软基上面板堆石坝加高可行性研究

汤浦水库东、西主坝拦河坝为混凝土面板堆石坝,坝高约30 m,建基面为第四系软基,为满足供水需求,需将坝高增加1.7 m,正常蓄水位增加2 m,大坝加高拟比选堆石体和空心箱体两种方案。首先通过土工试验初步确定了计算参数初始值,然后根据原型观测资料对老坝坝基参数进行了反演分析,确定了土体本构模型计算参数,最后对两种加高方案分别进行了三维有限元应力变形计算分析。研究表明,大坝经过15 a运行,地基固结已基本完成,为大坝加高创造了良好的条件。较之于空心箱体加高方案,堆石体加高方案对坝体变形、防渗体系应力变形以及周边缝变形的影响略大一些,但两种加高方案防渗体系的拉压应力均在混凝土抗拉和抗压强度允许范围内,周边缝的三向变位也小于设计允许值,两种加高方案均是可行的,空心箱体加高方案略优于堆石体加高方案。

Feasibility of Heightening Concrete Face Rockfill Dam on Soft Soil Foundation

The east and west barrage dams of Tangpu Reservoir are concrete face rockfill dams whose heights are about 30 m and was built on quaternary soft soil foundation.To meet the requirements of water supply,the dam height and the normal pool level should increase 1.7 m and 2 m.Two schemes of rockfill and hollow box were compared and selected.Firstly,the initial values of the calculated parameters are determined by the soil test,and then the soil constitutive model parameters of the soil foundation are determined by the inversion analysis based on the prototype observation data of the old dams.After 15 years operation the consolidation of soil foundation has been completed creating favorable conditions for dam heightening.Compareing with the hollow box scheme,the dam body deformation,the impervious system stress deformation and the peripheral joint deformation are slightly bigger than the rockfill scheme.However,the tensile and compressive stresses of the impervious system are within the allowable range of the concrete strength,the 3-D displacements of the peripheral joint are less than the design value.It is indicated that the two heightening schemes are feasible,but the hollow box scheme is slightly better than rockfill scheme.