Study on macro-meso shear transfixion mechanisms and mechanical properties of shear band-bedrock interfaces of dangerous rock on reservoir bank
Taking Banbiyan dangerous rock in the Three Gorges Reservoir Area as a research object,the formation process and characteristics of the shear band in the dangerous rock were summarized.In this paper,laboratory tests and numerical simulation were used to study the shear transfixion mechanism and mechanical properties of the shear band-bedrock interface from a macro-meso perspective.The results show that:(1)the shear band is the main controlling factor of the dangerous rock instability,and the internal filling material is laminar and unbonded.(2)Under the condition of constant normal stress,the failure modes of the interface can be summarized as step root tensile fracture-step climbing,rock slab damage-step shear fracture,rock slab crack coalescence-step shear broken.(3)Six typical stages can be observed in shear stress-shear displacement curves,including the compaction stage,the oblique crack occurring stage at the step root near the loading end,the approximate elastic deformation and micro-crack propagation stage,the step near the loading end shear fracture stage,the remaining steps shear fracture stage,and the residual stage.(4)The peak shear strength and the residual strength of the interface increase with the increase in normal stress,layer thickness and step height.The vertical cumulative displacement decreases with the increase in normal stress and increases with the increase in layer thickness and step height.(5)The interface crack number curve shape is"S"type,which can be divided into three stages,including the crack number slowly increasing stage(rock slab surface wear),the rapid crack propagation stage(steps shear fracture),and the crack number keeping stable stage(residual friction).The curve change trend of particle strain energy and cementation strain energy is similar to that of the shear stress-shear displacement curve,and the total energy,friction energy,and damping energy increase with the increase in shear displacement.The research results are of reference significance to the study of the mechanical properties of the shear band and the stability of the dangerous rock.
rock mechanicsthe Three Gorges Reservoirdangerous rockshear band-bedrock interfaceshear mechanical propertiesnumerical simulation
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