Volume compressibility and pore pressure response of kutch soils with varying plastic and non-plastic fines

Effect of fines content (FC) and its nature (plastic fines and non-plastic fines) on the volume compressibility and pore pressure response of 32 soils from 10 locations of Kutch (high seismicity region) is studied. Volume compressibility and pore pressure response of soils are studied and analyzed in the context of variations in plastic and non-plastic fines content. Volume compressibility increased with an increase in fines content: Influence of plastic fines is more compared to non-plastic fines. Fines content and nature of fines controlled the magnitude of excess pore water pressure generated within the soil mass. Plastic fines inhibited pore water pressure generation to a greater degree than non-plastic fines. Soils with same fines content but higher plastic fine content exhibited larger volume compressibility and lower pore water pressure evolution. Skempton’s pore pressure parameter (A) of these soils indicated similar response as that of liquefiable soils. FC and nature of fines affected the degree of brittleness, which has been evaluated by obtaining undrained brittleness index (I<inf>B2</inf>) with respect to pore pressure. The correlation between volume compressibility and pore water pressure response exhibited negative value (R = −0.14) indicating the opposite effect of FC.