青藏铁路含融化夹层路基热力响应监测分析

The monitoring analysis of the thermal-mechanical response on embankment with thawed interlayer along Qinghai-Tibet Railway

基于青藏铁路沿线P32和P33监测断面连续10年的含融化夹层路基的地温和变形场地实测数据,分析了该两处监测断面左路肩下多年冻土人为上限、季节冻结最大深度、融化夹层厚度及多年冻土人为上限附近地温的年变化过程;同时分析了P32和P33监测断面左右路肩的总沉降年变化过程、P32监测断面左路肩地温场对变形的影响及P33监测断面左右路肩地温场差异对左右路肩差异沉降的影响。结果表明:P32和P33监测断面左路肩下多年冻土人为上限逐年下降、季节冻结最大深度基本不变、融化夹层厚度逐年增厚及多年冻土人为上限附近地温逐年升高;观测期内,P32和P33监测断面左右路肩变形均以沉降为主,且P32监测断面左右路肩的总沉降变形量均小于P33监测断面;其中P32监测断面左路肩暖季沉降变形明显,冷季发生轻微的冻胀变形,且发生沉降和冻胀的时间略滞后于路基下部温度场的变化;P33监测断面左右路肩地温场的差异导致左右路肩存在差异沉降,且其差异沉降值随时间逐年变大。

Based on the ground temperature and deformation of the embankment with thawed interlayer at the monitoring sections of P32 and P33 along Qinghai-Tibet railway from 2005 to 2015, artificial permafrost table, maximum seasonal frozen depth, thickness of thawed interlayer and annual process of the ground temperature nearby artificial permafrost table are analyzed. Meantime, annual process of the total settlement of left and right shoulder at P32 and P33 sections, the effect of ground temperature at the left shoulder on deformation at P32 section and the effect of ground temperature difference at the left and right shoulder on its difference of settlement at P33 section are investigated. The results indicate that: at P32 and P33 sections, artificial permafrost table of left shoulder descended annually, maximum seasonal frozen depth remained nearly constant, thickness of the thawed interlayer thickened and the ground temperature nearby artificial permafrost table increased annually;during the monitoring period, the left and right shoulder deformation all performed mainly settlement and its magnitude at P32 section was smaller than at P33 section. Moreover, at P32 section, left shoulder settled during warm season and frost heave occurred slightly during cold season. The occurrence of settlement and frost heave lagged the variation of the ground temperature. The temperature difference can lead to differential settlement under left and right shoulder at the monitoring section of P33, and its value increased annually.