高面板坝地震工况坝坡稳定允许安全系数探讨

摘要

The allowable safety factors of slope stability for high concrete faced rockfill dams under seismic conditions were studied. Based on the statistical values of nonlinear shear strength parameters for soft and hard rockfills, safety factors and reliability indices of slope stability were computed for different dam heights, earthquake intensities and embankment materials. The relations between safety factors and reliability indices were investigated systematically and the safety factor criteria were discussed. It is concluded that the current safety factor criteria are not suitable for seismic stability assessment of concrete faced rockfill dams which are more than 200 meters high, different allowable safety factors of slope stability should be given for different dam height levels, seismic conditions and embankment materials according to the principle of equivalent reliability. If embankment materials are fresh hard rockfills, the ratio of dam slope proposed by the design code can be adopted, if embankment materials are soft rockfills, the ratio of dam slope should be determined by stability calculation, and the allowable safety factors should be greater than the values required by the current design code.%针对高混凝土面板堆石坝地震工况坝坡稳定允许安全系数标准问题，根据软、硬岩堆石料非线性强度指标的统计参数，计算了不同坝高、地震烈度、筑坝材料情况下的面板坝坝坡稳定安全系数和可靠度，系统研究了安全系数和可靠度之间的关系，在此基础上，对高面板坝地震工况坝坡允许安全系数标准进行了讨论。研究表明：200 m以上高面板坝的抗震稳定性评价不宜沿用现行规范安全系数标准，根据可靠度一致性原则，按坝高级别、地震工况和筑坝材料分别设置安全系数标准更为合理。采用质量良好的硬岩堆石料修建300 m以下的面板坝，坝坡坡比可采用规范建议值，当堆石料岩性偏软时，坝坡坡比应通过稳定计算确定，允许安全系数应在现行规范值基础上提高。