青藏铁路清水河地区路基下伏多年冻土地温变化特征研究

STUDY ON THE GROUND TEMPERATURE CHARACTERISTIC OF THE PLATEAV PERMAFROST UNDERLYING THE QINGHAI-TIBET RAILWAY EMBANKMENT

研究目的:分析青藏铁路施工区多年冻土上限的变化规律以及填筑铁路路基施工对下伏多年冻土赋存条 件的影响。 研究方法:系统分析埋设在青藏铁路清水河地区路基中2个断面内的共8个地温测试孔3年来采集的地温 观测资料,研究该地区铁路路基下伏高原多年冻土融化特征。 研究结论:由于受到填筑路基时赋存在路基填料内的热量的影响,铁路路基下伏多年冻土近地表的地温变 化特征与天然地面下的多年冻土的地温变化特征有明显的不同,且向阳面与被阴面差别较大。多年冻士的上限 在施工初期会有一个明显的下移沉降,随着时间的推移,虽然残存在路基中的热量逐渐消散,多年冻土上限下 降会逐渐稳定,但由于受到太阳辐射和路基边坡形状及融化夹层的影响,多年冻土上限会逐渐稳定,但不会在 短时期内上升到天然地面下多年冻土的上限水平。

Research purpose： this paper analysed the ground temperature of the plateau permafrost underlying the Qinghai-Tibet railway embankment and analysed on its the thawing feature. Research method： this paper is based on the measure dates for three years which have been taken from eight measure holes lain in the indicated that there are four features of the plateau permafrost. Research conclusion： the paper are four points： the first the average ground temperature of the plateau permafrost underlying the railway embankment is much higher than that under the natural ground. The second is the thawing-layer forming at 0.5m-3.Sm from the ground surface that controls the change of the plateau permafrost underlying the railway embankment. The third the decline of the upper limit of the plateau permafrost underlying the railway embankment would be stoped slowly as the heat existed in the railway embankment gradually lift. The last is obviously difference features in the ground temperature between the slope exposed to the sun and the shady slope.