an engineering geological characterisation of tropical clays - GBV

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100 Table 7.7. Results of grain size analysis for black clays and red soils in this study. Profile Sample No. Clay (%) Silt (%) Sand (%) Gravel (%) % fines Class (BS 1377: 1975) SA1-30cm 18 72 8 2 90 clayey silt A SA1-50cm 16 56 12 16 72 clayey silt SA2-30cm 26 64 8 2 90 silty clay with sand (black clays) SA2-70cm 26 62 9 3 88 silty clay with sand SA2-105cm 24 61 9 6 85 silty clay with sand SA28-30cm 23 71 5 1 94 silty clay with sand SA28-50cm 18 70 6 6 88 clayey silt SA37-30cm 32 57 9 2 89 silty clay SA37-50cm 31 61 4 4 92 silty clay SA37-80cm 34 56 8 2 90 silty clay SA41-30cm 37 59 3 1 96 silty clay SA41-50cm 44 45 6 5 89 clay SB1-30cm 30 60 6 4 90 silty clay B SB1-50cm 26 65 6 3 91 silty clay with sand SB1-70cm 25 66 5 4 91 silty clay with sand (black clays) SB5-30cm 29 60 7 4 89 silty clay with sand SB5-50cm 25 66 6 3 91 silty clay with sand SB5-70cm 26 64 6 4 90 silty clay with sand SB7-30cm 31 58 7 4 89 silty clay SB7-50cm 27 64 6 3 91 silty clay with sand SB7-70cm 26 64 6 4 90 silty clay with sand SB18-30cm 13 71 8 8 84 clayey silt SB18-50cm 14 74 9 3 88 clayey silt SB27-30cm 32 62 4 2 94 silty clay SB27-50cm 33 59 5 3 92 silty clay SB31-30cm 35 55 5 5 90 silty clay SB31-50cm 30 63 5 2 93 silty clay SB41-30cm 20 68 9 3 88 clayey silt SB41-50cm 22 64 7 7 86 silty clay with sand SB42-30cm 23 65 9 3 88 silty clay with sand SB42-50cm 21 65 8 6 86 silty clay with sand SC1-30cm 30 57 9 4 87 silty clay C SC1-50cm 27 63 7 3 90 silty clay with sand SC5-30cm 31 57 8 4 88 silty clay (black clays) SC5-50cm 27 64 6 3 91 silty clay with sand SC9-30cm 31 58 7 4 89 silty clay SC9-50cm 27 62 8 3 89 silty clay with sand SC17-30cm 29 59 8 4 88 silty clay with sand SC17-50cm 27 59 6 8 86 silty clay with sand SC25-30cm 23 71 5 1 94 silty clay with sand SC25-50cm 18 71 5 6 89 clayey silt SC29-30cm 28 63 8 1 91 silty clay with sand SC29-50cm 26 66 7 1 92 silty clay with sand SC33-30cm 27 64 8 1 91 silty clay with sand SC33-50cm 28 63 8 1 91 silty clay with sand SC41-30cm 16 58 8 18 74 clayey silt SC41-50cm 19 66 8 7 85 clayey silt
101 Table 7.7, continued. Results of grain size analysis for black clays and red soils. Profile Sample No. Clay (%) Silt (%) Sand (%) Gravel (%) % fines Class (BS 1377: 1975) SD1-30cm 32 59 7 2 91 silty clay D SD1-50cm 26 62 8 4 88 silty clay with sand SD1-80cm 27 65 6 2 92 silty clay with sand (black clays) SD5-30cm 31 60 7 2 91 silty clay SD5-50cm 26 62 8 4 88 silty clay with sand SD5-80cm 28 64 6 2 92 silty clay with sand SD7-30cm 32 58 8 2 90 silty clay SD7-50cm 26 63 7 4 89 silty clay with sand SD7-70cm 25 66 5 4 91 silty clay with sand SD17-30cm 13 71 8 8 84 clayey silt SD17-50cm 21 63 8 8 84 silty clay with sand SD25-30cm 24 60 8 8 84 silty clay with sand SD25-50cm 14 60 10 16 74 clayey silt SD29-30cm 27 63 6 4 90 silty clay with sand SD29-50cm 28 64 5 3 92 silty clay with sand SD33-30cm 29 61 6 4 90 silty clay with sand SD33-50cm 28 63 6 3 91 silty clay with sand SD41-30cm 35 57 7 1 92 silty clay SD41-50cm 41 48 6 5 89 clay SE1-30cm 31 58 7 4 89 silty clay E SE1-50cm 27 64 6 3 91 silty clay with sand SE1-70cm 26 65 5 4 91 silty clay with sand (black clays) SE5-30cm 31 58 7 4 89 silty clay SE5-50cm 28 63 5 4 91 silty clay with sand SE5-70cm 26 64 6 4 90 silty clay with sand SE13-30cm 33 60 5 2 93 silty clay SE13-50cm 34 58 5 3 92 silty clay SE21-30cm 24 70 5 1 94 silty clay with sand SE21-50cm 20 68 6 6 88 clayey silt SE29-30cm 27 65 7 1 92 silty clay with sand SE29-50cm 29 63 7 1 92 silty clay with sand SE37-30cm 33 57 5 5 90 silty clay SE37-50cm 31 61 5 3 92 silty clay SE41-30cm 19 70 8 3 89 clayey silt SE41-50cm 19 66 8 7 85 clayey silt Rd1 -30cm 18 73 9 0 91 clayey silt Red soils Rd1-100cm 20 74 6 0 94 clayey silt Rd1-200cm 24 69 7 0 93 silty clay with sand Rd1-400cm 20 72 8 0 92 silty clay with sand soils are presented in the chart (Fig. 7.3b). A more summarised classification of all tested samples based on this chart is given in Table (7.7). In this study therefore, the grading curves provided a means by which soils could be classified (Table 7.7) and their engineering properties broadly assessed. Engineering implications of grain size distribution and grading characteristics of black clays and red soils on construction practice are discussed in the next chapter.
