Fines Content Correction Factors for SPT N Values Liquefaction Resistance Correlation

Transcription

1 Fines Content Correction Factors for SPT N Values Liquefaction Resistance Correlation Marawan Shahien Professor of Geotechnical Engineering & Foundations Stuctural Engineering Department Tanta University, Tanta, Egypt

2 Content Introduction Liquefaction Resistance SPT N Correlations Existing Fines Content Correction Factors Motivation and Aim of the Paper Proposed Correction Factors: Methodology Influence of FC on (N 1 ) 60 Influence of FC on CRR Influence of FC on CRR-(N 1 ) 60 Proposed Relationship Concluding Remarks

3 Liquefaction Resistance SPT N Correlations

4 Liquefaction Resistance SPT N Correlation

5 Liquefaction Resistance, CRR Existing Fines Content Correction Factors N N D N 1 60 CS Sand with Fines Base Curve Clean Sand (FC 5%) D(N 1 ) 60 (N 1 ) 60 (N 1 ) 60-CS (N 1 ) 60 Values

6 Existing Fines Content Correction Factors Form Reference (N 1 ) 60-CS = (N 1 ) 60 + D(N 1 ) 60 D(N 1 ) 60 = constant Seed et al. (1983) D(N 1 ) 60 = f(fc) Tokimatsu and Yoshimi (1983) Seed et al.(1984) Terzaghi et al (1996) Kayen and Mitchell (1997) Shahien and Mesri (1999) Youd et al. (2001) Idriss and Boulanger (2006) D(N 1 ) 60 =g[fc,(n 1 ) 60 ] Idriss and Seed (1996) Robertson and Wride (1996) (N 1 ) 60-CS = C fines (N 1 ) 60 C fines = k[fc,(n 1 ) 60 ] Cetin et al. (2004)

7 Existing Fines Content Correction Factors Shahien &Mesri (1999) Form Reference (N 1 ) 60-CS = (N 1 ) 60 + D(N 1 ) 60 D(N 1 ) 60 = constant Seed et al. (1983) D(N 1 ) 60 = f(fc) Tokimatsu and Yoshimi (1983) Seed et al.(1984) Terzaghi et al (1996) Kayen and Mitchell (1997) Shahien and Mesri (1999) Youd et al. (2001) Idriss and Boulanger (2006) D(N 1 ) 60 =g[fc,(n 1 ) 60 ] Idriss and Seed (1996) Robertson and Wride (1996) (N 1 ) 60-CS = C fines (N 1 ) 60 C fines = k[fc,(n 1 ) 60 ] Cetin et al. (2004)

8 Motivation and Aim of the Paper Green et al. (2006) examined FC correction factors used 98 case records of SPT N with liquefaction/no liquefaction 14 earthquakes

9 Cyclic Resistance Ratio, CRR Proposed Correction Factors: Methodology FC 5% SPT Clean Sand Base Curve ((N 1 ) 60-CS, CRR) (1)Correct for influence of FC on (N 1 ) 60, and (2)Correct for influence of FC on CRR. Combining both correction factors Correction for influence of FC on CRR versus (N 1 ) (N 1 ) 60

10 Correction For Influence of Fines Content on Penetration Resistance Influence of FC on penetration resistance Standard Penetration Test (SPT) is a dynamic test. Du develops during penetration & rate of Du dissipation depends on k of soil FC contractiveness Du & k slower dissipation Du N

11 Correction For Influence of Fines Content on Penetration Resistance Influence of FC on penetration resistance (Data from Seed et al. (1984)) 10 N' Fines Content, FC, %

12 Correction For Influence of Fines Content on Penetration Resistance Penetration resistance versus Relative Density correlation N 1 Dr 2 N 1 Dr 2 Meyerhof (1957) a b 41 Skempton (1986) a b Cubrinovski & Ishihara (1999), (2000) & (2001) N 1 Dr 60 2 C D e e 1. 7 max 9 max min (e max -e min ) : void ratio range

13 Correction For Influence of Fines Content on Penetration Resistance Relationship between void ratio range and FC Void Ratio Range e max -e min Back calculated Based on Youd et al (2001) Proposed Cubrinovski & Ishihara (2002) Rang e by Cubrinovski & Ishihara (2002) Fines Content, FC, % N 1 Dr 60 2 C D e e 1. 7 max 9 max min

14 Void Ratio Range e max -e min N 1 Dr Correction For Influence of Fines Content on Penetration Resistance Proposed correction for influence of FC on N Back calculated Based on Youd et al (2001) Rang e by Cubrinovski & Ishihara (2002) Fines Content, FC, % Proposed Cubrinovski & Ishihara (2002) SPT (N 1 ) C 0 D e e 1. 7 max max Dr, % Fines Content, FC, %,

