某客专高含水率黄土隧道二衬力学特性分析

Analysis of the Force Characteristics of the Secondary Lining in a PDL High Water Loess Tunnel

以某客专高含水率黄土隧道开挖工程为依托,通过现场监测隧道二次衬砌受力随开挖时间的变化规律,分析隧道在高含水率地层中二次衬砌的受力特性.结果表明:二次衬混凝土应力和钢筋轴力均经历了初期波动—缓慢增长—趋于稳定3个阶段,受力稳定周期约20 d;二衬模板拆除对隧道二衬受力影响较大,在施工时拆除二衬模板应按照规范;仰拱处二衬受力较大,仰拱隆起趋势明显;高含水率黄土隧道开挖后坑道两侧破裂角大,导致隧道边墙位置受力明显大于其他部位,在设计时应加强仰拱和边墙部位支护参数.

Based on a high water loess tunnel,the force characteristics of secondary lining in high water loess layer is analyzed through on-site monitoring secondary lining stress with excavation time.The results show:The secondary lining concrete stress and rebar axle force have experienced three stages that are fluctuations in the early stage,steady growth stage,and tending to be stable,the stable period is about 20 days.Removed secondary lining concrete form has a great effect on its force characteristics,so it should be removed according to specifications during construction.The stress of inverted arch has a large force and obvious uplift trends.Sidewall area stress is bigger than other place because of large fracture angle of high water Loess.Support parameters should be increased on inverted arch and sidewall area when designing.