多年冻土区铁路拼装式涵洞基础稳定性研究

Base stability analysis of railway assembled culvert in permafrost region

根据青藏铁路清水河试验段两座拼装式涵洞工程近3年的监测结果,研究多年冻土区铁路涵洞下地基温度变化与涵洞基础沉降变形之间的关系.研究表明,多年冻土区涵洞工程在路基修筑的整个期间内,其基础会发生较大变形,且冻胀抬升变形量总值小于融化下沉变形量总值;涵洞建成初期,中部基础下沉速率较大,但2个冻-融循环后,涵洞中部的总下沉量较出入口过渡段的总下沉量小;涵洞出入口多渡段基础下地温差异与阳光照射有关,但这种地温差异对基础沉降变形的影响并不显著;路基和涵洞施工完成后对涵洞下地基冻土层具有明显的保护作用.

With the monitoring data of two assembled culverts on the Qingshuihe River in a permafrost region along Qinghai-Tibet Railway, the relationship between the ground temperature and the settlement was studied. The results show that the deformation of the culverts are large during the construction, and the total frost heave is less than the total settlement. The rate of settlement in the middle part of culvert is larger than the ones at the inlet and outlet transition zones at the beginning, but the total settlement in the middle part is smaller than the ones at the transition zones after two frost-thaw cycles. There is a difference of ground temperatures at the inlet and outlet transition zones because of the radiation. However, the radiation has less effects on the settlements. In addition, the completed railway base and culverts have protective function on the permafrost.