Numerical Model Studies of Deep Soil Mixing (DSM) Column to Mitigate Bridge Approach Settlements

The differential settlement at bridge approaches increases the cost of maintenance and repair of the distressed approach slabs. Among the ground modification alternatives, the deep soil mixing (DSM) column technique has proven to be simple and cost effective technique for settlement control. DSM is a process to improve the soil by injecting grout through augers that mix in with the soil, forming in-place soil-cement columns. In an on-going research project, deep soil mixing (DSM) columns were utilized to stabilize soft foundation soil to alleviate the settlements of a highway approach embankment in Arlington, Texas. As a part of the assessment of DSM improvements, both embankment and foundation soils were instrumented with a rod extensometer to monitor the settlements at different depths. In this paper, the DSM column supported highway embankment is simulated using finite element software to verify the long term performance of the DSM in mitigating the embankment settlements. Simulations are also performed on embankment resting on untreated foundation soils to compare the results. The predicted settlements from the model are verified with the field instrumentation data to validate the model.