兰州某黄土场地液化势评价及地基处理措施

Evaluation of liquefaction potential of Lanzhou loess site and the foundation treatment method

尝试应用了室内研究——反应分析的液化可能性估计方法与地震剪应力时程相结合的综合评价方法对处于黄河Ⅳ级阶地的兰州东岗某工程场地的饱和黄土液化势进行了评价。研究结果表明,该场地饱和黄土在超越概率为50年63%、10%和5%地震作用下均会产生完全液化;同时,根据对夯实后重塑黄土的液化势评价结果,我们提出可用夯实法对地基进行抗液化处理;强夯至干密度dρ≥1.6g/cm时,上述地震作用下该场地饱和黄土仅产生轻微或中等液化,地基抗液化处理效果明显。

This paper attempts to apply the method for evaluating loess liquefaction potential based on dynamic triaxial test-response analysis combined with an earthquake share stress time history to the evaluation of liquefaction potential of a loess site at Donggang town in Lanzhou city,which located in the Ⅳ terrace of the Yellow River.The results show that the saturated loess will completely liquefy under the earthquakes of exceedance probability of 63%,10% and 5% respectively in 50 years.Meanwhile,by controlling the density of the disturbed loess as ρd=1.5 g/cm and ρd=1.6 g/cm,according to the evaluating results of the compacted loess liquefaction,it is proposed that the compacted treatment can partly reduce the liquefaction potential of the loess.When ρd≥1.6 g/cm,the saturated loess is only light liquefied or middlingly liquefied under the above-mentioned seismic action,and the loess site can be better prevented from the earthquake liquefaction for the seismic intensity under 8 degree.