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AN ENGINEERING GEOLOGICAL CHARACTER
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i Contents Page Acknowledgements Su
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iii Chapter 8. Distribution of inde
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v 7.29 - 7.33 Correlation between s
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vii 136 139 7.13 Compressibility cl
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ix Acknowledgements I would like to
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1 Chapter 1 Introduction 1.1 Scope
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Figure1.1 Map of Nairobi region sho
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5 Plates 1.2 (a) & (b) Strong shrin
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7 Available literature in the form
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9 slopes. The northern boundary bet
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11 1.6 Climate The Nairobi area and
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13 marked daily range of relative h
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15 Chapter 2 Previous works 2.1 Sum
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17 Table 2.1 Stratigraphic correlat
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19 Chapter 3 Geology 3.1 Introducti
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21 metamorphic minerals sillimanite
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25 and prismatic apatite occur as a
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27 Table 3.2 Chemical analyses of s
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29 caused by partial segregation of
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32 could otherwise lead to erroneou
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34 The red soils in this study occu
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36 17 16 15 14 13 12 11 10 9 8 7 6
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38 4.4 Vane test 4.4.1 Introduction
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40 Table 4.1 Classification of soft
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42 The variation of vane shear stre
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44 And thirdly, the field vane appa
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46 horizon, most probably a result
Page 61 and 62: 49 The red friable clays on the who
Page 63 and 64: 51 Results of chemical analyses of
Page 65 and 66: 53 Results of previous soil classif
Page 67 and 68: 55 neighbouring metamorphic areas a
Page 69 and 70: 57 Table 5.10. Profile description
Page 71 and 72: 59 The presence of BaO in the red a
Page 73 and 74: 61 resulted most probably from supp
Page 75 and 76: 63 800 Impulse 700 600 500 SC 17 -5
Page 77 and 78: 65 sericite and chlorite (see next
Page 79 and 80: 67 Q: Quartz (1%) H: Haematite K: K
Page 81 and 82: 69 Plate 6.3. K-feldspar phenocryst
Page 83 and 84: 71 The trachytes generally show a r
Page 85 and 86: 73 Plate 6.16. Organic matter (rema
Page 87 and 88: 75 Plate 6.24. Solution pores/ cavi
Page 89 and 90: 77 Plate 6.29. Iron concretion with
Page 91 and 92: 79 The CS-225 is a micro-processor
Page 93 and 94: 81 The red soils generally exhibit
Page 95 and 96: 83 Chapter 7 Laboratory soils index
Page 97 and 98: 85 According to Johnson and Degraff
Page 99 and 100: 87 Table 7.2. Results of index test
Page 101 and 102: 89 Plate 7.2a. Apparatus for liquid
Page 103 and 104: 91 Activity chart Plasticity index
Page 105 and 106: 93 Table 7.3 (continued). Atterberg
Page 107 and 108: 95 where 7.1.4.4 Results V = volume
Page 109 and 110: 97 A standard classification of soi
Page 111: 99 Table 7.6. Viscosity and density
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Page 117 and 118: 105 Plate 7.7a. Shear testing showi
Page 119 and 120: 107 Shear stress / Displacement Cur
Page 121 and 122: 109 Table 7.10. Distribution and/ o
Page 123 and 124: 111 illustrated in Figures 7.6, 7.7
Page 125 and 126: 113 Black clays Cohesion c´ (kN/m
Page 127 and 128: 115 7.4 Oedometer consolidation tes
Page 129 and 130: 117 The compound coefficient, K/ρw
Page 131 and 132: 119 Primary consolidation is a time
Page 133 and 134: 121 where w (%) = moisture content
Page 135 and 136: 123 Relationships between values of
Page 137 and 138: 125 Plate 7.8. Oedometer consolidat
