In situ evaluation ofK₀in eastern Canada clays

An approximate value of the horizontal effective stress in an overconsolidated clay deposit is often determined from an estimate of the effective stress ratio, K 0 , using the equation [Formula: see text]. It is also generally considered that the α parameter is approximately equal to sin [Formula: see text]. For evaluating K 0 in sensitive clays of eastern Canada, a testing program has been initiated on three different sites representing a large range of overconsolidation ratios. Three different in situ devices were used: the Cambridge self-boring pressuremeter, the flat dilatometer, and hydraulic fracturing. The results show that the different techniques give essentially the same K 0 values. They also give K 0 values larger than those expected, with an α parameter typically between 0.75 and 1.15.