Geotechnical and Seismic Design Considerations for Coastal Protection and Retaining Structures in Reclaimed Lands in Manila Bay

Abstract

In recent years, more and more reclamation projects along the coastlines of the Philippines’ capital, Manila, are being envisioned and realized. With the commonly known poor ground conditions in coastal areas, characterized by soft and loose sedimentary soils, coupled with the combination of hazards that endanger the country, both seismic and climate related, the need for performance based, advanced engineering analyses has never been more important in the local design scene. This paper presents the geotechnical and seismic considerations in the long-term design of coastal protection and retaining structures of land reclamation projects in Manila Bay, aimed at addressing the multiple hazards inherent on the geographical location of the country. State-of-the-art technologies and approaches in geotechnical characterization and seismic analysis are discussed, including the seismic tests using seismic velocity logging (SVL) to obtain relevant dynamic properties of the soil, probabilistic seismic hazard analysis (PSHA) to quantify the overall seismic hazard of the area and obtain appropriate ground motions, and nonlinear time-history analysis (NLTHA) by finite element method (FEM) to simulate the response of the land mass and structures during earthquake events. A case study on a massive land reclamation development along the shorelines of Manila Bay is presented.