Rate-dependent Liquefiable Soil-pile Interaction

The liquefaction of saturated sand is one of the main reasons of pile failure. The liquefied soil-pile dynamic interaction is a hot spot issue in geotechnical earthquake engineering.The characteristics of liquefied soil-pile dynamic interaction were revealed in this paper by small scale shaking table experiments. The rate correlation of dynamic interaction was proved. On the basis, this paper took the liquefied soil as fluid. The rate pile-soil interaction simplified analysis method was presented, and the related factors of the rate interaction were analyzed.The main works as follows:1. Based on drag tube test, the liquefied sand with the "shear thinning" fluid characteristics is confirmed. Further more, the viscous shear by liquefied soil acting on the wall is considered to be the main load of soil and tube in the relative motion needed to overcome. And the rate correlation is significant. The visible positive correlation of bending moments and lateral velocity on the soil around piles can be founded through group piles in liquefied ground force response characteristics test. The aseismatic design of pile foundation should consider rate correlation of liquefied formation.2. The pile-soil ratio related action effects simplified analysis method is proposed for having been completed shaking table tests. Compare the pile reaction by simplifying the calculation methods of analysis with the test results, the reliability of this simplified analysis method is validated, along with analyzing these error sources. Finally, the section points out the advantages of the simplified analysis method.3. These factors including soil compactness, the thickness ratio of non-liquefied layer of covering layer and liquefied layer, the seismic dynamic loading frequency are analyzed to effect on rate-dependent interaction of pile-soil. The critical point pore pressure ratio is defined when the pile occurs maximum bending moment. It is summarized that the occurrence conditions of critical point of pile foundation in the inner force response. The characteristics of critical point is revealed.