Mechanism of Cracking Damage in the Bottom Structure of Carbonaceous Slate Tunnel
Carbonaceous slate softens and muds when exposed to water,with poor stability,making it a typical soft rock formation.During the construction period,carbonaceous slate tunnels are prone to deformation,leading to disease problems and seriously affecting the progress and safety of tunnel construction.Based on a tunnel under construction in the southwest region,this paper conducted indoor material phase composition analysis experiments on the carbonaceous shale formation in the section with structural defects at the bottom of the tunnel.It was determined that the carbonaceous shale in this section is mainly composed of minerals such as quartz and chlorite,which have the characteristics of softening and swelling when exposed to water.The reasons for the large deformation of the carbonaceous shale were identified.Establish a refined finite element mesh analysis model based on the extended Drucker-Prager criterion,and obtain the crack morphology at the bottom of the tunnel structure and the distribution of the plastic zone of the surrounding rock under different shear dilation angles.The comparison between the numerical simulation results and the actual on-site crack damage situation shows that the finite element results are in good agreement with the actual tunnel bottom structure disease characteristics.
tunnelscarbonaceous slatefinite element analysiscrack damage
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