A State-Dependent Hypoplastic Bounding Surface Model for Gassy Sand

As a kind of partially saturated soil often containing dissolved gas with high degree saturation (S > 85%), gassy sand sediment widely exists in the marine environment all over world. Due to effect dissolution and exsolution on pore fluid compressibility, its stress–strain pressure responses are quite different from those common unsaturated soils when subjected undrained loading. Since almost bubbles occluded water offshore sand, matric suction may be neglected, an constitutive model for is developed based existing hypoplastic bounding surface sand. Both Boyle’s Henry’s laws employed characterize equilibrium behavior compressibility solubility, then equivalent coefficient obtained. To avoid unrealistic volumetric expansion, concepts critical state state-dependent dilatancy stress ratio incorporated describe ultimate shear strength characteristics, respectively. Finally, triaxial test results gas-charged Hangzhou Bay analyzed at three initial degrees 85%, 90%, 100%, two effective confining pressures 50 kPa 200 kPa. Moreover, carbon dioxide (CO2) was selected test, samples were loose relative density 30%. It noted that good agreement achieved between simulation experimental data, including influence content mean increase beginning path, among others.