The Liquefaction Assessment Method Based On Central Point Method And Its Appication

Liquefaction of sandy and silty soil is one of most conspicuous seismic damage caused by earthquake, the following issues such as ground sinking,deformation ,frift ,sand blasting were the main reason caused the out-of-run of the engineering buildings, road, farmland and water engineering.In recent years, big earthquakes have taken place frequently all over the world,all these have the damage phenomena induced by liquefaction, a series issues caused by liquefaction were paid more attention to.With the rapid development of engineer construction, the methods which have been used to distinguish liquefaction were improved gradually, the results of reliability analysis was aslo needed. The reliability analysis method which regards project parameter as random variables, can solve the disadvantages of exsiting deterministic methods, such as disunity standard , parameter randomness.It is a better method and deserves further extension ,that ont only decides the safety of project, but aslo give the degree of safety .The main contents and conclusions of this paper are as follows:(1) The mechanisms and influencing factors of sand liquefaction , the investigation results and existing problems about sand liquefaction of the big earthquakes in recent years were discussed in this paper. Several classical common liquefaction estimation methods and some new estimation methods were presented and the disadantages of them were pointed out. Based on structure reliability analysis method, a few evaluation methods of reliability analysis and its feasible use in liquefaction discrimination were also invested.(2) According to the fundamental principle of the central point method ,limit state equation of blow count of SPT was established based on reliability analysis method, distribution inspection and distribution preference of blow count of SPT and depth of water table were performed using likelihood ratio test, and the corresponding programmes for computing liquefaction probability and liquefaction hazard probability werecompiled. Some meaningful results were obtained based on the analysis results of tangshan earthquake and the contradistinction with the results of the code methods and actual data.(3) The modified liquidity index adapted to the norm of China and the suggestion which grades the hazard degree of liquefaction in step with it were introduced. Considering the geomorphy of the construction site and the significance of the project , a allround estimated method for liquefaction estimation and liquefaction hazard evluation, the possibility and the hazard degree of liquefaction of Oupu limited company goods flow center foundation in Fushan city and welfare center of jiangmen city was analyzed. The feasibility and accuracy of analyzing sandy soil liquefaction with reliability method and the hazardness evalution were validated.