Introduction of biopolymer-based materials for ground hydraulic conductivity control

Abstract

The use of a hydraulic barrier to prevent or constrain the water flow or/and residual contaminant-containing water from leaking, flowing into underground constructions such as tunnels has been addressed in the past decades. There are different types of barrier materials used to improve hydraulic properties such as soil – bentonite, cement-bentonite, soil admixes using bentonite, cement, and asphalt, chemical and other additives mixed with the natural soil. In fact, the hydraulic barrier materials used for tunnels need to work well under the earth pressure and hydrostatic water pressure acting on the tunnel lining. In this study, a linear polysaccharide gellan gum, which has been investigated in the fields of pharmaceutical technology, biomedical applications, and food products, will be used to improve the hydraulic behavior of sand. The advantage of gellan gum biopolymer is its capable of forming hydrocol-loid gels when mixed with heated water and limiting water flow through the gel performance in soil hydraulic conductivity control at various depth and pore pressure conditions. A pressurized hydraulic system allows performing various pore water pressure and confinement condition to observe the pore clogging behavior of gellan gum biopolymer treated sands. Furthermore, soil hydraulic conductivity variations due to changes in confinement pressure and pore water pressure will be observed.