Book Description

"Buried pipes are safe and economical method of transporting natural resources. Failure of these infrastructures poses significant damage to the environment and people safety. Permanent ground deformation is one of the major causes of buried pipe failure. It was reported that axial force on pipes buried in dense granular material obtained using the current guidelines can be significantly smaller than the measured values. Standard finite element methods are known to be efficient in studying soil-structure interaction problems, however, modeling soil-structure interaction involving granular material and large deformation is challenging, particularly at the particle scale level. On the other hand, the discrete element method has proven its capability in capturing the response of granular material at the microscopic scale. However, the method has some limitation in modeling flexible structural elements. Coupling the discrete and finite elements methods is a promising approach that takes advantage of the two methods. In this thesis, the response of buried pipes subject to axial and lateral ground movements are evaluated using three-dimensional discrete and coupled discrete-finite element methods. The research results have been published in refereed journals and presented in seven chapters that comprise this manuscript-based thesis. The behavior of rigid pipe buried in dense sand under axial ground movement is first evaluated using discrete element method. The input parameters of the model are obtained using a precise calibration procedure and numerical results are validated using experimental data. Results indicated that, for the rigid pipes buried in dense sand, current equations may not properly consider the dilative behavior of the soil and underestimate the soil axial resistance. The numerical approach has proven to be efficient in modeling pipelines subjected to relative soil movement. The created model is then used to conduct a comprehensive parametric study to develop a new expression that estimates the earth pressure coefficient and the soil axial resistance acting on the rigid pipe. A three-dimensional coupled finite-discrete element framework has been developed and used to investigate the response of a (medium density polyethylene) MDPE pipe under axial and lateral relative ground movements. The pipe is modeled using finite elements while the surrounding soil is modeled using discrete elements. Interface elements are used to transfer forces between these two domains. The response of the soil at microscale level was analyzed and the deformations and strains developing in the MDPE pipe were investigated. Results showed that caution must be considered when using current methods in the analysis of MDPE pipes. Conclusions and recommendations have been made on the pipe-soil interactions under soil movement." --