不同密度粗粒料强度特性的大型真三轴试验

干密度对粗粒料的强度特性有重要影响，特别是三维应力状态下影响更为显著。通过不同密度粗粒料大型真三轴等小主应力等中主应力系数（b=0.25）加载试验和大三轴试验研究了干密度对粗粒料强度特性的影响。结果表明，大型真三轴试验的应力曲线基本呈爬升型，高于和陡于大三轴应力曲线，表现出较强的硬化性；粗粒料强度基本随初始干密度的增大或小主应力的增大呈线性增大；大型真三轴试验强度比大三轴试验强度增大20%～97%，且小主应力越小，强度增大幅度越大；令粗粒料黏聚力为0，则内摩擦角随初始干密度的增大基本呈线性增大，随小主应力的增大而减小；破坏应力比随初始干密度的增大呈线性增大，随小主应力的增大而呈线性减小，大型真三轴试验的破坏应力比小于大三轴试验的破坏应力比。

Investigation of strength properties of coarse granular material at different densities using large-scale true triaxial tests

Dry density has an important influence on strength properties of coarse granular material, especially in three-dimensional stress state. In this study, the effects of dry density on strength properties of coarse granular material were investigated using large-scale true triaxial tests under equal intermediate principal stress coefficient (b=0.25) loading condition with equal minimum principle stress and large-scale triaxial tests at different dry densities. The results show that the stress-strain curve of large-scale true triaxial test presents basically of climbing shape which is higher and steeper than that of large-scale triaxial test and shows strong hardening behavior. The strength of coarse granular material increases linearly with the increase of initial dry density or minimum principal stress. The strength of large-scale true triaxial test increases by 20%–97% compared with that of large-scale triaxial test, and the smaller the minimum principal stress, the greater the strength increase. If the cohesion of coarse granular material is 0, the internal friction angle increases linearly with the increase of initial dry density and decreases with the increase of minimum principal stress. The failure stress ratio linearly increases with the increase of initial dry density and decreases linearly with the increase of minimum principal stress. The failure stress ratio of large-scale true triaxial test is smaller than that of large-scale triaxial test.