粗粒土强度和变形的级配影响试验研究

开展了不同细粒含量的无黏性和含黏粒粗粒土的共8组大型三轴排水剪切试验,研究了级配对粗粒土强度、变形、剪胀特性和颗粒破碎的影响。试验结果表明细颗粒含量的大小、是否含泥是粗粒土力学特性的重要影响因素;分析了无黏性粗粒土的颗粒破碎率随围压大小、级配的变化;研究了剪切峰值随围压、细颗粒含量的变化规律,讨论了不同围压、不同级配特征情况下粗粒土的剪胀特性。根据含黏粒粗颗粒土的试验结果,分析了含泥量对强度和变形特性的影响,并从机理上分析了细粒含量对无黏性和含黏粒粗粒土的力学特性影响的差异性。试验结果表明对于土石坝工程良好的坝体填筑料级配、严格控制小于0.075 mm颗粒含量,有利于提高坝体的稳定性和减小坝体沉降。

Experimental study on effects of gradation on strength and deformation of coarse-grained soil

Eight large-scale triaxial tests on coarse-grained soil with different lithologies are carried out. The effects of gradation on strength, deformation, dilatancy and particle breakage characteristics of coarse-grained soil are discussed. The test results show that the grain-size composition is the important factor for the mechanical properties, and the strength and deformation characteristics change with the content of fine particles and the mud content. The particle breakage and the peak value of shear stress with the change of confining pressure and gradation are discussed. For the cohesionless coarse-grained soil with the same density, the strength and the stiffness increase with the increase of the fine-grained contents under high stress. For the cohesive coarse-grained soil, the strength and the stiffness of the materials with high mud content are smaller than those with low mud content. Good gradation and strict control of particle content less than 0.075 mm are propitious to improve the stability of the dam body and reduce the dam settlement for high earth and rockfill dams.