双应力主轴单调旋转下砂土强度及剪切带特性试验研究

Experimental study on strength and shear band characteristics of sand under biaxial rotation of principal stresses

为了进一步深化对土应力方向依赖性的认识,利用试样旋转和应力旋转一体化的方法实现双应力主轴旋转,并对饱和砂土开展一系列双应力主轴旋转试验。试验结果表明:饱和密砂的强度依赖于主应力方向和试样倾角,且受到两者的耦合作用;随着主应力方向和试样倾角的逐渐增大,相变强度呈现出逐渐减小的规律,破坏强度则表现为先增大后减小;不同的主应力方向和试样倾角对相变强度和破坏强度的耦合作用效果存在差异;此外,研究发现剪切带的发展规律主要取决于主应力方向。

In order to deepen the understanding of soil stress direction dependence,biaxial rotation of principal stresses was realized by integrating specimen rotation and stress rotation,and a series of undrained fixed-axis shear tests were carried out on saturated dense sand.The results show that the strength of sand is closely related to the principal stress direction and the specimen bedding angle,and is subject to the coupling effect of these two factors.With the increase of the principal stress direction and the specimen bedding angle,the phase transition strength decreases gradually,and the failure strength is first enhanced and then reduced.However,there are differences in the coupling effects of various principal stress directions and specimen bedding angles on the phase transition strength and the failure strength.Furthermore,it is found that the development pattern of the shear band is mainly affected by the principal stress direction.