COMBINED METHOD FOR RESTORING THE FROZEN STATE OF SOILS IN THE BODY AND BASE OF THE SUBGRADE
E.S. Ashpiz1, E.I. Nagaev2, D.A. Razuvayev2, A.O. Salmin1
1Russian University of Transport, Institute of Track, Construction, and Structures, Department of Track and Track Facilities, Moscow, Russia
2Siberian Transport University Construction, and Structures, Novosibirsk, Russia
Keywords: subgrade, foundation soils, permafrost soils, degradation of permafrost soils, thermal stabilization of soils, seasonal cooling device, freezing column
Abstract
The problem of railway operation in permafrost areas is associated with the degradation of permafrost at the subgrade base. A concept of the combined thermal stabilization of the subgrade base soils through their rapid cooling with liquid nitrogen with long-term maintenance of subzero temperatures using a vapor-liquid seasonal cooling device is suggested for the conditions that require immediate response to eliminate possible frost heaving. The results of a large-scale laboratory experiment allowing us to compare the efficiency of the combined thermal stabilization device with the widely used vapor-liquid seasonal cooling devices are presented. The experiment provided qualitative and quantitative empirical data for further substantiation and verification of analytical or numerical methods of thermal stabilization calculations in the chosen direction. Additionally, heat losses during the operation of the combined device in the rapid cooling mode with liquid nitrogen have been estimated.
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