Seismic Interactive Deformations of Pipeline Buried in Sandy Slopes Using Numerical Modeling with a Systematic Calibration Procedure

The seismic landslide-pipe problem was investigated numerically using finite-difference code and a bounding surface soil constitutive model [Simple ANIsotropic SAND constitutive model (SANISAND)]. The SANISAND model was calibrated using triaxial monotonic and cyclic tests at the element level and shaking-table test results at the boundary value level. The results show that the calibrated parameters of the SANISAND model can predict monotonic and cyclic triaxial test results and slope displacement response properly. After the verification process, the dynamic response of a slope with the presence of buried pipes under sinusoidal input acceleration was evaluated in terms of slope displacement and the pipe axial strain. The results show that the presence of buried pipes in the slope can reduce slope surface displacement by 50%, especially for shallower burial depths of pipe (i.e., 1-1.5 m). The results of the axial strain of the pipe for changes in the burial depth and location indicate that for pipes buried in the downslope and upslope sections, deeper and shallower burial depths, respectively, lead to less axial strain being imposed on the pipe under landslide actions. The variations of slope geometric parameters (slope width and inclination angle) on slope displacement response and pipe strain patterns show that with increasing slope width and inclination angle, the displacement of sliding mass increases, and the depth of the slope failure wedge decreases. Moreover, the maximum strain of the pipe increases by 150% as the width-to-height ratio (W=H) of the slope increases from 1 to 4. With the increase in soil density, the pipe axial strain increases. The results of dynamic analysis under earthquake records showed that the axial strain of the pipe has a high correlation with the cumulative absolute velocity of seismic input.