Dynamic Response of Seabed Under Wave-Induced Loading

In this paper, the characteristics of the development of effective stresses and pore water pressure in elastic or elasto-plastic seabed with time under a sequence of wave loading are studied by virtue of numerical finite element analyses. Compared with analytical solution for elastic problem, the numerical procedure proposed can deal with complicated situation of seabed and can predict residual pore pressure. For inelastic seabed, bounding-surface hypoplasticity model is employed to describe the nonlinear stress-strain relationship of sand under cyclic loading. The development pattern of pore pressure under undrained condition obtained from laboratory experiments is not necessary in the numerical simulation

A Simplified Method of Vibration Analysis of Layered Foundation and Applications in Pavement Parameter Identification

In this paper, a simplified approach based on spline semi-analytical method is proposed for dynamic response analysis of visco-elastic layered half-space foundation. For varied geometrical and physical properties, the compliance function of layered non-homogeneous foundation is studied. Then an efficient and reliable numerical procedure for back-calculating material properties of pavement through the data measured from in-situ Falling Weight Deflectometer (FWD) tests is presented. The simulation results for in-situ data show that the proposed methodology is workable and applicable

Effects of Dynamic Properties of Rockfill Materials on Seismic Response of Concrete-Faced Rockfill Dams

In this paper, the equivalent-linear method is used for three-dimensional seismic response analyses of concrete-faced rockfill dams (CFRDs). Different combinations of various parameters such as small-strain shear modulus, strain-dependent patterns of modulus and hysteretic damping, are considered to systematically investigate the effects of dynamic properties of rockfill-type coarse-grained materials on seismic dynamic response of CFRDs. It is concluded that the nonlinearity of embankment material has a significant effect on both vibration characteristics and seismic response behavior of CFRDs. Numerical results presented are instructive to gain a better understanding on earthquake-resistant behavior of CFRDs and the effects of dynamic properties of rockfills

Lumped-Parameter Model and Nonlinear DSSI Analysis

A 2-.degrees-of-freedom discrete model with 8 constant lumped parameters is developed to equivalently simulate frequency-dependent dynamic impedances of the elastic halfspace. The equations of motion for the nonlinear dynamic soil-structure interaction (DSSI) analysis are established in the time domain and then nonlinear seismic responses of the coupling system are predicted by the proposed iterative procedure. Based on numerical results for three typical shear-type structures, effects of the shear stiffness of underlying soils and different ground motions on dynamic responses are examined

Measurement of soil suction and soil-water characteristics of bentonite-sand mixtures

The soil-water characteristic curve(SWCC) is a widely used experimental means for assessing fundamental properties of unsaturated soils for a wide range of soil suction values. The study of SWCC is helpful because some properties of unsaturated soils can be predicted from it.Nowadays,much attention has been paid to the behaviours of highly compacted bentonite-sand mixtures used in engineering barriers for high level radioactive nuclear waste disposal. It is very important to study the various performances of bentonite-sand mixtures in order to insure the safety of high-level radioactive waste (HLW) repository.After an introduction to vapor phase method and osmotic technique, a laboratory study has been carried out on compacted bentonite-sand mixtures.The SWCC of bentonitesand mixtures has been obtained and analyzed. The results show that the vapor phase method and osmotic technique is suitable to the unsaturated soils with high and low suction

Estimating Model Parameters of Conditioned Soils by using artificial network

Abstract—The parameter identification of nonlinear constitutive model of soil mass is based on an inverse analysis procedure, which consists of minimizing the objective function representing the difference between the experimental data and the calculated data of the mechanical model. The ill-poseness of inverse problem is discussed. The classical gradient-based optimization algorithm for parameter identification is also investigated. Neural network models are developed for estimating model parameters of conditioned soils in EBP shield. The weights of neural network are trained by using the Levenberg-Marquardt approximation which has a fast convergent ability. The parameter identification results illustrate that the proposed neural network has not only higher computing efficiency but also better identification accuracy. The results from the model are compared with simulated observations. The models are found to have good predictive ability and are expected to be very useful for estimating model parameters of conditioned soils in EBP shield. Index Terms—parameter estimation, neural network, inverse problem, shield machin