Study On Fluid-Solid Coupling Law Of Deep Overburden Concrete Dam Foundation And Body Based On COMSOL

In the western mountainous area of China,the uneven settlement and seepage damage of the dam foundation is easily caused by deep overburden of the river.Dam type is the earth rock dam on this kind of deep overburden mostly,which is less affected by the dam foundation.When a gravity dam is needed,the deep overburden under the dam foundation is usually removed.Then its foundation is placed on the bedrock.However,due to the limitations of actual engineering,such as the construction space of the earth-rock dam does not meet the requirements,or the foundation pit of the gravity dam is difficult to excavate and the construction time is limited.It becomes a practical engineering problems to build concrete dams such as arch dams or gate dams on deep overburden.Therefore,The Jinpen hydropower station was taken as an example.Its feasibility both "Three cutoff walls combined with high-pressure whirl-spray grouting" as the foundation treatment measures of arch dam and COMSOL numerical simulation was proved by prototype observation of arch dam combined with numerical simulation of COMSOL.And taking Danba hydropower station as an example,the difference of seepage-stress-displacement in dam foundation,under different consolidation grouting depth was studied.The research results provided theoretical support for the foundation design of concrete dam built on deep overburden.The main conclusions are as follows:(1)If the deep overburden is similar to the dam foundation of Jinpen hydropower station,the double curvature arch dam like Jinpen dam can be built without removing the overburden.And the dam height should not exceed 35m.The dam foundation treatment measures of Three cutoff walls combined with high-pressure whirl-spray grouting can be adopted.According to the coupling results and monitoring data of the dam,it is shown that the seepage of the dam foundation is small.Its settlement is stable.And the arch dam works well.(2)In Jinpen arch dam,the data both displacement in fluid structure coupling and prototype observation can verify each other.It shows that the COMSOL coupling simulation is feasible.(3)If the deep overburden is similar to the dam foundation of Danba hydropower station,its control layers are the upper weak permeable layer and gravel layer.The former has a large amount of deformation,which mainly affects the distribution of the overall stress and horizontal displacement in the dam foundation.The latter plays a leading role in the settlement of the dam foundation.The displacement of this layer accounts for 70%～73%of the total displacement.(4)If the foundation of gate dam on deep overburden needs to be treated by the measure which is similar to the consolidation grouting,the foundation stiffness increases with the depth increase of consolidation grouting,when the grouting depth exceeds the upper weak permeable layer.The settlement of dam foundation and seepage of dam bottom decrease with the depth increase of consolidation grouting.And the horizontal displacement of dam foundation decreases with the depth increase of consolidation grouting.It can be seen that consolidation grouting improves the impermeability,integrity and rigidity of the dam foundation on deep overburden.