2005 Tri-Service Infrastructure Systems 2005 Tri-Service Infrastructure Systems US Army Corps Conference and Exhibition Conference and Exhibition of Engineers Sacramento District 2-D Liquefaction Evaluation with Q4Mesh -David C. Serafini, M.S., P.E. US Army Corps of Engineers, Sacramento, CA 3 August 2005 3 August 2005 1 1 2005 Tri- 2005 Tri -Service ISC Service ISC
Presentation Outline Presentation Outline US Army Corps of Engineers Sacramento District Liquefaction Evaluation Overview Liquefaction Evaluation Overview I I Overview of Quad4m Overview of Quad4m I I Overview of Q4Mesh Overview of Q4Mesh I I Liquefaction Evaluation with Q4Mesh Liquefaction Evaluation with Q4Mesh I I Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model I I 3 August 2005 3 August 2005 2 2 2005 Tri- 2005 Tri -Service ISC Service ISC
Liquefaction Evaluation Overview Liquefaction Evaluation Overview US Army Corps of Engineers Sacramento District I Two-dimensional seismic response and liquefaction I Two-dimensional seismic response and liquefaction evaluations of earth structures and soil deposits can evaluations of earth structures and soil deposits can be complex and time intensive be complex and time intensive I Techniques available for their evaluation range from I Techniques available for their evaluation range from simplified models to advanced constitutive and non- simplified models to advanced constitutive and non- linear models linear models 3 August 2005 3 August 2005 3 3 2005 Tri- 2005 Tri -Service ISC Service ISC
Liquefaction Evaluation Overview Liquefaction Evaluation Overview US Army Corps of Engineers Sacramento District I Simplified Models I Simplified Models – Simplified Seed and Idriss procedures – Simplified Seed and Idriss procedures – 1-D equivalent linear SHAKE type analysis at multiple locations – 1-D equivalent linear SHAKE type analysis at multiple locations – Evaluations can be made quickly – Evaluations can be made quickly I Advanced Models I Advanced Models – Most accommodate the non-linear behavior of soils – Most accommodate the non-linear behavior of soils – Evaluations are more complex and time intensive – Evaluations are more complex and time intensive I Equivalent Linear Models I Equivalent Linear Models – Can be used to approximate the actual nonlinear behavior of the soil – Can be used to approximate the actual nonlinear behavior of the soil – Quad4m (two-dimensional seismic response) – Quad4m (two-dimensional seismic response) 3 August 2005 3 August 2005 4 4 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Quad4m Overview of Quad4m US Army Corps of Engineers Sacramento District I Quad4m (A Computer Program For Evaluating I Quad4m (A Computer Program For Evaluating The Seismic Response Of Soil Structures) The Seismic Response Of Soil Structures) – U.C.Davis, 1993 – U.C.Davis, 1993 – by Martin Byrd Hudson, I.M.Idriss, and Mohsen – by Martin Byrd Hudson, I.M.Idriss, and Mohsen Beikae Beikae I MODIFIED FROM QUAD4, 1973 I MODIFIED FROM QUAD4, 1973 – by I.M. Idriss, J. Lysmer, R. Hwang and H. Bolton – by I.M. Idriss, J. Lysmer, R. Hwang and H. Bolton Seed Seed 3 August 2005 3 August 2005 5 5 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Quad4m Overview of Quad4m US Army Corps of Engineers Sacramento District I The Quad4m analysis numerically models a continuum I The Quad4m analysis numerically models a continuum with a finite number of elements interconnected at with a finite number of elements interconnected at their common nodes their common nodes I The analysis is done exclusively in the time domain, I The analysis is done exclusively in the time domain, and the response of the soil deposit follows the same and the response of the soil deposit follows the same approximation of nonlinear hysteretic manner that is approximation of nonlinear hysteretic manner that is conventional SHAKE (1-D) analysis when subject to conventional SHAKE (1-D) analysis when subject to loading loading 3 August 2005 3 August 2005 6 6 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Quad4m Overview of Quad4m US Army Corps of Engineers Sacramento District I Direct numerical integration by the software is used I Direct numerical integration by the software is used to solve an equation of motion for the finite element to solve an equation of motion for the finite element mesh to determine the developed: mesh to determine the developed: – Peak Element Shear Stresses (sig-xy, τ max ) – Peak Element