Loose fill slope stabilization with soil nails: Full-Scale test

Soil nailing is commonly used for stabilizing cut slopes and retaining structures. The technique is, however, seldom used in stabilizing old loose fill slopes that were not constructed to the current standards. There is a concern that soil-nailed loose fill slopes may not render safety during heavy rainstorms. Little work has been carried out to investigate the behavior of soil-nailed loose fill slopes. This paper presents a comprehensive field test on a loose fill slope that was constructed by end tipping without any compaction - in the same way old fill slopes were formed. The slope was 4.75 m high, 9 m wide, and 33deg to the horizontal. Two rows of five grouted nails were installed at a grid of 1.5 m × 1.5 m at an inclination of 20 deg from the horizontal. A surface grillage was used to connect the six nails in the middle of the grid. Performance of the nailed slope was monitored with various instruments for about six months until the slope was tested to fail by surcharging and wetting. The overall results show that soil nailing with a surface grillage is a potentially effective way to enhance the stability of old fill slopes.