| Permafrost is underground soils containing ice which keep frozen for several years, it is remains of ancient glacial climate. Patchy permafrost is ede of vast and continuous permafrost zone which is degrading, it is discontinuous horizontally. Since the cli- mate is changing warmer all over the globe and the thermal bal- ance of the ground is broken after making roads, and permafrost melt and ground sink, subgrade of road is destroyed. One more thing is all kinds of trouble of subgrade and pavement caused by freezingly cold climate in permafrost regions. In this paper, first of all, climatology ,thermal transmission theory and geocrylogy are used in studing distributive feature and evolutive tendency of patchy permafrost of Inner Mongolia; then starting from the thermal balance of permafrost under subgrade after making roads, main factors affecting thermal stabiliy of subgrade are studied; the equation for forcasting underground permafrost melting rate is built up from one-dimention-unstable heat transmission equation; The character of thermokarsting of permafrost, frost heaving principles of subgrade soil, pavement performance of asphalt mixture in tow temperature and thermo- physiciaity of road material are also probed with experiment; Theory of anti-frost heaving is studied, the new point of view for anti-frost heaving and principles for choosing road material in permafrost regions are put forward; finally, the scheme for test road is also put forward. |
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