基于变形监测的软岩隧道有限元反演分析研究

Finite Element Inverse Analysis of Soft Rock Tunnel Based on Deformation Monitoring

软岩隧道施工过程中需要对围岩进行及时有效的加固,以免变形过大威胁工程的安全性。依托天井山隧道工程,采用非接触位移测量监测围岩变形稳定性。为了更好地描述软岩的蠕变特性,结合位移监测数据以及有限元参数反演方法得到软岩蠕变参数,并以此分析开挖断面围岩的稳定性情况。得到以下结果:根据现场实际监测数据,隧道围岩的变形呈收敛趋势,但两侧变形并不对称;采用有限元反演方法得到的参数能较好地反应围岩开挖后位移变化的规律,其变化规律与实测数据一致;隧洞稳定性分析结果表明,现有支护措施下围岩流变塑性区范围将持续增长,最终会导致初砌破坏达不到支撑效果,需要采取进一步的加固措施。

In the excavation process of soft rock tunnel,it is necessary to retain and protect the surrounding rock timely and properly to prevent the huge deformation which may threaten the construction safety.Based on the Tianjinshan tunnel,the non-contact displacement measure is used to monitor the deformation stability of surrounding rock.To describe the creep characters of soft rock more specifically,the monitoring data and the finite element back analysis are combined together to calculate the creep parameters and the stability of surrounding rock at excavating sections can be evaluated.The results show that：（1）with the monitoring data,the deformation of surrounding rocks show the convergent tendency but the deformation at two sides of tunnel are not same;（2）the creep parameters got from finite element can well describe the change of deformation after excavating tunnel and are agreed with the monitoring data;（3）from the stability analysis,the area of rheological plastic zone will continually grow under existing retaining measures and the primary lining will fail to bear the surrounding rocks in the end.The further reinforcement measures are needed.