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Geotechnical Engineering–I [CE-221]
BSc Civil Engineering – 4th Semester
by
Dr. Muhammad Irfan
Assistant Professor
Civil Engg. Dept. – UET Lahore
Email: mirfan1@msn.com
Lecture Handouts: https://groups.google.com/forum/#!forum/geotech-i
Lecture # 3
31-Jan-2017](https://image.slidesharecdn.com/3-180923175732/85/Geotechnical-Engineering-I-Lec-3-Phase-Relationships-1-320.jpg)
Geotechnical Engineering-I [Lec #3: Phase Relationships]
- 1. 1 Geotechnical Engineering–I [CE-221] BSc Civil Engineering – 4th Semester by Dr. Muhammad Irfan Assistant Professor Civil Engg. Dept. – UET Lahore Email: mirfan1@msn.com Lecture Handouts: https://groups.google.com/forum/#!forum/geotech-i Lecture # 3 31-Jan-2017
- 2. 2 S: Solid Soil particle W: Liquid Water A: Air Air SOIL AS A THREE PHASE SYSTEM
- 3. 3 SOIL AS A THREE PHASE SYSTEM V = Total volume of soil mass Vs = Volume of soil solids Vw = Volume of water Va = Volume of air Vv = Va+Vw = Volume of voids W = Total weight of soil Ws = Weight of soil solids Wa = Weight of air ≈ 0 Ww = Weight of water
- 4. 4 1) Void ratio, e (0 < e < ∞) For sands, 0.5 ≤ e ≤ 0.9 For clays, 0.7 ≤ e ≤ 1.5 (or even higher) )V(solidsofVolume )V(voidsofVolume e s v VOLUMETRIC RATIOS
- 5. 5 2) Porosity, n (0 < n < 1) Typical range, 9-70% For sands, 25% ≤ n ≤ 50% 3) Air Porosity, na’ (0 < na’ < 1) 4) Percentage Air Voids, na (0 < na < 1) )V(samplesoilofvolumeTotal )V(voidsofVolume n t v VOLUMETRIC RATIOS )( )( ' t a a VsamplesoilofvolumeTotal VairofVolume n )( )( v a a VvoidsofVolume VairofVolume n
- 6. 6 5) Degree of Saturation/ Saturation Ratio, S (or Sr) (0 < Sr < 100%) 6) Volumetric Water Content, θv (0 < θv < 1) VOLUMETRIC RATIOS %100 )( )( v w VvoidsofvolumeTotal VwatercontainingvoidsofVolume S )( )( t w v VsamplesoilofvolumeTotal VwatercontainingvoidsofVolume
- 7. 7 1) Moisture/Water Content/Gravimetric Water Content, w (0 < w < ∞) Typical value for Sands >> 10-30% For clays >> 10% or higher typically For some organic soils w>100%, even up to 500%. For quick clays w is typically > 100%. WEIGHT RELATIONSHIPS %100 )( )( s w WsolidssoilofWeight WwaterofWeight w
- 8. 8 2) Unit Weight, γ 3) Dry Unit Weight, γd 4) Bulk Unit Weight, γb 5) Unit Weight of Soil Solids, γs WEIGHT RELATIONSHIPS );;( 333 cmgftlbmkN V Mg Volume Weight t s d V W VolumeTotal solidssoilofWeight t b V W VolumeTotal WeightTotal s s s V W soildssoilofVolume soildssoilofWeight
- 9. 9 6) Saturated Unit Weight, γsat 7) Submerged Unit Weight, γsub (or γbouyant) γw = 9.81 kN/m3 → 1 g/cm3 = 1000 kg/m3 = 62.4 lb/ft3 WEIGHT RELATIONSHIPS wsatsub VolumeTotal soilsaturatedofWeight sat Archimede’s principle: The buoyant force on a body immersed in a fluid is equal to the weight of the fluid displaced by that object.
- 10. 10 SPECIFIC GRAVITY (Gs) w s s CatwaterofvolumeequalofweightUnit soildssoilofweightUnit G 4 Generally for soils 2.6 ≤ Gs ≤ 2.7
- 11. 11 WEIGHT-VOLUME RELATIONSHIPS w b d 1 n n e 1 e e n 1 VG W n ws s 1 . 1 1 .. s ws W GV e e w G wsb 1 1 . e G ws d 1 . S Gw e s. e eG ws sat 1 e Gsw sub 1 1 rv Sn.
- 12. 12 CONCLUDED REFERENCE MATERIAL An Introduction to Geotechnical Engineering (2nd Edition) By R. D. Holtz, W. D. Kovacs and T. C. Sheahan Chapter #2 Geotechnical Engineering – Principles and Practices - (2nd Edition) By Donald P. Coduto, M. R. Yeung and W. A. Kitch Chapter #4 Fundamentals of Soil Mechanics By M. S. Qureshi & Aziz Akbar Chapter #3