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Liquefaction susceptibility study at commonwealth games village delhi
- 1. Sanjay Gupta Ravi Sundaram Sorabh Gupta CENGRS GEOTECHNICA PVT. LTD.CENGRS GEOTECHNICA PVT. LTD. G.V. RamanaG.V. Ramana IIT DelhiIIT Delhi
- 2. Location of the Games Village On Eastern Bank of River Yamuna Near Akshardham Temple
- 4. Structures to be Built Multi-Storeyed Housing Complex with stilts 5-9 upper storeys Single basement in Towers No basement in non-tower structures
- 5. Layout Plan
- 6. Scope of Geotechnical Investigations 14 boreholes to 30 m depth 8 static cone penetration tests 23 shear wave velocity tests along 6 lines by SASW Method
- 8. SPT using automatic trip hammer
- 9. SCPT (20T) in progress
- 10. The SASW Method SASW = Spectral AAnalysis of SSurface WWaves Non-destructive – no boreholes, time saving Based on Rayleigh (surface) waves Determines Shear Modulus versus depth profile
- 11. SASW Method 1 Hz Geo phone 4.5 Hz Geo phone NDT PC Dispersion Geo phones SASW … courtesy IIT DelhiIIT Delhi
- 12. SASW Test in progress … courtesy IIT DelhiIIT Delhi
- 13. Data Acquisition
- 14. Geological Setting Indo-Gangetic Alluvium Yamuna River bed Pleistocene and Recent deposits Newer Alluvium – KhadarKhadar Fine sand encountered in the project area
- 16. Design Profile Groundwater met at 7~8 m depth during the field investigation Due to the proximity of site to Yamuna River, and HFL, groundwater level was considered at ground surface for the analysis
- 17. Field SPT Values Profile
- 18. Cone tip Resistance vs Depth
- 19. Shear Wave Velocities Profile
- 20. Liquefaction Assessment – IS Code IS 1893 Part 1 (2002) states that: For Zones III, IV & V, liquefaction may occur in fine sands belowfine sands below water tablewater table for the following SPT (N) values: Depth ≤ 5 m : N < 15Depth ≤ 5 m : N < 15 Depth >10 m: N < 25Depth >10 m: N < 25 For 5For 5--10 m depth:10 m depth: Linear InterpolationLinear Interpolation
- 21. Liquefaction Analysis Project site is in Zone IV earthquake zone as per IS 1893 (Part 1): 2002 Design Earthquake Magnitude (Richter Scale) M : 6.7 Peak ground acceleration amax : 0.24g Analysis by NCEER Summary ReportNCEER Summary Report (2001)(2001) Youd & Idris approach
- 22. Cyclic Stress Ratio g a rCSR vo vo d vo av max '' )(65.0)( σ σ σ τ == ⎩ ⎨ ⎧ ≤≤−= ≤−= m239.15for0267.0174.1 m15.9for00765.00.1 zzr zzr d d Ref: Seed & Idris, 1982 g a rCSR vo vo d vo av max '' )(65.0)( σ σ σ τ == ⎩ ⎨ ⎧ ≤≤−= ≤−= m239.15for0267.0174.1 m15.9for00765.00.1 zzr zzr d d
