Experiments on Monotonic Shear Response of Sand-Rubber Mixture Considering Bidirectional Loads

It is well established that the mixture of sand and rubber powder (sand-rubber mixture [SRM]) is commonly used in embankments and foundations. The lightweight and high damping ratio of rubber can reduce the vibration in engineering practices. In this article, numerous simple shear tests involving unidirectional and bidirectional shear stress are conducted using the bidirectional simple shear apparatus to investigate the monotonic shear behavior of SRM. The specimens are consolidated under different conditions and are sheared monotonically. The results indicate that under drained conditions, the higher rubber content leads to a smaller normalized shear stress and a higher degree of noncoaxial angle during the early shearing stage, but the confining pressure slightly affects the normalized shear stress and degree of noncoaxial angle. In addition, the direction of consolidation shear stress (CSS) also affects the normalized shear stress and noncoaxial angle. The smaller angle between the CSS direction and the following shearing direction leads to a higher shear stress and a smaller noncoaxial angle. Under undrained conditions, the higher rubber contents and confining pressure reduce the stiffness of SRM and the development of pore water pressure.