Numerically predicting deflections of mat-sand interaction model under gravity loadings

This research proposes a novel mat-sand interaction model to evaluate limiting values of sand elastic modulus and super-imposed gravity load for a specific mat thickness to control vertical deflection of mat by using BNBC 2020 prescribed allowable deflection limit. For this reason, the linear elastic analysis is performed by using finite element-based software ETABS v.18.1.1, whereas the impact of sand on the mat is transferred by springs. The difference in results between present and previous studies is obtained to be 1.76%, which may indicate good accuracy of verification of the proposed model with the field study data. The difference in mat vertical deflections between two consecutive sand elastic moduli is obtained to be 7.1%, and it is found to be 32.8% in the case of the mat thickness variations. So, the difference in the case of the sand elastic modulus is reduced by 78.4% compared to the mat thickness. The limiting value of imposed gravity load is found to be 60 kPa for 150 mm mat thickness with a range of sand elastic modulus of (5–25) MPa. Similarly, it is obtained to be 120 kPa in the case of the 200 mm mat thickness for 5 MPa elastic modulus of sand. These findings may help engineers to select suitable mat thickness with corresponding sand elastic modulus and super-structure gravity load.