Thermal-mechanical effects on volume-change behavior of compacted GMZ bentonite during cyclic wetting-drying processes

摘要

For investigation of temperature and vertical stress influences on the swelling-shrinkage deformation of GMZ bentonite specimens, cyclic wetting-drying tests with suction ranging between 0 and 110 MPa were conducted under different constant vertical net stresses and temperatures using a suction-temperature controlled oedometer. Results show that temperature effects on the cumulative strains depend on the vertical stress. Under lower vertical stresses, rising temperature intensifies the tendency of the accumulation of expansive strains, while under higher stresses, rising temperature intensifies the tendency of accumulation of contractive ones. In addition, for a given constant temperature, the accumulative deformation recorded on the specimen tested was an expansion or a shrinkage strain depends on the vertical stress applied. Meanwhile, the corresponding vertical stress at transition was different at different temperatures. A logarithm correlation was developed between the final accumulative strain and vertical stress during wetting-drying cycles. According to the test results, the Barcelona expansive model was modified for simulation of the results of the cyclic wetting-drying tests conducted at temperatures. Simulation showed that the results calculated by the modified BExM agreed well to that measured in the present work.