Study On Liquefaction Characteristics Of Wenchuan Earthquake And Its Correlation With Site Engineering Geological Conditions

The earthquake liquefaction is one of the more common secondary geologicaldisasters caused by the earthquake, preventing and alleviating the liquefaction damage,become a hotspot, difficulty and frontier subject in the fieldof geotechnical earthquakeengineering, it has caught the high attention of scholars both at home and abroad and theengineering.The Wenchuan Ms8.0earthquake which occurrs Sichuan Province in China on May12th,2008is the most destruction, the widest influencing range, the most factors involved,the most disaster losses since the founding of new China. A large number of landslides,collapses mud-rock flow and other geological disasters were caused by earthquake in thevast mountainous area, it caught the wide attention of people. Meanwhile, soil liquefactionwas triggered in the vast region as the center of the Chengdu Plain. And compared to theprevious sand liquefaction, it showed different characteristics in various places. In thispaper, liquefied site survey data is sorted out and analysed, and liquefied and non-liquefiedsite engineering geological conditions are contrasted and studied. Some preliminaryconclusions are reached on the laws of the soil liquefaction in the Wenchuan earthquake.Mainly in the following several aspects:(1) Liquefaction shows typical spraying water and sand boil macroscopic phenomena,it appears in the field, indoor building foundation edge, schools, factories and housesoutside the ground, wells and other places. The majority of ejecta is all types of sand, oreven multiple spray of gravel and pebbles. Liquefaction damage shows cracks, settlementof foundation etc.(2) The characteristics of the geological environment of the main liquefied area(Chengdu Plain) is analysed landform,stratum lithology, geological structure, hydrogenolo-gical characteristics.Combined with the typical soil data and test data,the mainly liquefiedsoil layer of Chengdu Plain in the Wenchuan earthquake is gravel soil, is not common sandbefore the earthquake.(3) It has a significant effect on the earthquake liquefaction for engineering geologicalconditions. Drilling field test and laboratory test results are analysed and counted fromliquefied and non-liquefied sites through the project group during the period of2008to2010in Deyang area. The correlations are conducted a preliminary study between occurrence of earthquake liquefaction and site construction conditions. The results showthat liquefied soil liquefaction depth is less than5m, The liquefied ground groundwaterdepth is generally less than3m. When seismic intensity is higher, the larger site of soildepth can also occur liquefied. The dynamic test shot of liquefied ground soil is mostwhthin4strike. The degree of compaction loosely to slightly dense, The degree ofcompaction gradually increases with the intensity increasing. The shear wave velocity ofliquefied ground soil is generally less than210m/s. When seismic intensity is higher, thelarger site of shear wave velocity can also occur liquefaction.