采空塌陷区管道最大轴向应力计算及统计分析

Calculation and statistical analysis of maximal axial stress at mining subsidence area

采空塌陷对埋地油气管道的安全完整性构成了严重威胁。为此,在分析采空塌陷区管道变形基本特征和简化采空塌陷区管道半空间受力分析模型的基础上,对非沉陷区和沉陷区分别构建了计算模型,计算了不同工况条件下不同塌陷区长度、不同沉降量所对应的管道内部最大轴向应力,根据相关规范并采用最小二乘法,分别得出了只考虑管道内压不考虑强度折减系数和既考虑管道内压也考虑强度折减系数的沉陷区长度与对应的管道极限下沉量的统计关系,并得出以下结论:①在开采沉陷区,当没有发生塌陷时,埋地管道所承受的应力主要是其内压产生的轴向拉应力;②而当发生塌陷时,埋地管道所承受的应力主要是其内压和因塌陷产生的管道轴向拉应力之和;③在沉降区边缘的管道上部承受的应力值最大,其次是沉陷中心的管道下部,并承受着拉伸应力;④沉降盆地边缘的管道下部和沉陷中心的管道上部承受着压缩应力。

The mining subsidence has seriously threatened the security and integrality of the buried oil and gas pipelines.Based on the analysis of the basic characteristics of pipeline deformation and the half-space force analysis model being simplified in the mining subsidence area,the calculation models of the non-sedimentation area and sedimentation area were respectively established.The maximal axial stresses of the pipeline interior were calculated corresponding with the different lengths of the sedimentation area and settlement volume.According to the relevant rules and the least square method,we obtain the statistical relations between the subsidence area length and the corresponding utmost pipeline settlement volume when considering not the strength reduction factor but the pipeline internal pressure and when considering both two factors respectively.The results show that in the mining subsidence area,when mining collapse does not take place,the stresses of the buried pipelines are mainly the axial tension stresses caused by the internal pressure.When mining collapse takes place,the stresses are the sum of internal pressure and axial tension stress caused by the collapse.The top of the pipeline,which is on the edge of the subsidence area,has the maximal stress;the lower part of the pipeline,which is at the center of the subsidence area,bears the stretching stress;the lower part of the pipeline,which is at the edge of the subsidence basin and the upper side of the pipeline,which is at the subsidence center,bear the compression stress.The research results have great significance to the security and integrity management of the oil and gas pipeline at the mining subsidence area.