大跨度黄土隧道CRD法优化研究

针对大跨度隧道通常采用的交叉中壁（CRD）法的工法特点,以V级围岩条件下的某大跨度黄土隧道为研究对象,采用有限元数值模拟手段,对CRD工法中各个分部的开挖形状、开挖顺序以及支护形式进行了优化研究。研究结果表明,将传统CRD法的开挖顺序调整为CRD1-CRD3-CRD2-CRD4时,隧道各步位移及初期支护内力均较原CRD法要小;当采用直线型临时支护代替曲线型临时支护时,隧道初期支护内力会有一定幅度增大,但变化幅度小于10%。优化后的CRD法可以减少工序,加快大跨度黄土隧道的施工进度,提高经济效益。

Optimization Study on CRD Method for a Large-Span Loess Tunnel

Based on the characteristics of Cross Diaphragm（CRD） method in tunnel construction, a largespan loess tunnel in Rocks of Grade V was taken to optimize the shape and sequence of its excavation and the support type for CRD method with the FEM numerical simulation. The research reveals the following main results： （1） When the sequence of traditional CRD method is adjusted to CRD1-CRD3-CRD2-CRD4, the tunnel displacement in each phase and the internal force of preliminary supports are less than those with the original construction method. （2） When the line-type support instead of the curve-type support is applied in the construction, the internal force of tunnel preliminary supports will increase slightly. However, the increase of internal force is less than 10 percent, so the line-type support can be applied in the construction with the CRD method, and the optimized CRD method not only can speed up the construction, but also improve economic benefit because of the reduction of construction process.