Analysis of Local Variations in Free Field Seismic Ground Motion

摘要

Earthquake engineers are often faced with the problem of determining the temporal and spatial variation of near-surface seismic motions in a site. This type of information is needed for the evaluation of soil-structure interaction effects, liquefaction potential and the effects of local site conditions on surface motions. Actual ground motions are due to a complicated system of body waves and surface waves. However, it is usually assumed that near-surface motions consist only of vertically propagating waves. In order to examine the validity of this assumption for engineering design a theoretical investigation has been made into the nature of near-surface motions produced by horizontally propagating waves. These include inclined P-, SV-, and SH-waves, Rayleigh waves and Love waves in horizontally layered sites over a viscoelastic half space. The research involved five phases: (1) review of current knowledge, (2) development of new methods of site response analysis, (3) application to site response analysis, (4) application to soil-structure interaction analysis and, (5) evaluation of the relative importance of horizontally propagating waves in engineering design. (Author)