基于高精度光纤测温的水热耦合试验

Water-heat coupling test based on optical fiber temperature measurement with high-precious

为探究城市浅层地表下的水热耦合过程和影响因素,设计高精度传感器监测室内试验平台,开展考虑温度-渗流-覆盖层的水热耦合试验,以实现分布式温度场监测。结果表明:渗流参与时土体温度场变化剧烈,渗流速率更大,升温速率可提高数十倍以上;水温越高,与土体温差越大,温度场变化越明显;不同覆盖层下土体升温过程不同,聚乙烯板下土体温度升温最慢,且低于其他材料的;土层性质相同,温度变化速率较一致,渗透性高有利于渗流与传热;减弱覆盖层渗流流动,改变渗流场,进而影响温度场分布;渗流为热能载体,扰动初始热对流状态,温度场将重新分布;温度影响渗流黏滞系数等,改变渗流场;三者耦合决定了土体温度场。

In order to study the water-heat coupling process and its influence factors in urban subsurface,an indoor test platform with high-precision sensors was designed to operate the water-heat coupling test consid-ering temperature,seepage and coverage types herein to recognize distributed monitoring of temperature field.Results indicated that:The change of soil temperature field under seepage was more intensive,the larger flow rate makes heat rate increase by dozens of times;The higher temperature or temperature differ-ence between soil and flow,the greater temperature field changed;Heating process of the soil under differ-ent coverage was distinct,the heat rate of the soil under polyethylene board was the lowest;The heating rate was same with the same soil properties,especially higher permeability was benefit to heat and flow transmis-sion;The covering types weakened the seepage’s diffusion,disturbed seepage field,affected the distribution of temperature field;The seepage,carrying heat,disturbed the initial state of heat convection and motivated a new temperature field to appear;Heat affected the viscosity coefficient of seepage and changed seepage field,those of three factors were coupled to determine the soil temperature field.