水平地震力作用下浅埋偏压隧道围岩压力的简化理论分析

Simple theoretical analysis of rock pressure for shallow unsymmetrical-loading tunnels considering horizontal earthquake action

考虑到传统浅埋偏压隧道围岩压力的分析仅以计算摩擦角体现围岩材料特性,没有将内摩擦角和黏聚力作为独立参数分开研究,基于规范法,提出水平地震作用下独立考虑黏聚力的浅埋偏压隧道围岩压力的简化解析分析方法,获得隧道顶部竖直围岩压力、隧道两侧水平侧压力以及滑动面破裂角的理论表达式,并对影响顶部竖直围岩压力、水平侧压力和破裂角的因素进行了研究。结果表明,竖直围岩压力与滑裂面摩擦角、地面倾角呈正相关,与水平地震效应系数、滑裂面黏聚力呈负相关;滑裂面内摩擦角、黏聚力、地面倾角越大,破裂角越大,水平地震加速度系数越大,破裂角越小;水平侧压力随滑裂面内摩擦角和黏聚力的增大而减小,随水平地震效应系数和地面倾角的增大而增大。研究成果可为浅埋偏压隧道的围岩应力计算提供一定的理论依据。

The previous analysis of the rock pressure of shallow bias tunnel is based on the particular friction angle to reflect the material characteristics of rock mass. However, the rock internal friction angle and cohesion are not as the independent parameters in their studies. Based on the standard method, a simplified theoretical analysis method for the rock pressure of shallow bias tunnel is proposed to consider the horizontal earthquake action and rock cohesion. The theoretical expressions of the vertical rock pressure at the location of tunnel top, the lateral pressure at the location of both sides of tunnel and the rupture angle of sliding surface are obtained. The factors affecting the top vertical and horizontal lateral pressure of surrounding rocks, and fracture angle are studied. The results show that the top vertical pressure of surrounding rocks is positively correlated with the friction angle of sliding surface and the slope angle, and negatively correlated with the level of seismic effect coefficient and slip surface. The greater the internal friction angle, the cohesion of sliding surface and the slope angle become, the greater the rupture angle becomes, while the greater the horizontal seismic acceleration coefficient becomes, the smaller the rupture angle becomes. The horizontal lateral pressure decreases with the increasing of the internal friction angle and cohesion, increases with the increasing of seismic effect coefficient and slope angle. The results can provide a theoretical basis for the calculation of surrounding rock stress of the shallow bias tunnel. © 2016, Science Press. All right reserved.