Earthquake-Resistant Design of Earth Retaining Structures: An Overview

Ram Prasad Sharma

Department of Civil Engineering, B. I. T. Sindri, Dhanbad, India.


For earthquake-resistant design of earth retaining structures like retaining walls, bridge abutments, quay walls, anchored bulk-heads, and braced excavations, the knowledge of seismic earth pressures is essential to minimize the devastating effects of earthquake hazards. During earthquake shaking, soil pressures that act on retaining structures include both static and dynamic components. Dynamic forces vary as the shaking proceeds and reflect not only the type of wall and soil retained but also complex structure-interaction effects that in general are difficult to analyze. For example, motion components that are close to the natural period of the soil structure system can induce very large transient pressures. Also, phase difference along the length of the retaining structure may induce significant shear forces and bending moments. In practice, however,most walls are designed using simplified pseudostatic methods. The approach is to determine all static forces, along with psedostatic seismic forces, and proceed with conventional stability checks for overturning, sliding, bearing capacity, and overall stability. In this paper, differentmethods to calculate seismic forces and their point of application are reviewed, analysis of retaining wall for liquefied and weakened backfill soil is discussed and methods for earthquake analysis of restrained and temporary braced walls are presented.

Keywords: Earth retaining structures, Seismic active earth pressure, Seismic passive earth pressure, Pseudo-static analysis, Pseudo-dynamic analysis, Displacement based analysis.

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