基于平面电容的冻土检测传感器

Frozen soil detection sensor based on planar capacitance

在土壤冻融过程实验中,通过对空气、水、冰及干土的介电特性进行分析研究,发现了土壤中水和冰发生相变引起土壤总的电容发生很大变化,基于这一特性和LC振荡电路频率响应的原理,设计了一种基于平面电容分层检测冻土的传感器,实现了土壤冻融状态的判别和冻土深度的自动测量。与人工观测进行对比实验证明,当土壤中未冻水含量相对变化率在0.3以上时,土壤已经冻结。因此,利用基于平面电容的冻土检测传感器检测土壤的冻结状态,实现冻土深度自动化测量是可行的。

In the experiment of soil freezing and thawing process,through the analysis and study of air,water,ice and dry soil dielectric properties,it is found that the phase change of water and ice in soil results in the change of soil total capacitance. Based on this characteristic and the frequency response principle of the LC oscillation circuit,a planar capacitance based sen-sor for frozen soil layered detection was designed,which realized the discrimination of soil freezing/thawing states and automatic measurement of frozen soil depth. The experiment result from comparison with that of artificial observation proves that when the relative change rate of the unfrozen water content in soil is more than 0.3,the soil has been frozen. Therefore,it is feasible for frozen soil detection sensor based on planar capacitance to detect the freezing/thawing state of soil,and achieve the depth mea-surement of frozen soil.