基于恒热流法和恒温法的岩土热物性试验分析研究

Experimental Analysis of Rock-Soil Thermal Properties Based on Constant Heat Flow Method and Constant Temperature Method

目前岩土热物性测试仪采用的方法包括两种:恒热流法和恒温法,通过介绍两种测试方法的区别及模型算法,以北京市某公建项目岩土热物性测试结果为基准,利用TRNSYS软件分别模拟了恒热流法和恒温法的测试工况,针对模拟结果展开分析研究。经对比,试验时间至48 h时,两种测试方法利用软件模拟出的延米换热量与现场测试结果的误差在10%以内,表明若已知项目周边的地层热物性参数如地层的导热系数、热扩散率等,可将软件模拟结果作为前期地埋管系统设计的依据,并作为后续热物性勘察结果验证的参考数据。此外,根据模拟结果,由于夏季地埋管流体在设计工况下与土壤的温差值较大,为了使流体尽快达到设计工况点,恒温法测试时应选用较大的功率,否则48 h内的测试值结果与实际值偏差较大。

At present,there are two methods for measuring thermal properties of rock and soil:constant heat flow method and constant temperature method.This paper introduces the difference between the two test methods and the model algorithm.Based on the test results of a public construction project in Beijing,TRNSYS software is used to simulate the test conditions of constant heat flow method and constant temperature method respectively,and the simulation results are analyzed.By comparison,when the test time reached 48 hours,the error between the heat transfer of the two test methods simulated by software and the field test results was less than 10%,indicating that if the formation thermal property parameters around the project,such as the formation thermal conductivity and thermal diffusive rate,were known,the software simulation results could be used as the basis for the design of the early buried pipe system.It can be used as reference data for verification of subsequent thermal property survey results.In addition,according to the simulation results,due to the large temperature difference between the buried pipe fluid and the soil under the design condition in summer,in order to make the fluid reach the design condition point as soon as possible,a larger power should be selected during the constant temperature test;otherwise,the test results within 48 hours will greatly deviate from the actual value.