富水区衬砌-围岩接触关系对外水压力影响研究

Analysis of Impact of Contact Relationship between Lining and Surrounding Rock on External Water Pressure in Rich Water Areas

结合某大型富水区深埋隧洞工程,基于ABAQUS采用有限元分析法,通过调整过渡层渗透系数模拟围岩与隧洞之间的接触紧密程度,计算衬砌结构的受力特性,并结合规范中的外水压力折减系数法,提出合适的衬砌-围岩折减系数.结果表明:在主要考虑外水压力情况下通过调整过渡层单元的渗透系数来模拟衬砌与围岩的接触关系是合适的,围岩与衬砌的接触关系对于衬砌结构的受力有显著影响;当过渡层渗透系数增大到某一范围时,对衬砌受力影响逐渐变得不再敏感,此时基本处在衬砌与围岩之间有渗水通道的状态.当渗水通道存在时,计算外水压力时可以取折减系数在0.870左右.

Base on one large deep tunnel project in rich water region, this paper uses finite element method on ABAQUS to simulate the contact relationship between surrounding rocks and tunnels by adjusting the coeffi cient of permeability transition layer and calculate the stress of the lining structure features. Meanwhile, this paper also suggests a possible value of β based on the regulation. The results show that it is reasonable to simulate the contact relationship by adjusting the coefficient of permeability transition layer under the condition of main external water pressure. Plus, transition layer permeability coefficient has a significant influence on the compressive and tensile stresses; when the transition layer permeability increases to a certain extent, it gradually becomes no longer sensitive to the stress of lining, which means practical water seepage channels are appeared between the lining and surrounding rocks; 0. 870 is the advisable value of ; when the practical water seepage is existed.