考虑底部隆起的浅埋双侧偏压小净距隧道围岩压力计算分析

Calculation and analysis of surrounding rock pressure in shallow buried bilateral bias pressure small clear distance tunnel considering bottom uplift

为研究浅埋双侧偏压小净距隧道在开挖后底部隆起变形的围岩压力情况,采用极限分析上限法构建隧道破坏模式,推导了M-C准则下围岩压力计算式。运用Matlab软件,根据约束条件,求解围岩压力的最终解,将计算值与规范结果进行比较,验证所推公式的可行性,并分析推导公式中围岩压力与各影响参数间的联系。结果表明:随着隧道侧部和底部支护力系数、岩土体粘聚力和内摩擦角不断减小和隧道埋深不断增大时,围岩压力不断增加。当地表处于倾斜时,隧道两侧围岩压力明显不同,即随倾角的增大,隧浅埋侧围岩压力逐渐减小;但深埋侧则相反。这为浅埋双侧偏压小净距隧道的开挖、支护提供一定的理论指导建议。

In order to study the surrounding rock pressure caused by the uplift deformation at the bottom of a shallow buried double-sided bias small spacing tunnel after excavation,the limit analysis upper bound method was used to construct the tunnel failure mode,and the calculation formula for the surrounding rock pressure under the M-C criterion was derived.Matlab software was used to solve the final solution of surrounding rock pressure based on constraint conditions.The calculated values were compared with the standard results to verify the feasibility of the derived formula.The relationship was analyzed between the surrounding rock pressure and various influencing parameters in the derived formula.Research has shown that as the coefficient of support force at the side and bottom of the tunnel,the cohesion of rock and soil,and the internal friction angle continue to decrease,and the burial depth of the tunnel continues to increase,the surrounding rock pressure continues to increase.When the surface is tilted,the surrounding rock pressure on both sides of the tunnel is significantly different,that is,as the inclination angle of the surface gradually increases,the pressure of the surrounding rock on the shallow buried side continuously decreases,while on the deep buried side,it is the opposite.The research can provide certain theoretical guidance and suggestions for the excavation and support of shallow buried tunnels with small clear distance under biasing pressure on both sides.