A PET biaxial geogrid is adopted to reinforce the weathered expansive marlite in XinXiang,the midline of South to North Water Transfer Project (SNWT) in China.The saturated samples of reinforced expansive soils with the size of Φ101 mm×200 mm are adopted to carry out a series consolidation and drain (CD) shear test in different confining pressure. Results shows that, the unreinforced and reinforced expansive soils are strain hardening, and curves of stress vs strain are in accord with the Duncan Chang nonlinear elastic model.The initial yield stress, the corresponding strain,and the strength of reinforced soils are enhanced,and the increase quantity is bigger with more layers of reinforced geogrid.With more confining pressure,the initial yield stress,the corresponding strain,and the strength of reinforced soils are also increased. Compared with the unreinforced expansive soils,the adhesion and friction angle of reinforced soils are both heightened.
