富水地层多圈水平杯型冻结温度场分布形式及变化机理研究

Study on distribution form and variation mechanism of multi circlehorizontal cup freezing temperature field in water rich formation

为了掌握富水地层多圈水平杯型冻结温度场的分布形式及发展规律,以昆明地铁城市轨道交通5号线冻结加固工程为背景,通过现场监测、数值计算、室内试验对冻结帷幕温度场变化规律及内在机理展开研究,分析冻结壁温度场在形成过程中的变化规律.试验结果表明:在外部降温计划的作用下,冻结壁温度场按照温度变化过程分为快速降温阶段、潜热释放阶段、稳定温度阶段及冻结维护阶段4个阶段.各阶段曲线变化速率与加固范围内试样未冻水含量变化具有一定的关联,未冻水往往通过影响比热容、导热系数与潜热等热参数对冻结壁温度场的变化规律从而影响到整体下的温度场分布规律.未冻水含量变化通过改变冻结冰体圆柱与土柱的几何位置关系从而影响试样冻结过程中的热传导形式,其中比热容在正温阶段时随温度降低逐渐增加.

In order to master the distribution form and development law of multi circle horizontal cup freezing temperature field in water rich stratum,taking the freezing reinforcement project of Kunming Metro Urban Rail Transit Line 5 as the background,the variation law and internal mechanism of freezing curtain temperature field are studied through field monitoring,numerical calculation and indoor test,and the variation law of freezing wall temperature field in the formation process is analyzed.The test results show that under the action of external cooling plan,the temperature field of freezing wall can be divided into four stages according to the temperature change process:rapid cooling stage,latent heat release stage,stable temperature stage and freezing maintenance stage.There is a certain correlation between the rate of curve change in each stage and the change in unfrozen water content of the samples within the reinforcement range.Unfrozen water often affects the overall temperature distribution of the frozen wall by influencing thermal parameters such as specific heat capacity,thermal conductivity,and latent heat.The change of unfrozen water content affects the heat conduction form during the freezing process of the sample by changing the geometric position relationship between the frozen ice cylinder and the soil column,and the specific heat capacity increases gradually with the decrease of temperature in the positive temperature stage.