青藏铁路块石路基结构的冷却效果监测分析
Monitoring and analysis of cooling effect of block-stone embankment for Qinghai-Tibet Railway
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摘要: 块石路基是青藏铁路积极保护多年冻土极为重要工程措施之一,60%的高温高含冰量路段采用了这种工程措施。通过对青藏铁路沿线块石路基下部土体温度监测分析,块石路基正在积极地发挥冷却路基的工程效应,极大地促进了多年冻土上限的抬升,但也引起了多年冻土温度升高。多年冻土温度升高随着工程热扰动的降低和块石路基"冷量”积累,已逐渐被抑制。然而,对于低温多年冻土来说,块石路基下部多年冻土上限附近温度有了较大的“冷量”积累,多年冻土正在朝着有利于热稳定方向发展。对于高温多年冻土来说,尽管多年冻土上限也得到了较大幅度的抬升,但升温过程和土体年收支的不平衡都在朝着不利于多年冻土热稳定方向发展。块石路基结构在高温多年冻土区适应性问题仍值得讨论,应采取相对应的补强措施,确保高温多年冻土区路基稳定性。Abstract: Block-stone embankment is one of the most important engineering measure for protecting permafrost of Qinghai-Tibet Railway which has been used in about 60% sections of warm permafrost with high ice content.After monitoring analysis of soil temperature beneath the block-stone embankment of Qinghai-Tibet Railway,it can be concluded that the block-stone embankment is working positively for cooling the roadbed and making the great rise of permafrost table,but also causing a temperature rise of permafrost.The trend of permafrost temperature rise will be gradually restrained by reducing engineering thermal disturbances and soil temperature drop beneath the block-stone embankment.And,for cold permafrost,a better thermal stability situation will be developed under the condition that the temperature near the permafrost table beneath the block-stone embankment has largely dropped.But,even the permafrost table has highly raised the annual thermal imbalance of soil and the process of temperature rise,it is disadvantageous for the thermal stability of permafrost.Thus,the applicability of block-stone embankment structure is worth to be discussed in order to take corresponding measures to solve the stability problems of embankment in warm permafrost regions.