考虑黏聚力与内摩擦角的变坡面 浅埋偏压隧道围岩压力计算方法

为了研究变坡面浅埋偏压隧道中黏聚力与内摩擦角对围岩压力的影响规律,基于极限平衡法求解变坡面浅埋偏压隧道深、浅埋侧推力,进而推导出变坡面下独立考虑黏聚力与内摩擦角的围岩压力计算方法,通过与规范公式以及既有文献对比分析,验证了文章所提方法的合理性,并探讨了深埋侧水平侧压力系数的影响因素.结果 表明:水平侧压力系数随地面坡角的增加逐渐增大,随夹角(岩土体)的增加呈现先减小后增大的趋势,随黏聚力与内摩擦角的增加逐渐减小.此外,黏聚力的分算有利于考虑环境因素(如降雨)引起的岩土体力学参数(黏聚力)急剧变化带来的不利影响;而内摩擦角对隧道深埋侧水平侧压力系数影响较大,表明将内摩擦角进行分算对围岩压力计算具有重要意义.相关研究成果可为类似变坡面浅埋偏压隧道结构设计提供理论依据.

Calculation Method of Surrounding Rock Pressure of Shallow-buried and Asymmetrical Pressure Tunnel under Variable Slopes Considering Cohesion and Internal Friction Angle

To examine the influence of cohesion and internal friction angle on surrounding rock pressure of shallow-buried and asymmetrical load tunnel under variable slopes, the thrusts on both deep and shallow sides of shallow-buried and asymmetrical load tunnel under variable slopes are obtained using limit equilibrium theory, and then the calculation methods are derived for surrounding rock pressure under variable slopes independently consider? ing cohesion and internal friction angle. The rationality of the proposed calculation methods in this paper is verified by comparison with the normative formula and existing literature. The influencing factors on the horizontal lateral pressure coefficient of the deeply buried side of the tunnel are discussed. The results show that the horizontal lateral pressure coefficient increases with the increase of the slope of the ground surface, decreases and then increases with the increase of the angle of the rock-soil, and decreases with the increase of the cohesion and internal friction angle. Besides, the split calculation of the cohesion is helpful to consider the adverse effects of the rapid changes of the me? chanical parameters (cohesion) of rock soil caused by environmental factors (such as rainfall). The internal friction angle has a greater influence on the horizontal lateral pressure coefficient of the deeply buried side of the tunnel, which shows that the split calculation of the internal friction angle is of great significance to the calculation of sur? rounding rock pressure. The relevant research results can provide a theoretical basis for the structural design of simi? lar shallow-buried and asymmetrical pressure tunnels under variable slopes.