孔隙水运移特性及对尾矿细观结构作用机制试验研究

EXPERIMENTAL STUDY OF MIGRATION CHARACTERISTICS OF PORE WATER AND ITS EFFECT ON MESO-STRUCTURE OF TAILINGS

利用自行研制的尾矿细微观力学与形变观测试验装置,研究尾矿充水过程、荷载作用和排水过程中孔隙水的运移特征及其对尾矿细观结构作用机制。结果显示:尾矿水位线实际达到高度大于计算获得的水位线高度;受荷载作用,充水条件下各层尾矿颗粒沉降位移显著大于未充水条件下相同位置颗粒的沉降位移;充水条件下尾矿颗粒沉降位移随荷载的增加可分为线性增长阶段、显著增长阶段和稳定阶段,显著增长阶段出现在200～400 kPa荷载下;受荷载与孔隙水的作用,尾矿细观结构会形成曲折复杂供水运移的通道,该通道的形成过程发生在尾矿颗粒沉降位移的显著增长阶段;孔隙水夹带尾矿小颗粒运移,对尾矿颗粒分布有一定的影响;尾矿颗粒沉降位移与细观结构受排水影响较小,其变化主要在排水初期。最后,提出水的毛细管作用下尾矿坝实际浸润线的概念与计算方法,研究孔隙水与荷载综合作用下尾矿细观结构变形破坏机制,为深入探索水引起的尾矿坝灾变机制及稳定性评价等具有重要的实际意义。

The migration characteristics of pore water and its effect on meso-structure oftailings, which includes migration characteristics of pore water in water filling and draining processes, under load, and their effect on meso-structure of tailings, etc., have been studied with a self-made observation testing apparatus of micromechanics and deformation oftailings. The results show that： the actual height of water level in tailings is higher than calculation value; the settlements of all tailings layers particles after water filling are larger than that of those without water filling under the same load; the settlements of the tailings particles after water filling could be divided into 3 stages as the increase of load. linear growth stage, steep growth stage and stable stage, and the steep growth stage occurs under the load of 200 - 400 kPa; the complex and tortuous channels for water migration caused by the effect of load on pore water pressure emerge in the meso-structure of tailings, which occurs at the steep growth stage; the pore water drives fine particles to move upward so as to the fine tailings become less in lower layer and more in upper layer： the settlements of tailings particles and meso-structure of tailings change little with the effect of drainage, which occurs in initial stage of drainage. This paper provides the concept and calculation method of actual saturated surface after capillary action in railings dam, and studies the meso-structure failure mechanism by combined action of pore water migration and load, it has important actual significance to further explore for disaster mechanism affected by water and evaluate stability of tailings dam.