基于动力离心模型试验的弱透水夹层尾矿库地震响应研究

Examining the seismic behavior of tailings reservoir sandwiched with relatively impermeable thin layers using dynamic centrifuge tests

尾矿库是具有高势能的泥石流灾害源,一旦发生溃坝会对下游人员和设施造成极大威胁。本文基于离心机振动台,针对含弱透水夹层的上游法堆石尾矿坝开展了动力离心模型试验,模拟了典型尾矿库在地震作用下的破坏过程。重点探究了尾矿库内部孔隙水压力变化规律、地震作用下尾矿液化的形成和发展规律以及库内弱透水层对液化破坏过程的影响。试验结果表明:尾矿坝受地震荷载作用时,初期坝的安全程度较高,不易发生破坏,溃坝则主要是由于尾矿库内部孔压升高造成局部发生液化,进而导致尾矿坝发生变形和破坏。尾矿坝发生变形前期,主要以尾矿水平向下游流动为主,未发生液化的部分则以相对完整的整体发生位移;尾矿库内部的弱透水层会影响内部孔压积累的过程,同时会加速附近土体的液化过程。

Breach of tailings dams can cause massive debris flow,threatening the safety of downstream hu-man beings and facilities. In order to examine the failure process of tailings reservoir with relatively imper-meable thin layers, dynamic centrifuge model tests were carried out using an advanced centrifuge shakingtable. The development of pore pressure in tailings,the mechanisms of liquefaction and the influence of rel-atively impermeable layers on the liquefaction process were investigated. The tests successfully simulated thedam breach behavior of tailings reservoir under seismic loading. The dam breach is mainly induced by thelocal liquefaction caused by the continuous pore pressure generation in tailings during shaking, while thereis minor damage on the starter dam. The relatively impermeable thin layers can inhibit dissipation of excesspore pressure and then lead to accumulation of excess pore pressure beneath those layers, making tailingsmore prone to liquefaction.