宁波地区地层温度的原位测试分析

In-situ Observation of the Stratum Temperature in Ningbo Area

气温波动会影响浅部地层温度的分布特征,改变地下工程的环境温度,从而影响轨道建设的设计和施工过程。依托宁波轨道交通3号线勘察工程,对沿线地层温度进行全年原位观测,分析了不同深度地层温度的分布特征,获得了以下基本结论:宁波地区恒温层的起始深度在地表以下10 m,地层温度约为18.7℃。深度5 m以上范围为气温强烈影响区,不同深度的地温差别较大,而5～10 m范围的温差相对较小,该范围地层为气温的微弱影响区。在气温强烈影响区的地层中,夏季和冬季地层温度随着深度的改变而发生明显变化,夏季平均地温约为18.1℃～26.8℃,而冬季平均地温为10.8℃～17.9℃。研究结果表明,地层深度和季节是影响地层温度分布的主要因素,在浅部地层内进行地下工程设计和施工中,要考虑气温对地层温度的影响。

Atmospheric temperature fluctuation affects the design and construction process of track construction because of the changes of the environmental temperature in underground engineering,which affects the shallow stratum temperature distribution.Based on the investigation of No.3 line in Ningbo rail transit,the formation temperature along the line was tested in situ for more than a year.Conclusions are obtained by analyzing the distribution characteristics of formation temperature at different depths.Firstly,the temperature is about 18.7℃in the stratum blow 10 m,which is the isothermal layer in different seasons.Secondly,the temperature difference at different depths is large in the formation above 5 m,because the temperature distribution is strongly affected by atmospheric temperature.However,the temperature difference between 5~10 m is small,and the affection of atmospheric temperature in this range is weak.Thirdly,the formation temperature difference along the depth direction is obviously in the summer and winter period in the formation above 5 m.In the summer the average temperature in the formation above 5 m is about 18.1℃~26.8℃,while it is 10.8℃~17.9℃in winter.The results show that the formation depth and season period are the main factors affecting the distribution of stratum temperature,and the influence of temperature on the formation temperature should be taken into account in the construction of underground engineering.