Research on Formation Stability of Shallow Buried Partial Pressure Tunnel and Slope based on Strength Reduction Method
In order to solve the problem of the stability and safety of the combined stratum of the slope and tunnel when the tunnel in the shallow buried and shallow unsymmetrical pressure section intersects with the weak interlayer,the tensile strength is reduced based on the theory of shear strength reduction,namely the synchronous reduction of tensile shear strength,through theoretical analysis and FLAC 3D finite difference numerical simulation method,This theory is used to simulate different dip angles of soft interlayer and different relative positions of soft interlayer and tunnel,and analyze the variation law of safety factor of slope and tunnel combined stratum and the development process of plastic zone.The results show that the formation instability can be divided into two types:tunnel influence and tunnel and slope influence.Considering the synchronous reduction of tensile shear strength,the shear yield zone generated at the bottom of the tunnel is connected with the tensile yield zone at the top of the surface,and the slope gradually loses stability and slides.The modified M-C criterion is more accurate than the M-C criterion because it considers the reduction of tensile strength,which is more consistent with the failure type of rock and soil mass.
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