Numerical study of lateral soil resistance to pipe movement in sandy slopes

Abstract

The lateral pipe-soil interaction in sloping ground is numerically simulated, with a modified Mohr-Coulomb model adopted to capture the state-dependent behavior of dense sand. The numerical model is first validated by previous physical tests in level ground. Then, both peak and residual lateral resistance are investigated in nonpositive slopes (pipeline moves relatively outwards the slope), while only the former is focused in opposite cases. The effects of burial depth ratio, interface roughness and slope angle on soil resistances are specially discussed. It is found that in terms of the failure mechanisms, increasing the slope angle implies to some extent an increase of burial depth ratio in level ground. A positive slope usually provides higher soil resistance than a negative slope for a given burial depth ratio as the normalized normal pipe-soil contact stress on the pulling side increases with the slope angle. The difference in peak resistance between the perfectly smooth and generally rough pipeline is amplified in positive slopes, which is associated with the transition of the failure mechanisms. Finally, a preliminary methodology to evaluate the soil resistances in sloping ground is presented, based on the improved implicit limit equilibrium method for level ground and newly proposed slope effect coefficients.