由于3参数、6参数、7参数指数流变模型以及Merchant模型和H-K模型均仅有一个指数式进行堆石坝流变收敛率调节，难以同时合理地反映蓄水初期和蓄水后期的堆石坝沉降变化规律；而9参数幂函数流变模型虽然可以较好地反映堆石坝的沉降变化规律，但数学运算较复杂。类比混凝土热学力学性能变化规律的组合指数式，从唯象角度建议了一种既能较好地反映堆石坝流变变形规律，又便于数学运算的组合指数型流变模型，并推导了组合指数型流变模型有限元计算公式。实例分析表明，组合指数式只需取2项，由于具有2个指数式协调调整，可较好地反映堆石坝流变变形规律且数学运算方便；而一个指数式流变模型是组合指数式流变模型的特例，难以合理反映蓄水后期堆石坝的沉降变化规律。

Since there is only one exponential formula which is used to adjust the rheological convergence rate in the exponential rheological model of 3 parameters, 6 parameters, 7 parameters and Merchant model and H-K model, the deformation of rockfill dam in early impounding period and later impounding period cannot be reflected reasonably at the same time. While the 9 parameters power function rheological model, which can reflect the deformation of rockfill dam well, is inconvenient for mathematical operation. By the way of analogy with compound exponential formula for thermal and mechanical of concrete, a compound exponential rheological model, which can better reflect the rheological deformation law of rockfill dam and is convenient for mathematical operation, is advised from phenomenological perspective, and the finite element calculation formula is deduced based on compound exponential rheological model. Example analysis shows that only taking two compound exponential formulae, with two exponential coordinate adjustment, can better reflect the rheological deformation law of rockfill dam and is convenient for mathematical operation. While one exponential formula is a special case of compound exponential formula, and it cannot reflect the deformation of rockfill dam in later impounding period well.