CN-122020997-A - Three-dimensional discrete fracture network modeling and simulation method based on fracture statistics characteristics

CN122020997ACN 122020997 ACN122020997 ACN 122020997ACN-122020997-A

Abstract

The invention discloses a three-dimensional discrete fracture network modeling and simulation method based on fracture statistics characteristics, and relates to the technical field of hydraulic and hydroelectric engineering geotechnical. The method comprises the steps of collecting rock fracture geometry and distribution characteristics on site, constructing a random statistical model containing parameter relevance, generating a three-dimensional DFN model based on the random statistical model, embedding the three-dimensional DFN model into a numerical platform, constructing a fracture-rock mass system, giving mole-coulomb structure parameters, sequentially completing ground stress inversion, excavation support and operation load simulation, obtaining mechanical response data, and finally analyzing surrounding rock damage characteristics and optimizing a support scheme. The method solves the problem that the traditional model is difficult to characterize the discontinuous structure and the local instability, improves the prediction precision, is suitable for various complex fracture rock mass projects, and provides reliable support for stability evaluation and support design.

Inventors

Wen Dieran
YU HUI
HUA JUNJIE
LI KUN
MOU CHUNLAI
QIAN LIYUN
LIU MINGMING
WU CHAO
LI JUN
HU ANYU

Assignees

长江勘测规划设计研究有限责任公司

Dates

Publication Date: 20260512
Application Date: 20260119

Claims (9)

1. The three-dimensional discrete fracture network modeling and simulation method based on fracture statistics is characterized by comprising the following steps of: The method comprises the following steps of S1, carrying out statistical characteristic characterization on geometric parameters of a rock mass fracture system, wherein the statistical characteristic characterization comprises the steps of collecting geometric parameters and distribution characteristics of rock mass fractures in a research area, constructing a multi-dimensional parameter system and establishing a rock mass fracture random statistical model, wherein the multi-dimensional parameter system comprises fracture geometric parameter statistics, fracture space distribution parameter statistics and parameter correlation analysis, and the rock mass fracture random statistical model takes field measured data as input to quantify random characteristics and internal correlation of fracture key parameters; S2, constructing a three-dimensional discrete fracture network model, namely, based on the rock mass fracture random statistical model established in the step S1, defining a calculation domain, establishing an engineering entity three-dimensional model as a space constraint of fracture generation and cutting, converting on-site statistical parameters into a geometric model through a Monte Carlo random simulation program, and completing three-dimensional DFN model construction through fracture intersection logic processing, invalid fracture elimination and boundary truncation effect correction; S3, based on the rock mechanical response numerical simulation of the DFN model, embedding the three-dimensional DFN model generated in the step 2 into a numerical calculation platform, mapping the numerical calculation platform into joint or structural surface units, constructing a discontinuous medium system of cracks and rock blocks, endowing surrounding rock with mole-coulomb constitutive parameters, and sequentially carrying out initial ground stress inversion, engineering excavation supporting simulation and load loading simulation in an operation period to obtain rock mechanical response data; and S4, verifying a simulation result and applying engineering, analyzing the surrounding rock destruction form and distribution characteristics based on the mechanical response data in the step S3, and optimizing a supporting scheme by combining the actual requirements of the engineering, thereby providing a basis for evaluating the stability of the complex fractured rock mass engineering.
2. The method for modeling and simulating a three-dimensional discrete fracture network based on fracture statistics according to claim 1, wherein the method for constructing the three-dimensional discrete fracture network DFN model in the step S2 comprises the following steps: defining a calculation domain range based on engineering actual demands, establishing an engineering entity three-dimensional model, defining a space boundary generated by cracks, and forming cracks generated subsequently only in the rock mass calculation domain range; A Monte Carlo random simulation program is compiled, namely the maximum iteration number and convergence condition of random sampling are set; The parameter conversion and the fracture generation are carried out, namely the total number of fracture generation is determined through poisson distribution according to the volume density parameter in a rock fracture random statistical model, fisher distribution is adopted to randomly sample fracture trend and dip angle, and fracture equivalent radius is extracted based on lognormal distribution, so that the fracture is simplified into a disc unit; automatically identifying intersecting lines among disc units, reserving effective cracks forming a communication network, marking isolated cracks, and removing ineffective cracks which are completely outside a calculation domain or have no interaction with engineering entities; And (3) model correction, namely performing boundary truncation effect correction on the screened fracture to complete the construction of the three-dimensional discrete fracture network DFN model.
3. The method for modeling and simulating a three-dimensional discrete fracture network based on fracture statistics according to claim 1, wherein the method for simulating the rock mechanical response value based on the DFN model in the step S3 is characterized by comprising the following steps: embedding the three-dimensional DFN model generated in the step S2 into a numerical computing platform such as FLAC3D, mapping the DFN model into joint or structural surface units, and constructing a discontinuous medium system of cracks and rock blocks; giving mole-coulomb structure parameters, namely respectively giving corresponding mole-coulomb structure parameters to rock blocks and joint/structure surfaces in the system; Adopting a multiple regression analysis method, selecting hydraulic fracturing method measuring point data as a fitting target, setting model boundary normal displacement as a constraint condition, and expressing an initial ground stress field in a calculation domain as linear superposition of a dead weight stress field and a structural stress field; Simulating engineering excavation supporting, namely simulating the excavation process of structures such as tunnels and the like according to the actual construction flow of engineering, synchronously simulating the application of supporting measures, and reducing the influence of excavation unloading and supporting reinforcement on the mechanical state of a rock mass; Load loading simulation in the operation period, namely applying corresponding loads according to the load demand in the engineering operation period, wherein the load comprises equivalent concentrated force and uniformly distributed loads applied according to the double-lane standard; and (3) mechanical response data acquisition, namely outputting mechanical response data of the rock mass through a numerical calculation platform to complete the mechanical response numerical simulation of the rock mass, wherein the mechanical response data comprise, but are not limited to, displacement fields, stress fields and plastic region distribution of the rock mass.
4. The method for modeling and simulating a three-dimensional discrete fracture network based on fracture statistics according to claim 1, wherein in the step S2, the number N of the generated fractures is determined by using Poisson distribution, and the estimated relationship is N (V.P 32 )/EA, wherein V is a domain volume, P 32 is the volume density of each dominant fracture group and background fracture, and EA is the average area of fracture discs.
5. The method for modeling and simulating a three-dimensional discrete fracture network based on fracture statistics according to claim 1, wherein in the step S2, the fracture strike and the dip angle are randomly sampled by using Fisher distribution, and a probability density function of the Fisher distribution is adopted The method comprises the following steps: Wherein the method comprises the steps of For the Fisher constant, the temperature of the sample is, Is the angle between the normal vector and the average vector of the fracture.
6. The method for modeling and simulating a three-dimensional discrete fracture network based on fracture statistics according to claim 1, wherein in the step S2, the fracture equivalent radius is extracted based on lognormal distribution, the fracture is simplified into a disk unit, the generation range of the center of gravity of the disk is set in a space range which is 20% of the expansion of the boundary of the calculation domain, and the center of gravity coordinate of the disk unit after the fracture simplification Obeys a three-dimensional uniform distribution.
7. The method for modeling and simulating a three-dimensional discrete fracture network based on fracture statistics according to claim 1, wherein in the step S3, the initial ground stress inversion is to calculate an initial ground stress field in a domain Expressed as a linear superposition of the dead-weight stress field and the structural stress field: In the middle of Represents the self-weight stress of the steel plate, The structural stress in the X-direction is indicated, Representing the structural stress in the Y-direction, Is a contribution coefficient, adjusts the respective influence weights of dead weight, X or Y directional structural stress, Is a correction constant.
8. An apparatus, comprising: and a memory communicatively coupled to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-7.
9. A computer-readable storage medium, storing a computer program, characterized in that the computer program, when executed by a processor, implements the method according to any one of claims 1 to 7.

