基于盲数理论的液化等级风险评价模型

Application of unascertained number theory to risk evaluation of liquefaction grade

影响评价潜在液化土层液化危害等级的因素,具有多种不确定性信息共存或交叉存在的特征,而传统液化指数计算方法求得的某点数值不能给出相应的应用可靠性信息,此对整个土层的地震液化风险决策分析不利。应用盲数理论,探讨了基于不确定信息下的、潜在液化土层液化等级的盲数风险评价模型,实现计算过程中实测数据保留原有信息直接参与风险运算,并确保累积误差最小,避免人为假设和最大限度的忠实于给定实测数据,同时给出结果应用的风险度。实例应用表明:将盲数理论应用于液化等级风险评价是有效可行的,且取得较好的结果。此对其它工程风险分析也具有一定参考价值。

The traditional method used to specify the liquefaction grade may not provide the reliability information of the evaluation value from any single site for seismic design and decision-makers,which is important for risk decision and risk analysis of liquefaction hazard.Based on the uncertainty characteristics of risk evaluation on liquefaction grade and unascertained mathematics theory,a novel unascertained risk evaluation model is proposed.On the basis of a concept of unascertained number,the parameters of geological environmental system such as groundwater table,buried depth and clay particle content of soil layer,value of site standard penetration tests（SPT） and etc.are specified as unascertained parameters in order to establish a risk evaluation model.The possible interval value and faith degree responding to the liquefaction grade can be obtained through this model.This proposed method carries out directly the analysis process with all actual information of parameters.It can ensure the accumulated error to be minimized,and avoid the artificial supposition,and simultaneously give the faith degree of evaluation results.The results from the practical example show that the method used to assess sand liquefaction grade is feasible and effective,and that the results are satisfactory.This proposed method is of certain reference value to the risk analysis of other projects.