Effect of organic content and frequency on degradation and pore pressure in marine organic soils

Abstract

ABSTRACTThe effects of organic content and the frequency of cyclic shear straining on the cyclic degradation and the normalized pore water pressure in 27 fibrous marine organic soil specimens were investigated with the two-way cyclic strain-controlled dynamic triaxial testing system. The testing program included three cyclic shear strain amplitudes, γc = 0.25, 0.5, and 1%, three ranges of the organic contents, OC = 13.3–18.4%, 23.3–27.9%, and 36.9–45.3%, and three loading frequencies, f = 0.05, 0.25, and 1 Hz. The results clearly exhibit that the degradation parameter, t, which means the rate of the cyclic degradation with the number of loading cycles, N, decreases with the OC and increases with the f. At the γc = 0.25–1%, if the OC decreases from 40.8 to 13.3%, the degradation parameter t may increase by 82.9–221.1%. If f is increased 20 times, from 0.05 to 1 Hz, then t may increases by 34.7–117.9%. The cyclic pore water pressure normalized by the effective consolidation pressure, , increases with the OC and decreases with the f was also observed.