断层影响下隧道围岩变形监测与特征分析

断层等软弱结构面是隧道工程中经常遇到而又必须有效处理的不良地质体.诸多工程实践和有关研究均表明,隧道围岩的变形与破坏一般受断层等软弱结构面控制;而断层对于隧道围岩变形与破坏的影响程度及其机理仍是一个模糊问题.因此,对于断层影响下隧道围岩变形与破坏的研究具有重要的理论意义和实用价值.黄河大柳树水利枢纽地处青藏褶皱系与阿拉善地块过渡带,区域断层发育,工程中的隧道大多为受断层影响的隧道.本文以黄河大柳树水利枢纽1号导流隧洞为例,对不同地段(根据断层的发育状况)在开挖过程中围岩变形的现场监测,试图对断层影响下隧道围岩变形特征与机理进行定量地深入分析.此外,为更准确监测隧道围岩变形,作者根据对该隧道变形特点的初步分析自行设计了监测仪器,即分点锚固式多点伸长计.这也是隧道工程监测技术的积极探索.

Monitoring and analysis on the deformation of tunnel surrounding rock affected by faults

Weak structural planes such as faults are typical defective geological bodies,which are often encountered and must be solved effectively in tunnel engineering.Many corresponding cases and studies show that the deformation and failure of tunnel surrounding rock are mainly controlled by weak structural planes,while the mechanism of this control is still an ambiguous question.Therefore, the study on the deformation of tunnel surrounding rock affected by faults is necessary and valuable.This study was carried out in the river diversion tunnel No.1 on the Daliushu hydro-junction,the Yellow River.Daliushu hydro-junction is located at the transition belt of Nyainqentanglha fold system and Alashan block,and faults are well developed in this area.During the process of tunnel excavation,deformations of different surrounding rocks were monitored on the spot.The further analysis was carried out to explore the mechanism of faults affecting tunnel surrounding rock deformation in term of monitoring results.Besides,an anchored multiple-point extensometer was designed to ensure accurate monitoring according to the engineering conditions.