An unsaturated hydraulic conductivity model for compacted GMZ01 bentonite with consideration of temperature

摘要

As one of the most important properties of compacted bentonite used as buffer/backfill materials, hydraulic conductivity is influenced by various factors including temperature, microstructure and suction (or degree of saturation), etc. Based on the readily available results of both temperature-controlled water-retention tests and unsaturated infiltration tests under confined (constant volume) conditions, influences of temperature and micro-structure variations on unsaturated hydraulic conductivity of the compacted Gaomiaozi (GMZ01) bentonite were analyzed. Then, a revised unsaturated hydraulic conductivity model considering temperature effects and micro-structure changes was developed. With this proposed model, prediction and comparison were made on the unsaturated hydraulic conductivity of the compacted GMZ01 bentonite at 20 ℃. Results show that water-retention capacity of compacted GMZ01 bentonite decreases as temperature increases and the degree of the temperature influence depends on suction. Under confined conditions, influence of hydration on microstructure of compacted GMZ01 bentonite depends on pore size. The proposed model can well describe the variations of unsaturated hydraulic conductivity with suction at different temperatures. However, further improvement of the proposed model is needed to account for the phenomenon of inter-aggregate pores clogging that occurred at the initial stage of hydration of compacted GMZ01 bentonite under confined conditions.