1. Correlating, V s, q c and Cyclic Resistance of a Silty Sand through Laboratory Calibration Tests An-Bin Huang, Yao-Tao Huang, and Yu-Chen Kuo Department of Civil Engineering National Chiao Tung University Hsin Chu, TAIWAN

2. Effects of nonplastic fines on CRR Higher CRR ? Lower CRR ? Depends… ?

3. Effects of nonplastic fines on q c Variation of q c under the same void ratio and stress conditions as the fines content changes ? What void ratio ?

4. Seed and de Alba (1986)

5. Ishihara (1993)

6. Stark and Olson (1995)

7. Effects of nonplastic fines on V s Variation of V s under the same void ratio and stress conditions as the fines content changes ? What void ratio ?

8. Andrus and Stokoe (2000)

9. Youd et al. (2001) …The CRR corrections based on fines contents should be used with engineering judgment and caution…

10. Liquefaction potential mapping qcqc VsVs

11. Laboratory calibration tests CPT calibration tests Vs measurements with bender elements Cyclic triaxial tests Use Mai Liao Sand (MLS), a typical silty fine sand in Central Western Taiwan

13. Coarse grainsFine grains

15. CPT calibration tests in MLS FC = 0%, 15%, 30% and 50% Dro = 50%, 70% and 85%  ’ v = 100, 200 and 300 kPa K = 0.5, 1 and 2

16. The calibration chamber

18. Sample preparation Dry deposition Saturated under a backpressure or dry Stresses applied in steps follow the designated K value

21. = n = C 1 +C 2

22. Fines content C0C0 C1C1 C2C2 C3C3  % n = C 1 +C 2 03830.030.42-2.020.94 152360.230.44-1.630.96 30*260.020.77-1.040.95 50 + 3160.690.11-6.050.93

25. Effects of fines on in MLS Reference state of density FC % K=0.5K=1.0 0.51.02.00.51.02.0 e c =0.67 150.680.790.910.680.790.92 300.080.100.130.100.130.16 50-- 0.040.060.07 e c = 0.73~79 150.780.911.050.790.921.06 30-- 50-- e c =0.95 151.211.411.631.221.421.65 30--

26. Cyclic triaxial tests Sample preparation by wet tamping in 4 layers K = 1 Saturated under a back pressure  ’ v = 100 kPa Bender element V s measurement on the same triaxial specimen

30. Tentative due to differences in sample preparation methods

34. Concluding remarks The current q c and V s methods too conservative? Not necessarily, due to differences in  Shearing mode  K values Fines affect CRR and Vs through soil structure, grain characteristics and compressibility Drainage effects are much more significant to q c

35. When using CPT for liquefaction potential assessment in MLS Make adjustment based on t 50 from pore pressure dissipation test or change of q c after pore pressure dissipation But not I C