1 2 1 4 Grain Size mm Silt

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1. 4 흙 입자의 크기와 입도분석 Grain Size (mm) Silt and Clay F M

1. 4 흙 입자의 크기와 입도분석 Grain Size (mm) Silt and Clay F M Gravel C Size (mm) 0. 075 4. 75 Sieve No. 200 4 Fine-grained soils 세립질 비중병 시험 광물종류 수분(연경도) 0. 075 mm 75 m 1000 75 uld e Sand 100 rs 10 Bo 1 s 0. 1 bb le 0. 01 Co 0. 001 300 Coarse-grained soils 조립질 체분석 시험 입자모양, 크기(분포)정도 Packing 14

Sieve Analysis (Mechanical) Coarse. Grained Sieves d > 75 m Sieve Number Sieve #

Sieve Analysis (Mechanical) Coarse. Grained Sieves d > 75 m Sieve Number Sieve # = # openings per inch 16

Sieve Analysis (Mechanical) PROCEDURE Largest Openings Sieve Stack • Place known mass of soil

Sieve Analysis (Mechanical) PROCEDURE Largest Openings Sieve Stack • Place known mass of soil in top sieve • Shake sieve stack • Weigh soil retained on each sieve Smallest Openings 17

Sieve Analysis (Mechanical) PROCEDURE Largest Openings Shaking table • Place known mass of soil

Sieve Analysis (Mechanical) PROCEDURE Largest Openings Shaking table • Place known mass of soil in top sieve • Shake sieve stack • Weigh soil retained on each sieve Smallest Openings 18

Sieve Analysis (Mechanical) Potential Problems: Square openings measure only one characteristic length Applied mechanical

Sieve Analysis (Mechanical) Potential Problems: Square openings measure only one characteristic length Applied mechanical forces may break particles 19

Sieve Analysis (Mechanical) We compute: % retained on n-th sieve = wn wtotal X

Sieve Analysis (Mechanical) We compute: % retained on n-th sieve = wn wtotal X 100% % finer than nth sieve = To plot: Grain Size Distribution Curve 21

Sieve Analysis (Mechanical) ACEE 212 – 토질역학의 기본 22

Sieve Analysis (Mechanical) ACEE 212 – 토질역학의 기본 22

Index Properties of Coarse-Grained Soils Factors affecting engineering behavior Index properties • Grain size

Index Properties of Coarse-Grained Soils Factors affecting engineering behavior Index properties • Grain size distribution • D 50, D 10, Cu, Cc, etc. • Grain shape • Relative Density (2장) • Grain packing 23

Hydrometer Analysis Silts & clays too small for sieve analysis Hydrometer measures Gs of

Hydrometer Analysis Silts & clays too small for sieve analysis Hydrometer measures Gs of a suspension • • Mix small mass of soil into a suspension with dispersant (Na. PO 3)6 Lower hydrometer into suspension Hydrometer sinks until buoyancy force = hydrometer weight L = f( suspension, temp) 25

Hydrometer Analysis • • Particles settle according to size Density changes with time, so

Hydrometer Analysis • • Particles settle according to size Density changes with time, so hydrometer sinks Hydrometer readings taken with time Readings corrected for temp 26

Hydrometer Analysis 27

Hydrometer Analysis 27

Hydrometer Analysis 28

Hydrometer Analysis 28

1. 4 흙 입자의 크기와 입도분석 • Qualitative descriptors: • Well graded • Poorly

1. 4 흙 입자의 크기와 입도분석 • Qualitative descriptors: • Well graded • Poorly graded (uniform or gap graded) 31

1. 5 점토광물 세립질 – 입자크기 < 0. 075 mm (#200) – 광물특성, 수분(연경도)

1. 5 점토광물 세립질 – 입자크기 < 0. 075 mm (#200) – 광물특성, 수분(연경도) 기호 : 산소 Silica tetrahedron Silica (tetrahedral) sheet 기호 Alumina octahedron Alumina (octahedral) sheet gibbsite sheet (after Budhu, 2000) 32

1. 5 점토광물 Index Properties of Fine-Grained Soils Factors affecting engineering behavior • Clay

