A modified method for estimating permeability of clayey soils based on piezocone sounding results

Abstract

A modified method for estimating permeability of clayey deposits in the horizontal direction (kh) based on piezocone sounding (uCPT) results is proposed. Most of the currently available methods relate the value of kh with the Δu/[Formula: see text] ratio (Δu is the measured excess pore pressure from uCPT at the shoulder of the cone and [Formula: see text] is the initial vertical effective stress at the measurement location). However, it has been understood that the effect of the overconsolidation ratio (OCR) on the Δu/[Formula: see text] ratio is more significant than that on the value of kh. As a result, for an overconsolidated deposit, there is no suitable method for estimating the value of kh based on uCPT results. Based on the results of laboratory model uCPT, an empirical equation for considering the effect of the OCR on Δu/[Formula: see text] and then kh corresponding to the yield vertical effective stress ([Formula: see text]) and initial vertical effective stress ([Formula: see text]) for OCR > 1.0 is established. The modified method for kh corresponding to [Formula: see text] requires two parameters: OCR and a model parameter (α). In addition, for kh corresponding to [Formula: see text], two more soil parameters are needed: the swelling index (Cs) and the initial void ratio (e0). The methods for estimating these parameters are also proposed. Finally, the modified method is applied to three field case histories to show its usefulness.