原位扩建既有隧道围岩应力变化特征  

Stress Change Characteristics of the Existing Tunnel Surrounding Rocks by In-situ Expansion

作　　者：孙大增 赵文[1] 王鑫 柏谦 SUN Da-zeng;ZHAO Wen;WANG Xin;BAI Qian(School of Resources&Civil Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学资源与土木工程学院,辽宁沈阳110819

出　　处：《东北大学学报（自然科学版）》2023年第4期565-572,共8页Journal of Northeastern University(Natural Science)

基　　金：国家自然科学基金资助项目(51878127).

摘　　要：为了评估既有隧道扩建开挖的应力扰动程度和重分布特征,以南岭单线铁路隧道原位扩建工程为研究背景,基于经典弹塑性理论,结合Mohr-Coulomb屈服准则,推导扩建过程围岩径、环向应力变化量计算式,分析不同地层条件、初始应力、等代圆计算方法对应力变化的影响规律.结果表明:二次开挖导致径向应力较扩建前不同程度减小,环向应力先减小后增加,最后趋于原应力状态;围岩应力分布状态与围岩条件、初始应力、等代圆计算方法均相关,采用1/4高度与跨度之和的等代圆计算简化方法,对单线隧道原位扩建的围岩应力变化量求解具有较好的适用性;通过围岩环向应力演化特征的现场实测,验证了应力变化量计算式的准确性,为扩建隧道开挖方案设计及支护参数优化提供理论依据.In order to evaluate the stress disturbance degree and redistribution characteristics of the expansion and excavation of existing tunnels,taking the in-situ expansion project of the Nanling single-track railway tunnel as the research background,based on the classical elastic-plastic theory,and combined with the Mohr-Coulomb yield criterion,the calculation formulas of the surrounding rock diameter and circumferential stress change during the expansion process were deduced,and the influences of different formation conditions,initial stress,and equal-circle calculation methods on stress change were analyzed.The results showed that the second excavation causes the radial stress to decrease in varying degrees compared with that before the expansion,and the circumferential stress first decreases and then increases,and finally remains in the original stress state;the surrounding rock stress distribution state is closely related to the surrounding rock conditions,initial stress,equal-circle calculation methods,and the simplified calculation method of the equal-circle calculation of the sum of 1/4 height and span has good applicability to the calculation of the stress change of the surrounding rocks for the in-situ expansion of a single-line tunnel.The on-site measurement has verified the accuracy of the calculation formula of stress change,and provided a theoretical basis for the design of the excavation scheme of expansion tunnels and the optimization of the support parameters.

关 键 词：隧道工程 原位扩建 二次扰动 应力演化 变化特征 敏感性分析 

分 类 号：U218[交通运输工程—道路与铁道工程]