- 23. Cyclic Resistance Ratio If (qc1N )cs < 50 ⇒ CRR7.5 = 0.833 (qc1N )cs 1000 ⎡ ⎣⎢ ⎤ ⎦⎥ + 0.05 If 50 ≤ (qc1N )cs < 160 ⇒ CRR7.5 = 93 (qc1N )cs 1000 ⎡ ⎣⎢ ⎤ ⎦⎥ 3 + 0.08 ⎧ ⎨ ⎪⎪ ⎩ ⎪ ⎪ CRR from SPT CRR from SCPT qc CRR7.5 = 1 34 − (N1)60 + (N1)60 135 + 50 [10.(N1)60 + 45]2 − 1 200 S C R C B C H C N C field NN ..... 60 ) 1 ( = 601601 )N(cs,)N( βα += S C R C B C H C N C field NN ..... 60 ) 1 ( = 601601 )N(cs,)N( βα += If (qc1N )cs < 50 ⇒ CRR7.5 = 0.833 (qc1N )cs 1000 ⎡ ⎣⎢ ⎤ ⎦⎥ + 0.05 If 50 ≤ (qc1N )cs < 160 ⇒ CRR7.5 = 93 (qc1N )cs 1000 ⎡ ⎣⎢ ⎤ ⎦⎥ 3 + 0.08 ⎧ ⎨ ⎪⎪ ⎩ ⎪ ⎪ S C R C B C H C N C field NN ..... 60 ) 1 ( = 601601 )N(cs,)N( βα +=
- 24. CRR from Shear Wave Velocity Vs1 = Vs Pa σvo ' ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ 0.25 Corrected Vs CRR from Vs ⎟⎟ ⎟ ⎠ ⎞ ⎜⎜ ⎜ ⎝ ⎛ − − +⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ = * 11 * 1 2 1 11 100 sss s VVV b V aCRR Vs1* = limiting value of Vs1 for liquefaction Ref: Andrus & Stokoe, 1997 Vs1 = Vs Pa σvo ' ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ 0.25 ⎟⎟ ⎟ ⎠ ⎞ ⎜⎜ ⎜ ⎝ ⎛ − − +⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ = * 11 * 1 2 1 11 100 sss s VVV b V aCRR
- 25. CSR & CRR Based on SPT Liquefaction to 10 m depthLiquefaction to 10 m depth
- 26. CSR & CRR based on SCPT (qc) Liquefaction to 14 m depthLiquefaction to 14 m depth
- 27. CSR & CRR based on Vs Liquefaction to 9 m depthLiquefaction to 9 m depth
- 28. Analysis Case Approx Depth of Liquefiable Zone, m IS 1893 (Part 1): 2002 14~16 m SPT values 10 m SCPT Profile 14 m Shear Wave Velocities (SASW) 9 m RECOMMENDEDRECOMMENDED DEPTHDEPTH 9.5 m9.5 m
- 29. Computed Capacities – Bored Piles Pile Dia, mm Pile length below COL, m Safe Compressive Capacity, Tons Normal Condition Liquefaction Case 500 18 66 58 20 74 67 750 18 115 101 20 131 116 800 18 126 113 20 142 129 Cut-off-level: 2 m below GL
- 30. Pile Load Test in progress..
- 31. Pile Load Test Results PilePile Dia,Dia, mmmm PilePile length,length, mm TestTest Load,Load, TonsTons DesignDesign LoadLoad (normal(normal condition)condition),, TonsTons Settlement, mm atSettlement, mm at 1.5 x1.5 x DesignDesign LoadLoad 2 x2 x DesignDesign LoadLoad TestTest LoadLoad 500 20 230230 74 8.3 10.2 20.6 750 20 375375 131 1.9 2.7 65.4 800 20 417417 142 7.5 62.5 84.1 Cut-off-level: 2 m below GL Pile should be tested to verify safe load under normal condition so as to ensure that the piles shall be safe under liquefaction condition during earthquake
- 32. Working Piles in progress…
- 33. Concluding Remarks A detailed geotechnical investigation is essential to properly assess liquefaction potential during earthquakes. The scope should include Boreholes Static cone penetration tests Shear wave velocity tests
- 34. Concluding Remarks The CW Games village site may experience liquefaction to 9.5 m depth under the design earthquake Safe load for piles should be worked out ignoring the skin friction in the liquefiable zone Piles should be load tested for safe load as per normal condition
- 35. ThankThank You!You! CENGRS GEOTECHNICA PVT. LTDCENGRS GEOTECHNICA PVT. LTD IIT DELHIIIT DELHI