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管道穿越采空区时可能形成暗悬,长距离的管道暗悬会使管道产生较大的应力应变,严重时会拉断失效。基于非线性有限元法,建立了三维暗悬管道力学计算数值模型,采用基于应变的设计准则对采空暗悬管道进行安全性评价。模型考虑了管材、管土相互作用及几何大变形多重非线性因素,采用非线性土弹簧单元模拟管土作用,采用壳单元描述管道变形。分析了暗悬管道在不同工况下的应力应变响应,对比了采用基于应力与基于应变失效准则判断暗悬管道极限状态的差异。分析结果表明:针对暗悬管道,采用基于应力的准则偏于保守,采用基于应变的准则能够更多地利用管材的塑性性能。本文可为管道的完整性管理与安全评价提供一定的理论参考。
The pipe may form a dark suspension when it passes through the gob, and the long pipe dangling will cause large stress and strain in the pipe and will fail in severe cases. Based on the nonlinear finite element method, a numerical model of three-dimensional dark-suspended pipe is established, and the safety of the mined-out dark pipe is evaluated based on the design criterion of strain. The model takes into account the multiple non-linear factors of pipe, soil-pipe interaction and large geometric deformation. The nonlinear soil spring unit is used to simulate the pipe-soil interaction and the shell element is used to describe the pipe deformation. The stress-strain response of the suspended pipe under different working conditions is analyzed. The difference between the limit state of the suspended pipe based on the stress and the strain failure criterion is compared. The results show that the stress-based criterion is conservative for drowned pipelines, and the strain-based criterion can make more use of the plasticity of pipe materials. This paper can provide some theoretical reference for the integrity management and safety evaluation of pipeline.