Page 139 and 140: 127 Cumulative log-time/settlement
Page 141 and 142: 129 Ranges of values of coefficient
Page 143 and 144: 131 is most probably due to the ten
Page 145 and 146: 133 The results of correlation show
Page 147 and 148: 135 by differences in lithology, mi
Page 149 and 150: 137 Black clays and red soils Swell
Page 151 and 152: 139 Testing procedure involved cutt
Page 153 and 154: 141 Black clays Swelling pressure S
Page 155 and 156: 143 Black clays: P (kPa) vs S (%) P
Page 157 and 158: 145 The same relationship is repres
Page 159 and 160: 147 Alternatively, percentage swell
Page 161 and 162: 149 Combined sample results: S % vs
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151 Black clays: Greek method P% =
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153 partly produced by effects of w
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155 Chapter 8 Distribution of index
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157 the study area, respectively. R
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159 Liquid limit variation; 0,50m a
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161 Liquid limit (LL) variation (>
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163 (8.6). The few isolated patches
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165 Similarly, soil thicknesses of
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167 Free swell variation; 0,50m dep
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169 fraction at the two depth inter
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171 Variation of fines (%), < 0,50m
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173 %coarse % coarse fraction varia
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175 1°19´S 22 Shear angle variati
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177 9.2 Grain size distribution The
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179 rapid dissipation of pore water
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Chapter 10 181 Correlation of index
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183 Black clays; plasticity index/
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185 On the other hand, laboratory m
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187 Red clays; measured/ calculated
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189 These two relationships could b
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191 Diagram: PImeasured/ PIcalculat
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193 Table 10.5, continued. Calculat
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195 Table 10.6. Calculated and labo
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197 The swelling capability in term
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199 Free swell/ clay fraction Free
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201 There has also been a decrease
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203 PI = 1,88*LS A comparison of pl
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205 cc = 0,0099(122-LL) for black c
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207 Chapter 12 Recommendations Anal
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209 cc = 0,0099(122-LL) for black c
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211 References Abebe, S. T., 2002.
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213 Galster, R.W., 1977. A system o
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215 Mitchell, J.K., 1993. Fundament
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217 ------,1964. Long term stabilit
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Appendix A: Oedometer consolidation
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Table A7. Consolidation parameters
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Results of swelling tests on black
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Appendix D Distribution/ variation
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 1000 Distance (m) We
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 Distance (m) 1000 We
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4000 3000 2000 Distance (m) 1000 We
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Appendix E Geotechnical soil map of
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