Evaluation of Hydraulic Conductivity Functions of Saturated Soft Soils

Hydraulic conductivities of soils rely significantly on three factors, the properties of their pore water, the relative quantity of their pore water, and changes in their pore structure. For saturated soft soils, that demonstrate a considerable degree of alteration in pore structure during densification, it is important to consider their volume change behavior when evaluating their transitional hydromechanical properties during evaporation. This paper reports on the evaluation of hydraulic conductivity functions (HCF) of two saturated soft soils using the evaporation method. The HCF of the samples will be established using the measurement of water loss and the associated gradient during evaporation. By recognizing the importance of the volume change behavior of deformable soft soils on their transitional hydromechanical properties, a theoretical formulation is suggested to incorporate their volume change behavior when estimating their transient hydraulic conductivities. An increase in the hydraulic conductivities of approximately one order of magnitude has been observed when volume change in the samples have been quantitatively considered in their calculation compared with cases when this type of effect is not considered. HCFs established using this approach, taking into consideration the volume change behavior of the samples, will be compared with those obtained through one-dimensional consolidation tests. The proposed method has the potential to provide HCF measurements at high void ratio ranges, where 1D consolidation tests would not be effective due to the highly fluidized condition of the material. Based on experimental results and analysis, this paper establishes a generalized theoretical formulation to appraise the hydraulic conductivity functions of deformable soft soils using the evaporation method and takes into consideration the volume change behavior of the sample. (C) 2020 American Society of Civil Engineers.