Abstract: In view of that the existing method of slope seismicity hazard assessment rarely mentioned instability scale, and that fuzzy comprehensive decision-making method used frequently in hazard assessment has strong subjectivity, the authors of this paper have developed a fuzzy comprehensive statistical method for evaluation of highway slope seismic instability scale. Based on the traditional fuzzy statistical principle, 408 unstable roadway slopes recorded in Post-earthquake investigation data of Wenchuan earthquake were taken as samples, the authors divided the value range for each index of this assessment method into several intervals and conducted fuzzy statistics on every intervals, then the fuzzy statistical results were curve fitted to obtain the interval membership degree of each index. Next, using the fuzzy comprehensive decision-making model, instability scale was determined according to the observed value. At last, the developed assessment method was used to assess the seismic instability scale of other 45 highway slopes. The accuracy of the evaluation results obtained by this method is 88.6%, indicating that the method is effective. Because the method has no other correction process, and that the number of slope samples is relatively small, there is still room for improving the accuracy of this method.

Key words: slope instability scale in earthquake, unstable slope samples, fuzzy statistics, fuzzy comprehensive decision, interval membership, curve fitting