过去的研究情况我国多年冻土地区主要分布在东北的大兴安岭北部和小兴安岭北部、青藏高原以及西部的一些高山如天山、阿尔泰山等地区。总面积约190万平方公里,占我国领土总面积的20%左右。在多年冻土地区修建公路,有一系列特殊的工程地质问题,如冰丘、冰椎、地下冰、热融沉陷、热融滑塌、热融湖塘、融冻泥流等,需要专门考虑。还有一些工程地质问题,如冻胀、翻浆、沼泽、湿地等,虽不是多年冻土地区所特有,但在多年冻土地区它们有很大的特殊性,并达到很大的规模,也需要专门考虑。除此而外,还不能不考虑这样一些情况:多年冻土地区短暂的暖季、漫长的冷季、极端的严寒,使公路的施工和养护十分困难;而在平均海拔4500米以上的青藏高原,更由于空气稀薄而使公路修建的困难大为增加。所有上述问题和情况,构成多年冻土地区公路设计、施工与养护的特殊性和复杂性。而这也正是公路部门长期以来把多年冻土地区作为一个筑路的特殊地 Past research The permafrost regions in our country are mainly distributed in the northern part of Daxinganling in the northeast and the northern part of Xiaoxing’anling, the Qinghai-Tibet Plateau and some high mountains in the west such as the Tianshan and Altai Mountains. The total area is about 1.9 million square kilometers, accounting for about 20% of the total territory of our country. There are a series of special engineering geological problems in the construction of roads in permafrost regions such as ice mounds, ice spines, underground ice, thermal melting and subsidence, thermal slump, hot melting lake ponds, thawing muds, etc., which require special consideration. There are also some engineering geological problems, such as frost heaving, dredging, swamps, wetlands, etc., which are not unique to permafrost regions. However, they have great peculiarities in permafrost regions and reach large scale. Special consideration. In addition, we can not but consider such situations as the brief warm season in the permafrost region, the long cold season and the extremely severe cold so that the construction and maintenance of highways are very difficult. On the Tibetan Plateau where the average altitude is over 4,500 meters, , The difficulty of road construction is greatly increased due to the thin air. All the above problems and circumstances constitute the particularity and complexity of highway design, construction and maintenance in permafrost regions. And this is why the highway department has long characterized the permafrost region as a road