ABSTRACT
Structures founded on liquefiable soils are vulnerable to large rotation and settlement during seismic events. Expressions for settlement calculation during design are based on free-field conditions. Consequently, they do not capture soil-structure interactions, often resulting in unconservative and inaccurate settlement predictions. To reduce the probability of excessive settlement or rotation, mitigation measures such as soil drains are becoming increasingly popular. Experimental studies have shown that appropriate use of soil drains usually reduces permanent settlement and rotation of the structure but increases the seismic demand. In dense urban environments, where the region of drain influence extends under adjacent structures, there is concern that improved soil drainage may have a detrimental effect on the performance of unmitigated neighbouring structures. A series of centrifuge tests, conducted at the University of Colorado Boulder, investigated the performance of neighbouring structures, and the influence of soil drains when installed around just one structure. Results show serious detrimental consequences for unmitigated structures located next to a structure protected by soil drains, which should be considered in design when in dense urban settings.
