Abstract: With USTX-2000 automatic unsaturated and saturated dynamic triaxial testing system developed by GCTS (Geotechnical Consulting and Testing Systems) company, a series of dynamic triaxial tests under cyclic loadings are performed on saturated sand reinforced with horizontal-vertical(H-V) inclusions of perspex with different confining pressures. The results of dynamic elastic modulus of saturated sand reinforced with H-V inclusions influenced by confining pressure, dynamic elastic strain and the height of vertical reinforcement are studied. Then, the relations between the maximum dynamic elastic modulus which is useful for practical engineering and confining pressure are gained. It is found that the dynamic elastic moduli of both unreinforced sand and reinforced sand decrease with the increment of dynamic elastic strain, and increase with the confining pressure increase; H-V inclusions reinforced sand improves the dynamic elastic modulus along with the increase of the height of vertical inclusion compared to unreinforced sand and conventional reinforced sand with horizontal inclusions. The maximum dynamic elastic moduli of both unreinforced sand and reinforced sand increase with the increase of confining pressure. The damping ratios of both unreinforced sand and reinforced sand increase with the increase of dynamic elastic strain. Neither the damping ratio of unreinforced sand nor that of reinforced sand is sensitive to the change of confining pressure; however, it has the tendency to decrease as the accretion of confining pressure. In addition, the damping ratio of reinforced sand is obviously decreased compared to that of unreinforced sand.

Key words: horizontal-vertical (H-V) reinforcement, dynamic elastic modulus, damping ratio, height of vertical reinforcement