an engineering geological characterisation of tropical clays - GBV

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108 Table 7.9. Shear strength parameters of black clays and red soils. Results of natural moisture content (Wn), plasticity index (PI) and relative consistency (Cr) also included for comparison purposes. Profile Sample No. Wn (%) PI (%) Cr Cohesion c´(kN/m²) Shear angle φ´ (degrees) A SA2-30cm 34 54 1,094 23,10 22 SA2-70cm 34 54 1,04 35,60 19 (black clays) SA41-30cm 23 47 1,387 29,80 29 SA41-50cm 25 49 1,334 41,00 19 SB1-30cm 23 47 1,237 46,70 17 B SB1-50cm 27 48 1,197 39,50 12 SB1-70cm 30 51 1,187 17,40 19 (black clays) SB5-30cm 24 47 1,212 47,40 17 SB5-50cm 27 48 1,205 36,60 13 SB5-70cm 31 51 1,19 16,00 19 SB7-30cm 23 48 1,235 44,90 17 SB7-50cm 26 49 1,222 36,20 13 SB7-70cm 30 49 1,179 37,60 14 SB41-30cm 23 44 1,491 30,20 30 SB41-50cm 24 47 1,415 28,60 22 SC1-30cm 24 48 1,218 47,20 18 C SC1-50cm 26 48 1,224 31,80 14 SC17-30cm 21 41 1,329 11,50 22 (black clays) SC17-50cm 22 48 1,219 33,70 14 SC33-30cm 20 49 1,248 25,10 25 SC33-50cm 21 50 1,233 34,90 22 SD1-30cm 27 46 1,203 47,90 17 D SD1-50cm 27 47 1,19 38,40 16 SD1-80cm 30 49 1,248 33,80 15 (black clays) SD5-30cm 26 47 1,217 44,00 16 SD5-50cm 27 48 1,188 36,10 13 SD5-80cm 30 50 1,243 35,10 13 SD7-30cm 27 48 1,198 45,40 16 SD7-50cm 27 49 1,205 36,80 14 SD7-70cm 30 52 1,177 35,50 13 SD33-30cm 20 47 1,37 32,00 30 SD33-50cm 21 50 1,287 28,00 21 SE1-30cm 24 48 1,229 46,40 16 E SE1-50cm 27 48 1,214 39,00 12 SE1-70cm 30 52 1,181 42,50 11 (black clays) SE13-30cm 21 47 1,391 42,60 16 SE13-50cm 24 49 1,338 35,10 12 SE29-30cm 22 46 1,301 25,80 26 SE29-50cm 23 47 1,279 36,20 23 SE41-30cm 22 47 1,381 26,00 28 SE41-50cm 21 48 1,403 29,00 22 Rd1 -30cm 39 18 0,512 0,00 29 Red soils Rd1-100cm 24 21 1,316 0,00 29 Rd1-200cm 24 20 1,27 0,00 28 Rd1-400cm 25 18 1,278 0,00 28
109 Table 7.10. Distribution and/ or variation of shear strength parameter (φ´) across study area. Profile Depth (m) Sample No. Sta. position (m) PI (%) Shear angle (φ´) in degrees Depth (m) Sample No. PI (%) SA1-30cm 0 41 SA1-50cm 39 Shear angle (φ´) in degrees A < 0,50 SA2-30cm 250 54 22 ≥ 0,50 SA2-70cm 55 19 SA28-30cm 6750 45 SA28-50cm 47 SA37-30cm 9000 43 SA37-50/80cm 39 SA41-30cm 10000 47 29 SA41-50cm 49 19 SB1-30cm 0 47 17 SB1-50/70cm 50 15 B < 0,50 SB5-30cm 1000 47 17 ≥ 0,50 SB5-50/70cm 50 16 SB7-30cm 1500 48 17 SB7-50/70cm 49 14 SB18-30cm 4250 43 SB18-50cm 39 SB27-30cm 6500 47 SB27-50cm 49 SB31-30cm 7500 49 SB31-50cm 48 SB41-30cm 10000 44 30 SB41-50cm 47 22 SB42-30cm 10250 44 SB42-50cm 47 SC1-30cm 0 48 18 SC1-50cm 48 14 C < 0,50 SC5-30cm 1000 48 ≥ 0,50 SC5-50cm 47 SC9-30cm 2000 48 SC9-50cm 48 SC17-30cm 4000 41 22 SC17-50cm 48 14 SC25-30cm 6000 49 SC25-50cm 48 SC29-30cm 7000 49 SC29-50cm 43 SC33-30cm 8000 49 25 SC33-50cm 50 22 SC41-30cm 10000 47 SC41-50cm 47 SD1-30cm 0 46 17 SD1-50/80cm 48 15 D < 0,50 SD5-30cm 1000 47 16 ≥ 0,50 SD5-50/70cm 49 13 SD7-30cm 1500 48 16 SD7-50/70cm 51 14 SD17-30cm 4000 44 SD17-50cm 49 SD25-30cm 6000 39 SD25-50cm 45 SD29-30cm 7000 47 SD29-50cm 51 SD33-30cm 8000 47 30 SD33-50cm 50 21 SD41-30cm 10000 46 SD41-50cm 49 SE1-30cm 0 48 16 SE1-50/70cm 50 11 E < 0,50 SE5-30cm 1000 48 ≥ 0,50 SE5-50/70cm 49 SE13-30cm 3000 47 16 SE13-50cm 49 12 SE21-30cm 5000 49 SE21-50cm 49 SE29-30cm 7000 46 26 SE29-50cm 47 23 SE37-30cm 9000 48 SE37-50cm 48 SE41-30cm 10000 47 28 SE41-50cm 48 22 max 30 max 22 Statistical < 0,50 min 16 ≥ 0,50 min 11 analysis range 14 range 11 median 17 median 15 mode 17 mode 22 mean 21 mean 16 standard dev. 5,50 standard dev. 3,76 variance 30,26 variance 14,10 covariance covariance -0,08 correlation correlation 0,89
Page 1 and 2:
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
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49 The red friable clays on the who
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51 Results of chemical analyses of
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53 Results of previous soil classif
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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 and 112: 99 Table 7.6. Viscosity and density
Page 113 and 114: 101 Table 7.7, continued. Results o
Page 115 and 116: 103
Page 117 and 118: 105 Plate 7.7a. Shear testing showi
Page 119: 107 Shear stress / Displacement Cur
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
Page 163 and 164: 151 Black clays: Greek method P% =
Page 165 and 166: 153 partly produced by effects of w
Page 167 and 168: 155 Chapter 8 Distribution of index
Page 169 and 170: 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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