Study On Connectivity And Permeability Of Analysis Fracture Network In Rock

After long geological process and human influence,a large number of fractures are generally developed in the natural rock.The whole permeability of rock is negligible compared with fracture,so the permeability of rock mass is mainly affected by fracture,and the permeability of fracture network depends on its connectivity and spatial distribution.In the study of fracture network connectivity,the influence of fracture geometry on connectivity is usually considered,and the influence of fracture network spatial distribution on connectivity is not considered comprehensively,so it is difficult to accurately characterize fracture network connectivity.Through theoretical analysis and numerical simulation,taking two-dimensional fracture network as the research object,the permeability characteristics and flow law of fracture network flow in fractured rock mass are studied.The connectivity under the influence of spatial distribution of fracture network is quantified by using geological entropy,and the geometric distribution of fracture network in rock mass is evaluated by using the concept of fractal dimension.The main research contents are as follows:(1)With the help of visual studio platform,based on the Monte Carlo random simulation technology and the basic assumption of fracture network model,through the analysis of the random distribution law of rock fracture geometric characteristics,the two-dimensional fracture network simulation is generated,and the boundary conditions are added to the fracture network model to complete the permeability calculation.The basis for the calculation and research of the two-dimensional fracture network is provided.(2)The concept of geological entropy is introduced to characterize the connectivity of fracture network,which is compared with the existing connectivity indicators to verify the applicability of geological entropy to the connectivity characterization.For the two-dimensional fracture network,the calculation of the geological entropy is programmed.By generating 1500 groups of fracture network,the relative entropy index and the standardized permeability coefficient are compared to verify the accuracy of the representation of the geological entropy for the connectivity of fracture network.The influence of fracture geometry such as trace length and density on geological entropy is analyzed.(3)Based on the study of fractal characteristics of fracture network,this paper uses MATLAB software to program the calculation of fractal box dimension of two-dimensional fracture network,and explores the relationship between fractal dimension of fracture network and geological entropy which verifies the possibility that geological entropy characterizes the spatial distribution of fracture network.