A prediction model for the tensile strength of cement-admixed clay with randomly orientated fibres

Abstract

The deep cement mixing technique is widely used to improve the properties of natural soft clays. Previous studies have shown that introducing fibres improves the ductility of cement-admixed clays. The tensile strength of the improved soil is critical to some underground constructions, such as tunnelling. This paper proposes a prediction model for estimating the tensile strength of fibre–cement–clay mixtures. By assuming that fibres were uniformly orientated, we developed a numerical method that considers fibre orientation randomness. Based on the numerical simulations, a normalised surface area was determined and correlated with tensile strength by considering the hooked-end effect. The proposed relationship easily applies to predict the tensile strength of fibre–cement–clay mixtures with different fibre contents and lengths by giving the tensile strength of the mixture with 1% content of 6 mm-long fibres. The experimental results verified that the proposed model predicted the tensile strength of the fibre–cement–clay mixture.