高地应力千枚岩大变形隧道支护参数试验研究

乌鞘岭隧道岭脊段由于位于祁连山断褶带内F4-F7断层“挤压构造带”中,地层中储存了较高的初始地应力,当隧道掘进至较软弱的千枚岩地层时,高地应力便通过千枚岩位移而卸载,使得隧道结构位移较大。本文通过收敛量测,对不同支护参数的4个实验段支护效果进行了对比分析,初步得到能有效控制乌鞘岭隧道岭脊段高地应力条件下千枚岩大变形的初期支护参数,指出翼缘较厚的H175型钢能提供较大的早期支护强度,特别是能保证钢拱架水平方向的安全与稳定。运用小直径岩石锚索锚固技术能对支护结构提供较大支护抗力,同时具有先柔后刚、先放后抗控制大变形的性能特征。

EXPERIMENT RESEARCH ON SUPPORT PARAMETERS OF LARGE STRAIN PHYLLITE TUNNEL UNDER HIGH STRESS

The mountaintop section of Wushaoling tunnel lies in the F4-F7 compression faultage of Qilianshan tectonic area, in which has high original stress. The high stress will be decreased for the displacement of phyllite because the excavation and construction in the weak ground will lead to the larger strain from structure of tunnel. The differential support parameters from four experiment sections have been compared with and analyzed by the displacement tests, so we can drawn the followings conclusions by series of the studies in this paper: the preparatory support parameters on the experiment section of Wushaoling tunnel can be gained; and the H175_type steel with thick limb can offer enough support strength during early phase, especially can ensure the horizontal safety and stabilization of the steel arch; the small diameter rock anchor can offer the support structure larger force. And it shows the large deformation characters which control the support structure the strain from flexible to rigid as well as from free to restraining.