Description

Three-dimensional discrete fracture network modeling and simulation method based on fracture statistics characteristics Technical Field The invention relates to the technical field of geotechnical engineering in hydraulic and hydroelectric engineering construction, in particular to a digital rock mass modeling technology for representing complex geological conditions, and particularly provides a three-dimensional discrete fracture network modeling and simulation method based on fracture statistics. Background In the construction of water conservancy and hydropower engineering, the long-term stability of key structures such as dam foundations, side slopes, workshops, long-distance diversion tunnels and the like is a fundamental premise for guaranteeing the benefit. The water conservancy and hydropower construction area is often located in mountain areas with complex geological conditions, and faults, joints, cracks and the like are widely developed in the rock mass. The presence of these discontinuous structural planes causes the rock mass to exhibit significant mechanical behavioural heterogeneity and anisotropy. Conventional rock mass stability analysis often adopts mature numerical software, such as FLAC3D and other software to establish an equivalent continuous medium model, and the influence on the fracture is usually realized by only adjusting rock mass mechanical parameters. Although the method is simple and convenient, the method has inherent defects, such as difficulty in truly reflecting shear slip and tension cracking of the rock mass along the dominant fracture surface under the action of stress when the problem of local instability controlled by the structural surface is treated, and larger deviation between a prediction result and on-site actual monitoring is caused. Disclosure of Invention The invention aims to provide a three-dimensional discrete fracture network modeling and simulation method based on fracture statistics characteristics, which aims to solve the problem that a traditional equivalent continuous medium model is difficult to truly represent a discontinuous structure and a local instability mechanism of a complex rock mass, so that accuracy and reliability of mechanical response prediction of the rock mass under the action of excavation and operation load are improved. In order to achieve the above object, the present invention provides a technical method comprising: A three-dimensional discrete fracture network modeling and simulation method based on fracture statistics comprises the following steps: The method comprises the following steps of S1, carrying out statistical characteristic characterization on geometric parameters of a rock mass fracture system, wherein the statistical characteristic characterization comprises the steps of collecting geometric parameters and distribution characteristics of rock mass fractures in a research area, constructing a multi-dimensional parameter system and establishing a rock mass fracture random statistical model, wherein the multi-dimensional parameter system comprises fracture geometric parameter statistics, fracture space distribution parameter statistics and parameter correlation analysis, and the rock mass fracture random statistical model takes field measured data as input to quantify random characteristics and internal correlation of fracture key parameters; the internal association refers to quantitative correspondence existing between different parameters of rock mass cracks, and comprises the following steps: The correlation between geometric parameters, such as the positive correlation between the length of the crack and the opening degree, namely the distance between two walls of the crack, is that the long crack is stressed more fully when being formed, and the opening degree is larger, such as the correlation between the roughness and the shear strength, and the rough crack surface has large friction resistance and the shear strength is higher; Correlation of spatial distribution and geometric parameters, such as correspondence of fracture tendency and density, if a research area is subjected to structural stress dominance in a certain direction, the number of the fractures in the direction, namely the dominant tendency, is high, namely the density is high, and the inclination angle can be more concentrated; Correlation of size with distribution pattern, such as correlation of fracture radius or length with spacing, may be denser around large-size fractures due to secondary small fractures induced in surrounding rock mass by large-size fracture formation; S2, constructing a three-dimensional Discrete Fracture Network (DFN) model, namely, based on the rock mass fracture random statistical model established in the step S1, defining a calculation domain, establishing an engineering entity three-dimensional model as a space constraint of fracture generation and cutting, converting on-site statistical parameters into a geometric m