上游型尾矿坝液化前后渗流场与孔压分布数值模拟

Numerical Simulation of Seepage Field and Pore Pressure Distribution for Tailings Dam by Upstream Method before and after Liquefaction

摘要:

针对地震(或静力)液化作用对尾矿坝渗流场和孔压分布的影响进行研究,基于多孔介质渗流理论,考虑到尾矿坝渗流特性,编写分析程序SAFTD。根据程序假设的初始浸润面,通过调整浸润面处网格迭代求解最终浸润面的位置,选取一个经典算例验证程序的可靠性。针对典型的上游法尾矿库,采用SAFTD程序分析液化前后尾矿坝的渗流场与孔压分布特征。数值模拟结果表明,液化后尾矿坝的浸润面中间部分发生明显抬升,而在入渗点处和出渗点附近变化不大;液化后尾矿坝的孔压明显增加,坝体内部孔压增大约18%~280%,最大的孔压增量发生在初期坝的右下部,数值模拟结果与Ishihara对Mochikoshi 2号坝的分析结果相似。

Abstract:

The impact of the liquefaction of tailings on a seepage field and the pore pressure distribution in a tailings dam are studied in this paper.A program named SAFTD is created based on the theory of seepage for porous media considering the characteristics of seepage in a tailings dam.SAFTD could predict the final phreatic surface by adjusting the mesh grids near the phreatic surface on the assumption of the initial phreatic surface,and a classic example is given to validate the reliability of this program.Then,SAFTD is used to simulate the seepage field and pore pressure change of the typical upstream tailings dam prior to and after the liquefaction.The numerical results indicate that the center section of the phreatic surface raises remarkably after liquefaction,but changes little near infiltration points and frozen points.The pore pressure in the tailings dam increases by 18%~280% approximately,and the lower right of the initial starter dam has the largest pore pressure increment.The simulation result is consistent with the analytical result of Mochikoshi's #2 tailings dam discussed by Ishihara.