A Hydro-mechanical Approach to Model Swelling Tests of Clay-Sulfate Rocks

Abstract

We developed a coupled hydro-mechanical (HM) model based on a semi-logarithmic swelling law to reproduce the outcomes of swelling tests of a clay-sulfate rock specimen collected from the Freudenstein tunnel, which was constructed in Triassic Grabfeld Formation (formerly Gipskeuper = “Gypsum Keuper”) in Southwest Germany in the period of 1987–1991. The swelling tests were conducted using an oedometer apparatus under constrained (no strain) or constant load conditions. We used the strain–time data obtained from the laboratory testing to calibrate the HM model. We then ran a sensitivity analysis to reveal the importance of influential parameters, namely the maximum swelling pressure $${\sigma }_{max}^{sw}$$ σ max sw , swelling parameter $$k$$ k , and diffusion coefficient $$D$$ D on the long-term swelling behaviour of clay-sulfate rocks under the oedometer conditions. The HM model is capable of predicting long-term swelling deformations, i.e., model results were found to agree reasonably well with the experimental data. The results also show that using only 12 months experimental strain–time data to calibrate the HM model leads to an underestimation of swelling strains at the equilibrium condition. The findings show that at least 24 months experimental data is required for the model calibration.

Experimental Data on Maximum Swelling Pressure of Clayey Soils and Related Soil Properties

“…Engineers and practitioners dealing with expansive soils can derive practical insights from the maximum swelling pressure data to address challenges in these areas [26]. For foundation engineering, the dataset could help estimate the potential uplift pressures of structures built on expansive soils, guiding the selection of appropriate foundation types and materials to mitigate the effects of soil swelling [3]. It allows for informed decisions on using flexible materials or void forms beneath foundations in high-swelling potential areas.…”

“…This study addresses the critical need for comprehensive and accessible data on the maximum swelling pressure of expansive soils, which may pose significant geohazards causing damage to civil infrastructure [1]. Understanding the behavior of clay soils under varying environmental conditions is crucial to designing secure and resilient civil infrastructure [2,3]. The dataset compiled from experimental studies on naturally occurring and laboratory-engineered clayey soils provides an invaluable resource for researchers and practitioners working on expanisve soils.…”