某超高面板砂砾石坝面板缝局部失效渗流场有限元分析

为了掌握高水头作用下面板缝止水局部失效时坝体和坝基特别其垫层局部饱和区的渗流特性,针对拟建的某混凝土面板砂砾石坝,采用饱和-非饱和渗流理论,拟定不同失效缝长、缝宽、位置和垫层渗透系数等情况,建立三维有限元模型,计算面板缝失效情况下坝体和坝基的渗流场,分析不同作用水头条件下面板缝不同失效程度对渗流场的影响。计算结果表明,某处面板缝小范围失效只对失效部位附近的渗流场产生较大影响,并导致局部渗透变形,而对坝体渗流场全局的影响不大;随着失效缝长、缝宽的加大,失效缝位置的降低和垫层渗透系数的增大,失效部位附近局部饱和区变大,其中,失效缝位置的影响最大,失效缝长的影响次之,失效缝宽的影响最小;当超高水头作用下面板缝通长失效时,坝体内浸润面显著升高,因此设计时应严格控制面板缝可能失效的范围,避免出现面板缝大范围失效。

Finite element analysis for seepage field of slab joint local failure of a superhigh concrete faced sand gravel dam

We applied saturated and unsaturated theory to establish a three dimensional finite element model (FEM), based on a proposed concrete faced sand-gravel dam, aiming to simulate the seepage field of the dam and its foundation under the condition of slab joint local failure. The different length, width, and position of the slab joint local failure were combined in the simulation condition. Overall, the results showed that a single local failure of slab joint had large influence on the local seepage field around the slab joint failure and little influence on the entire seepage field. Additionally, the saturated field is enlarged by the increase of length and width of the slab joint failure and the decrease of the position, besides the seepage field is affected mostly by the position and minimally by the width. The results also revealed that the great increase of the saturated surface was caused by the slab joint full-length failure under the action of superhigh-head. Thus, these factors should be taken into consideration during the design in order to avoid large-scale failure of slab joint.