尾矿坝静力稳定分析的探讨与建议

Discussion and suggestions on static stability analysis of tailing dam

尾矿坝不同于传统水库土石坝,不应完全按照传统土石坝的稳定分析方法。探讨了上游式尾矿坝静力稳定分析中的常见问题,分析了尾矿坝中孔隙水压力与超孔隙水压力来源,提出dp不大于0.05mm的尾矿坝年上升速率应不大于20m/a,对于上升速度过快的尾矿坝内应增设排水设施,以利于超孔隙水压力及时消散。在抗滑稳定分析方面,依据土力学的基本原理,明确了有效应力与总应力稳定分析方法的适用条件,将尾矿坝生命周期初期坝施工结束期、堆坝期、退役期等三个阶段,分别采用不同的稳定分析方法与强度参数。还讨论了尾矿坝中的两种特殊材料饱和松砂与尾矿泥的强度指标,提出稳定分析中应注意饱和松砂静力液化和尾矿泥欠固结的特性,对于大于临界孔隙比的饱和松砂,在一定触发条件下,可采用稳态强度。对于欠固结的尾粘土,建议采取不固结不排水强度指标或cu/p'估计不排水强度。

The tailing dam is different from the traditional earth and rockfill dams of the reservoirs, so the slope stability analysis method for traditional dam should not be adopted to the tailing dam completely. In this paper, some common problems encountered in the static stability analysis of the upstream tailing dam were discussed. The sources of pore water pressure and excess pore water pressure were analyzed, and it was proposed that the raising velocity per year for the dam with dp being not exceed 0.05mm should not exceed 20m/a. For the dam with overrapid raising velocity, the drain apparatus should be added in the dam to facilitate the timely disappearance of excess pore water pressure. In the aspect of anti-sliding stability analysis, according to the basic principle of soil mechanics, the life span of a applicable conditions of effective stress and total stress stability analysis methods were defined. The tailing dam was divided into three periods, including starter dam construction ending period, embank- ment period and retired period, where different stability analysis methods and corresponding strength parameters should be used in different periods. At last, the strength parameters of two kinds of special materials, saturated loose sand and tailing silt, in tailing dam were discussed, and it was put forward that the characteristics of static liquefaction for saturated loose sand and under consolidated for tailing silt should be noticed in stability analysis. For the saturated loose sand bigger than critical void ratio, under a certain triggering conditions, the steady state strength can be applied. For the under consolidated tailing silt, the undrained strength should be estimated by applying non-consolidation and non-draining strength index or cu/p′.