花岗岩残积土的分类研究

从结构性角度出发，在花岗岩残积土粒度组成、微结构及物理力学指标研究基础上，分析现有分类法存在的问题和不足。根据实际工程土工实验资料，研究粒度对分类的定量影响，得到主要结论如下：花岗岩残积土是“混粒土”，土质分类应综合考虑粗、细粒组的影响；扰动对它的物理力学指标有不同程度的影响，其中孔隙比、内摩擦角、塑性指数受扰动影响较小，适宜作为土质分类研究指标，而黏聚力和压缩系数(或压缩模量)受扰动影响较大，不可作为土质分类研究指标；《土的工程分类标准》(GBJ145－90)关于粗、细粒土的分类原则，适用于花岗岩残积土；大于0.5 mm颗粒含量35 %是粒度影响指标的分界值。最后依据上述结论提出新分类法-综合分类法。新分类法将有助于花岗岩残积土工程性质的更深入研究。

Study on classification of granite residual soils

Based on structure nature, firstly, the granularity constituent, micro-structure and physico-mechanical parameters of granite residual soil (GRS) are studied; secondly, the shortages of the existing classification methods are analyzed; thirdly, the granularity quantitatively affecting on classification is studied; so that, main conclusions are drawn as follows: GRS is a mixed-particle soil or a mixture of coarse and fine soil particles, so both coarse and fine faction should be comprehensively considered for the classification; the physico-mechanical parameters are affected in varying degrees by disturbance, in which, the cohesive force and compression coefficient (or compression modulus) are much more serious than the porosity ratio, internal friction angle and plastic index, so the latter is suitable for the classification study, but the former isn’t; Soil Engineering Classification Criterion (GBJ145－90) is suitable for GRS on classifying coarse and fine soils; the content 35 % of granule over 0.5 mm is the dividing line for granularity effects. Finally, a new classification method or comprehensive classification method is advanced. The new method will contribute to study in depth on engineering natures of GRS.