1. 5 점토광물 Index Properties of Fine-Grained Soils Factors affecting engineering behavior • Clay mineralogy • Chemical and electrical bonds between clay particles Index properties • Atterberg limits (2장) • Interaction between clay particles and water 33

1. 5 점토광물 1. 5. 1 점토광물 1) 점토광물의 기본단위 (1) silica tetrahedron ⇒

1. 5 점토광물 1. 5. 1 점토광물 1) 점토광물의 기본단위 (1) silica tetrahedron ⇒ silica (tetrahedral) sheet (2) alumina octahedron ⇒ alumina (octahedral) sheet (또는 gibbsite sheet) 34

1. 5 점토광물 Kaolinite (1: 1) “Strong” bonds “Large” particles 0. 72 x 10

1. 5 점토광물 Kaolinite (1: 1) “Strong” bonds “Large” particles 0. 72 x 10 -9 m (after Budhu, 2000) 36

1. 5 점토광물 Illite (2: 1) “Medium” bonds “Medium” particles 0. 96 x 10

1. 5 점토광물 Illite (2: 1) “Medium” bonds “Medium” particles 0. 96 x 10 -9 m (after Budhu, 2000) 37

1. 5 점토광물 Montmorillonte (2: 1) “Weak” bonds “Small” particles 0. 96 x 10

1. 5 점토광물 Montmorillonte (2: 1) “Weak” bonds “Small” particles 0. 96 x 10 -9 m (after Budhu, 2000) 38

1. 5 점토광물 1 cm Volume Surface Area 1 cm 3 6 cm 2

1. 5 점토광물 1 cm Volume Surface Area 1 cm 3 6 cm 2 1 cm 3 12 cm 2 1 cm 3 24 cm 2 1 cm 39

1. 5 점토광물 Clay Mineral Typical Thickness (mm) Typical Diameter (mm) Specific Surface (m

1. 5 점토광물 Clay Mineral Typical Thickness (mm) Typical Diameter (mm) Specific Surface (m 2/g) Sand 1 1 0. 01 Kaolinite 5 x 10 -5 to 2 x 10 -3 3 x 10 -4 to 4 x 10 -3 10 to 20, ~15 Illite 3 x 10 -5 1 x 10 -2 65 to 100, ~80 Montmorillonite 3 x 10 -6 1 x 10 -4 to 1 x 10 -3 Up to 1000, ~800 40

1. 5 점토광물 Montmorrilonite particle Kaolinite particle Adsorbed water (after Lambe, 1958) 45

1. 5 점토광물 Montmorrilonite particle Kaolinite particle Adsorbed water (after Lambe, 1958) 45

Clay Image Kaolinite illite Montmorillonite http: //blass. com. au/ 46

Clay Image Kaolinite illite Montmorillonite http: //blass. com. au/ 46

Homework Assignment – Chapter 1 Assignment # 1 Due: Next week 연습문제 1 (모눈종이)

Homework Assignment – Chapter 1 Assignment # 1 Due: Next week 연습문제 1 (모눈종이) 47

Hydrometer Analysis **Based on Stoke’s Law** At terminal velocity (zero acceleration): W – B

Hydrometer Analysis **Based on Stoke’s Law** At terminal velocity (zero acceleration): W – B – F = 0 Where weight W= s. V V=1/6 d 3 B = w. V F = 6 v (d/2) buoyancy drag v=velocity of sedimentation = viscosity 48

Hydrometer Analysis Particle diameter d at time t based on Stoke’s Law Where: =

Hydrometer Analysis Particle diameter d at time t based on Stoke’s Law Where: = viscosity of water (1 c. P at 20°C) L = hydrometer reading Gs = specific gravity of solids w = unit weight of water 49

Hydrometer Analysis Assumptions of Stoke’s Law d • • Spherical particles Free-falling particles Particles

Hydrometer Analysis Assumptions of Stoke’s Law d • • Spherical particles Free-falling particles Particles all have similar Gs Particles are dispersed Effective size range: 200 m → laminar flow conditions 0. 2 m → Brownian motion 50

Grain-Size Distribution • • Soil classification Selection of fill materials Selection of aggregates Selection

Grain-Size Distribution • • Soil classification Selection of fill materials Selection of aggregates Selection of road base materials Drainage filters Permeability estimates Viability of grouting and chemical injection 51