尾矿库筑坝土石料大型三轴试验与力学模型研究

针对沙溪铜矿龙王顶尾矿库工程初设土石坝建设方案,配置了3种含石量(5%、15%和30%)的筑坝土石料,开展了常围压条件下的大三轴压缩试验。试验表明,在低围压下土石料表现出明显的剪胀变形,在高围压条件下其变形以剪缩为主。随试样含石量从5%增加至30%,土石料的应力应变曲线形态相似,但强度和剪胀效应均明显增大。基于试验成果分析,构造适用于描述土石料剪缩/剪胀变形规律的塑性加载和流动方向矢量。在广义塑性本构模型框架内,建立了一个适用于土石料的弹塑性力学模型,阐述了模型参数的确定方法。将此力学模型应用于土石料的大型三轴试验模拟,发现该力学模型能较好地模拟土石料的剪缩/剪胀变形规律。

Large-scale triaxial tests and modelling mechanical behaviors of soil-rockfill materials for a mine tailings dam

Based on the preliminarily designed construction plan of a soil-rockfill dam for Longwangding tailing dam project in Shaxi Copper Mine, the soil-rockfill materials with three different stone contents (5%, 15% and 30%) are compounded. A series of large-scale triaxial compression tests under various confining pressures are conducted on the soil-rockfill materials. The test results show that the soil-rockfill materials exhibit shear-dilatation and shear-comtraction deformations under low and high confining pressures, respectively. With the increase of stone content from 5% to 30%, the stress-strain curves are similar, but the strength and dilatation effects obviously increase. Based on the test result analysis, the plastic loading and flow direction vectors are constructed to build an elastoplastic mechanical model within the generalized plasticity framework. The method for determining the model parameters is described. Then, the model is applied to the simulations of the large-scale triaxial compression tests, and satisfactory simulation on the shear-comtraction/dilatation deformations of the soil-rockfill materials is obtained.