Monte Carlo Simulation to Perform Liquefaction Evaluation of Conveyance Systems

Field investigations can be very expensive for the liquefaction evaluation of buried pipelines, which may traverse through miles of potentially liquefiable zones in seismic regions. Liquefaction phenomenon as a natural process is inherently random and affected by the earthquake magnitude, peak ground acceleration, soil type and relative density, effective overburden pressure, thickness of liquefiable soil, and depth to groundwater and their variabilities. The state of such processes is naturally indeterminate and thus cannot be described with certainty. As such, decisions required for emergency planning of possible pipeline failure are invariably made under conditions of uncertainty. The quantification of the uncertainties and proper evaluation of their adverse effects on the performance of a pipeline can be estimated by performing a probabilistic liquefaction hazard analysis (PLHA) using the Monte Carlo simulation (MCS). MCS uses principles of probability in which the uncertainties are identified, quantified, and combined in a rational manner in order to explain the impact of uncertainties in prediction and forecasting liquefaction hazards along a pipeline. This paper evaluates probabilistically the adverse effects of liquefaction hazards on the structural integrity of a hypothetical pipeline while traversing through miles of saturated and potentially liquefiable young alluvium in the San Fernando Valley and Los Angeles Basin due to earthquakes either on the south San Andreas fault (SSAF) or Newport-Inglewood fault (NIF).