DYNAMIC ANALYSIS OF CONFINED GEOMATERIAL SUBJECTED TO VIBRATORY LOADING

Abstract

The reinforcement using single-layer geogrid on a confined geomaterial is an effective way of solving practical problems. With the use of multi-layered reinforcement, this study aims to offer a superior alternative design for supporting heavy loads on geomaterial. The location of reinforcement plays a crucial role in the overall strength. The experimental investigations were conducted on poorly graded sand (SP) whose angle of internal friction and cohesion are 36.6º and 4.4 kPa, respectively. The effect of single-layer geogrid reinforcement placed at different depths of the geomaterial was evaluated. Further, the bearing capacity of the geomaterial was compared for single, double and triple-layered geogrid reinforcement. A laboratory Digital Static Cone Penetration Test (DSCP) was performed to assess the load-displacement behaviour of unreinforced and reinforced geomaterial. The result shows that reinforced geomaterial achieved higher resistance compared to unreinforced systems. An optimum combination of placement depths of double-layered reinforcement is proposed. Additionally, the dynamic response of the confined geomaterial subjected to vibratory load has been investigated using a numerical program supported by experimental findings. An accelerometer has been used to report the acceleration, velocity, and displacement of confined geomaterial fill along the depth at varied frequencies of vibratory load. Further, the experimental findings were used in the numerical program to obtain the shear modulus and damping of confined geomaterial. The stress-strain response shows compounded effects with an increase in frequency and modulus of elasticity. It has been observed that displacement is amplified by 10-90 % for a frequency range of 5-75 iv Hz. The shear stress-strain results showed that the shear modulus is magnified by 50 % for varied input parameters considered in the study. The damping of the confined geomaterial has been found to be 0.5-5 % for varied unit weight inputs (16 - 22 kN/m3 ). The results are compared with the outputs obtained by numerical simulation and experimental analysis for estimating the dynamic properties of the confined geomaterial subjected to vibratory load. Further, the study utilized various numerical simulation and experimental data to train and evaluate different models to generate predictions. These predictions were essential for the research. The models employed included ensemble boosted tree, squared exponential Gaussian Process Regression (GPR), Matern 5/2 GPR, exponential GPR, and decision tree architectures (fine and medium). These models greatly facilitated the analysis of the collected data and enabled accurate result predictions. Among the examined models, the Matern 5/2 GPR model exhibited exceptional accuracy with an R2 value of 0.99, demonstrating its remarkable predictive capability. The outcomes highlight the proficiency of the Matern 5/2 GPR and Boosted Tree models in forecasting displacement patterns and enhancing the comprehension of the relationship between displacement and depth. The outcomes of the present study can effectively be adopted by engineers and partitioners for estimating the dynamic properties of the confined geomaterial in construction practices.