关键词: 砾石土; 粗粒含量; 渗流安全; 蓄水速度; 分期蓄水;

Abstract: The coarse-grained content in core wall gravelly soil may be larger than 50%and this does not meet the standard requirement, which may have a great influence on seepage safety of high earth-rock dam.A finite element model was established based on the typical dam section of the Lianghekou core wall rockfill dam.Through random sampling, the elements in the corewallwere assigned with high permeability coefficient to simulate the case of local coarse-grained content exceeding 50%.The influence of coarse-grained content in the gravelly soil was studied according to the unsaturated seepage theory.The results show that the maximum seepage gradient in the corewall increases greatly with the impounding speed under even impounding, no matter the coarse-grained content exceeds 50% or not, which is adverse for seepage stability of core wall.For the case that the coarse-grained content is larger than 50%,the maximum seepage gradient during impoundment is greater than that of case that the coarse-grained content is not larger than 50%,and the growth rate is up to 50%,however the growth of maximum seepage gradient has a weak relationship with the un-attainment rate and the impoundment speed.By adopting a suitable staging impoundment scheme, the maximum seepage gradient has an obvious decrease even if the coarse-grained content is larger than 50%,which can meet the demand of safe impoundment within a short time, so the impoundment scheme should be designed appropriately in engineering practice.

Key words: gravelly soil; coarse-grained content; seepage safety; impounding speed; staging impoundment;