Measurement of Suction Stress and Soil Deformation at High Suction Range

Abstract Suction stress is the effective stress independent of mechanical boundary conditions but is due to water content variation. It occurs on or near particle contacts and does not directly transfer through the soil skeleton and hence can only be and has been measured indirectly and deduced from soil’s strength or deformation. In this work, a new technology to measure the soil-water retention curve, soil shrinkage curve, and suction stress characteristic curve in a high suction environment is established. A humidity-controlled device to measure suction stress was developed based on a previously established drying cake method. Nitrogen gas and molecular sieves were introduced as desiccant in addition to saturated salt solutions to generate an extreme dry environment up to 850 MPa of matric suction for the first time. A focus on the effect of adsorptive soil-water interaction on hydromechanical properties of expansive soils provides enriched information on elastic modulus variation, soil deformation evolution, and matric suction development of soil in very low water contents, making the suction stress measurement possible for matric suction as high as 850 MPa.