Abstract: Tianxian Lake face rockfill dam which lies in Three Gorges Reservoir is a typical reservoir dam. According to the specialty of the reservoir dam at the upstream and downstream water level, the influence caused by the water level of the Three Gorges Reservoir area as well as the new stability problems caused by the traffic after dam widening, the stability of downstream dam body after widening Tianxian Lake’s face rockfill dam was researched by strength reduction FEM method and limit equilibrium method, in the cases of different water level combinations, the water level plummet and the traffic loads. Calculation results show that when the upstream and downstream in water level combination stay low water level, the stability of dam body is lowest; the water level plummet makes the safety coefficients reduce, however, the safety coefficients are still higher than those of both the upstream and downstream at low water level; the dam body stability also decreases under the vehicle load at the top of the dam. All calculation results in the design condition satisfy the requirements of specification for stability, and the scheme of widening dam for vehicle operation is feasible.

Key words: geotechnical engineering, face rockfill dam, stability, strength reduction method, limit equilibrium method, widening dam, water level combination

摘要： 三峡库区天仙湖面板堆石坝属于典型的库中坝。针对该库中坝上下游水位的特殊性、受三峡库区的蓄水位影响和坝体加宽通车带来的新的稳定性问题，采用有限元强度折减法和极限平 衡法，研究了天仙湖面板堆石坝拓宽后在不同水位组合、水位骤降、通车荷载作用下的下游坝体稳定性。计算结果表明：在水位组合上下游都为低水位时坝体稳定性最低；水位骤降使坝体的 安全系数降低，但高于上下游同为低水位时的安全系数；坝顶车辆荷载作用下也使坝体稳定性有所降低；所有设计工况计算结果都满足规范对稳定性的要求，坝体加宽通车可行。

关键词: 岩土工程, 面板堆石坝, 稳定性, 强度折减法, 极限平衡法, 加宽坝体, 水位组合