Concrete tunnel-pile interaction in local sand of Bangladesh under dynamic loading

Abstract

This research presents the concrete tunnel-pile interaction behaviors under dynamic loading considering dry local sand in Bangladesh. For this reason, the shake table test has been conducted in the BUET (Bangladesh University of Engineering and Technology) concrete laboratory considering the relative densities of the dry local sand of 27%, 41%, and 55%. The dynamic loading is of sinusoidal form with frequencies of 1 Hz, 3 Hz, 5 Hz, and 7 Hz for the peak ground acceleration of 0.05 g. The interactive performance of the tunnel-pile model is evaluated in terms of the tunnel moment, tunnel strain, and displacements. The numerical simulation is performed by using the finite element-based code PLAXIS3D. The validation results of PLAXIS3D with the previous studies are found to be approximately 5% which shows a reasonable agreement. The experimental results of the tunnel-pile interaction model are compared to the previous field studies and numerical analysis to obtain the ranges of variations of results of (1 ~ 4.2)% and (5 ~ 10)%, respectively. The interaction zone shows the maximum SRSS (square root sum of squares) responses of the tunnel strain and moment based on the experimental study due to the influence of piles on the tunnel body. In addition, the SRSS vertical displacement of sand shows the lower value to compare the tunnel lateral and vertical displacements due to the higher damping of the sand than the tunnel and piles with caps.