Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a ...Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a distributed measurement system for in-situ soil moisture content （SM-DTS） is introduced.The system is based on carbon-fiber heated cable （CFHC） technology that has been developed to enhancethe measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristicvalue （Tt） can be defined from temperatureetime curves. A relationship among Tt, soil thermalimpedance coefficient and soil moisture content is then established in laboratory. The feasibility of theSM-DTS technology to provide distributed measurements of in-situ soil moisture content is verifiedthrough field tests. The research reported herein indicates that the proposed SM-DTS is capable ofmeasuring in-situ soil moisture content over long distances and large areas.展开更多
The subgrade soil scaling factor （SSSF） shows the basic properties of soil such as stiffness, gravimetry, density, and particle distribution, which are essential for disaster prediction and geotechnical engineering ...The subgrade soil scaling factor （SSSF） shows the basic properties of soil such as stiffness, gravimetry, density, and particle distribution, which are essential for disaster prediction and geotechnical engineering activities. In this paper, methods used for soil properties analysis are firstly summarized, and then a fiber Bragg grating （FBG） sensing technology is introduced. In order to acquire the properties and mechanical characteristics of soil accurately, a vibration-based method is presented, and an experiment for judging the properties of soil is conducted. As for the experiment, an FBG sensor is adhered to the upside of the vibration rod to measure its fundamental frequency. The rod vibrates freely at different-depth level of soil, and the changed data of wavelength from the FBG sensor are carefully collected. The Winkler spring model is used to analyze the relationship between the fundamental frequency and stiffness of soil. The results of this experiment suggest that data collected from FBG sensor can reflect vibration situation clearly and quantitatively. Thus the SSSF value can be calculated from the frequency-stiffness equation. The experimental results are almost identical with the theoretical derivation results. This confirms that the method presented in the paper can determine the SSSF effectively.展开更多
基金The financial supports provided by the National Natural Science Foundation of China(Grant Nos.41230636,41372265,41427801)National Basic Research Program of China(973 Project)(Grant No.2011CB710605)
文摘Moisture content is a fundamental physical index that quantifies soil property and is closely associatedwith the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisturecontents, a distributed measurement system for in-situ soil moisture content （SM-DTS） is introduced.The system is based on carbon-fiber heated cable （CFHC） technology that has been developed to enhancethe measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristicvalue （Tt） can be defined from temperatureetime curves. A relationship among Tt, soil thermalimpedance coefficient and soil moisture content is then established in laboratory. The feasibility of theSM-DTS technology to provide distributed measurements of in-situ soil moisture content is verifiedthrough field tests. The research reported herein indicates that the proposed SM-DTS is capable ofmeasuring in-situ soil moisture content over long distances and large areas.
文摘The subgrade soil scaling factor （SSSF） shows the basic properties of soil such as stiffness, gravimetry, density, and particle distribution, which are essential for disaster prediction and geotechnical engineering activities. In this paper, methods used for soil properties analysis are firstly summarized, and then a fiber Bragg grating （FBG） sensing technology is introduced. In order to acquire the properties and mechanical characteristics of soil accurately, a vibration-based method is presented, and an experiment for judging the properties of soil is conducted. As for the experiment, an FBG sensor is adhered to the upside of the vibration rod to measure its fundamental frequency. The rod vibrates freely at different-depth level of soil, and the changed data of wavelength from the FBG sensor are carefully collected. The Winkler spring model is used to analyze the relationship between the fundamental frequency and stiffness of soil. The results of this experiment suggest that data collected from FBG sensor can reflect vibration situation clearly and quantitatively. Thus the SSSF value can be calculated from the frequency-stiffness equation. The experimental results are almost identical with the theoretical derivation results. This confirms that the method presented in the paper can determine the SSSF effectively.
