强降雨作用下山谷型尾矿坝浸润线演化规律

Evolution Law of Phreatic Line in Valley-type Tailings Dam under Heavy Rainfall

强降雨常导致山谷型尾矿库水位快速涨落,揭示强降雨作用下降雨过程与雨停后浸润线变化规律对保证该类尾矿坝安全运行至关重要。以某山谷型尾矿坝为依托,建立了相应的有限单元网格数值模型,基于非稳定非饱和渗流理论系统研究了库水涨落全过程降雨与库水涨落共同作用下坝体浸润线位置的变化规律。计算结果表明:①降雨初期只有初期坝附近浸润线升高;②降雨继续一段时间后,浸润线全面升高,干滩长度不断变小;③降雨停止不久,浸润线会持续全面抬升并达到最高位置,干滩长度达到最短;④降雨停止一段时间后,浸润线逐渐全面下降直至回归初始位置,且浸润线回位时刻远滞后于雨停时刻。因此,为保障山谷型尾矿坝遭遇强降雨时的安全,建议根据坝体浸润线演化特点分期突出重点进行监测,特别要重视雨后几天浸润线的监测工作。

It is very important to reveal the evolution law of phreatic line caused by rainstorm during and after rainfall for the safety of tailings pond in operation,as heavy rainfall often leads to quick fluctuations of water level for valley-type tailings dam.Taking a valley-type tailings reservoir for example,the corresponding finite element mesh model is created,and the evolution of phreatic line under the rainfall and changing water level is studied systematically with unsteady and unsaturated seepage theory in the process of one water level fluctuation.The simulation results are shown as followings：①At the first stage of rainfall,only the phreatic line near the original tailings dam uplifts;②With the lasting rainfall,the phreatic line uplifts everywhere and the beach length keeps decreasing;③Just after the ending of rainstorm,the phreatic line continues uplifting and reaches the highest position,and the beach length becomes shortest at that time;④In a longer time after ending rainfall,the phreatic line drops gradually and goes back to its initial position,however the moment of return of phreatic line lags longer behind the time of ending rainfall.Consequently,in order to ensure the safety of valley-type tailings dam under heavy rainfall,monitoring the phreatic line should be focused on different key items by stages according to its evolution characteristics,and especially during several days after rainfall.