桂林压实红粘土抗剪强度与含水率关系

Relationship between Shear Strength and Moisture Content for Guilin Laterite

红粘土是一种典型的特殊土,其强度特性较普通粘土复杂.为了探讨影响红粘土强度的因素,对干密度相同而含水率不同的压实桂林红粘土试样进行了一系列固结快剪试验,得到了粘聚力和内摩擦角与初始含水率的关系.试验结果表明,峰值凝聚力和残余粘聚力都随试样初始含水率的增大而减小,峰值内摩擦角和残余内摩擦角均随试样初始含水率增大先增大后减小.另外,探讨了剪切过程中桂林红粘土的剪胀性.最后,将试验结果与Bishop和Fredlund非饱和土强度公式的计算值进行比较,指出目前非饱和土强度公式无法预测非饱和桂林红粘土的强度.

Laterite is a typical problematic soil. Its strength characteristics are more complex than ordinary clay. A series of consolidated quick direct shear tests on compacted Guilin laterite with the same initial dry density and different moisture contents were performed to investigate the factors affecting the strength of the laterite. Changes in cohesion and internal friction angle with moisture content were obtained. Test results show that the cohesions decrease as the initial moisture content increases. The friction angles at peak and residual increase firstly and then decrease as the initial moisture content increases. Besides, the dilatancy of Guilin laterite during shearing is discussed. Comparison of the test data and the calculated values by using Bishop＇s and Fredlund＇s equations for unsaturated soils show that the two equations cannot properly predict strength of unsaturated Guilin laterite.