Study on the Effects of Seawater and High Temperature Environment on the Rheological Properties of Bentonite Slurry
For tunnelling in seabed by a slurry shield,it is of great importance to prepare a suitable slurry that en-sures desirable rheological properties and permeability characteristics in an environment with seawater intrusion and high temperature.In order to ascertain the effects of high temperature and seawater intrusion on the rheological property of bentonite slurry,a set of rheological tests have been conducted by using the Brookfield RST Soft Solids Tester Rheometer,and the flow pattern and constitutive model of slurry in an environment with high temperature and seawater intrusion have been analyzed.As the results indicate:In high temperature environment,bentonite slurry clearly experiences thinning induced by temperature rise.As the temperature increases,the rheological model of bentonite slurry does not change.With seawater intrusion,the water retention capacity and physical stability are di-minished and it experiences segregation.The bentonite slurry virtually loses the rheological characteristics of power-law fluid and yield fluid,and the flow pattern of slurry is degraded to that of Newtonian fluid.Besides,the results of electron microscope scanning indicate that the space structure of fresh water slurry appears as lumpy flocculent shape,there are dense and contiguous lumps,and the space structure is complete and dense.In 50%of the seawater slurry,space structure appears as flaky form,there is noticeable gap between the flakes,and local areas have accu-mulation of discrete particles.
Subsea tunnelSlurry shieldSeawater intrusionHigh temperature environmentRheological propertiesLaboratory test
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