STRESS PATH DEPENDENT PORE PRESSURE PARAMETER AF

THE SETTLEMENT ANALYSIS OF NORMALLY CONSOLIDATED, SATURATED DEPOSITS INVOLVES THE COMPUTATION OF PORE WATER PRESSURES BY THE USE OF SKEMPTON'S PORE WATER PRESSURE PARAMETER A AT FAILURE. AF (SKEMPTON & BJERRUM, 1957; SCOTT, 1933). IN GENERAL, AF IS FOR THE PARTICULAR STRESS PATH WHERE THE VERTICAL PRINCIPAL STRESS IS INCREASING IN THE TRIAXIAL (AXIALLY SYMMETRIC) STRESS SYSTEM WITH THE HORIZONTAL PRINCIPAL STRESS BEING KEPT CONSTANT DURING UNDRAINED SHEAR. FOR STRESS PATHS OTHER THAN THIS, THE PARAMETER AF HAS HAD TO BE OBTAINED BY RESORTING TO GRAPHICAL CONSTRUCTION. NOW THAT POWERFUL COMPUTATIONAL METHODS ARE AVAILABLE, IT HAS BECOME NECESSARY TO OBTAIN STRESS PATH DEPENDENT VALUES OF AF TO DETERMINE THE PORE WATER PRESSURE DISTRIBUTION. WITH THIS IN MIND, RELATIONSHIPS ARE HEREIN DERIVED TO PREDICT THE STRESS PATH DEPENDENT AF. ALSO, A METHOD IS SUGGESTED FOR OBTAINING THE UNDRAINED SHEAR STRENGTH OF A CLAY SAMPLE FROM ITS EFFECTIVE STRESS FAILURE ENVELOPE.