中文摘要：

在危岩稳定性评价中,地震作用方向是一个极为重要的因素。为解决目前危岩稳定性评价中仅把地震作用方向假定为水平向的问题,借助函数极值理论建立了地震最危险作用方向的计算公式,并结合统计方法进行分析验证。最后,利用该公式研究了某公路隧道出口不同类型危岩的最危险地震作用方向,计算结果表明：地震最危险作用方向在347.4°~359.8°,与水平面夹角随着地震动峰值加速度增大而减小,并且当地震动峰值加速度超过0.4g,地震最危险作用方向与水平面夹角在0°~30°,此时危岩体可能产生抛射破坏。

英文摘要：

The direction of seismic force is an extremely important factor in the stability assessment of dangerous rocks. Currently in the stability assessment of dangerous rocks, the horizontal direction is taken as the action direction of the seismic force. To resolve this problem, the calculation method considering the critical direction of the seismic force is put forward with the theory of function extreme values, and is verified by circular distribution. Finally, we use the formula to study the different types of dangerous rocks＇ critical seismic force direction at a road exit zone. The analysis shows that the critical action direction of the seismic force is from 347.4°to 359.8° , the angle between the action direction and the horizontal plane decreases with the increase in the peak ground acceleration. When the peak ground acceleration is greater than 0.4 g, the angle between the critical action direction of the seismic force and the horizontal plane ranges from 0° to 30°. At this moment, the dangerous rock may failure in the mode of a trajectory.