某水电站坝前堆积体稳定性的三维数值模拟分析

某水电站坝前堆积体边坡的稳定性关系到该大坝的建设与运营。野外工作发现,它是深切冲沟型崩塌式堆积体,由下伏基岩和松散的堆积物组成。在1360~1450m高程之间堆积体有一个较为明显的收口转向特征,这有利于增加其稳定性。在野外工作的基础上,采用目前较为通用的两种三维有限元软件(3D-Sigma和3D-Flac)对其稳定性进行数值模拟研究。结果表明:(1)堆积体的应力场主要表现为以自重应力场为主,其应力分布主要受岩性控制;(2)堆积体的潜在滑动面为堆积体与其下伏基岩接触部位的一定范围内;(3)堆积体的位移表现为向坡外(临空面方向)滑移,且中前缘的位移量相对较大;(4)堆积体前缘的收口效应改善了其应力状态,增加了稳定性;(5)堆积体的整体稳定性较好,在1472~1610m高程之间的堆积体有可能发生局部的中浅层破坏。

Study on stability of talus slope in front of a dam in a huge hydroelectric station by using 3D numerical simulation

The stability of the talus slope is important to its construction and operation. We draw a conclusion on site that it is a incised gully collapsing talus slope that are consisted of bedrock and unconsolidated deposit. There are evidence close up and turn around between the elevations of 1 360－1 450 m, the elevations of elevation which are contributed to its stability. The data that by using 3D numerical simulation (3D-Sigma and 3D-Flac) show that ⑴Stress field of the talus slope is main weight field, its stresses distributes is mainly controlled by lithology; ⑵ Latent sliding surface is the interface of talus and the bedrock and above it in some height. ⑶ The displacement is toward to limit surface; and the displacement of the middle-front part of the talus slope is large; ⑷ The front zone’s close up improves stress state and raises the stability of talus slope; ⑸ It is wholly stable, but it maybe occurs middle-superficial layer failure between the elevations of 1 472－1 610 m .