Monitoring of drying-induced soil moisture loss with PZT-based EMI technique

Abstract

Air-drying process of soil is a crucial procedure in geological and geotechnical engineering. Drying-induced ground subsidence and damage to overlying buildings is a widespread and urgent problem. Monitoring of drying-induced water evaporation in soil is of great importance. In this paper, soil moisture loss monitoring based on lead zirconate titanate (PZT) transducer using electro-mechanical impedance (EMI) technique was investigated. A physical model test in our laboratory was conducted to study the feasibility and applicability. In the experimental research, three identical PZT transducers that were wrapped with waterproof insulation glue were pre-embedded inside a cohesive soil specimen. In addition, another PZT transducer was embedded in a sandy soil specimen to explore the application effect in soil with different composition. EMI signatures of these four PZT patches during the air-drying process were collected and analyzed. Experimental results indicated that the peak frequency in the conductance signatures presented a rightward shift as the water evaporates. Moreover, the corresponding peak magnitude keep decreasing with the continuous development of soil moisture loss. To better quantify the variations, two statistical metrics including root mean square deviation (RMSD) and mean absolute percentage deviation (MAPD) were employed to study the changing characteristics of the EMI signatures. All these two metrics increase coincidentally in the process. Experimental results demonstrate that cohesive and sandy soil moisture loss monitoring by using the embedded PZT transducer is feasible and reliable. This work also serves as a proof-of-concept study to demonstrate the performance of the EMI technique in monitoring the soil moisture content.

Monitoring of soil water content using spherical smart aggregates based on electromechanical impedance (EMI) technique

“…Monitoring of soil water content or soil moisture is of great significance for geotechnical engineering and civil engineering [1,2]. On the one hand, the increase of the soil water content will reduce the soil shear strength and increase the weight of the soil, which can cause slope failures and landslides [3][4][5].…”

“…On the one hand, the increase of the soil water content will reduce the soil shear strength and increase the weight of the soil, which can cause slope failures and landslides [3][4][5]. On the other hand, the decrease of the water content will induce soil solidification, densification, and cracking to a certain degree, which will greatly affect the mechanical and hydraulic properties of the soil body [6,7], and may result in slope instability or even landslide [1]. In addition, the cyclic drying and wetting due to the seasonal cycles in the case of pile foundation will affect the adhesion factor of piles, which may cause potential safety hazards [8].…”

Monitoring of crack repair in concrete using spherical smart aggregates based on electromechanical impedance (EMI) technique

“…The EMI technique was first introduced by Liang et al [57,58], which mainly utilizes the lead zirconate titanate (PZT) transducer that acts as both an actuator and a sensor based on the principle of inverse and direct piezoelectric effects [59]. In the test, the PZT transducers are coupled with a host structure by attaching to the structure surface [60] or embedding into the structure inside [61], and use the electromechanical coupling effect to sense the status changes of the host structure [62].…”