摘要
为评估热参数取值对冻土温度场的影响,将导热系数、比热、潜热作为冻土温度场的影响因素进行试验设计。通过室内试验测定了饱和粉质粘土在不同负温下的导热系数、比热及潜热值,并基于Johansen法提出了考虑冻土未冻水含量的热参数修正算法,按照变参数和常参数形式代入数值分析软件ABAQUS,获取了不同的温度场计算值。将不同负温下的热参数和某负温阶段的平均热参数代入数值分析软件,分析热参数变化对冻土温度场的影响。依据冻结试验获取了冻结150 h的模型箱温度场实测值,并将计算值与实测值进行了比较。结果表明:不同的热参数对冻结初期影响较大,随着冻结的深入各计算值间的差值逐渐缩小。采用一定负温阶段的平均热参数作为恒定热参数进行数值计算,从微观上不能满足精度要求。潜热是影响冻结温度场计算精度的主要因素,考虑不同负温土体导热系数、比热、潜热的计算更接近于实测值。研究成果为寒区水利工程设计和施工提供参考。
In order to evaluate the impact from the value selection of thermal parameter on the temperature field of frozen soil,thermal conductivity,specific heat and latent heat are taken as the factors of the impacts on the temperature field of frozen soil for the experiment design. The thermal conductivity,specific heat and latent heat of the saturated silty clay under different negative temperatures are measured through the relevant lab test,and then an algorithm for modifying the thermal parameters under the consideration of the unfrozen water content of the frozen soil is proposed herein based on Johansen method; from which the calculated values are substituted into the numerical analysis software—ABAQUS with the forms of variable parameter and constant parameter,thus the calculated values of different temperature fields are obtained. Substituting the thermal parameters under different negative temperatures and the average thermal parameters in a negative temperature stage into the numerical analysis software,the impacts from the changes of the thermal parameters on temperature field of the frozen soil are analyzed. In accordance with the relevant freezing test,the measured value of the temperature field in the model box which is frozen for 150 h is obtained; furthermore,the calculated value is compared with the measured one. The result shows that the impacts from different thermal parameters are larger in the initial freezing stage and then the differences among all the calculated values are gradually reduced. Taking the average parameters in a certain negative temperature stage as the constant thermal parameters for the numerical calculation,the precision requirements cannot be microscopically met. The latent heat is the main factor to impact freezing temperature field,while the values from the calculation with the consideration of the thermal conductivity,specific heat and latent heat of the soil mass with different negative temperatures are more close to the measured ones. The research results will provide refe
出处
《水利水电技术》
CSCD
北大核心
2017年第5期136-141,共6页
Water Resources and Hydropower Engineering
基金
国家自然科学基金项目(41472253)
天津市自然科学基金重点项目(16JCZDJC39000)
天津市建设系统科学技术项目发展计划(2016-25)
关键词
冻土
热参数
温度场
数值模拟
未冻水
冻胀
相变
潜热
frozen soil
thermal parameters
temperature field
numerical simulation
unfrozen water
frost-heave
phase transition
latent heat
