期刊名称：IOP Conference Series: Earth and Environmental Science
印刷版ISSN：1755-1307
电子版ISSN：1755-1315
出版年度：2020
卷号：570
期号：2
DOI：10.1088/1755-1315/570/2/022033
语种：English
出版社：IOP Publishing
摘要：Contractional valley deformation is a phenomenon quite specific to high dams in the southwest of China. Numerical simulations with coupling of stress and seepage were performed to study the mechanisms of valley deformation after impoundment and to determine whether and when valley contraction could develop at the Baihetan site. The initial generic study highlighted two competing mechanisms, a "Mattress Effect" and a "Swelling Effect", associated with dam impoundment. The comprehensive FLAC3D model incorporates detailed rock mass property values, a grout curtain, an impounding plan, and the drainage volumes. The large-scale coupled seepage-mechanical simulations show that the convergence mechanism is activated by fluid diffusion in the valley. At sites upstream and up to about 400 m downstream of the dam, the valley deformation occurs shortly after the impoundment water level is raised; this behaviour reflects the impact of the mattress effect caused by the weight change of the standing impoundment water. However, deformation also occurs during periods when the impoundment level remains the same; this behaviour is caused by the large-scale water seepage associated with pore-pressure changes under and around the dam in the valley banks. The maximum convergence along the monitoring lines does not exceed 5 cm in the simulations, where affected by the presence of faults and bedding planes.
