内马铁路残坡积土石混合体含石量对抗剪强度影响分析

针对内马铁路二标大量分布的残坡积土石混合体材料抗剪强度易受含石量影响的问题，选取了具有代表性的圆砾和角砾，并配置成不同含石量的试样进行不排水三轴剪切试验，系统研究了砾石含量和形状对土石混合体强度特性的影响规律。试验结果表明:土石混合体砾石含量阈值分别为40%和80%，即含石量小于40%时，土石混合体峰值内摩擦角基本不变，且不受砾石形状影响；含石量由40%增至80%时，土石混合体试样峰值内摩擦角逐渐增大，且角砾试样的大于圆砾；含石量超过80%时，试样峰值内摩擦角缓慢增加，并发现试样峰值抗剪强度有相似的变化规律。

Study on Influence of Gravel Content of Residual Soil-gravel Mixture at Nairobi-Malabar Railway on the Shear Strength

In view of the fact that the shear strength of the residual soil-gravel mixtures distributed in section II of Nairobi-Malabar Railway are susceptible to the influence of the gravel content, the representative gravel and breccia are selected and the samples with different stone contents are used to carry triaxial shear test that is undrained and consolidated. The test systematically studied the influence of gravel content and shape on the strength characteristics of the soil-gravel mixtures. The experimental results show that the gravel content threshold of soil-gravel mixtures is 40% and 80% respectively. When the stone content is less than 40%, the peak internal friction angle of the soil-gravel mixtures is basically unchanged and is not affected by the gravel shape; when the stone content is increased to 80% from 40%, the peak internal friction angle of the soil-gravel mixture sample increases gradually, and the peak internal friction angle of breccia sample is faster than the round gravels; when the stone content exceeds 80%, the peak internal friction angle of the sample increases slowly. Furthermore, it is found that the peak shear strength has a similar variation with the peak internal friction angle.