防渗墙对坝坡渗流和稳定性的影响研究

Influence of cutoff wall on seepage flow and stability of dam slope

库水位变化会产生非稳定渗流,土体的渗透性质会影响土体中水压力分布,这些因素都将直接影响到坝坡的稳定性。文章利用有限元ABAQUS软件,对建立混凝土防渗墙前后的坝坡进行渗流分析,并采用3种不同的判据(塑性区贯通、坡顶位移、计算不收敛),对下游坝坡进行稳定性分析。计算结果表明,建立防渗墙后,坝体下游土体孔压减小,浸润线也相应的降低;上下游坝坡的竖向应力有明显差异,但总体应力大小相差较小;利用3种不同判据计算得到的坝体安全系数相差较小,建立防渗墙后下游坝体的稳定性明显提高。

The change of water level may cause the unsteady seepage. The permeability of soil mass has influence on distribution of water pressure in the soil mass. These factors would directly affect the stability of dam slope. By using the finite element ABAQUS software, the paper analyzes the seepage of the dam slope before and after the building of cutoff wall, and analyzes the stability of downstream slope with three different criterions with the breakthrough in plastic zone, the displacement of slope top and no convergence in calculation. Four research conclusions are obtained. After the building of the cutoff wall, the pore pressure of soil mass in the downstream the dam is decreased, and the phreatic line is decreased accordingly. The vertical stress on slopes of upstream and downstream has obvious difference, but the difference between overall stresses is small. The calculated safety factors of dam body under the three different criterions have smaller gap. The stability of downstream dam body has obviously improved after the building of the cutoff wall.