Research on the Sealing Ability of Saturated Compacted Bentonite/Sand Mixture

This paper focuses on the experimental research of water and gas transport in a compacted bentonite/sand mixture under flexible condition. The main contribution of our study is to provide insights into water and gas transport properties in the compacted bentonite/sand mixture. Experimental results indicate that water tightness can be achieved after full saturation, and the water permeability of the sample is at the magnitude of 10(-20) m(2). Gas breakthrough tests show that gas migration properties depend on both external stress state and internal fluid pressure. In addition, change of the external stress also has a hysteresis effect on the gas transport properties. At certain stage, the increasing rate of downstream gas pressure continue decreasing even though the gas pressure was increased while the confining pressure was kept constant. During the whole process, gas migration properties were determined by the coupling effects of confining pressure and gas pressure.