Numerical Analyses of Interaction Between Adjacent Structures on Liquefied Soil

Abstract eng:
In all major earthquakes, structures in the proximity of rivers and coastal plains, are often affected by substantial excess pore-water pressure which may lead to soil liquefaction. The excess pore-water pressure will lead to soil softening and change in structural response. However, in the few cases where soil-structure interaction is considered during the analysis process almost always a linear model of the soil and structure is employed. While this model is simple and therefore convenient, the analyses are a poor representation of real soil behaviour. Additionally, in major urban areas most structures are closely adjacent. Therefore, the situation is more complex than free-field condition or just a stand-alone structure. The analysis of a single structure cannot capture the major characteristics of the seismic response of closely adjacent structures. In this work an elasto-plastic multi-mechanism model was used to represent soil behaviour. A coupled solid-liquid phase formulation was utilised. A single degree-of-freedom structure was employed using frame elements. At this stage, a linear structure and nonlinear soil are considered. The coupled soil-structure model is used to simulate the behaviour of single and adjacent structures on sand under conditions of substantial excess pore-water pressure. The analyses show lower settlement under free-field conditions than that evident in the presence of a structure. Also, lower settlement (but higher than the freefield case) was observed for closely adjacent structures compared with the case of an isolated structure. A higher increment in pore-water pressure (but a lower pore-water pressure build-up ratio) beneath structures was also observed. Differences in the response spectrum were evident between an isolated structure and a structure closely adjacent to a rigid block.

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