an engineering geological characterisation of tropical clays - GBV

iv
4.5 Principle of vane shear test 38
4.6 Variation of field vane shear strength with soil depth 41
4.7 Variation of field vane shear strength with natural moisture content of soils 42
4.8 Variation of field vane shear strength with bulk density of soils 43
5.1 Distribution of soils of the study area 47
6.1 – 6.6 X-ray diffraction diagrams of black clays 61-64
6.7 – 6.10 X-ray diffraction diagrams of red soils 65-67
6.11 Variation of carbon content of red soils with depth 80
6.12 Variation of carbon content of black clays with depth 81
6.13 Variation of carbon content of both black clays and red soils with depth 82
7.1 A plasticity chart classification of black clays and red soils 90
7.2 Activity level classification of black clays and red soils 91
7.3a Particle size distribution curves for black clays and red soils 102
7.3b Triangular classification chart for black clays and red soils 103
7.4 Shear stress/ displacement curves of black clays and red soils 107
7.5 Coulomb or shear failure envelopes obtained for black clays and red soils 110
7.6 Correlation between shear paramters (c´, φ´) and relative consistency,
Cr, as well as moisture content, Wn, of black clays 111-112
7.7 Correlation between shear paramters (c´, φ´) and plasticity index (PI)
of black clays 112-113
7.8 Correlation between shear paramters (c´, φ´) and reciprocal of
plasticity index (1/PI) of black clays 113
7.9. Correlation between shear paramters (c´, φ´) and ratio Cr/PI
for black clays 114
7.10 – 7.12 Time factor Tv related to degree of consolidation U% 117-118
7.13 Log-time/settlement curve analysis method showing phases
of consolidation 118
7.14 Analysis of square-root time/ settlement curve 118
7.15a. Log-pressure/ voids ratio (e/ log p) curve 122
7.15b. Determination of coefficient of secondary compression cα 122
7.16 Conventional log-time/settlement curves for black clays during
loading and unloading stages 127
7.17 Unconventional log-time/settlement curves for red soils
during loading and unloading stages 127
7.18 Voids ratio/ log Pressure (e/ log p) curves for black clays and red soils 128
7.19 - 7.20 Permeability/ log pressure (K/log p) curves for black clays
and red soils 130-131
7.21 Coefficient of volume compressibility/ log pressure (mv/log p)
curves for black clays and red soils 131
7.22 Coefficient of consolidation/ log pressure (cv/log p) curves for black
clays and red soils 132
7.23 – 7.24 Correlation between laboratory determined liquid limits and
compression indices for black clays and red soils 134
7.25 – 7.26 Correlation between swell index and Atterberg
limits for black clays and red soils 137
7.27 Correlation between swell index and free swell for black clays
and red soils 137
7.28 Swelling pressure curves obtained for black clays 139