【摘要】 高面板堆石坝面板发生挤压或张拉等破损,从而使面板出现局部集中渗漏点或条带是大概率事件,垫层防渗是防渗体系的第二道防线。研究了面板局部破损后垫层与过渡层中的水力条件。指出垫层必须是内部稳定的,过渡层必须对垫层构成反滤保护。过渡层一般也应满足内部稳定性条件。砂砾石的内部稳定性可以根据颗粒级配曲线判别。过渡层满足内部稳定性条件时,第二道防渗体系是渗透稳定的。若过渡层不能满足内部稳定性要求,非饱和情况下,过渡层也有可能发生管涌。非饱和渗流的管涌临界渗流速度,可通过流量可控的非饱和向下渗流试验测量。过渡层非内部稳定时,其中的渗流速度应小于非饱和临界渗流速度。更多还原

【Abstract】 The appearance of compression or tension breakage of a panel in a high concrete face rockfill dam is a high probability event, so that the panel may appears concentrated leaks locally. A Cushion layer is the second seepage prevention system. The hydraulic conditions in the cushion layer and in a transition layer while leakage occurs is studied. The cushion layer must be internal stable and the transition layer should meet filtration criteria to the cushion layer. The transition layer generally should be internal stable also. Internal stability of sand and gravel soils can be distinguished by methods based on the grain size distribution curve. When both layers are internal stable, the second seepage prevention system is seepage stable. If the transition layer is not internal stable, under unsaturated conditions, piping may also occur in this layer. There is an unsaturated critical piping seepage velocity, which can be measured in a flow rate controlled unsaturated downward flow test. The seepage velocity should be less than the critical seepage velocity while the transition layer is internal unstable.更多还原