Università degli Studi Roma Tre Scuola Dottorale SDiGAR XXVIII Ciclo Sezione Geologia delle Risorse Naturali Assessment of Soil Shaking Features in Urban Areas PhD Student Dott. Maurizio Piersanti Tutor Prof. Giuseppe Della Monica Co-Tutor Dott. Arrigo Caserta PhD Roma, 11 marzo 2016 INDEX 1. INTRODUCTION ..................................................................................................................... 5 1.1 OBJECTIVES OF THE PHD PROJECT ...................................................................................... 6 1.2 THESIS OUTLINE .................................................................................................................. 7 2. GEOLOGICAL SETTINGS .................................................................................................... 9 2.1 GEOLOGY ............................................................................................................................ 9 2.2 MORPHO – TECTONIC ........................................................................................................ 17 2.3 SEISMOLOGY ..................................................................................................................... 18 2.4 HYDROGEOLOGY ............................................................................................................... 24 3. SEISMIC WAVES................................................................................................................... 27 3.1 BODY WAVES .................................................................................................................... 27 3.2 SURFACE WAVES .............................................................................................................. 30 3.3 DISPERSION OF SURFACE WAVES ...................................................................................... 31 3.4 GENERAL SETTING ............................................................................................................ 36 4. SITE EFFECTS ....................................................................................................................... 39 4.1 EFFECTS OF SOFT SURFACE LAYERS: THE AMPLIFICATION FUNCTION .............................. 40 4.2 SEISMIC NOISE ANALYSIS ................................................................................................. 44 4.2.1 Single Station Measurements ....................................................................................... 47 4.2.1.1 H/V Spectral Ratio and Body Waves ................................................................................. 49 4.2.1.2 H/V Spectral Ratio and Ellipticity ..................................................................................... 50 4.2.1.3 H/V Spectral Ratio and Love Waves ................................................................................. 52 4.2.1.4 H/V Spectral Ratio and Complex Wavefield: Results from Numerical Simulation ........... 53 4.2.2 Array Analysis .............................................................................................................. 54 4.2.2.1 The frequency-wavenumber Power Spectrum ( f-k Spectrum) .......................................... 55 4.2.2.2 Conventional f-k Analysis (CVFK) ................................................................................... 58 4.2.2.3 Capon’s Analysis (HRFK) ................................................................................................. 59 4.2.2.4 Array Geometry, Resolution and Aliasing ......................................................................... 60 4.2.2.5 Array Transfer Function .................................................................................................... 62 4.2.2.6 Multichannel Analysis of Surface Waves (MASW) .......................................................... 65 4.3 SOIL BEHAVIOR UNDER CYCLIC STRESS ............................................................................ 66 4.3.1 Resonant Column Test (RCT) ....................................................................................... 69 4.3.2 Cyclic Torsional Shear Test (CTS) ............................................................................... 71 4.4 SOIL LIQUEFACTION .......................................................................................................... 72 4.4.1 Testing Liquefaction Risk: Simplified Procedures ....................................................... 73 5. DATA ANALYSIS AND RESULTS ...................................................................................... 77 5.1 SEISMIC NOISE MEASUREMENTS: SINGLE STATION ANALYSIS ......................................... 77 5.2 GEOGNOSTIC DRILLINGS ................................................................................................... 82 5.3 DOWN-HOLE TEST ............................................................................................................ 86 5.4 SEISMIC NOISE MEASUREMENTS; ARRAY ANALYSIS ........................................................ 87 5.4.1 Site S5 ........................................................................................................................... 87 5.4.2 Site Piazza Haring ........................................................................................................ 92 5.5 GEOLOGICAL RECONSTRUCTION OF THE STUDY AREA ..................................................... 96 5.5.1 Test Site Area ............................................................................................................... 97 5.5.2 High Crati Valley Area ................................................................................................. 98 5.6 LABORATORY TESTS ......................................................................................................... 99 5.6.1 Site S1 ......................................................................................................................... 100 5.6.2 Site S2 ......................................................................................................................... 101 5.6.3 Site S3 ......................................................................................................................... 102 5.6.4 Site S4 ......................................................................................................................... 103 5.6.5 Site S5 ......................................................................................................................... 104 __________________________________________________________________________ 2 5.6.6 Resonant Column and Cyclic Torsional Tests ............................................................ 106 5.7 TESTING LIQUEFACTION RISK ......................................................................................... 111 5.8 1D MODEL OF SEISMIC LOCAL RESPONSE AT SITE S5 ..................................................... 117 6. CONCLUSIVE REMARKS ................................................................................................. 122 6.1 AMBIENT VIBRATION ANALYSIS: H/V ............................................................................ 122 6.2 BOREHOLES ..................................................................................................................... 122 6.3 AMBIENT VIBRATIONS ANALYSIS: SEISMIC ARRAYS ...................................................... 123 6.4 GEOLOGICAL RECONSTRUCTION OF THE CONTACT SEDIMENTARY COVERS-METAMORPHIC BEDROK ........................................................................................................................................ 123 6.5 LABORATORY TESTS: TESTING LIQUEFACTION RISK....................................................... 123 6.6 LABORATORY TESTS: RESONANT COLUMN AND CYCLIC TORSIONAL SHEAR TESTS ....... 124 6.7 1D MODELLING ............................................................................................................... 124 6.8 FUTURE RESEARCH ......................................................................................................... 125 7. APPENDIX A: EQUIVALENT LINEAR MODEL FOR SOIL RESPONSE ................. 127 7.1 ONE-DIMENSIONAL STRESS-STRAIN RELATIONSHIP ........................................................ 128 7.2 EQUIVALENT LINEAR APPROXIMATION OF NONLINEAR STRESS-STRAIN RESPONSE ....... 129 7.2.1 Model 1 ....................................................................................................................... 131 7.2.2 Model 2 ....................................................................................................................... 132 7.3 ONE-DIMENSIONAL GROUND RESPONSE ANALYSIS ........................................................ 133 7.3.1 Free surface, bedrock outcropping and rock outcropping motions ........................... 136 7.3.2 Transient Motions ...................................................................................................... 137 7.3.3 Iterative Approximation of Equivalent Linear Response ............................................ 137 7.3.4 References (Appendix A) ............................................................................................ 139 8. APPENDIX B: H/V FUNCTIONS INSIDE TEST SITE ................................................... 142 9. ACKNOWLEDGMENTS ..................................................................................................... 145 BIBLIOGRAPHY .........................................................................................................................