Changes in surface roughness in multi-reverse sand-steel interface tests

摘要

The mechanical response of sand-steel interfaces evolves with shear displacement. Whereas the peak and immediate post-peak stages have often been the main focus, the response at substantially larger displacements has received much less attention. Here it is demonstrated that sand-steel interfaces are subject to wear processes and that interfacial wear can have a profound effect on ultimate response. Multi-reverse interface tests conducted within a modified direct shear apparatus demonstrate the occurrence of both sand particle attrition and steel surface abrasion even at low stress levels. Fractal geometry is used to show that surface abrasion can increase or decrease surface roughness. At quite modest shear displacements a 'run-in' angle of friction is mobilized that is both constant and virtually independent of the initial surface roughness. It may represent the most appropriate operational angle of interface friction in many field situations.