岩土热响应测试中地温场的ANSYS模拟

The ANSYS Simulation to Geotechnical Heat Response Test in Geothermal Field

应用ANSYS软件,建立二维的单井单U型传热模型对岩土热响应测试中地温场的分布规律进行模拟,模拟区半径设为5m,模型传热遵循瞬态热分析理论。为了控制精度,使分析结果更符合实际情况,采用智能网格划分,精度控制为3。在PE管内侧施加恒定热流,温度为37.6℃,热流密度为660 W/m2,在模拟区外边界施加恒定温度13。经过72h的测试过程,得出测井周围岩土体的温度分布规律,模拟区内最高温度37.6℃,最低13℃,影响半径约为1m,地温梯度在测井附近最大,离测井越远地温梯度越小。对模拟结果的分析得出,在测试48h时地温场就达到稳定状态,这与实际的测试时间相吻合。又通过模拟和数理统计得出回填料导热系数、岩土体导热系数与影响半径之间的关系。

This paper applies the ANSYS software, establishes a heat transfer model of two-dimensional sin- gle hole,single u-shaped to simulate the distribution rules in geotechnical heat response test in geothermal field. The simulation zone radius is set to be 5 m,the model of heat transfer follows the theory of transient thermal analysis. In order to control accuracy to make the analysis results more in line with the actual situa- tion,intelligent meshing precision control is 3 adopted, and the accurate control is 3. Inside the PE tube in- fliction constant heat flow is installed with the temperature of 37.6 ℃ ,and the heat flow density of 660 W/m2. The constant temperature outside simulation boundary area is 13. After 72 hour test processes,the gneiss tem- perature distributed rule is obtained around the well logging. The maximum temperature in simulation area is 37.6 ℃ ,and the lowest is 13 ℃ ,the radius of influence is approximately 1 m. The geothermal gradient appears the biggest nearby the well logging,and the smallest far away the well logging. The simulation re- sults obtains that the geothermal field is in a steady state when test time is 48 hours, which is consistent with the actual test time. Through the simulation and the mathematical statistic, this article obtains the backfill thermal conductivity,and the relationship between the thermal conductivity of rock and soil and the radius of influence.