Shear Stresses (sig-xy, τ max ) – Peak Element Shearing Strains (eps, γ max ) – Peak Element Shearing Strains (eps, γ max ) – Peak Element Principle Stresses (sig-x, sig-y) – Peak Element Principle Stresses (sig-x, sig-y) – Peak Nodal Accelerations (a max ) – Peak Nodal Accelerations (a max ) 3 August 2005 3 August 2005 7 7 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Q4Mesh Overview of Q4Mesh US Army Corps of Engineers Sacramento District I The Q4Mesh program is a modification of the I The Q4Mesh program is a modification of the WinMesh program to create and analyze Quad4m WinMesh program to create and analyze Quad4m data data I Q4mesh was developed by ERDC (Engineering I Q4mesh was developed by ERDC (Engineering Research and Development Center) at WES Research and Development Center) at WES (Waterways Experimental Station) with some (Waterways Experimental Station) with some assistance provided from the USACE Sacramento assistance provided from the USACE Sacramento District District 3 August 2005 3 August 2005 8 8 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Q4Mesh Overview of Q4Mesh US Army Corps of Engineers Sacramento District I Q4Mesh can be used to: I Q4Mesh can be used to: – Create the Quad4m finite element mesh – Create the Quad4m finite element mesh – Interpret the output files from Quad4m and two – Interpret the output files from Quad4m and two additional user files to conduct a liquefaction additional user files to conduct a liquefaction evaluation evaluation 3 August 2005 3 August 2005 9 9 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Q4Mesh Overview of Q4Mesh US Army Corps of Engineers Sacramento District I Q4Mesh I Q4Mesh – (Main Screen) – (Main Screen) 3 August 2005 3 August 2005 10 10 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Q4Mesh Overview of Q4Mesh US Army Corps of Engineers Sacramento District Additional Input Files for Q4Mesh Additional Input Files for Q4Mesh 1) 2) 3) 4) 5) Blowcount File Surface, Phreatic, and Earthquake File 3 August 2005 3 August 2005 11 11 2005 Tri- 2005 Tri -Service ISC Service ISC
Overview of Q4Mesh Overview of Q4Mesh US Army Corps of Engineers Sacramento District I Basic Liquefaction Procedure Equation I Basic Liquefaction Procedure Equation CSR (Cyclic Stress Ratio) CSR (Cyclic Stress Ratio) CRR (Cyclic Resistance Ratio) CRR (Cyclic Resistance Ratio) K σ (Stress Correction K σ (Stress Correction K α (Sloping Ground Correction) K α (Sloping Ground Correction) MSF (Magnitude Scaling Factor) MSF (Magnitude Scaling Factor) 3 August 2005 3 August 2005 12 12 2005 Tri- 2005 Tri -Service ISC Service ISC
Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model US Army Corps of Engineers Sacramento District I Cyclic Resistance Ratio, CRR (Vs1 Data) I Cyclic Resistance Ratio, CRR (Vs1 Data) 3 August 2005 3 August 2005 13 13 2005 Tri- 2005 Tri -Service ISC Service ISC
Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model US Army Corps of Engineers Sacramento District I Cyclic Resistance Ratio, CRR (N1,60 Data) I Cyclic Resistance Ratio, CRR (N1,60 Data) 3 August 2005 3 August 2005 14 14 2005 Tri- 2005 Tri -Service ISC Service ISC
Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model US Army Corps of Engineers Sacramento District I Stress Correction Factor, K σ I Stress Correction Factor, K σ Default K α =1.0 3 August 2005 3 August 2005 15 15 2005 Tri- 2005 Tri -Service ISC Service ISC
Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model US Army Corps of Engineers Sacramento District I Magnitude Scaling Factor (MSF) I Magnitude Scaling Factor (MSF) 3 August 2005 3 August 2005 16 16 2005 Tri- 2005 Tri -Service ISC Service ISC
Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model US Army Corps of Engineers Sacramento District Embankment Dam on a Liquefiable Embankment Dam on a Liquefiable Foundation (EDOLF) Foundation (EDOLF) 3 August 2005 3 August 2005 17 17 2005 Tri- 2005 Tri -Service ISC Service ISC
Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model US Army Corps of Engineers Sacramento District I Finite Element Mesh I Finite Element Mesh 3 August 2005 3 August 2005 18 18 2005 Tri- 2005 Tri -Service ISC Service ISC
Example Q4Mesh Liquefaction Model Example Q4Mesh Liquefaction Model US Army Corps of Engineers Sacramento District I Material Properties I Material Properties 3 August 2005 3 August 2005 19 19 2005 Tri- 2005 Tri -Service ISC Service ISC
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