Biotechnical Stabilization of Highway Cut Slope

Abstract

Various schemes are considered in order to stabilize a road cut along a scenic highway in Massachusetts. These schemes include a drained rock blanket, rock blanket with brush-layer inclusions, and a composite drained rock buttress and earthen brush-layer fill. A brush-layer fill consists of alternating layers of compacted soil and live cut stems that eventually root and sprout. Scenic and environmental considerations in combination with stability analyses dictates the use of a composite drained rock and earthen brush-layer fill. The rock section is placed at the base or toe of the slope. Placement of a rock buttress at the toe provides an extra margin of safety by interception of the critical toe failure surface through the rock. Live cut branches in the overlying earthen fill act as both reinforcements and horizontal drains. Adventitious rooting along the length of the imbedded stems provides secondary stabilization. Stems and branches of plant species are used that root readily from cuttings such as willow and dogwood.