Tempo-spatial Evolution Law of Valley Width Deformation of High Arch Dams and Analysis of the Causes

Abstract

Abstract In China, some high arch dams have undergone valley width contraction after water storage, which affects the behavior and long-term safety of the dams. This paper reviews typical cases of high arch dam valley width deformation in the world and analyzes its characteristics and causes. From this it continues to address the deformation of the Xiluodu arch dam valley and studies its width deformation monitoring data, revealing the temporal evolution and spatial distribution characteristics of the deformation. The mechanism of the deformation is then studied in the context of the engineering geology and hydrogeological conditions of the dam site. The results suggest that with the seepage force acting on P2βn after water storage, the effective stress in this rock layer fell and the rock mass might undergo displacement and creep deformation along P2βn, causing the valley to narrow. Therefore, the contraction of the Xiluodu arch dam valley was caused by the reduction of the effective stress in the rock mass during the evolution of the seepage field following water storage under the specific hydrogeological and geostress field distribution conditions.