砂页岩缓倾地层隧道围岩破坏特征及影响因素
Failure Characteristics and Influencing Factors of Tunnel Surrounding Rock in Gently Dipping Sandshale Stratum
张黎杰 1王天勇 1白银银 1汪精河2
作者信息
- 1. 中铁十二局集团有限公司,陕西西安 710000
- 2. 兰州交通大学土木工程学院,甘肃兰州 730070
- 折叠
摘要
砂页岩缓倾地层常为近水平软硬互层岩体,强度和变形各向异性显著,隧道围岩稳定机理复杂.以西延高铁宜君隧道某深埋段为研究对象,在现场地质调查的基础上,采用RFPA建立砂页岩水平互层数值模型,研究无支护条件下的围岩破坏特征,分析软硬岩层厚比、强度比和侧压力系数对隧道围岩破坏的影响规律,并通过现场变形监测进行验证.结果表明:(1)砂页岩缓倾岩体各向异性特征显著,隧道开挖后在拱顶产生沿层面的张拉破坏,随层厚比减小,围岩破坏范围逐渐减小.(2)强度比越小,岩体各向异性越显著,拱顶软硬层交界处易产生剪切破坏,且破坏范围越大.(3)侧压力系数为0.25时,围岩呈现X形破坏,拱顶产生张拉破坏,随侧压力系数增加,围岩破坏范围减小,呈现月牙形分布;侧压力系数为1时,围岩呈现圆环形破坏.(4)围压、层厚比和强度比的增大均可弱化砂页岩缓倾岩体的各向异性特征,声发射数减少,岩体破坏程度降低.
Abstract
The gently dipping sandshale stratum is often a nearly horizontal soft-hard interbedded rock mass,with significant anisotropy in strength and deformation,and the stability mechanism of tunnel surrounding rock is complex.Taking a deep-buried section of Yijun Tunnel on Xi'an-Yan'an HSR as the study object,based on on-site geological survey,this paper establishes a numerical model of horizontal sandshale interbedding by RFPA,studies the failure characteristics of surrounding rock under unsupported conditions,analyzes the influence law of layer thickness ratio,strength ratio and lateral pressure coefficient of soft and hard rock on tunnel surrounding rock failure,and verifies through on-site deformation monitoring.The results show that:(1)The anisotropic characteristics of gently dipping sandshale rock mass are significant.After tunnel excavation,tensile failure along the bedding plane occurs at the arch crown,and the failure range of surrounding rock gradually decreases with the decrease of layer thickness ratio.(2)The smaller the strength ratio,the more significant the anisotropy of the rock mass.Shear failure is prone to occur at the junction between soft and hard layers of arch crown,and the range of failure is larger.(3)When the lateral pressure coefficient is 0.25,the surrounding rock presents X-type failure and tensile failure occurs at the arch crown.With the increase of the lateral pressure coefficient,the failure range of the surrounding rock decreases and presents a crescent-shaped distribution.When the lateral pressure coefficient is 1,the surrounding rock presents circular failure.(4)The increase of confining pressure,layer thickness ratio and strength ratio can weaken the anisotropic characteristics of gently dipping sandshale rock mass,reduce the acoustic emission number,and decrease the damage degree of rock mass.
关键词
西延高铁/隧道围岩/砂页岩缓倾地层/围岩破坏/数值模拟/RFPA/宜君隧道Key words
Xi'an-Yan'an HSR/tunnel surrounding rock/gently dipping sandshale stratum/surrounding rock failure/numerical simulation/RFPA/Yijun Tunnel引用本文复制引用
出版年
2024
NETL
NSTL
万方数据