关角隧道F2–1断层破碎带支护结构优化设计

OPTIMIZING DESIGN OF SUPPORT STRUCTURE FOR GUANJIAO TUNNEL IN FAULT-RUPTURE ZONE F2–1

依托关角隧道F2–1断层破碎带段,开展断层破碎带隧道支护结构优化设计研究。对采用原设计方案的支护结构位移、围岩压力、钢架应力、锚杆轴力进行现场监测,结果表明:施工工序对支护结构影响明显;钢架最大应力超过钢架强度,围岩压力分布不均匀,锚杆作用效果不明显,说明现有的施工方案无法满足施工安全要求,需要及时对其调整;经综合分析,提出提高钢架刚度、设置临时横撑、边墙小导管注浆等一系列改进措施,并采用数值计算软件FLAC3D验证其可行性。通过现场实施及监测结果的反馈,证明改进措施效果明显,研究成果可为断层破碎带隧道支护参数的确定提供理论依据和基础数据。

Fault-rupture zone F2-1 of Guanjiao tunnel has done a series of research on optimizing support structure design of tunnel in fault-rupture zone. Displacement,pressure of surrounding rock,stress in the steel frames and axial force of rock bolts were obtained by monitoring in the section with original design scheme. The result indicates that construction process has significant effect on support structure;the steel frame stress exceeded steel strength;the distribution of surrounding rock pressure is uneven;the rock bolts do not work effectively. It is shown that the original support scheme could not meet the safety requirements;and it should be modified in time. By a comprehensive analysis of monitoring data,some optimizing methods such as increasing frame steel strength level,temporary supports,small pipe grouting at the side wall,etc. have been used in construction;and their feasibility also be verified by numerical analysis with software FLAC3D. From feedback of field implement and monitoring result,the effect of optimizing method is significant. These research results can provide theoretical basis and underlying data for support scheme in the fault-rupture zone.