15 Correction For Influence of Fines Content on Penetration Resistance Proposed correction for influence of FC on N Void Ratio Range e max -e min N SPT (N 1 ) 60 Back calculated Based on Youd et al (2001) Proposed Cubrinovski & Ishihara (2002) Rang e by Cubrinovski & Ishihara (2002) Fines Content, FC, % 1 60 Dr C D e e 1. 7 Dr, % max 9 max Fines Content, FC, %, RN FC =N 60 /N 60-CS =(N 1 ) 60 /(N 1 ) 60-CS Fines Content, FC, %,

16 RCRR FC =CRR FC /CRR Correction For influence of FC on CRR Polito (1999) Polito and Martin (2001) 1.2 Cubrinovski and Ishihara (2002) Yatesville silt/sand mixture Dr = 30% Coarse grained Behavior Limiting Fines Content Transition Zone LFC Fines Content, FC, %, Non/Low Plastic Silt Behavior

17 RCRR FC =CRR FC /CRR Cyclic Resistance Ratio, CRR Combined Correction For influence of FC on CRR-(N 1 ) 60 Relationship 0.5 Correction for FC LFC FC 5% 0.3 RN FC =N 60 /N 60-CS =(N 1 ) 60 /(N 1 ) 60-CS SPT Clean Sand Base Curve Fines Content, FC, %, 0.1 ((N 1 ) 60-CS, CRR) (N ) Coarse grained Behavior Limiting Fines Content Transition Zone Non/Low Plastic Silt Behavior Fines Content, FC, %,

18 Cyclic Resistance Ratio, CRR Combined Correction For influence of FC on CRR-(N 1 ) 60 Relationship RCRR FC =CRR FC /CRR Cyclic Resistance Ratio, CRR 0.5 Correction for FC LFC FC 5% RN FC =N 60 /N 60-CS =(N 1 ) 60 /(N 1 ) 60-CS Fines Content, FC, %, SPT Clean Sand Base Curve 0.3 ((N 1 ) 60-CS, CRR) Coarse grained Behavior Limiting Fines Content Transition Zone Non/Low Plastic Silt Behavior Fines Content, FC, %, (N ) (N 1 ) 60

19 RCRR FC =CRR FC /CRR Cyclic Resistance Ratio, CRR Combined Correction For influence of FC on CRR-(N 1 ) 60 Relationship 0.5 Correction for FC>LFC FC 5% 0.3 RN FC =N 60 /N 60-CS =(N 1 ) 60 /(N 1 ) 60-CS SPT Clean Sand Base Curve Fines Content, FC, %, 0.1 ((N 1 ) 60-CS, CRR) (N ) Coarse grained Behavior Limiting Fines Content Transition Zone Non/Low Plastic Silt Behavior Fines Content, FC, %,

20 Cyclic Resistance Ratio, CRR Combined Correction For influence of FC on CRR-(N 1 ) 60 Relationship RCRR FC =CRR FC /CRR Cyclic Resistance Ratio, CRR 0.5 Correction for FC>LFC FC 5% RN FC =N 60 /N 60-CS =(N 1 ) 60 /(N 1 ) 60-CS Fines Content, FC, %, SPT Clean Sand Base Curve 0.3 ((N 1 ) 60-CS, CRR) Coarse grained Behavior Limiting Fines Content Transition Zone Non/Low Plastic Silt Behavior Fines Content, FC, %, (N ) (N 1 ) 60

21 Cyclic Resistance Ratio, CRR Combined Correction For influence of FC on CRR-(N 1 ) 60 Relationship FC 15 5% 0.3 SPT Clean Sand Base Curve (Figure 1) % 80% 60% (N 1 ) 60

22 Cyclic Resistance Ratio, CRR Cyclic Resistance Ratio, CRR Field Case Records Consideration and Proposed Relationship FC 15 5% 0.5 Liquefaction No Liquefaction 35<FC 92% Green et al. (2006) 0.3 SPT Clean Sand Base Curve (Figure 1) 0.3 (This Paper) FC = 35% Youd and Idriss (2001) FC 35% % 80% 60% Proposed -This Paper FC > 35% (N 1 ) 60 (N 1 ) 60

23 Cyclic Resistance Ratio, CRR Field Case Records Consideration and Proposed Relationship FC 15 5% 0.3 SPT Clean Sand Base Curve 0.1 FC > 35% - Proposed (N 1 ) 60

24 Concluding Remarks This paper presents an alternative approach to obtain FC correction to the liquefaction resistance versus penetration resistance ((N 1 ) 60 ) relationship. The obtained correction confirmed the already existing one for FC 35% (Youd et al., 2001). However, it provided new correction for FC> 35% that is consistent with field case records.

25 Thank you