含环向表面裂纹埋地管道的沉降裕度

Settlement allowance of the buried pipeline with circumferential surface cracks

为了确保含环向表面裂纹埋地管道的安全,需要准确获取埋地管道所能承受的最大沉降量。在设计压力下,采用全尺寸管道的四点弯沉降模拟试验,获得含环向表面裂纹管道的极限承载弯矩。建立沉降模拟试验的有限元模型,以断裂韧度为失效指标,计算模拟含环向表面裂纹管道的极限承载弯矩。通过模拟试验验证有限元模型的有效性,改变管道模型的裂纹深度可以得到一系列含不同深度环向表面裂纹管道的极限承载弯矩。同时,采用ANSYS软件建立场地不均匀沉降时的管土模型,分析管道埋深对沉降管道承载弯矩的影响。分析含不同深度环向表面裂纹管道的极限沉降量可知,当管道埋深不变时,管道发生失效的极限沉降量与裂纹深度呈近似线性负相关;当管道裂纹深度不变时,管道的极限沉降量与埋深呈非线性负相关。

In order to ensure the safety of a buried pipeline with circumferential surface cracks,it is necessary to accurately figure out the maximum settlement that the buried pipeline can bear.In this paper,the simulation test on the four-point bend settlement of full-size pipeline was carried out under the design pressure to get the ultimate bearing bending moment of the pipeline with circumferential surface cracks.Then,the finite element model for the settlement simulation test was established,and the ultimate bearing bending moment of the pipeline with circumferential surface cracks was calculated and simulated by taking the fracture toughness as the failure indicator.After the finite element model was verified effectively by the simulation test,a series of ultimate bearing bending moments of the pipeline with circumferential surface cracks of different depths could be obtained.Meanwhile,a pipe-soil model for the uneven settlement of the site was established using the software ANSYS,and the influence of pipeline depth on its bearing bending moment was analyzed.It is indicated from the analysis on the ultimate settlement of the pipeline with circumferential surface cracks of different depths that when the pipeline depth is constant,the ultimate settlement of pipeline failure is in an approximate linear negative correlation with the crack depth.And when the crack depth of pipeline is constant,the ultimate settlement corresponding to pipeline failure is in a nonlinear negative correlation with the pipeline depth.