each surface patch on the spherical core is extruded outward along a direction away from the spherical center based on a number of direction vectors on the corresponding surface patch; count the number of direction vectors on each surface patch on the spherical core, and determine a maximum extrusion surface patch from the surface patches based on the number of direction vectors on each surface patch; and determine a main rupture direction of the blind fault based on an extrusion direction corresponding to the maximum extrusion surface patch.

7. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to implement the method for determining a main rupture direction of a blind fault based on microseismic monitoring according to any one of claims 1 to 5.

8. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the method for determining a main rupture direction of a blind fault based on microseismic monitoring according to any one of claims 1 to 5.

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