榴桐寨隧道高地应力软岩大变形机理研究与施工措施应用分析

Study on Large Deformation Mechanism of Stress Soft Rock in Highland of Liutongzhai Tunnel and Application of Construction Measures

软弱围岩在高地应力作用下发生大变形及破坏的特征不仅受围岩本身力学性质的影响,还与原始地应力状况及工程因素等有关。榴桐寨隧道埋深约1 400 m,围岩以软岩为主,构造带可能应力集中,软岩存在大变形问题。隧道软质岩大变形主要影响因素包括地应力条件、岩体强度、地质构造影响程度、地下水发育特征、围岩分级、岩石膨胀性。当围岩内部的最大地应力与围岩强度的比值达到某一水平时才可能发生软岩大变形。研究表明,当强度应力比小于0.3～0.5时,即能产生比正常隧道大一倍以上的变形。通过对榴桐寨隧道发生软岩大变形的机理研究,找到一套行之有效的施工控制措施是保障施工及运营期安全的关键。

The characteristics of large deformation and destruction of weak surrounding rock under the action of Highland stress are not only influenced by the mechanical properties of the surrounding rock,but also related to the original stress conditions and engineering factors.The depth of the Liutongzhai tunnel is about 1400 m,and the surrounding rocks are mainly soft rocks.The stress in the tectonic zone may be concentrated,and there is a problem of large deformation in the soft rocks.The main factors affecting the large deformation of soft rock in tunnel include:stress conditions,rock mass strength,degree of influence of geological structure,groundwater development characteristics,classification of surrounding rock,and rock expansion.When the ratio of the maximum stress inside the surrounding rock to the strength of the surrounding rock reaches a certain level,a large deformation of the soft rock may occur.Studies show that when the strength stress ratio is less than 0.3 to 0.5,the deformation can be more than twice as large as the normal tunnel.By studying the mechanism of large deformation of soft rock in Liutongzhai tunnel,finding a set of effective construction control measures is the key to ensure the safety of construction and operation period.