粘土防渗尾矿库地震永久位移数值模拟

Numerical simulation on seismic permanent displacement of clay anti-seepage tailing pond

我国目前的防渗尾矿库数量越来越多,但对其动力分析相对较少。结合工程实际,使用FLAC2D软件建立了有限差分数值模型,对采用粘土垫层防渗的尾矿库进行二维地震动力响应分析,并将计算得到的坝顶最大水平位移与传统简化方法的计算结果进行了对比分析。计算结果表明,由于数值分析考虑了尾矿坝对地震波的放大效应,通过有限差分数值模型计算的水平位移比简化方法的计算结果大60%。参数分析表明：防渗垫层的抗剪强度对于尾矿库动力响应影响较大,其虽有一定隔震作用,使得防渗层上部的最大水平加速度低于其下部的最大水平加速度约5%～30%,但随着防渗垫层抗剪强度的降低,尾矿库的失稳模式由经过尾矿内部的圆弧形滑动向经过防渗层的楔形滑动转变,尾矿库的屈服加速度显著降低,永久水平位移从小于5cm增加到近70cm,可能造成震陷等灾害。该分析方法和结果对于地震区防渗尾矿库工程的设计有一定的参考价值。

The quantity of anti-seepage tailing ponds is increasing in China, but the corresponding dynamic analysis is relatively less. Combined with engineering practice, a finite difference numerical model was established by FLAC2D software. Two-dimensional seismic dynamic response analysis was conducted on clay-lined anti-seepage tailing pond, and the calculation result of maximum horizontal displacement in dam crest was comparatively ana-lyzed with that of traditional simplified method. It showed that because the numerical analysis considered the magni-fication effect of tailing dam to seismic wave, the horizontal displacement calculated by the finite difference numeri-cal model was approximately 60% larger than that by simplified method. The parameters analysis showed that the shear strength of bottom clay anti-seepage liner had a significant impact on the dynamic responses of tailing pond. Although the clay anti-seepage liner had a certain isolation effect, which made the maximum horizontal acceleration above the clay anti-seepage liner being 5%-30% smaller that under the liner, but with the decrease in shear＆amp;nbsp;strength of bottom clay anti-seepage liner, the instability mode of tailing pond transferred from the circular arc slid-ing through the inside of tailing to the wedge sliding through the clay anti-seepage liner. The yield acceleration of tailing pond decreased obviously, and the permanent horizontal displacement increased from less than 5 cm to near-ly 70 cm, which might cause earthquake subsidence hazard. The analysis methods and results has a certain refer-ence value for the design of anti-seepage tailing pond in earthquake zones.