Study On Reliability-Based Procedure For Evaluating Liquefaction Potential

Liquefaction-induced damage phenomena occurred during many earthquakes last century, such as Niigata, Xingtai, Haicheng, Tangshan, Alaska, Kobe, Chi-Chi earthquake et.. A series issues induced by liquefaction were paid more and more attention to, the first issue should be solved is that sand liquefies or not after experiencing the given earthquake. So the prediction of sand liquefaction has been a global important study subject in engineering seismology.After field and laboratory test studied for more than four decades, assessment liquefaction has been made great progress, and many different parameter-based deterministic methods were proposed in China and abroad. However, many procedures used in engineering were developed from empirical or heuristic method because of incomplete understanding of the sand liquefaction mechanism, and could only provide the assessing result of"yes"or"no".As the rapid development of engineering construction, the demands of evaluating liquefaction increase gradually, which should not only provide the assessing result of"yes"or"no", but also give the reliability analysis result. Adopting reliability theory for evaluating liquefaction is just at the beginning by now, there are still many key issues should be solved.The main contents and achievements of this paper include:1. The paper has discussed the liquefaction mechanism and effect factors, summarized the new achievements of recent research, analyzed the existent issues, and got some new realizations.2. The paper has summarized some domestic and abroad typical deterministic methods of predicting liquefaction, and introduced the artificial intelligence and specialist system adopted in evaluating liquefaction, pointed out the existent issues and some aspects need to be improved, and got some new realizations.3. The paper has introduced the general theory of reliability analysis, concentrated the key issues during using in assessing liquefaction.4. The paper has studied the new method of getting the probability of liquefaction based on the field investigated data, analyzed the proposed formula's discrete extent, succeed ratio of judging and predicting, and compared the proposed formula with the seismic code procedure.5. The paper has thorough studied the reliability issue of the seismic code procedure, and given its probability results. The succeed ratio of judging, the discrete extent of correlation between the ratio of SPT-N value and the probability of liquefaction, the conservative extent of the code procedure, were checked by using the domestic data, and also the succeed ratio of predicting was checked by using Chi-Chi earthquake data during the reliability analyzing.