Mechanics of unlubricated sliding

Abstract

Hubbert and Rubey's terms (1-lambda) in their expressions for subaerial sliding and (1-lambda sub a) in those for submarine sliding can be replaced with greater generality by delta equals (1-lambda)/(1-lambda sub e), where lambda is the ratio of pore-fluid pressure to total normal stress, and lambda sub e is the ratio of ambiant fluid pressure (air or water) total normal stress, both at the sliding surface. The critical slope theta down which subaerial and submarine sliding can take place is given by tan theta equals (tau sub o/sigma sub e) plus delta tan phi, where tau sub o is the initial shear strength of the material at the sliding surface, sigma sub e is the normal component of the loading or active stress, and tan phi is the coefficient of sliding friction for the materials of the sliding surface. For evaluating the mechanism of submarine slides revealed by marine seismic surveys, the following expression may be useful when the initial shear strength of the material can be regarded as negligibly small compared to sigma sub e: delta equals tan theta/tan phi. From the value of delts an estimate of the pore-fliud pressures at the sliding surface at the time of sliding can be obtained. /Author/