To study the mechanical behavior of different steel-sand interface shear,a new torsional shear device for pile-soil interface shear testing is developed.Some interface torsional shear tests between steel pipe pile and uniform fine sand,Fujian sand,and American Davis sand are performed based on this new device.The test pressures are between 200 kPa and 800 kPa.The mechanical behavior of different pile-soil interfaces can be studied by testing and analyzing the torsion properties of the interface shear.The results show that with the increase of the shear displacement,the interface shear strength increases and remains unchanged finally.But when the shear displacement becomes bigger,the interface shear strength will change slightly.Moreover,both the shear displacement and interface frictional angle of the inflection point of pile-soil interface shear curve increase linearly as the normal stress increases.