1. Definition of Fines and Liquefaction Resistance of Maoluo River Sand
Tzou-Shin Ueng
Chia-Wen Sun and Chieh-Wen Chen
National Taiwan University

2. INFLUENCE OF FINES ON LIQUEFACTION RESISTANCE
Youd, et al. (2001)
(N1)60cs = a + b (N1)60
FC ≤ 5%, a = 0, b = 1.0
5% < FC < 35%,
FC ≥ 35%, a = 5.0, b = 1.2
FC ↑ Liquefaction Resistance (CRR) ↑

3. DEFINITION OF FINES Fines Content
FC = Percent of soil with grain size, D < No. 200 sieve
(0.075 mm)

4. ALTERATIVE DEFINITIONS OF FINES
Clay size, D < 5 mm (Chinese Criteria)
FC = Percent of soil with grain size, D < No. 400 sieve
Any difference or better?
(0.038 mm)

5. MAOLUO RIVER SILTY SAND
Specific gravity
2.68
In situ rd
1400 kg/m3
D50
0.078 mm Cu 43
Maximum rd
1717 kg/m3
Minimum rd
1290 kg/m3 LL 23 PI NP
FC (< mm)
48 %
USCS SM

6. PROPERTIES OF DIFFERENT GRAIN SIZE RANGESGs LL PI
USCS
> #200 sieve (> mm)
2.67 ─ SP
< #200 sieve (< mm)
2.69 36 8 ML
> #400 sieve (> mm)
2.68 29 SM
< #400 sieve (< mm)
2.70 38 15 CL
Mineral Compositions (%)
Grain size
Rock fragments
Quartz
Feldspar
Mica
Illite
Chlorite
Kaolinite
> #200 24 68 5 3
< #200
> #400 87 7
≤ #400 41 28 25

7. CYCLIC TRIAXIAL TESTS Dry density, rd = 1400 kg/m3 Fines contents
Defined as D < #200 sieve: 0%, 20%, 48%*, 65%, 100%
Defined as D < #400 sieve: 0%, 10%, 20%, 30%, 37%*, 100%
* in situ soil
Confining press, s’c = 78 kPa
Frequency = 1 Hz

8. LIQUEFACTION RESISTANCES
Fines defined as D < #200 sieve

9. EFFECT OF FINES CONTENT ON LIQUEFACTION RESISTANCE

10. INDEX DENSITIES FOR DIFFERENT FINES CONTENTS

11. SOIL STRAIN AND STRESS RESPONSES
Fines defined as D < #200 sieve

12. LIQUEFACTION RESISTANCES
Fines defined as D < #400 sieve

13. SOIL STRAIN AND STRESS RESPONSES
Fines defined as D < #400 sieve

14. COMPARISON OF EFFECT OF FINES CONTENTS

15. EQUIVALENT FINES CONTENTS
Fines Definition
Fines Contents (%)
D < #400 sieve 10 20 30 37
100
D < #200 sieve
17.5
25.7 34
42.2 48

16. EQUIVALENT FINES CONTENTS
Fines Definition
Fines Contents (%)
D < #200 sieve 20 48 65
100
D < #400 sieve
15.4 37 50 77
Equivalent D < #400 sieve

17. CONCLUDING REMARKS
Soils with particle size between mm and mm is essential a very fine sand.
The effect of FC on the liquefaction resistance is more prominent for fines defined as D < mm than those with fines defined as D > mm.
Corrections solely based on FC without considering the properties of fines cannot truly reflect the influence of fines on liquefaction resistance.
No clear benefit yet to change the present definition of fines, i.e., D < mm.