摘要
毛细作用对诸多工程的变形与稳定有影响,传统方法难以精确监测毛细水上升过程的动态变化。首先研究了风积沙图像RGB(red(红)、green(绿)、blue(蓝))信息与含水率的关系,由此开发了一种利用图像RGB信息测试含水率并获取湿度场的方法与技术;基于此探究了风积沙毛细水上升过程中含水率的时空变化,提取了湿润锋轮廓,分析了湿润锋运移规律。结果表明,风积沙的归一化颜色特征值ξRnor与含水率θ间存在显著的线性负相关关系,用于预测风积沙含水率效果良好;研发的基于图像RGB信息测试湿度场的技术,具有cm级分辨率和较高精度,能直观展示风积沙柱毛细水上升过程中含水率的时空变化;对毛细水上升过程的图像采用改进的k-means聚类分割法进行分析,能精确识别和量化湿润锋的轮廓信息,比目测法更加准确可靠;在表面张力和惯性力作用下,风积沙毛细水上升初期各高度处含水率存在明显的冲高现象,经历几次小幅波动后回落,稳定含水率相较峰值含水率降低约1.5%;毛细水上升高度与相对密实度Dr成正比,幂函数和双对数二次多项式均能较好拟合湿润锋上升过程。研究工作为毛细水上升试验测试提供了一种精确快捷的新途径。
Capillary action has an important impact on the deformation and stability of various geotechnical engineering structures.It is challenging to accurately monitor the dynamic changes in the capillary water rising process by traditional methods.In this study,the relationship between RGB(red,green,blue)information and water content of aeolian sand images was firstly investigated.The methodology and technology for measuring water content and obtaining centimeter-level resolution moisture fields via image RGB information were developed.According to this method,the spatial-temporal variation of water content during capillary water rising in aeolian sand was further explored,and the wetting front profile was precisely distinguished.Furthermore,the wetting front transport law was analyzed.The results show that a negative linear relationship exists between the normalized color featureξRnor and the water contentθof aeolian sand,which brings about a good prediction for the water content of aeolian sand.The proposed technology for measuring the water content field based on image RGB information,with centimeter-level resolution and high accuracy,can visualize the spatiotemporal changes of the water content during the rising of capillary water in the aeolian sand column.An improved k-means clustering segmentation method was adopted to analyze the sand images of the capillary water rising process,allowing precise identification and quantification of the profile information of the wetting front.This method is more accurate and reliable than the visual inspection method.Under the action of surface tension and inertial force,the water content at each height of the aeolian sand in the initial capillary water rising period has obvious overshoot phenomena.After several small fluctuations,it falls back,and the stable water content is about 1.5%lower than the peak value.The rising height of the capillary water is proportional to relative density Dr.The rising process of the aeolian sand wetting front can be well fitted both by the power and double logarithmic quadratic polynomialfunctions. The research provides an accurate and rapid novel approach for the capillary water rise test.
作者
田升奎
刘观仕
赵青松
徐国方
蔡铭炫
TIAN Sheng-kui;LIU Guan-shi;ZHAO Qing-song;XU Guo-fang;CAI Ming-xuan(Guangxi Key Laboratory of Rock and Soil Mechanics and Engineering,Guilin University of Technology,Guilin,Guangxi 541004,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2023年第9期2525-2536,共12页
Rock and Soil Mechanics
基金
国家自然科学基金资助项目(No.52179115,No.52178372)。
关键词
风积沙
毛细作用
数字图像
湿度场
湿润锋轮廓
aeolian sand
capillary action
digital image
moisture field
wetting front profile
