Model studies on fly ash slopes reinforced with planar steel grids

Abstract

Fly ash, waste by-product from coal industries, is being used extensively in construction of highway and railway embankments. This paper describes the effectiveness of steel grid reinforcement in the form of planar mattress along with jute geotextile at facia throughout the slope and with fly ash as backfill material. The models were subjected to loading in the form of uniform and strip loading by means of rigid steel plates as footings. Series of laboratory model tests were carried out on homogeneous unreinforced and reinforced fly ash slopes with slope angle 60° on rigid base to check the efficacy of reinforcement in improving the load carrying capacity and stability of slope. For fly ash slope on rigid base, length of the reinforcement was varied from 0.7H to 0.2H (H = Height of the slope). The steel reinforcement having grid thickness of 1.2 mm with square openings of 15 mm was laid along the width of the slope in continuous form as well as with coverage ratios (Cr) of 0.5 and 0.6. All the tests were conducted by applying both uniformly distributed load (UDL) and strip loading until failure. Based on the experimental results, for all types of reinforcement cases, slope with continuous grid of length 0.7H supports maximum for strip loading before failure as compared to UDL. The variation in length of the reinforcement showed significant effect on the settlement of the backfill.