确定岩质边坡地震安全系数的简化方法

SIMPLIFIED METHOD FOR DETERMING SEISMIC SAFETY FACTOR OF ROCK SLOPE

作为岩质边坡地震稳定性评价的规范方法,拟静力法忽略岩体的动力特性和地震动大部分特性的影响,而地震时程分析法考虑的因素较全面,却相对费时费力。目前岩质边坡地震稳定性评价缺乏较好地考虑岩体的动力特性和地震动特性的简化方法。为此,综合利用时程分析法和拟静力法的各自优点,建立地震安全系数与拟静力安全系数间的关系,提出2种岩质边坡地震稳定性评价的简化方法:(1)对于重要边坡,建立边坡地震安全系数与地震动峰值、边坡拟静力安全系数的统计经验公式;(2)对于一般边坡,统计边坡地震安全系数与拟静力安全系数的修正系数,建议相应的修正方案。以典型岩质边坡为例,采用显式波动有限元–极限平衡法,阐述所提出的简化方法的详细实施步骤,初步证明所提出方法的可行性和合理性。所建议的简化方法为重要工程岩质边坡震后快速评估和一般工程岩质边坡抗震稳定性评价提供有益的思路和重要参考。

The pseudo-static method for the seismic stability evaluation of rock slope is recommended by most codes at home and abroad,but it neglects the effects of dynamic properties of rock mass and most of earthquake ground motion characters.Furthermore,the method of earthquake time-history reasonably considering the effects of main factors is time-consuming and laborious.Nowadays,such simplified methods are lacking in the seismic stability evaluation of rock slope,which can reasonably consider the impacts of dynamic properties of rock mass and the characters of earthquake ground motion.Thus,the relation between the seismic and pseudo-static safety factors is constructed and two simplified methods,which can comprehensively utilize respective advantages of the time-history method and pseudo-static method for determining the seismic safety factor of rock slope,are put forward as follows：（1） The statistical models of seismic safety factor of rock slope and pseudo-static safety factor,peak acceleration are provided for the critical slopes.（2） The rectified coefficients of seismic safety factor of rock slope and pseudo-static safety factor are derived,and corresponding correction schemes are suggested for general slopes.The execution procedures of the simplified methods are illustrated using the method combining finite elements with limit equilibrium method through a typical rock slope.The results prove the feasibility and rationality of the suggested methods.The simplified methods proposed provide the valuable methods and the important reference for rapid evaluation aftershock of critical slopes and seismic stability evaluation of general slopes.