Stabilization of steep slope with micro soil nails

摘要

A large, steep road cut had been undergoing erosion and shallow mass wasting for several decades. The eroded fine-grained sediment has been delivered into the adjacent stream. Frequent road maintenance was required to maintain safe traffic, and to keep sediment out of the river. Past attempts to stop the slope erosion were unsuccessful. Subsurface investigation and subsequent slope stability analysis indicated that reinforcement of the soil layer with micro soil nails ("pseudo roots") would stabilize the slope. The basic elements of the slope stabilization consisted of toe protection with a gabion wall, prevention of the translational sliding using micro soil nails, and arresting surface erosion by applying jute matting. All existing, significantvegetation was preserved. The unit cost of this stabilization method, in 1995, was 59 dollar per square meter (5.50 dollar per sq ft), approximately 1/3 of any other feasible alternative considered. The project was highly successful in eliminating erosion at the site. This slope stabilization method may prove useful for over-steepened, barren slopes where surface bioengineering methods alone are not sufficient to stop erosion, i.e., road cuts, road fills and stream banks.