Estimating earth loads on buried pipes under axial loading condition: insights from 3D discrete element analysis

Abstract

The response of a buried pipe subjected to relative axial ground movement is investigated in this study using three-dimensional discrete element analysis. A discrete element model that is able to simulate the particulate nature of the granular material and the continuous nature of the pipe was developed. The micro-parameters of the model were calibrated using triaxial tests. The developed pipe–soil model was validated using experimental data and then used to calculate the pipe response to axial loading under varying soil conditions. A comparison was also made between the calculated response and the available closed-form solutions. Results indicated that, for pipes installed in dense sand, existing solutions may not properly account for the dilative behavior of the soil and hence underestimate the axial soil resistance. A parametric study was performed using the validated model to evaluate the factors controlling the axial soil resistance under these loading conditions. The contributing parameters are found to be the pipe diameter, burial depth, and soil properties. Results of the parametric study were used to develop an expression to estimate the earth pressure coefficient that reflects the dilative nature of the soil. An example is provided to illustrate the use of the proposed expression in estimating the maximum soil resistance to pullout loading.