清洁粗中砂的强度特性研究

Study on Strength Characteristics of Clean Coarse Medium Sand

摘要: 岩土工程和土力学理论的发展离不开对土体性质的认识，土强度与变形特征基本上受2类关键因素控制和影响：土颗粒物理属性及土体存在状态。因此设计直接剪切试验和十字板方案，研究了中粗砂的剪切强度特性，探索各因素的作用规律和作用机理。研究结果表明：1) 砂土的干密度随着粒径的增大而增大且在饱和状态下的干密度最大，在潮湿状态下的干密度最小；在粒径较小时，砂土的内摩擦角受含水状态的影响较小，而在粒径较大时，受含水状态的影响较大。2) 砂土的粘聚力随着平均粒径的增大而减小；在粒径较小时，砂土的内摩擦角受含水状态的影响较小，而在粒径较大时，受含水状态的影响较大。3) 砂土的内摩擦角随着平均粒径的增大而增大；在粒径较小时，砂土的剪切强度受含水状态的影响较大，而在粒径较大时，受含水状态的影响较小。4) 砂土的剪切强度随着平均粒径的增大而增大；在粒径较小时，砂土的剪切强度受含水状态的影响较大，而在粒径较大时，受含水状态的影响较小。5) 干密度与砂土的剪切强度具有一定的相关性。

Abstract: The development of geotechnical engineering and soil mechanics theory cannot be separated from the understanding of soil properties. The strength and deformation characteristics of soil are basically controlled and affected by two key factors: the physical properties of soil particles and the existence state of soil. Therefore, the direct shear test and cross plate scheme are designed to study the shear strength characteristics of medium coarse sand and explore the action law and mechanism of various factors. The results show that: 1) the dry density of sand increases with the increase of particle size, and the dry density is the highest under saturated condition and the minimum under wet condition. When the particle size is small, the internal friction Angle of sand is less affected by the water state, while when the particle size is large, it is more affected by the water state. 2) The cohesion of sand decreases with the increase of average particle size; When the particle size is small, the internal friction Angle of sand is less affected by the water state, while when the particle size is large, it is more affected by the water state. 3) The internal friction Angle of sand increases with the increase of average particle size; When the particle size is small, the shear strength of sand is greatly affected by the water state, while when the particle size is large, it is less affected by the water state. 4) The shear strength of sand increases with the increase of the average particle size. When the particle size is small, the shear strength of the sand is greatly affected by the water state, but it is less affected by the water state when the particle size is large. 5) There is a certain correlation between dry density and shear strength of sand.