Undisturbed block sampling and its use in the investigation of very stiff to hard residual soils and extremely weathered rock

Undisturbed sampling of very stiff to hard residual soils and extremely weathered rock can be problematic due to difficulty in penetrating these materials and ensuing disturbance. Traditional methods for undisturbed sampling of very stiff to hard residual soils and extremely weathered rock are reviewed in this paper. Block sampling, while not commonly used, allows greater control over sampling and often leads to less disturbance and high-quality samples for testing. A method for taking undisturbed block samples is presented. This sampling method can be completed relatively cheaply with commonly available equipment and basic training. The size of the block sample allows a wide range of laboratory tests to be completed on material exhibiting similar properties and offers the possibility of better characterisation of the soil behaviour. The discussion presented herein includes the materials and equipment used, the time required for sampling and proposed safety measures.