高地应力软岩大变形输水隧洞处理措施研究

RESEARCH ON TREATMENT MEASURES FOR WATER-CONVEYANCE TUNNEL IN HIGHLY DEFORMED SOFT ROCK WITH HIGH GROUND STRESS

隧洞在穿越高地应力引起的软岩大变形问题是隧洞建设施工中的难点,给隧洞建设的施工安全和进度带来了很大的影响。结合高地应力软岩大变形段地质情况和变形原因分析,采取三台阶开挖、双锁脚锚管、让压锚杆、双层支护和开挖预留变形量等措施。通过收敛监测点、锚杆应力计、钢板计安全监测分析,研究结果表明,除开挖落下台阶时变化相对较大外,其余收敛监测断面收敛测值及变化量较小,锚杆应力、锚杆支护应力以及钢板计实测钢拱架应变的发展趋势也相对稳定,未见异常情况,抑制围岩变形,围岩稳定,采取三台阶开挖、双锁脚锚管、让压锚杆、双层支护和开挖预留变形量等措施是合理的。

The large deformation of soft rock caused by a tunnel passing through soft rocks with high ground stress is a difficult problem in the construction of tunnels,which badly affects the safety and progress of tunnel construction.In this paper,such measures as using the three-level benching tunneling method,double-locking anchor pipes,pressure-shifting anchor rods,double-layer support and reserving deformation space for excavation are taken in combination with geological conditions and analysis of deformation causes in the section of highly deformed soft rock with high ground stress.The safety monitoring analysis on convergence monitoring points,anchor rod stress meter and steel plate meter shows that in addition to the large deformation in the course of excavating the lower bench of a tunnel,the convergence measurement value and variation on other convergence monitoring sections are all small,and the changing trend of anchor rod stress,anchor rod support stress and steel arch strain measured by steel plate meter is relatively stable without anomalies,and surrounding rock is stable without deformation.Therefore,such measures as the three-level benching tunneling method,double-locking anchor pipes,pressure-shifting anchor rods,double-layer support and reserving deformation space for excavation have been proven to be reasonable.