浅层地温场连续监测和高精度模拟时空误差研究

Research on Time-Space Error of Continuous Monitoring and High-precision Simulation of Shallow Ground Temperature Field

为探究浅层地温场的时空演化规律,综合使用多种温度传感器,获得了南京市3个钻孔0~100 m的连续高精度温度数据。采用不同精度的地层模型和上边界温度条件,开展了3个月时间尺度的地温数值模拟,分析了地温在模拟时间内时空变化规律和模拟精度。相对于平均热扩散系数,采用分层热扩散系数时提高了浅部0~4 m模拟温度的精度,降低误差为2%~4%;与高精度边界模拟结果相比,边界为日均温度时的模拟结果相差不大,而月均温度降低了0~5 m模拟温度的精度,增大误差为2%~3%,但对于均质地层影响深度较小。对于浅地表变温层处的地温模拟,在浅部0~5 m处使用分层热扩散系数,以日均温度作为边界条件能够在保证结果准确的前提下减少监测成本。文章也为南京市浅层地温长期预测和评价提供了参考。

To investigate the temporal and spatial evolution of ground temperature,using a variety of temperature sensors comprehensively,continuous high-precision temperature data of 0 to 100 m in three boreholes in Nanjing City were obtained,and the change in ground temperature for 3 months was simulated based on the one-dimensional heat conduction equation.By analyzing the temporal and spatial variation laws of measured and simulated ground temperature,the simulation error of shallow ground temperature field under different spatial and temporal accuracy modeling conditions is explored.Compared with the average thermal diffusion coefficient,when the layered thermal diffusion coefficient is used,the shallow simulated temperature of 0-4 m reduces the error by 2%-4%.Compared with the results of high-precision boundary simulation,the results don’t show much difference when the boundary is the daily average temperature,while the accuracy of monthly average temperature is reduced by 2%-3%between 0-5 m,and the influenced depth on the homogeneous layer is smaller.For the simulation of the ground temperature at the shallow temperature layer,the use of segmented thermal diffusion efficient at the depth of 0-5 m and the daily average temperature as the boundary condition can reduce the monitoring cost while ensuring the accuracy of the results.It also provides a reference for the long-term prediction and evaluation of shallow ground temperature in Nanjing.