Experimental and numerical investigation of lateral interaction between buried polyethylene pipe and sandy soil subjected to strike-slip faulting

Buried pipelines are vital infrastructures and are mostly used to transport energy and other essential commodities. One of the most important seismic hazards on buried pipelines is movement of faults crossed by them. In general, pipeline can be simplified as a beam, while pipe-soil interaction can be represented by soil springs in the axial, horizontal and vertical direction. Although this method has been implemented previously by ASCE and ALA guidelines the specifications of these springs are not well-defined. In this study, a full-scale tests were carried out on polyethylene pipe buried in dense sandy soil (with 120.5 mm of diameter). The response of the system (such as displacements and reaction loads) were recorded during the tests. A computer program was developed to optimize the specifications of the equivalent springs using Python scripts in MATLAB and ABAQUS environments. In this way, the deformation of the pipe along its length would have the highest level of congruence with the experimental results. Using the proposed approach, the initial stiffness and maximum soil-pipe interaction force have been calculated and compared to the criteria recommended by ASCE and ALA standards. The results showed that the value of yield force capacity and stiffnesses for the soil lateral equivalent springs, provided by ASCE and ALA codes, are determined to be in a great value of error. For polyethylene pipe at the condition of strike-slip faulting, these values were too smaller than the values put forth by ASCE and ALA .