Optimization of random rubble masonry retaining wall design

Abstract

The conventional earth retaining structures built using Random Rubble Masonry (RRM) are designed as gravity retaining structures where weight of the structure is used for its stability. In Sri Lanka, RRM retaining walls is the most common type of retaining structure for low retaining heights .However; in general, engineers are reluctant to adopt RRM for retaining heights more than 3m high, due to comparatively large sections obtained as the result of conventional design practice. More optimal and creative solutions could be obtained even for low retaining heights, if design material properties of RRM are known. In this study, use of flexural strength of RRM and adopting a Reinforced Concrete (RC) Tieback at the top of the retaining wall to optimize the conventional design was explored. The experimental investigation was carried out to find out the flexural, compressive and shear strength of RRM. Further, bond strength between Reinforced Concrete (RC) and RRM was investigated. These tests results have been used to ascertain the adoptability of suggested optimizations. From the experimental study, it was concluded that magnitude of material strengths of RRM are sufficient for considerable optimization by taking into account the effect of flexural strength of RRM and adopting a Tie- back. The width of the base of wall section reduction for 3m high retaining wall was 28% as the result of the optimization.