Effect of soil stratification on deformation of buried pipelines

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 FLAC^3D 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.