及时支护隧洞变形规律研究及稳定性评价

Analysis of deformation and failure characteristics for surrounding rock of soft-rock tunnel and stability evaluation

针对软岩及土质隧洞围岩强度低、稳定性差及现有隧洞围岩稳定性评价方法对及时支护隧洞的不适用性,通过数学模型试验系统研究了弹性模量、泊松比、黏聚力、内摩擦角、埋深、洞径和侧压力系数等与需及时支护隧洞拱顶围岩变形和喷层受力的相互关系,并据此探讨了以支护结构安全性为标准的隧洞围岩稳定性评价新理念。该理论在新疆库尉输水工程的成功应用表明其具有较好的可靠性。数值试验结果显示各因素对拱顶围岩变形和喷层应力影响显著,且对大主应力的影响尤为明显,随变形的发展喷层拱顶处应力主轴对调,大、小主应力名称互换。喷层大主应力随弹性参数的增大而增大,随强度参数的增大而减小。该研究成果能为软岩隧洞工程的设计和施工提供理论指导。

Soft-rock tunnels are more and more widely used in metal mines, traffic tunnel and hydraulic projects. Because the soft rock has low strength and poor stability, the tunnels excavated in the soft rocks must be supported immediately. The current stability evaluation methods given in the design specifications cannot be used for the tunnels which should be supported at once. To deal with these problems, the interrelationships of vault deformation and spray stress in the soft-rock tunnel are investigated based on several numerical experiments including the interrelations between different elastic modulus, Poisson ratio, cohesion, internal frictional angle, buried depth, diameter, lateral pressure coefficient, and so on. Based on the interrelationships, a new concept of the stability evaluation of the rock mass is discussed based on the security of the supporting structure, and the reliability has been demonstrated by the water diversion project located at Kuyu in Xinjiang Uygur Autonomous Region. The numerical test results show that all variables have significant influences on the vault deformation and spray stress, especially for the major principal stresses. With the development of the deformation, the principal stress axes are exchanged and the names of major and minor principal stresses interchanged. The major principal stress of shotcrete increases with the increase of elastic parameters and decreases with the increase of strength parameters. The research results can provide a theoretical guidance for the design and construction of the similar soft-rock tunnels.