固结灌浆深度对丹巴水电站深厚覆盖层坝基中流固耦合的影响

Effect of Consolidation Grouting Depth on Fluid-solid Coupling in Deep Overburden Dam Foundation of Danba Hydropower Station

中国西南地区水利工程多建于有明显强弱相间结构的河谷深厚覆盖层上,此类大坝通常采用垂直防渗墙或帷幕灌浆等防渗措施,但这些措施不能有效提高坝基承载力,坝基不均匀沉降反而会造成防渗体的破坏和失效。因此,引入多孔介质存储系数S_α,采用有限元软件Comsol Multiphysics建立双场耦合模型,探寻固结灌浆联合垂直防渗墙条件下深厚覆盖层渗流场和应力场演化规律。研究发现,层状深厚覆盖层中,上部弱透水层、弹性模量较小而厚度较大的强透水层是固结灌浆的控制层。当上部关键层固结灌浆后,且灌浆深度达到总坝基深度50%以上时,再增加灌浆深度意义不大。研究成果可为类似工程提供参考。

Water conservancy projects in southwest China are mostly built on the deep overburden of valleys with distinct structure of strength and weakness.The seepage control measures of such dams include vertical cutoff wall or curtain grouting,but these measures can not effectively improve the bearing capacity of the dam foundation.On the contrary,the uneven settlement of the dam foundation will cause the destruction and failure of the seepage control body.Therefore,the storage coefficient S_αof porous media was introduced.A two-field coupling model was established by using finite element software Comsol Multiphysics.And then the seepage field and stress field evolution law of deep overburden under consolidation grouting combined with vertical cut-off wall were explored.It is found that the upper weak permeable layer,the strong permeable layer with smaller elastic modulus and bigger thickness are the control layer of consolidation grouting in the layered deep overburden.When the grouting depth of the upper key stratum reaches 50%of the total dam foundation depth after consolidation grouting,it is not significant to increase the depth of grouting.The research results can provide reference for the similar projects.