区域土壤地震液化预测简化方法

Simplified prediction method for regional seismic soil liquefaction

利用可大范围获取的空间参数给出区域土壤液化的评估方法,可预估震前各地区土壤液化可能性,可快速评估震后震区土壤液化情况,对预防减轻地震灾害以及地震快速响应救援都具有重要意义的.本文以我国1976唐山大地震液化调查资料为背景,提出了区域土壤液化预测的四参数简化评估方法,并用2011年新西兰基督城地震进行了检验.选取场地平均剪切波速V s30、复合地形指数CTI、场地到河流的距离DR以及地面峰值加速度PGA,分别代表土壤密实程度、饱水状态、地质年代和遭遇的地震作用大小,并基于我国唐山地震液化区域调查资料生成的样本,运用经典二元Logistic回归方法,建立了区域土壤液化预测模型和评估公式,回归检验结果良好,整体回判成功率为77%,非液化和液化区域成功率分别为73%和78%.将公式应用于评估2011年新西兰基督城地震液化情况,区域液化和非液化成功率分别为82%和88%,总体成功率为84%.以上结果表明本文模型可靠,方法正确,可用于区域土壤液化震前预估以及土壤液化震后快速评估.

It is possible to model regional liquefaction extent based on broadly available geospatial variables,which permits to predict regional soil liquefaction possibility before earthquakes or rapid assessment of post-earthquake soil liquefaction,which will aids in preventing or relieving seismic hazard and quick-response for the emergency rescue.In this work,we proposed a novel simplified four-parameter prediction method of regional seismic soil liquefaction based on data of the 1976 Tangshan M 7.8 earthquake and tested it by the 2011 Christchurch earthquake in New Zealand.The four parameters in this method includes the mean value of shear-wave velocity V s30 for soil compactness,compound topographic index CTI for water-saturated state,the distance to river DR for geologic age,and PGA for bearing seismic action.The prediction model and evaluate formula for regional seismic soil liquefaction were established using the two-dimensional classical logistic regression based on samples from surveys to the 1976 Tangshan earthquake,and yielded satisfactory results.The overall regression successful rate is 77%,73%for non-liquefaction and 78%for liquefaction areas,respectively.The proposed model was applied to the 2011 Christchurch earthquake.Consequently,the overall regional regression successful rate is 84%,82%for non-liquefaction and 84%for liquefaction areas,respectively.These test results show that the model is reliable and the accuracy of the prediction is high,and can be used in prediction of regional pre-seismic soil liquefaction and rapid assessment of post-earthquake soil liquefaction.