研究结论:认为按地质和地温条件处理冻土，保持多年冻土上限不下降后，路基结构按“封闭系统”冻结 条件进行设计，表层冻融层内用不冻胀的粗粒料填筑，其它部分按常规路基设计，即可满足多年冻土区路基结 构功能的要求

Research conclusions: It is believed that the requirements of structural function of the subgrade in permafrost region can be satisfied by making design of subgrade structure in accordance with the frozen condition of“enclosed system”，filling the active layer on the surface by unfrozen coarse materials and making design of the rest parts of the subgrade like ordinary subgrade，after the permafrost is treated in accordance with the geological conditions and ground temperature condition and upper limitation of permafrost is no longer lowering.