Primary Study On Analysis Method For Earthquake-induced Differential Settlement Of Buildings Caused By Liquefaction

Foundation settlement caused by soil liquefaction is a crucial subject when doing the structure seismic design. Liquefaction of saturated sand during earthquake is one of the most important reasons why buildings are destroyed. The earthquake-induced settlement on liquefiable field are normally uneven, thus this kind of differential settlement has the same hazard as the differential settlement on static situation.In the past considerable research productions have been made in the realms of investigation on liquefiable field, liquefaction mechanism, liquefaction prediction, and analysis method of effective strength. However, the analysis method of buildings'settlement caused by liquefaction is developed relatively slow. Hence it is an emergency problem that to form an effective method when analyzing the earthquake-induced differential settlement caused by liquefaction.This paper mainly did some fundamental research works about earthquake-induced settlement caused by liquefaction on saturated sand soils. Progresses were made in the following items:(1) Illustrated the increase model of pore water pressure and the calculating formula that the saturated sand consolidates under anisotropic conditions, based on the dynamic triaxial tests results. Some numerical simulation concerning several main influence factors were did, analyzed the influence factors of the increase of pore water pressure such as amplitude and waveform of input waves, asymmetric of waves, soil features, and consolidation ratio.(2) Summarized the past researches of the earthquake hazard, finite element method, shaking table tests about soil-structure interaction. The mechanism of earthquake-induced differential settlement on liquefiable soil layers was given. Based on this issue, key points of calculating the earthquake-induced differential settlement on liquefiable soil layers was organized.(3) According to the mechanism of earthquake-induced differential settlement, when considering the cooperative reaction of earthquake wave, soil foundation conditions, and the distribution of loads acted on buildings, a preliminary finite element method for earthquake-induced differential settlement caused by liquefaction was given. When forming this method, two models were used: increase model of pore water pressure under irregular loads and anisotropic consolidation conditions; improved model of soil gradually soften.