青海省共和-玉树高速公路沿线典型冻土路基保护多年冻土效果的初步分析

A preliminary analysis of protective effect on permafrost of typical embankment along Gonghe—Yushu highway

基于青海省共和—玉树（共玉）高速公路修筑初期的地温监测资料,对3种典型冻土路基措施,即保温路基、块石路基和通风管路基下部浅层（0～4 m）地温、深层（4 m以下）地温以及多年冻土人为上限变化情况进行对比分析,研究路基修筑初期下伏多年冻土的变化过程,并且对各种路基技术措施的效果进行比较。监测结果表明,对浅层地温,保温路基左右路肩处一定深度有降温,块石路基仅在右路肩有降温,通风管路基左右路基及中心孔均有较大范围的降温,3种措施均面临不同程度的阴阳坡热不对称问题,以保温路基最为显著;深层地温均有升高的趋势,相同深度下保温路基升温幅度最大,块石路基次之,通风管路基最小;多年冻土人为上限均有显著抬升,并有继续抬升的趋势。初步监测结果显示了保护多年冻土措施的3种路基结构均具有一定的效果,由于道路修筑时间较短,冻土路基的长期效果还需要进一步的监测分析。

Along the Gonghe—Yushu highway,three typical permafrost embankments,namely insulated board embankment,block-stone embankment and ventilated embankment were utilized. In order to study the process of variation of the underlying permafrost and to compare three measures,the temperature variations of the shallow layer（0–4 m） and deep layer（below 4 m） were analyzed. The chosen sections have a similar underlying permafrost conditions. The results showed that all three measures were confronted with the thermal asymmetry from the shady to sunny slope and the thermal asymmetry damaged the embankment stability. The deep temperature showed a continuous trend of increase. At the same depth,insulated embankment had the largest rate of increase,followed by the crushed-rock embankment,and the ventilated embankment had the smallest one. There was an uplift of artificial permafrost table for all three measures and still showing a continuous uplifting trend. The preliminary monitoring results showed that all three measures were effective in protecting permafrost from thawing. However,it has just been a short period since the construction of the highway,whether the measures are efficient to protect permafrost in the future is unknown,and further study is still ongoing.