Study On Loess Liquefaction Evaluation Based On Physical Indexes And Depth Limit

The evaluation of liquefaction potential in loess area is a prediction whichforecasts the probability and severity of the loess liquefaction. The anti-liquefactionmeasures of the loess site could be taken by the use of the evaluation results. Theprevious evaluation methods of the loess liquefaction potential were based on thedynamic triaxial test results. Although these results have high accuracy, it is hard toapply in practice because of the high requirement for the test skill, time-consumingtest procedure and the complicated calculation.As one of the special soils, the loess has remarkable granularity, density,humidity and degree of structuration, which could be measured easily in practice bysimple physical indicators. The previous researchers indicated that the initial voidratio, plastic index and depth of the loess are the most important influential indicatorsto the loess liquefaction. Therefore, using these indicators to reflect the characteristicsof the loess liquefaction and putting forward the evaluation method will meet the needof the engineering in loess area.The main contents of this paper include:(1) on the basis of the dynamic triaxialtest results of the groups of saturated loess samples, the curve of the liquefactionshear stress ratio–vibration numbers of every group has been drawn and then theliquefaction stress ratio corresponding to different-equivalent earthquake intensity hasbeen determined.(2) Using the response analysis, the anti-liquefaction shear stress,the average shear stress during earthquakes and the seismic response underdifferent-equivalent earthquake intensity have been calculated. And the evaluation ofloess liquefaction has been made.(3) The liquefaction characteristics of the saturatedundisturbed loess under different liquefaction levels has been obtained on the basis ofthe dynamic triaxial liquefaction test results and the evaluation of liquefactionpotential on the saturated loess.(4) Through the comprehensive analysis of theliquefaction test results of the remolded loess with different physical indicators, therelationship between liquefaction stress ratio, the main physical indicators (initial voidratio and plastic index) and depth has been established. And through thecomprehensive analysis of the liquefaction test results from the different loess site, the liquefaction evaluation method using the main physical indicators and the depth limithas been obtained.The innovative achievements have been made in the paper:(1) the liquefactioncharacteristics of saturated undisturbed and disturbed loess under differentliquefaction levels have been obtained.(2) The relationship between the mainphysical indicators, depth and the liquefaction stress ratio of the saturated loess hasbeen established.(3) The physical indicators and depth limit of the evaluation of theloess liquefaction has been established.