摘要
甘肃庆阳新近纪上新统红层由于特殊的成因,其工程力学特性与南方红黏土有较大差别。为系统研究穿越该地层大断面隧道支护结构的受力特征,以银西高铁庆阳隧道为研究对象,通过现场实测和有限元模拟获得衬砌结构内力、围岩压力、5～10 m围岩深部位移、支护收敛变形的时空分布特性,对现场监测结果体现的衬砌-围岩复合结构受力状态产生的原因进行分析,并利用ABAQUS软件模拟隧道开挖过程以对比验证衬砌结构受力规律,得出该地层隧道地应力、围岩压力、衬砌结构内力特征。研究结果表明:1)围岩各项指标属于极硬土—极软岩临界范畴。2)该地层衬砌结构围岩质量较好,水平地应力为垂直地应力的2倍,可优化为Ⅲ—Ⅳ级围岩进行设计的同时增大侧压力系数。3)未闭合的初期支护不能有效限制围岩变形,可通过设置临时仰拱等措施改善受力状态;数值模拟结果与现场实测规律相符。4)该地层变形剧烈区为洞周开挖界限向围岩内1倍洞径范围,变形区域主要集中在拱顶;延迟开挖仰拱可有效减少仰拱内衬砌结构受力。
Neogene Pliocene series red beds in Qingyang of Gansu Province, due to special origin, the engineering mechanical properties are different from that of the southern red clay. It is important to systematic study the mechanical characteristics of large cross-section tunnel support structure through the stratum. Taking Qingyang Tunnel of Yinxi High-speed Railway as the research object, the spatiotemporal distribution characteristics such as internal force of lining structure, surrounding rock pressure, deep displacement for 5-10 m surrounding rock, and convergence deformation of support are obtained through field measurement and finite element simulation. The causes of stress state of lining- surrounding rock composite structure that reflected by field monitoring results are analyzed. In addition, ABAQUS software is used to simulate the process of tunnel excavation so as to contrast and verify the force law of lining structure. The characteristics of crustal stress-surrounding rock pressure-internal force of lining structure in the tunnel of this stratum are obtained. The results show that:( 1) The indexes of surrounding rock belong to the critical category of extremely hard soil and extremely soft rock.(2)The surrounding rock of the lining structure at this stratum is with good quality, and the horizontal crustal stress is twice as big as the vertical crustal stress. Therefore, it can be optimized to level Ⅲ-Ⅳ surrounding rock and increase the lateral force coefficient.(3)The primary support without closure cannot effectively limit the deformation of surrounding rock, and the stress state can be improved by measures such as setting temporary invert. The numerical simulation results are consistent with the field measurement.(4) The severe deformation area is within 1 time hole diameter range from the excavation limit around the cave to the surrounding rock, the deformed areas are mainly at crown. The stress on the invert of inner lining can be effectively reduced by delaying excavation.
作者
谢卓吾
叶万军
刘禹阳
XIE Zhuowu;YE Wanjun;LIU Yuyang(School of Architecture and Civil Engineering, Xi′an University of Science and Technology,Xi′an 710054, Shaanxi, China;School of Highway, Chang′an University, Xi′an 710064, Shaanxi, China)
出处
《隧道建设（中英文）》
北大核心
2019年第4期609-618,共10页
Tunnel Construction
基金
中国铁路总公司科技研究开发计划课题(2017G007-G)
关键词
隧道工程
大断面隧道
受力特征
监控量测
有限元模拟
tunnel engineering
large cross-section tunnel
mechanical characteristics
monitoring measurement
finite element simulation
