Hydro-mechanical coupling mechanism on joint of clay core-wall and concrete cut-off wall
来源期刊：中南大学学报(英文版)2013年第9期
论文作者：LUO Yu-long(罗玉龙) ZHAN Mei-li(詹美礼) SHENG Jin-chang(盛金昌) WU Qiang(吴强)
文章页码：2578 - 2585
Key words：high earth and rockfill dam; soil/structure interface; hydro-mechanical coupling mechanism; seepage failure; shear failure
Abstract: The joint of clay core-wall and concrete cut-off wall is one of the weakest parts in high earth and rockfill dams. A kind of highly plastic clay is always fixed on the joint to fit the large shear deformation between clay core-wall and concrete cut-off wall, so the hydro-mechanical coupling mechanisms on the joint under high stress, high hydraulic gradient, and large shear deformation are of great importance for the evaluation of dam safety. The hydro-mechanical coupling characteristics of the joint of the highly plastic clay and the concrete cut-off wall in a high earth and rockfill dam in China were studied by using a newly designed soil-structure contact erosion apparatus. The experimental results indicate that: 1) Shear failure on the joint is due to the hydro-mechanical coupling effect of stress and seepage failure. The seepage failure will induce the final shear failure when the ratio of deviatoric stress to confining pressure is within 1.0-1.2; 2) A negative exponential permeability empirical model for the joint denoted by a newly defined principal stress function, which considers the coupling effect of confining pressure and axial pressure on the permeability, is established based on hydro-mechanical coupling experiments. 3) The variation of the settlement before and after seepage failure is very different. The settlement before seepage failure changes very slowly, while it increases significantly after the seepage failure. 4) The stress-strain relationship is of a strain softening type. 5) Flow along the joint still follows Darcian flow rule. The results will provide an important theoretical basis for the further evaluation on the safety of the high earth and rockfill dam.
LUO Yu-long(罗玉龙), ZHAN Mei-li(詹美礼), SHENG Jin-chang(盛金昌), WU Qiang(吴强)
(College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China)
Abstract:The joint of clay core-wall and concrete cut-off wall is one of the weakest parts in high earth and rockfill dams. A kind of highly plastic clay is always fixed on the joint to fit the large shear deformation between clay core-wall and concrete cut-off wall, so the hydro-mechanical coupling mechanisms on the joint under high stress, high hydraulic gradient, and large shear deformation are of great importance for the evaluation of dam safety. The hydro-mechanical coupling characteristics of the joint of the highly plastic clay and the concrete cut-off wall in a high earth and rockfill dam in China were studied by using a newly designed soil-structure contact erosion apparatus. The experimental results indicate that: 1) Shear failure on the joint is due to the hydro-mechanical coupling effect of stress and seepage failure. The seepage failure will induce the final shear failure when the ratio of deviatoric stress to confining pressure is within 1.0-1.2; 2) A negative exponential permeability empirical model for the joint denoted by a newly defined principal stress function, which considers the coupling effect of confining pressure and axial pressure on the permeability, is established based on hydro-mechanical coupling experiments. 3) The variation of the settlement before and after seepage failure is very different. The settlement before seepage failure changes very slowly, while it increases significantly after the seepage failure. 4) The stress-strain relationship is of a strain softening type. 5) Flow along the joint still follows Darcian flow rule. The results will provide an important theoretical basis for the further evaluation on the safety of the high earth and rockfill dam.
Key words:high earth and rockfill dam; soil/structure interface; hydro-mechanical coupling mechanism; seepage failure; shear failure
