| Popis: |
The Ballina Bypass motorway was constructed over deep deposits of soft soils. Large embankment settlements and embankment failures have historically occurred in this region. Key project challenges were managing multiple critical paths through the construction program and achieving tight settlement design criteria. Dry cement soil mixing (DSM) was the key ground improvement technology that allowed these requirements to be met. Installation of DSM allowed rapid construction of bridge abutments, kept settlements near bridges to small values, and allowed a progressive settlement transition from the bridges to low embankments where ground was not improved. Construction occurred in several phases. Lessons learned in each phase were incorporated into subsequent phases until an optimized process was developed that was used for the majority of the project. Lessons included improving the testing, trial, and production testing processes along with installation processes and managing ground conditions. Settlement of the majority of embankments was 30–50% of prediction. Settlement in transition zones progressively increased as designed. No signs of embankment instability were observed. The motorway was opened 6 months early, and DSM was a key enabler of this achievement. |
