隧道挤压型变形与支护特性研究

Study of squeezing deformation and support characteristics of tunnels

针对挤压型大变形问题,通过木寨岭隧道科研试验与相关资料分析,得出挤压型大变形具有变形量大、持续时间长的特点,一般两侧为变形优势部位。测试数据表明,刚性支护中围岩压力、拱架应力、锚杆轴力值均较大,其中拱架应力值可能超过材料屈服强度,边墙锚杆较拱部锚杆作用明显,围岩压力与变形增量呈反比关系;在挤压型变形隧道中允许有控制性地释放围岩变形,能够减小支护结构上的围岩压力,有利于隧道结构的长期稳定。文中阐述了可让式支护原理,对可让式支护结构预留变形量进行初步预测,数值计算表明,采用刚性支护将位移控制在较小的范围内需要足够大的刚度,而可让式支护具有能够允许围岩一定程度的变形同时减小支护结构受力的优势,可在铁路隧道中推广使用。

In light of the squeezing deformation problem,based on Muzhailing tunnel research and other relative data analysis,it is concluded that large value and long time deformation are the squeezing deformation characteristics,both sides are usually advantage location in the whole deformation of tunnel.Test data show that surrounding rock pressure,stress of steel arch centering,axial force of anchor have a larger value in rigid support,where stress of steel may exceed the yield strength of material;anchor is more effective on side walls than other position;surrounding rock pressure and deformation increment is inversely proportional.The results show that rock pressure can be reduced by control release of surrounding rock deformation,is beneficial to the long-term stability of the tunnel structure.Yielding support is proposed,and reserved deformation can be predicted preliminarily.Numerical calculation shows that large enough stiffness is required for rigid support to control displacement in a small range,Yielding support has advantages in control deformation and reduces stress of steel;it is a better control technology in squeezing deformation tunnels.