Field Studies of Response of Peat to Plate Loading

This paper presents the results of a series of small-scale field tests carried out to investigate the in situ deformational characteristics of a soft peat, particularly in the vicinity of a load discontinuity. A 3-ft diam plate was used to apply loads to the surface of a 10-ft thick stratum of nonwoody fine fibrous peat with a moisture content of about 950%. Rates and magnitudes of settlement, and pore pressures at five positions were measured and compared. Field results were supplemented by data obtained from a limited number of oedometer-type laboratory consolidation tests, conducted with and without pore pressure measurements. The geometry of the settlement-logarithmic time plots is described. Emphasis is placed on the prevalence of horizontal drainage and its significance. The departure of soft organic materials from the predicted behavior as based upon the linear theory of elasticity is described, and possible reasons for lack of agreement are presented.