Stability analysis and application of soft rock tunnel based on Hoek-Brown strength criterion
To solve the stability analysis problem of the tunnel construction stage under complex geological occurrence conditions,based on the Hoek-Brown strength criterion,this paper obtains the calculation formula of the plastic zone radius of the circular tunnel under the condition of lateral pressure coefficient of 1.0.And the evolution coefficient of the surrounding rock plastic zone was proposed.The relationship between the evolution coefficient of the surrounding rock plastic zone and the buried depth of the tunnel and geological strength index GSI was studied.Taking part of the Chuxiong section of the Dianzhong Water Diversion Project as the engineering background,the uniaxial compressive strength of argillaceous siltstone in the cave section was obtained by a point load tester,and one of the key parameters of Hoek-Brown-rock material constant was determined by combination with tensile strength.Combined with the longitudinal deformation curve of the surrounding rock,the characteristic curve of the surrounding rock,and the support characteristic curve,the stability of the primary support structure of the Wuzhuangcun tunnel was analyzed,and compared with the Carranza normalization method.The results show that with the decrease in the quality of the surrounding rock and the increase of the buried depth,the range of surrounding rock that enters the plastic state after tunnel excavation also increases.The plastic zone range of surrounding rock obtained by this method is larger than that obtained by the Carranza normalization method.For this tunnel,the safety factor of the existing primary support structure is greater than 1.0,which can keep the tunnel stable,and the stability analysis using the proposed method is safer and more conservative than the normalization method using Carranza,which is beneficial for the safe construction of soft rock tunnel engineering under complex geological conditions.
tunnel engineeringHoek-Brown strength guidelinesplastic zone of surrounding rockpoint load testconvergence-confinement method
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