FULLY COUPLED INELASTIC SITE RESPONSE ANALYSIS FOR 1986 LOTUNG EARTHQUAKE

Two major earthquakes (M = 6.2 and M = 7) with different characteristi cs took place in the eastern coast of Taiwan in 1986 within a 4-month period. A test site at Lotung was located near the epicenters of the t wo quakes. The site was instrumented with three-dimensional (3D) surfa ce and downhole accelerometer arrays and pore-pressure transducers emb edded at depths from 3 to 16 m below the ground surface. Field investi gation of the site, including sampling ''undisturbed'' soils, was carr ied out before the two events, and followed by a laboratory test progr am aimed at gaining detailed soil properties. Based on the available i nformation, numerical analyses were performed using a fully coupled mu ltidirectional dynamic procedure incorporating a bounding surface hypo plasticity model. The calculated responses for the two different event s showed equally reasonable agreements with the field records in both 3D acceleration and pore-pressure time histories. This paper reports t he methodology of the analyses and presents the recorded data and calc ulated results.