基于应变理论在采空区管道失效分析中的应用

Application of strain-based theory in failure analysis of pipeline subjected to mining collapse areas

长输油气管道下伏采空区是一类复杂的管-土耦合作用问题,由于采空塌陷作用造成的地表变形给管道安全评价带来了特殊的困难。针对采空区空间位置的变化和不同的开采工况,采用基于应变理论的Ramberg-Osgood本构关系,建立采空塌陷区油气管道的有限元仿真计算模型,分析不同开采条件下管道的变形规律,讨论采用基于应变和基于应力两种不同理论对采空塌陷区管道失效判据的影响。结果表明:管体应变与采深H呈负相关,与采厚M呈正相关;采深采厚比H/M一定时,采深对管体应变的影响更大,多层重复采动方式更容易引起管体发生较大的变形;采用基于应变设计理论作为管道失效判据,可充分发挥管道的抗大变形能力。

The interaction of long-distance oil and gas transportation pipeline and underlying mined-out area is a kind of complicated pipe-soil coupling mechanical problem, and it is difficult to give a safety evaluation of pipeline subjected to ground movement and surface subsidence due to mining collapse. Based on the Ramberg-Osgood constitutive equation, the deformation regulations of pipeline subjected to mining collapse were analyzed using finite element numerical simulation by taking into account the change of spatial position of mined bed and different mining ways. The effects of strain-based theory and stressbased theory on failure criteria of pipeline were compared. The results indicate that the pipe strain has a negative correlation with the mining depth H, and a positive correlation with the mining thickness M. The mining depth has a more important in- fluence on pipe strain than the mining thickness when H/M is constant. The multiple repeated mining is more likely to cause larger deformation of pipeline than single mining. The ability to resistance to great deformation of pipeline can be utilized sufficiently taking the strain-based theory as failure criteria of pipeline subjected to mining collapse.