排水板改善坝前淤泥层固结效果的数值模拟

摘要

Taking the project of Yashigou Reservoir as an example,the variation of consolidation rate was simulated by finite element software of PLAXIS and the contribution of adding vertical drains to original method made to consolidation effect was analyzed. And the permeability coefficient of sedimentation in the model was adjusted to search the differences of contribution which vertical drains made to consolidation effect in varied permeability coefficient. Result shows that a)when heightening fill the upstream sedimentary,the biggest excess pore water pressure in sedimentation foundation appears after one of soil layers filling finished,and this moment the sedimentation foundation has the smallest effective stress and the worst stability;b)adding vertical drains has a remarkable effect to raise the rate of consolidation,it can reduces about 70% construction period under ideal conditions and;c)adding vertical drains has more engineering significance when the permeability coefficient of sedimentation is smaller.%以雅石沟水库除险加固为例，通过 PLAXIS有限元软件模拟计算了单一堆载预压和堆载预压加竖向排水固结两种情况下坝前淤积体的固结速率，讨论了增设竖向排水板对坝基淤积土固结效果的贡献，并通过改变模型中土的渗透系数，探究了不同渗透系数下竖向排水对固结效果的影响。结果表明：①坝前淤泥面加坝过程中，淤积体内最大超静孔隙水压力出现在某一层加坝施工结束时，此时土体有效应力最小，稳定性最差；②布置竖向排水体对促进淤土坝基固结的效果较为显著，理想状况下可缩短约70％的工期；③土体渗透系数越小，布设塑料排水板对加快土体固结速率的贡献越大。