水对三峡库区碎石土的弱化作用

通过筛分试验对三峡库区现场取得的碎石土确定平均级配，然后用代替法设计其试验级配。结合碎石土的特点，采用细粒土含量控制试样的含水量，在同一竖向压力下制样。通过对库区不同含水量和不同含石量碎石土的剪切强度及参数的研究，结果表明，含水量不同，碎石引起强度变化的临界含石量也不同；碎石含量不变时，c值随含水量变化幅度不大，但 值随含水量变化会有较大变化；碎石土从天然状态到饱和状态，内摩擦角依据碎石含量不同，可降3°～10°左右。为估计三峡库区蓄水后旱桥桥基与路基承载力的降低提供了依据。

Weakening effect of water on gravel-soil in Three Gorges Reservoir area

The average particle gradation can be obtained after sieving the local gravel-soil from the Three Gorges Reservoir area, and then its experimental particle gradation is designed with replacement method. According to the feature of gravel-soil, the water content of sample is controlled by granule soil content and sampled under the same vertical pressure. The following conclusions are drawn on the shear strength and parameter of gravelly soil with different water contents and different rock contents: with different water contents, the critical rock content with changed strength will be different; with different rock contents, c value changes little with water content, while ? value changes remarkably; the internal friction angle changes with different rock contents, probably reducing by 3° -10° or so, when gravelly soil changes from the original condition to its saturation. These conclusions uill to be a basis for estimating the carrying capacity reduction of overpass and roadbed after the Three Gorges Reservoir filling.