特大断面板岩隧道施工期围岩变形时空效应分析

Analysis of Time-space Effect for Surrounding Rock Deformation in Super-large Cross Section Slate Tunnel During Construction Period

目前,关于特大断面板岩隧道施工期围岩时空变形规律缺乏系统性的总结。以沪昆客运专线长昆湖南段姚家隧道为例,结合变形监测资料,分析在不同开挖方法下特大断面板岩隧道施工期围岩时空变形规律,划分围岩变形-时间特征曲线及围岩变形-距掌子面距离关系曲线的类型;分析围岩位移释放率与时间和距掌子面距离的关系,研究围岩级别和空间位置对特大断面板岩隧道施工期围岩变形时空效应的影响规律。结果表明：围岩变形-时间特征曲线的类型可分为＂弯弓＂型和＂台阶＂型。＂弯弓＂型划分三个变形阶段,适用于Ⅲ、Ⅳ级围岩;＂台阶＂型划分四个变形阶段,适用于Ⅴ级围岩。围岩变形与距掌子面距离的关系曲线的类型可分为＂单厂＂型和＂双厂＂型。＂单厂＂型曲线出现在Ⅲ、Ⅳ级围岩地段,当监测断面距掌子面超过5倍洞径时,围岩变形趋于稳定,空间效应趋于消失;＂双厂＂型曲线出现在Ⅴ级围岩地段,当监测断面距掌子面超过3倍洞径时,围岩变形基本趋于稳定。最后,提出了不同围岩级别下隧道围岩径向位移释放率随时间和距掌子面距离的变化规律,研究结论对于特大断面板岩隧道围岩长期稳定性的研究具有借鉴价值。

Currently the time-space deformation regular pattern of the surrounding rock of superlarge cross sectional slate tunnel during construction period is short of systematic summary.Taking Yaojia tunnel in Chang-Kun Hunan Section of Shanghai-Kunming Passenger Dedicated Line as an example,the time-space deformation regular pattern of tunnel under conditions of different excavation approaches was analyzed based on the field deformation monitoring data.The types of the relationship curves of the surrounding rock deformation with time and the distance to the tunnel working face were divided.The relationship of the surrounding rock displacement releasing rate with time and the distance to the tunnel working face was analyzed.The influence of surrounding rock grade and space location on time-space effect of surrounding rock deformation was researched.The results show that the surrounding rock deformation-time curve can be divided into ＂Bow＂type and＂Bench＂type.The＂Bow＂type can be concluded into 3 deformation stages and it is suitable for surrounding rocks of grade III and grade IV.The＂Bench＂type can be divided into 4 deformation stages and it is suitable for surrounding rock of grade V.The relationship curve between surrounding rock deformation and the distance from the working face can be divided into＂Single Chang＂type and＂Double Chang＂type.＂Single Chang＂type curve is fit for surrounding rocks grade III and grade IV.The surrounding rock deformation tends to be stable and the timespace effect disappears when the distance from the monitoring site to the working face is larger than 5 times of the tunnel diameter.＂Double Chang＂type curve is suitable for surrounding rock of grade V.The surrounding rock deformation tends to be stable when the distance from the monitoring site to the working face is larger than 3 times of the tunnel diameter.Finally the surrounding rock displacement releasing rate under different rock grades with the change of time and the distance to the working face is put forward.The results can be taken as a reference for the research on long-term stability of surrounding rock of super large cross sectional soft rock tunnel.