Abstract：Based on observed data of particle reformative roadbed，normal roadbed and natural ground in Beiluhe test site of Qinghai—Tibet Railway，the characteristics of underlying ground thermal regime of three modes are quantitatively analyzed. Results indicate that the endothermic quantity of constructing embankment is greater than that of natural field. The thaw period of particle reformative roadbed is longer than that of natural field，but less than that of normal roadbed. By contrast with natural ground，the thermal exchange of the particle reformative roadbed is almost equal to natural ground according to thermal exchange state. The exothermal intensity is greater than the endothermal intensity. It entirely presents exothermal state. The thermal exchange state can be restored by using the particle reformative roadbed. It takes on the effect that the particle reformative roadbed can protect frozen soil and it is also an effective way to actively protect frozen soil.
