An overview of existing rock excavatability assessment techniques

Abstract

Surface excavation work is one of the most common problems that may cause dispute between contractors and clients when they do not reach mutual agreement regarding the price of excavating rock and soil. This is because the terms "rock" and "soil" are loosely defined in the contract document. Normally, blasting method would only be considered necessary if the physical limit of ripping is reached or when the cost of ripping is uneconomical. Similarly, the term "weathered rock" and its excavating method have been subjectively and differently defined. Further complication may arise in sedimentary rock masses where different layers of rock are interbedding, thus might be misjudged during the early excavation assessment. Different nature of rock indicates different weathering profile. Most of the existing rippability assessment methods are less accurate because they do not consider the weathering state at various rock mass layers. A more appropriate and practical rippability assessment method is required to economically assess the site during the preliminary stage. This paper evaluates the current surface excavation assessment techniques and their limitations especially in dealing with different nature of rock type.