Seismic Vibration Control of Retaining Walls Using a Compliant-Tuned Liquid Damper

Abstract

Seismically induced active earth pressure is one of the prime causes of the failure of retaining walls. As an alternative to the conventional ductility-based seismic design of an elastic retaining wall, this work explored the potential of a compliant tuned liquid damper (CTLD) for seismic vibration control of a cantilever retaining wall. The liquid (water) in CTLD sloshes with a certain phase difference to the motion of the wall to reduce vibration and dissipate the vibrational energy through wave breaking. A typical retaining wall geometry was adopted to ensure its static stability and safety against buckling under the weight of the CTLD. A single-degree-of-freedom (SDOF) reduced-order model of the retaining wall was derived from the finite-element-based modal analysis of the combined soil–wall system. Sun's model was adopted for the sloshing of liquid in the CTLD. The response time histories of interest were obtained by numerical integration of the equations of motion for the combined SDOF-CTLD system, solved iteratively for nonlinear sloshing. Selecting optimal parameters ensured the best efficiency (of response reduction) of the CTLD through a parametric study. A suite of input ground motions pertaining to varying hazard levels was employed to verify the effectiveness of vibration control. The average displacement and acceleration control efficiency varied from 13.95% to 50.04% and 13.51% to 53.21%, respectively, with the backfill soil type and damping. Considerable response reduction demonstrated the efficiency of the CTLD. The performance robustness was demonstrated through a parametric study. Traditionally, retaining walls are designed to be safe from seismic activities incorporating the lateral earth pressure under earthquake conditions. In contrast, the present study recommends a vibration reduction technique using a compliant-tuned liquid damper (CTLD), in which the seismic demand of a cantilever retaining wall is reduced directly by reducing the shaking of the wall. The CTLD, which is made up of a long channel-like tank mounted along the top of the wall, reduces the vibration of the soil–wall system by controlling its acceleration and displacement. The seismic force transmission is reduced by applying the CTLD, leading to a more economical wall design. The robustness of the CTLD system is checked in terms of its efficiency by varying soil properties and tuning parameters, which are presented graphically and in tabular form. The use of CTLD for vibration control of cantilever retaining walls or other geotechnical structures in different settings can be decided based on these results. The CTLD tank that holds water can also serve additional water storage/supply purposes.