中文摘要：

主动加热光纤法（Actively Heated Fiber Optic method,简称AHFO）实现了土的含水率大面积连续性测量,但该方法中采用的数学模型还不完善。通过试验测试了AHFO法中采用的几种常用数学模型,在此基础上提出了分段函数模型,并通过试验对分段函数模型的计算结果进行了论证。研究结果表明：指数函数模型获得的土的含水率结果误差较大;幂函数和对数函数模型获得的结果误差较小但整体值偏大;线性模型获得的结果误差最小,但在含水率较小时,测值偏小;分段函数模型对土的整个含水率变化范围内的含水率测定都具有很高的精度,绝对误差平均值达到了1.16%,可以满足土的含水率测试要求。分段函数模型的提出,对提高土的含水率AHFO法测定精度和促进方法的推广具有重要意义。

英文摘要：

Continuous and large-area measurements of soil moisture have been achieved with the Actively Heated Fiber Optic method （AHFO）. However, improvements to the mathematical models adopted in this method are still needed. In this paper, four common models used in the AFHO method are tested and verified by laboratory experiments. Based on experimental results, a piecewise function model is proposed, and its effectiveness is confirmed by laboratory experiments. The experimental results indicate that the exponential function model has large errors, the power function and logarithmic function modes have larger estimated values, and the linear function model becomes unsuited when the soil is dry. The tests also suggest that the piecewise function model has high precision in soil moisture monitoring in the whole moisture variation scope, and its absolute error reaches to 1.16% , which can satisfy the major requests of soil moisture measurements. The piecewise function model is of significance in improving the AHFO measurement precision and promoting popularizing of this method.