粗粒土大型剪切试验剪切带变形特征分析

采用含有叠环的大型粗粒土直剪试验设备进行试验,叠环作为剪切盒的重要组成部分,可以在剪切时根据粗粒土的结构形成多组剪切面,能够明显地展现出粗粒土的剪切变形特征.为了分析硬质岩粗粒对粗粒土的剪切强度和变形的影响,对粗粒岩性为花岗岩的粗粒土进行大型叠环式直剪试验.通过分析得到试验特征规律,研究粗粒土在剪切过程中的颗粒运动,得出花岗岩粗粒对其组成的粗粒土的剪切强度和变形有很大的影响.硬质岩性的花岗岩颗粒在剪切时不易被剪碎,在剪切过程中主要做错位、翻滚运动.低轴压下,剪切带位移会出现阶梯现象,而在高轴压下,剪切带位移为线性变化,并表现出更加明显的剪胀现象.粗粒土在剪切破坏后依然具有较高的抗剪强度和稳定性,为工程建设中土石体材料的选取提供了一定的借鉴.

ANALYSIS OF SHEAR ZONE DEFORMATION BEHAVIOR IN COARSE-GRAINED SOIL BY LARGE SCALE DIRECT SHEAR TEST

The large scale direct shear test system includes overlaying rings that are the important component of shear box. Multiple sets of shear surfaces can be formed according to the structure of coarse-grained soil, which can reflect shear deformation characteristics clearly. In order to analyze the influence of coarse granules composed of hard rock material on the strength and deformation, the large scale direct shear test is made on coarse-grained soil. The coarse grain lithology is granite. The paper analyzes experiment laws and particle motion of the hard rock coarse-grained soil and finds that granitic coarse grains have a significant impact on the strength and deformation. Because of their hard rock lithology, granitic particles are not easy to be broken. In fact they mainly do the position adjustment and rolling motion. Staircase of shear displacement emerges in shear zone under low axial stress. Nevertheless, shear displacement in shear zone manifestations linear variation and more apparent dilatancy effect under high axial stress. The coarse-grained soil has high shear strength and stability after shearing failure. The results provides certain reference for engineering construction.