A new-style sandwich reinforced soil is clay reinforced with geogrid encapsulated in thin layers of sand. To investigate the interfacial shear behavior of sandwich reinforced soil

a series of cyclic shear tests was performed through a large-scale direct shear device. The influence of thickness of sand layer

shear amplitude and normal stress on the interface shear behavior were investigated. Results indicated that the peak shear stress of the interface increased with the increase of cycle number. When the thickness of sand layers were 5

6

7

8

9 mm in the last cycle number

the corresponding peak shear stresses of the interface were 24.84

27.4

27.94

26.33

24.68 kPa

respectively

showing the maximum peak shear stress of the interface occurred with 7 mm of the thickness of thin sand layer. The ultimate vertical displacement increased with the increase of cyclic shear amplitude

and shear stiffness and damping ratio of the interface decreased with the increase of cyclic shear amplitude at the same cycle number. When the normal stresses were 30

60

90 kPa

in the last cycle number

the corresponding peak shear stresses of the interface were 20.4

25.14

32.96 kPa

respectively

showing the peak shear stress increased with the increase of normal stress

and the shear stiffness increased with the increase of normal stress at the same cycle number.