Mechanism of valley narrowing deformation during reservoir filling of a high arch dam. Issue 6 (26th April 2023)

• Record Type: Journal Article
• Authors: Li, Biao; Xu, Jianrong; Xu, Weiya; Wang, Huanling; Yan, Long; Meng, Qingxiang; Xie, Wei-Chau
• Is Part Of: European journal of environmental and civil engineering. Volume 27:Issue 6(2023)
• Page Start: 2411
• Page End: 2421
• Publication Date: 2023-04-26
• Subjects: Valley narrowing lateral deformation (VNLD) -- reservoir filling -- time-dependent deformation -- hydrogeological conditions -- high arch dam; Sustainable engineering -- Periodicals; Civil engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; 628
• DOI: 10.1080/19648189.2020.1763843
• Languages: English
• ISSNs: 1964-8189

Abstract

Abstract: During the reservoir filling of many high arch dams, it was observed that the valley slopes on both sides deformed towards the river. The measured value of valley narrowing lateral deformation (VNLD) reached 89.54 mm by October 2018. This rare phenomenon contradicts the traditional experience of dam engineering and lacks a convincing explanation. An arch dam project in China is selected as a case study to analyze the mechanism of the VNLD. Based on a comprehensive analysis of the geological background and the VNLD measurements, a numerical study is performed to identify the main factors that may contribute to the VNLD phenomenon. It is concluded that the time-dependent valley deformation is due to the rheological behaviour of rock mass with the change of hydrogeological conditions. The artesian water head in the deep-confined aquifer is increased and the mechanical parameters in fault and shear zones are weakened after reservoir filling, which is associated with the specific hydrogeological structures. The rise of artesian water head is the main induced factor that contributes to the uplift deformation, which is observed at the dam site, and can cause the VNLD in the horizontal direction. The simulated results considering these factors agreed well with the observed data.