| A catastrophic earthquake is unpredictable and its influence is widespread,and earthquake-induced slope instability always brings serious damage,which will consequently cause human society inestimable loss of possessions and life.Seismic stability of a slope in a certain period of time is mainly affected by two kinds of factors,the potential earthquake influence degree of the slope site and the anti-seismic ability of the slope.If the two kinds of factors are correctly evaluated before an earthquake,and accordingly the slope seismic failure mode and its instability possibility are obtained,it is of great practical value and theoretical significance to the formulation of seismic mitigation measures for slope.Previous studies on slope seismic stability focused either on the qualitative evaluation of the dynamic stability of a single slope,or on the hazard zoning of the earthquake-induced landslides in a regional scale.There is no effective method for quantitative analysis of seismic instability probability of a certain slope till now.Therefore,this paper proposed such a scientific problem: in a certain period of time in the future,for a certain slope with a certain seismic failure mode,how large the instability probability will be? To solve this scientific problem,a system for probability analysis and evaluation of slope seismic instability is established.In this system,the horizontal peak acceleration of ground motion(as)and the horizontal component of slope critical seismic peak acceleration(ac)are taken as assessment parameters,and the curve of seismic exceedance probability in a certain period of time is taken as a link.The proposed method is applied to the analysis of a historical landslide induced by Haiyuan earthquake of 1920,and its effectiveness is further verified.The main results are as follows:(1)The seismic risk assessment method considering potential hypocentral location is further improved.The three-component calculation formula of the site peak ground acceleration is proposed,which lays a foundation for the dynamic stability analysis of slopes under seismic actions with different vibration directions.(2)A method of seismic response analysis of slopes excited by incident plane waves from any direction is formed,which is of great significance for studying the dynamic response of slopes under different seismic modes and revealing the diversity of slope seismic damage.(3)A set of probability analysis and evaluation system for slope instability based on the seismic parameters is proposed.The system establishes the slope seismic stability evaluation and failure probability analysis on the basis of comparison between potential seismic intensity and slope seismic capacity,which will provide technical support for slope quantitative evaluation and prevention before an earthquake in strong earthquake areas.(4)The proposed probabilistic analysis and evaluation method of slope seismic instability is applied in Zhenhu slope of Xiji County.The failure probability and its uncertainty of Zhenhu slope under the influence of potential sources with different locations is analysed,which verified the effectiveness of the proposed method. |
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