87 11 1
(Soil Mechanics) (Geotechnical Engineering) (Soil Mechanics) (Foundation Engineering) (Engineering Geology) (Rock Mechanics) 1925 Karl Terzaghi Terzaghi (Rock Cycle) 2
(Specific Gravity, G s ) 2.65-2.80 3
(1) Name Cobble D > 150 mm Gravel 4.75 mm < D < 150 mm Coarse Sand 2.00 mm < D < 4.75 mm Medium Sand 0.425 mm < D < 2.00 mm Fine Sand 0.075 mm < D < 0.425 mm Silt 0.002 mm < D < 0.075 mm Clay D < 0.002 mm (a) ( ) #4 (4.76 mm)#200(0.074 mm) ( ) (b) ( ) Stoke s Law γ γ = η 4
= η γ γ v γ s γ w η D (Turbulent Flow) (Particle Size Distribution Curve, PSD Curve) (Well Graded) PSD (Poorly Graded) PSD (Gap Graded) (Coefficient of Uniformity)c u = D 60 PSD 60% D 10 PSD 10% c u >6 c u >4 (Coefficient of Curvature)c z = 1<c z <3 (2) (Unified Soil ClassificationUSDAFAA) A. (Texture System) USDAFAA B. (Cohesion) Cohesionless Soil 5
Cohesive Soil C.AASHTO A-1, A-2, A-7A-8 Group Index, GI = (F-35)[0.2+0.005(LL-40)]+0.01(F-15)(PI-10) F #200 D. (Unified Soil Classification) 1.5 m 1.5 m 1.5 m 6
1. 7
2. (Hand Auger) 3. (1) (Split Spoon) 8
1.5 m (2) 3 1 m 3 15 cm 60 cm 9
(3) ( ) (4) 10
4 C () (Block Diagram) v v v A v w w A w w v s w s ( )(Void Ratio) e = (Porosity) n 11
= = + = + (Water Content) w = (Degree of Saturation) S 0 100% = (Unit Weight) γ γ = γ = (Dry Unit Weight) γ d γ γ = + (Moist Unit Weight) γ m 12
γ = = γ + γ + γ = = + + + + = γ + (Saturated Unit Weight) v v γ w = w s w v s eγ w = G s γ w v s w e = w G s S v v γ w = w s w S e = w G s γ b = γ sat - γ w γ w( Gs + e) ( Gs 1) = γ w = γ 1+ e 1+ e w = γ γ () 1. (Relative Density) 13
D r = e e max max e e min x 100% D r (%) 0-15 Very Loose 15-35 Loose 35-65 Medium 65-85 Dense 85-100 Very Dense (Honeycombed Structure) (< 0.02 mm) 2. (1) (Flocculated Structure) (2) (Dispersed Structure) (Sensitivity) S = 14