Measurement and evaluation of soft soil strength development during freeze-thaw process based on electromechanical impedance technique

Abstract

Abstract In-situ monitoring of soft soil strength development is of great significance in artificial ground freezing (AGF) projects. It can not only help engineers estimate the soil freeze-thaw status, but also provide useful data for predicting and controlling the concurrent adverse effects which may cause serious engineering accidents. As a useful nondestructive testing method, the electromechanical impedance (EMI) method has already been extensively employed in a wide range of monitoring applications. In this research, the applicability of the EMI method was extended to monitoring the soil freeze-thaw process and the strength development for the first time. Through the experimental research, a lead zirconate titanate transducer was adopted to measure the changes in the conductance signature during the freeze-thaw process. Furthermore, the lateral and vertical shifts of the resonance peak in the electromechanical spectra and three statistic indices were employed as indicators for the quantitative evaluation of the unconfined compressive strength of the soil specimen. The experimental results verified the effectiveness and reliability of the proposed method in monitoring the soil compressive strength development. This method will have broad prospects in in-situ monitoring of the soil strength development in AGF projects.