隧道上覆压力对中岩柱稳定性的影响研究

Research on the Influence of Tunnel Overlying Pressure on the Stability of Middle Rock Column

研究目的:山地城区复杂周边环境对地铁车站修建有潜在较大施工风险。针对超大断面地铁车站暗挖隧道的施工规范与技术设计,目前尚无确切的标准可循。基于此,提出一种采用预留中岩柱的施工工法,其中岩柱的承载能力与隧道埋深及中岩柱宽度有着密切的关系。为研究隧道上覆压力对隧道中岩柱的稳定性影响,本文通过对不同埋深下的中岩柱稳定性进行数值研究,揭示上覆压力为主控因素的隧道变形破坏机制。研究结论:(1)埋置深度从1至1. 5倍隧道高度范围内时,中岩柱的塑性应变随着埋深的增加而增加,并且塑性应变的增加幅度也随着埋深的线性增加;(2)在埋深为1. 5倍隧道高度以后,中岩柱的塑性应变随着埋深增大而非线性增大,中岩柱应力集中区域出现在中部,并呈现由中部两侧向四周扩散现象;(3)考虑了上覆压力的影响,隧道预留中岩柱的方法与加固措施能有效运用到复杂环境的地铁隧道施工中。

Research purposes: The complex surrounding environment of mountainous urban area has great potential construction risk for subway station construction. In view of the construction code and technical design of underground tunnel in subway station with large section,there is no definite standard to follow. Based on this,a construction method using reserved middle rock columns is proposed,in which the bearing capacity of rock columns is closely related to the buried depth of tunnels and the width of middle rock columns. In order to study the influence of the overlying pressure on the stability of the pillar in the tunnel,the deformation failure mechanism of the overlying pressure as the main control factor is revealed by numerical study on the stability of the pillar in the tunnel under different buried depths.Research conclusions:(1) When the buried depth is within the range of 1 to 1. 5 times the height of the tunnel,the plastic strain of the middle rock column increases with the increase of the buried depth,and the increase amplitude of the plastic strain also increases linearly with the buried depth.(2) The plastic strain of middle rock column increases nonlinearly with the increase of buried depth after 1. 5 times tunnel height. The stress concentration area of the middle rock column appears in the middle part and shows the phenomenon of spreading from both sides of the middle part to the surrounding area.(3) Considering the influence of overlying pressure,the method reserving rock column in tunnel and reinforcement measures can be effectively applied to the subway tunnel construction in complex environment.