摘要
堡镇隧道地质条件复杂,埋深大且地应力高,地下水丰富,岩体软弱破碎,隧道自稳能力差,存在顺层偏压。围岩变形具有"变形速度快、变形量大且破坏严重、持续时间长"的基本特征,同时又表现出时间上和空间上不均匀、不对称等诸多特性。通过对隧道左线出口段围岩变形量测资料和掌子面地质素描的比较分析后发现,掌子面有软弱夹层沿洞室径向分布时,其变形破坏程度较相邻段同类围岩严重得多,不同夹层厚度对围岩变形的影响程度也不同。因此,依据堡镇隧道开挖以来变形破坏程度最严重的高地应力炭质页岩段软弱夹层和围岩的典型组合结构,设计了不同厚度软弱夹层的三轴试验方案,进行了含软弱夹层围岩的室内三轴试验研究和三轴力学性质测试,描述了软弱夹层厚度为2.5 cm和围压为4 MPa时的全应力–应变曲线特征,探讨了系统强度变化规律,分析了围压和夹层厚度对系统强度变化的作用机理及特点。
Baozhen tunnel is the only soft rock tunnel and the key project of Yichang-wanzhou Railway. The complex geological environments, such as high earth stress, deep-buried rock mass, rich groundwater, very weak and cracked rock masses and bias pressure along the rock seam, make the self-stability of the tunnel unfavorable. During construction, intense deformation and serious failure happened. Many serious failures happened due to large deformation, for example, roof subsidence, wall crushing, shotcrete flaking, s-shape twisted steel support, broken lining, floor upheaval, invert crazing and lots of cracks distributed everywhere. The monitoring data show that deformation is rapid with long duration, and at the same time, the deformation presents asymmetric and uneven features. For either sandy shale whose strength is higher or macker whose strength is lower, by comparing and analyzing the monitoring data of surrounding rock and the geologic sketch of work face, the weak interlayer is thought to be the key cause of induced intense deformation and serious failure. So according to the typical composite structure between weak interlayer and surrounding rock in the heaviest deforming section, the rock strength tests on surrounding rock contained weak interlayer are executed, the stress-strain complete procedure curves are described （the thickness of weak interlayer is 2.5 centimeters and confining pressure is 4 MPa）, and their variation rules of system strength with both the confining pressure and the thickness of weak interlayer are analyzed. In addition, the mechanics and features, including the effect of both the confining pressure and the thickness of weak interlayer on strength, are studied.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2009年第5期720-726,共7页
Chinese Journal of Geotechnical Engineering
关键词
软弱夹层
高地应力
大变形机理
围岩稳定性
岩石试验
weak interlayer
high earth stress
mechanics of large deformation
surrounding rock stability
rock test
