Isotropic Pressure Membrane Sensor to Establish Shrinkage Stress Evolution in Clayey Soil

The shrinkage behavior of clay has been identified to have a significant influence on many geotechnical problems that include foundation failure, slope instability, damages in buried pipelines, crack formation in liner systems, etc. In this context, researchers have focused on understanding and quantifying the effect of shrinkage behavior of fine-grained soils in terms of volumetric shrinkage and crack propagation. But it has been realized that shrinkage stresses would also develop in fine-grained soil mass in tandem with volumetric shrinkage owing to tensile stresses and particle rearrangement. This necessitates mapping shrinkage stress evolution in clayey soils of distinct mineralogical and plasticity characteristics. Under these circumstances, the authors have developed a novel isotropic pressure monitoring device (I-PMD) and test protocols to measure shrinkage stress in clayey soil. The results obtained from the present study demonstrate the efficacy of employing I-PMD for establishing (i) soil shrinkage stress curve and (ii) maximum shrinkage stress σsmax of clayey soils while drying. From the present study, it has been inferred that the shrinkage stress initiation point is dependent on its liquid limit, and also, a steady increase in stress generation has been identified in its semisolid state. The result obtained from the experimental studies has been utilized to establish the empirical relationship to estimate shrinkage stress from clay characteristics.