Reinforced soil embankment for shallow landslide protection in New Zealand 

Following the 2010/11 Canterbury earthquake sequence, the loess slope below Maffeys Road in Christchurch, New Zealand was identified as one of the areas with high risk of mass movement. Green Terramesh® with 70 degrees inclined face reinforced soil bund was adopted. 

 

Following the 2010/11 Canterbury earthquake sequence, the loess slope below Maffeys Road in Christchurch, New Zealand was identified as one of the areas with high risk of mass movement. The potential failure mechanism was identified as a shallow sliding of overlying loess on top of the basalt bedrock surface. 

 

Instead of stabilizing or re-grading the slope, it was decided that in the event of slope failure, the debris flow shall be deflected, intercepted and contained behind a protection barrier, mitigating the risk of impacting the infrastructure down slope. 

 

Limited space available between the slope and the properties meant that a reinforced soil protection bund had to be used to reduce the footprint. The Green Terramesh® with 70 degrees inclined face reinforced soil bund was adopted. 

 

The design of the reinforced soil bund had to fulfil several technical requirements such as guarantee a design life of 50 years with a minimum maintenance required. 

 

This mass soil movement was treated as debris flow consisting of impact waves developing dynamic forces and static forces. 

 

Seismic and static internal and global stability analysis have been performed to ensure that the structure is stable under its own weight. 

 

The actual alignment of the Green Terramesh® bund with an apex nearer to the source area helps to divert and deflect the soil mass to both sides of the apex. 

 

This approach ensured that the height requirement of the bund would be significantly reduced. The construction of the apex near the main source and the long curve shape layout of the bund left and right of the apex area helped to reduce the dynamic impact pressure. 

 

The total length of the Green Terramesh® bund was approximately 140 m with height ranging between 3 and 5.4 m and crest width of 1.5 m For more information about this project, please contact us.