The Research Of Environmental Monitoring System Of Seasonal Frozen Subgrade Based On ZigBee And GPRS

In 2015,China put forward on " the Belt and Road "," the Beijing-Tianjin-Hebei integration","Northeast-East Mongolia Economic Zone" development strategy,covering almost all the permafrost regions of China.With the rapid development of social economy,road traffic and other infrastructure construction will be intensified.Seasonal frozen soil is a kind of complex geological body.Under the strong interaction of freezing and melting,road embankment is prone to occur road subgrade diseases,such as pumping,subsidence and intensity weaken.The change of temperature and humidity(moisture content)of subgrade is the direct factor of many road disasters.In order to prevent and cure the road freeze-thaw disease and prolong the service life,the temperature and humidity of subgrade must be monitored in real time,we must grasp the change rule and made corresponding remedial measures in time.In this paper,based on the actual requirements of temperature and humidity monitoring during freeze-thaw cycle of subgrade in seasonal frost area,we design a kind of subgrade environment monitoring system based on ZigBee and GPRS.Monitoring system is mainly composed of three part,including data acquisition terminal equipment,ZigBee-GPRS gateway coordinator and host computer monitoring center.The terminal node equipment includes a sensor and a ZigBee RF transceiver,obtain data by a thermistor sensor temperature acquisition,soil humidity data is obtained based on the principle of FDR,the dielectric constant and the water content has a certain relationship,by medium frequency electromagnetic pulse propagation is obtained.The temperature compensation algorithm embedded in the design unit good control of the terminal node,the soil humidity well after temperature compensation,the radio frequency is sent to the ZigBee network.The gateway coordinator including ZigBee coordinator,gateway controller and GPRS module,the coordinator in addition to receiving device data,also has the components,management and maintenance of the entire ZigBee network gateway controller through the serial port.The coordinator after the data processing by software ZigBee and GPRS protocol conversion,and finally by the host computer monitoring module is sent to the remote sensing GPRS host computer monitoring center is used to monitor the network connection request,at the same time has the data receiving,display and storage function.The system will be two kinds of wireless communication technology combined with 20 cm and 40 cm,on the two test points for continuous data acquisition.Through the actual verification of the acquisition system with high precision,stable and reliable,easy to operate,can be realized on the season internal temperature of permafrost subgrade,real-time monitoring of humidity.