Properties of soils using laboratory seismic methods and numerical modelling

Abstract

CHAPTER 4: Finite Element Modelling 4.1 Outline and Purpose 4.2 Introduction to LS-DYNA 4.3 Calibration for stiffness response 4.3.1 The Timoshenko beam effect 4.3.2 Verification of the finite element model 102 4.3.3 Finite element simulation program 104 4.3.4 Correction factor for the Timoshenko beam effect 105 4.3.5 Validation of correction factor χ m 108 4.4 Calibration for damping response 114 4.4.1 The Viscoelastic material model 114 4.4.2 Input Parameters for Viscoelastic Model 118 4.4.3 Finite element simulation program 120 4.4.4 Calibration of viscoelastic model using simulated resonant column test 122 4.4.5 Wave Propagation in a semi-infinite medium 125 4.5 Simulations for the Verification of the Hilbert Transform Method 128

Application of sand-rubber mixtures to mitigate vibration and ground shock

“…To study the effects of size ratio on SRM, linear upper and lower bounds for this study are plotted in Figures 3.17 and 3.18. Normalised V s and to the damping ratio obtained byCheng (2015) and fall closer to the upper bound of the normalised V s and to the lower bound of the damping ratio obtained for this study (low size ratio), respectively. This observation shows that the normalised V s and damping ratio obtained for this study are reasonable.…”

“…The use of SRM as a seismic wave barrier to mitigate vibration from surface waves and ground shock has not been fully investigated. To date, only a handful of researchers , Kim and Santamarina 2008, Lee et al 2010, Feng and sutter 2000, Pamukcu and Akbulut 2006, Cheng 2015) investigated the wave propagation properties of SRM with limited range of rubber content. Damping or relative size ratio were not investigated.…”

“…This observation is due to smaller displacement of the bender element in the extension mode (Lings and Greenings, 2001) which resulted in the P-wave signal being weak and noisy. This problem becomes more pronounced with tests involving loose granular soil or specimen with high damping ratio at low confining pressure (Cheng, 2015).…”

“….4 shows the weight compositions of sand and rubber chips to form the SRM of different rubber content used for this study Cheng (2015). performed tests on perfectly segregated SRM specimen and concluded that the V s shows a maximum reduction of 19% from homogenous SRM specimen and suggested that intermediate segregation will incur less discrepancy.…”