Probabilistic Assessment of Pseudo-Static Design of Gravity-Type Quay Walls

Abstract

Failure of the quay walls due to earthquakes results in severe economic loss. Because of hazards threatening such inexpensive nodes of national and international transportation networks, seismic design of quay walls is still an evolving topic in marine structural engineering. This study investigates the sensitivity of the gravity-type quay wall stability respect to uncertain soil and seismic properties using ultimate limit-sate pseudo-static design process. Stability is defined in terms of safety factor against sliding (<em>sfs</em>), overturning (<em>sfo</em>) and exceeding bearing capacity (<em>sfb</em>). In order to assess the forces exerting on quay walls, to be more accurate, pore water pressure ratio, horizontal and vertical inertia forces, fluctuating and non-fluctuating components of hydraulic and soil pressure were considered. It was found that the increase of water depth in front of the quay, vertical and horizontal seismic coefficients, and pore water pressure ratio play important roles in reduction of all mentioned safety factors. Increase of specific weight of the rubble mound, backfill and foundation soil, friction angle of wall-foundation/seabed interface and wall back-face/backfill interface and friction angle of backfill soil, lead safety factors to magnify. A comprehensive sensitivity analysis was also performed using the tornado diagrams. Results of this study could give designers insights into the importance of uncertain soil and seismic factors, in order to choose geometry of the design in a way that its analysis and assessment is less relied on severely uncertain parameters and to introduce more reliable and economic quay walls.