Experimental and Analytical Research on Frictional Behavior between Cohesive Soil and Construction Materials during Earthquake

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In this study several sets of element tests on the frictional resistance between clay and steel were carried out. The factors influencing the frictional resistance selected in this study are surface roughness of steel, rate of loading and consolidation pressure of clay. Tests were carried out by the shear box type apparatus under monotonic or cyclic loading. The results are compared to the results of shear tests of clay on similar condition. Pore water pressure was measured on the surface of steel.The knowledge aquired through this study are as follows: 1. It was found that there was the boundary roughness,R_b, by reason of follows; if the surface roughness is larger than R_b, horizontal displacement at peak strength, peak strength, residual strength and friction angle between clay and steel in terms of effective stress have upper limiting values. In contrast, if the surface roughness is smaller than R_b, each above value increses with surface roughness. 2. The above upper limiting values nearly agree with the values of shear tests of clay. Therefore, if the surface roughness is smaller than R_b, the slip occurs between clay and steel, and if the surface roughness is larger than R_b, the failure occurs in clay specimen. 3. The peak strength is much influenced by rate of loading with increse of surface roughness, but the residual strength is not influenced. This behavior is found in shear tests of clay. 4. The friction angle between clay and steel in terms of effective stress is not influenced by consolidation pressure of clay, and increses with surface roughness. 5. Under cyclic loading, the shear stress settles down to the constant value with several cycles when the surface of steel is smooth, and decreses gradually when the surface of steel is rough or in shear tests of clay.