Effect of Drying-Wetting Cycles on Saturated Shear Strength of Undisturbed Residual Soils

Abstract

Due to worldwide distributions and extensively used as construction materials, geotechnical engineers are interested in understanding the mechanical behavior of residual soils which are sometimes referred in the literature as problematic soils. The climatic zones where residual soils occur are often experienced by many drying-wetting cycles due to seasonal variations. This seasonal variation in the water content termed as drying-wetting cycle is regarded as the most destructive environmental factor that may cause many foundation diseases. Considering these, the purpose of this study is to understand the effects of drying-wetting cycles on saturated shear strength characteristics of undisturbed residual soil. A series of consolidated drained (CD) triaxial tests are conducted on multiple drying-wetting soil specimens to analyze the saturated shear strength. The test results indicate that the stress-strain relationships appear to be strain-hardening. The deviatory stress and initial stiffness of saturated soils increase and the volume of soils becomes contractive as the net normal stress increases but decrease with increasing drying-wetting cycle numbers. The cohesion (c d) and internal friction angle (φ d) decrease with increasing cycle number (N) but the attenuation rate of φ d is less than c d. The variations of c d and φ d with respect to drying-wetting cycles can be expressed by exponential function. The saturated shear strength and it's attenuation rate due to drying-wetting cycles are analyzed. The effect is more significant for the first cycle and decreases with subsequent cycles and finally reaches to a constant state after 4 cycles. Furthermore, a mathematical function is proposed in this paper which can describe the saturated shear strength attenuation rate of drying-wetting cycle samples. Such studies are useful to understand the possible changes in shear strength behavior of residual soils below the engineering structures that are subject to periodic drying and wetting from climatic variations.

Prediction Model of Residual Soil Shear Strength under Dry–Wet Cycles and Its Uncertainty

“…This dynamic process paves the way for water and ionic species to penetrate the soil particles, thereby inducing alterations in its permeability [40,41]. Therefore, due to the effects of multiple drywet cycles, the mechanical properties and stability of granite residual soil will gradually decrease, while its permeability will slowly increase [42,43].…”

Development of a Multiphase Numerical Modeling Approach for Hydromechanical Behavior of Clay Embankments Subject to Weather-Driven Deterioration

“…The decay factor, , can be determined experimentally. Based on data compiled from literature for 21 different soils subject to varied wet-dry cycles and amplitudes (not discussed herein for brevity; Kayyal and Wright 1991;Wright et al 2007;Sayem et al 2016;Khan 2016;Charkley et al 2019;Xu et al 2021;Niu et al 2022;Xie et al 2022), a value of −0.1 was deemed reasonable for to represent the decay in peak strength parameters for BIONICS embankment fill and near-surface moisture fluctuations. This value reduces the peak shear strength parameters from their as-compacted values to their fully softened values in approximately 20 seasonal wet-dry cycles, which is the number of cycles adopted by Kayyal and Wright (1991) to reach fully softened strength.…”