地层非均质成层性对地下管道的变形影响

Effect of soil stratification on deformation of buried pipelines

地层成层性会对地下管道的变形产生重要影响,针对地层成层特性及管道变形规律的研究还很不成熟。基于弹性层状理论,利用传递矩阵法和有限差分法建立了能够考虑土体非均质条件下的地下管道变形计算方法。结合算例与传统理论法及FLAC3D法进行对比验证,并进一步讨论了地基的成层特性及土体影响随深度的衰减规律。结果表明：管道下方首层土性对其力学反应的影响最为显著,各土层影响随其埋深的增加而逐渐减弱;未考虑土层成层性的均质化处理方法得到的计算结果,对于上软下硬地层偏于危险,而上硬下软地层偏于保守;考虑土层影响衰减规律的均质解与成层解较为接近,采用权重分析法得出的衰减函数符合负指数分布,上软下硬地层的影响衰减速度要快于上硬下软地层。

Soil stratification exerts an important influence on deformation of buried pipelines, and stratified characteristics and deformation laws still need further to be studied. A method for calculating deformation of pipelines is established based on the theory of elastic multi-layer foundation, considering the non-homogeneous features of soils by the transfer matrix method and the finite difference method. The results are compared with those of the traditional theory and FLAC3 D via examples. A further study is made to investigate the stratified features of soils and the attenuation laws with depth. The results show that the first underlying soil layer has a significant impact on mechanical response of pipelines and the influence of each layers decreases with the increase of its buried depth. The calculated results obtained by the homogenization method without consideration of the stratification features of soils are dangerous for the upper-soft and lower-hard strata and conservative for the upper-hard and lower-soft strata. The homogeneous solutions which take the attenuation laws of layered soils into account approach to those of stratification. The attenuation function obtained by the weight analysis method accords with the negative exponential distribution, and the attenuation rate in the upper-soft and lower-hard strata is much faster.