关键词: 砂土液化 , 评价指标 , RBF神经网络 , 液化等级

Abstract: The neural network toolbox of MATLAB7.0 was used to train and test some sample data of sand liquefaction collected by Tokimatsu Kohji. Eight eigenvectors clay content (ρ_c),relative compaction(D_r),critical depth of soil layer(d_s),vertical effective stress(σ′),groundwater level(d_w),magnitude of earthquake(M),maximum horizontal ground acceleration(α_max) and standard penetration number(SPT-N) were selected as input parameters of the RBF neural network. Furthermore,the established RBF neural network model was used to analyze the effect of each factor on the sand liquefaction. Results of the relative contribution of each factor showed that α_max was the biggest influencing factor on the evaluation index of sand liquefaction,followed by SPT-N and d_w. The evaluation index increased with the rise of α_max,while reduced with the increase of SPT-N and d_w. The evaluation index shows a logarithmic relation with α_max,cubic polynomial relation with SPT-N,and a negative linear relation with d_w . It’s revealed that the established RBF network model fully meets the requirement of evaluation accuracy for sand liquefaction. It can simulate the complex nonlinear mapping relation between the input and output data and also gives high prediction precision.

Key words: sand iquefaction , evaluation index , RBF neural network , liquefaction level