Title

Laboratory studies on the effect of Gas bubbles on clay

Document Type

Conference Proceeding

Date of Original Version

1-1-2015

Abstract

Gas bubbles in offshore soil are created when gas hydrate is dissociated due to changes in pressure and/or temperature, and cracks may appear in the soil. In deep waters, even a small amount of gas dissolved in the pore water will come out of solution when samples are recovered from the sea bottom to deck level, causing significant sample disturbance. In this study, a laboratory programme consisting of various tests was developed to observe the effect of gas bubbles on the behavior of clay. Tests involved a Freon hydrate in both a transparent soil and intact samples of marine clay, and DSS and consolidation tests on undisturbed samples with carbon-dioxide saturated water as the pore fluid. Bubble and crack development was observed both visually and using X-ray computed tomography (CT). The experimental work showed that gas bubbles can be formed when temperature or pressure is changed, and bubbles can become diskshaped with increasing volume and fractures can develop in the final stage. Values of undrained shear strength in simple shear were reduced by 15% from gas bubble formation.

Publication Title

Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015

Volume

6

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