摘要
通过现场监测试验,研究了黄土隧道围岩变形、围岩压力、初支钢拱架应变、初支与二衬间接触压力随时间变化的规律和空间分布特征,并计算得到二次衬砌的荷载分担比.另外,将实测得到二衬荷载通过荷载结构法计算得到二衬内力,求出实测荷载下的二衬安全系数.结果表明:洞身围岩在黄土范围内变形较大,泥岩范围内变形较小;围岩总变形的60%~77%在开挖后4~6 d内完成,之后持续缓慢增长8~10 d达到稳定;拱顶沉降达到稳定的平均时间为20 d,周边收敛为16 d;围岩变形达到稳定的时间与钢拱架受力时态一致;围岩压力和接触压力的变化为先快速增大、再缓慢增长、最后趋于稳定的三阶段变化规律,围岩压力会受开挖工序、开挖步骤等显著影响,拱腰处二衬在承担围岩荷载方面具有重要作用;二次衬砌结构的安全性在实测荷载下安全系数相对较大,除拱脚处外,其余各部位均由混凝土的抗压强度控制,充分发挥了混凝土的抗压性能.
Through the field monitoring test,the laws and spatial distribution characteristics of loess tunnel surrounding rock deformation,surrounding rock pressure,initial support steel arch strain,and contact pressure between initial support and secondary lining with time are studied.The load sharing ratio of secondary lining is calculated.In addition,the internal force of the secondary lining is calculated by the load structure method,and the safety factor of the secondary lining under the measured load is obtained.The results show that the deformation of surrounding rock is larger in the loess area while smaller in the mudstone area.60%~77%of the total deformation of surrounding rock is completed within 4~6 d after the excavation,and then it continues to increase slowly and reaches a stability after 8~10 d;The average time of vault settlement reaching a stability is 20 d,and the surrounding convergence is 16 d;the stability time of surrounding rock deformation is consistent with the stress state of steel arch.The change of surrounding rock pressure and the contact pressure is a three-stage change rule,which increases rapidly first,then slowly increases,and finally tends to be stable.The surrounding rock pressure will be significantly affected by the excavation process and excavation steps.The secondary lining at the arch waist plays an important role in bearing the surrounding rock load.A safety factor of secondary lining structure is relatively large under measured load.Except for its foot,the rest arch parts are controlled by the compressive strength of concrete,giving full play to the compressive properties of concrete.
作者
师凯强
夏琼
黄志军
杜耀辉
王强
王国靖
SHI Kai-qiang;XIA Qiong;HUANG Zhi-jun;DU Yao-hui;WANG Qiang;WANG Guo-jing(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;National Experimental Teaching Demonstration Center of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;CCCC First Highway Engineering Bureau Co.,LTD.,Bejjing 100024,China)
出处
《兰州交通大学学报》
CAS
2022年第5期13-22,共10页
Journal of Lanzhou Jiaotong University
基金
甘肃省道路桥梁与地下工程重点实验室开放基金(GSDQ-KF2020-2)。
关键词
黄土隧道
围岩变形
荷载分担比
荷载结构法
接触压力
安全系数
loess tunnel
surrounding rock deformation
load sharing ratio
load structure method
contact pressure
safety factor
作者简介
第一作者:师凯强(1994-),男,甘肃定西人,硕士研究生,主要研究方向为隧道工程.E-mail:577172855@qq.com;通信作者:夏琼(1977-),女,甘肃兰州人,副教授,工学博士,主要研究方向为岩土工程.E-mail:929473279@qq.com.
