Study On Evolution Mechanism Of Fracture And Seepage Of Fault Zone Rockmass Under Osmotic Pressure

As the exploration of mineral resources goes deeper,water inrush disaster has become one of the major threatens to the safety of mine production,the main manifestation of which is the water inrush in fault zone.Thus,to study the evolution mechanism of fault permeability in the fault zone under seepage pressure is of great theoretical and engineering significance for revealing the mechanism and precursory law of water inrush in fault zone as well as predicting and warning mine water inrush disaster in advance.This paper based on the F3 fault zone,the main water conducting fault structure of Sanshan island Gold Mine,Shandong gold group,and by means of theoretical analysis,field investigation,laboratory test and numerical simulation,makes in-depth research on the failure mechanism and seepage evolution law of fault induced fracture zone rock mass and sliding fracture zone earth rock mixture.The main contents are as follows:(1)Based on the inclusion theory,the stress analysis of the fractured rock mass under the action of osmotic pressure is carried out,the calculation formula of the additional water pressure in the fracture is established,and the calculation formula of the fracture strength of the fractured rock mass with influence of the additional water pressure is deduced.The seepage pressure is analyzed by the laboratory test and numerical simulation test of the single fracture and multiple fractures with different dip angles.The fracture failure law of the lower fractured rock mass proves the rationality and correctness of considering the influence of additional water pressure in the theoretical derivation of fracture strength of fractured rock mass.(2)Combined with 3D printing technology,through the permeability test of through filling fracture rock mass with different roughness and gap width,the influence mechanism of confining pressure,roughness and gap width on the permeability of through filling fracture is analyzed,and the function relationship between permeability and confining pressure of through filling fracture is established.Based on the numerical simulation of two groups of rock mass with different through filling fractures,the law of permeability evolution of rock mass with multiple through filling fractures is revealed.(3)Using the self-designed small-scale test device of fluid solid coupling of soil-rock mixture,a series of permeability tests without confining pressure,confining pressure loading and unloading conditions,uniaxial stress seepage and triaxial stress seepage coupling loading tests were carried out for different rock bearing ratio soil rock mixture weight plastic samples.Combined with real-time CT scanning,the seepage pressure,confining pressure and axial load and different rock bearing ratio soil were established respectively.The functional relationship between the permeability coefficients of rock mixtures reveals the evolution law of the cracking and permeability of the soil-rock mixtures in the fault sliding fracture zone.(4)A set of similar model test device for seepage conduction evolution of fault sliding fracture zone is designed,which can realize three-dimensional unequal stress-seepage coupling loading.By carrying out experimental research under different filling material ratio,different filling thickness,different seepage pressure and different confining pressure,the migration flow of filling particles in fault sliding fracture zone under the coupling effect of stress-seepage is analyzed.The characteristics of water loss explain the formation mechanism of water inrush channel in the sliding fracture zone.