A well-established ground improvement approach, the polymer injection technique has the advantages of being durable, hydro-insensitive, fast curing, and easy to deploy in dense urban environments. It is being widely employed with much success, primarily for uplifting embankments, releveling slabs and foundations, and erosion control. In view of the aforementioned advantages, its potential as a soil liquefaction countermeasure is of current interest. In this regard, the main objective of this dissertation is to explore viability of the polymer injection technique as a soil liquefaction countermeasure.

This objective is achieved in three phases. First, a large-scale shake table test series is conducted to assess potential of the polymer injection technique as a countermeasure against seismically induced soil liquefaction. Specifically, mitigation of settlement for a shallow foundation supported on a liquefiable sand deposit is explored. In a series of two shake table experiments, system response is studied first without (baseline) and subsequently with the injection of polymer into the liquefiable stratum. Upon application of the polymer injection countermeasure, results show a significant reduction in the tendency for liquefaction and resulting foundation settlement. After the test, careful excavation of the deposit provided additional insights into the injected polymer configuration, creating solidified zones that further support the shallow foundation load and increasing the overall stratum strength (relative density and confinement).In the second phase, insights gained from the test series are leveraged to calibrate a nonlinear solid-fluid coupled finite element model. In this regard, stress-strain properties of the solidified polymer zones and surrounding strengthened ground are developed. This calibrated model was then extended to explore additional scenarios beyond the scope of the original test series. Effects of geometric configuration of the solidified polymer zones, and state of compacted soil around the solidified zones were explored in detail.

Finally, within a computational framework, a representative practical application of the polymer injection technique as a liquefaction countermeasure is addressed. For that purpose, numerical modeling scenarios of polymer injection are studied to mitigate the damage reported in a well-documented bridge seismic response case history, where large lateral spreading ground deformations ultimately resulted in unseating of a railroad bridge-deck span. Detailed post-earthquake reconnaissance surveys and observations are used to computationally simulate the bridge-ground system, and capture the documented damage mechanisms. Three different polymer injection configurations are studied, and the response of the remediated bridge-ground system is explored. In these configurations, injections of the order of 10 % (volume of liquid polymer to soil) resulted in a major reduction of lateral spreading deformations, precluding the observed bridge-deck unseating damage mechanism. Overall, the insights gained from this research indicate that the polymer injection technique has considerable potential for mitigating soil liquefaction.