软岩隧洞可缩性U型钢支架压缩量研究

Study on amount of compression of yieldable U-steel support for soft rock tunnel

以深埋软岩输水隧洞为工程背景,研究了钢支架压缩量的计算方法,提出软岩隧洞钢支架压缩量的控制标准。借助数值软件进行U型钢支架压缩量影响因素的定量分析,研究表明:(1)压缩量设计适当的可缩性U型钢支架既能满足深埋软岩隧洞支护"高阻让压"的需要,以保持围岩稳定,又能合理释放掉部分原岩应力,改善衬砌的应力应变状态;(2)确定钢支架压缩量设计值,可根据隧洞支护结构受力状态和围岩塑性区半径划定范围后综合判定;(3)隧洞埋深和围岩类别不仅对U型钢支架压缩量的影响很大,还一定程度上影响钢支架缩动收敛时间,岩体类型和隧洞洞型对U型钢支架压缩量也有较明显的影响。

By taking the deep-buried soft rock tunnel as the engineering background,the calculation method for the amount of compression of steel support is studied herein,and then the control criterion for the amount of compression of steel support for the soft rock tunnel is proposed as well. By means of the relevant numerical software, a quantitative analysis is made on the factors to impact the amount of compression of the U-steel support. The study shows that：（ 1） the yieldable Usteel support with the appropriately designed amount of compression can not only meet the demand of the high resistant and yielding property of the deep-buried soft rock tunnel for maintaining the stability of surrounding rock,but can also improve the stress-strain status of the lining by relieving a part of the stress in the original rock;（ 2） the design values can be determined in accordance with the stress condition of the tunnel supporting structure and the comprehensive judgment made after delimiting the range of the radius of the plastic zone of the surrounding rock;（ 3） the tunnel buried depth and the surrounding rock types have large impacts not only on the amount of compression of the steel support,but also on the yielding convergence time of the steel support to some extent,meanwhile,the rock types and the shape of tunnel have more obvious impacts on the U-steel support as well.