Research On Real-time Monitoring System And Its Application In Metro Tunnel Construction

Because there are many invisible factors in subway tunnel construction process, liable to collapse or ground movement, effect the stability of peripheral building. So using monitoring control and survey techniques in the tunnel construction process. Therefor easy to promptly grasp stability of surrounding rock and security of supporting structure. Meanwhile, provide direct and effective original data for optimization design parameters and adjust the construction craft. Traditional manual monitoring cannot meet the demand for high-precision, high-frequency monitoring. With the rise of the Internet of Things technology, combined the characteristic and superiority the Internet of Things technology, real-time monitoring of metro tunnel construction system was designed.According to the functional and performance requirements of the system, this article has given the overall design plan of the system:the monitoring system composed by ZigBee wireless sensor network and GPRS. Simple analysis the system of interference and anti-jamming measures. In perception layer, articles selects cluster topology as the Metro wireless network topology. Describe procedure of ZigBee establishing network, research devices how to establish, join and leave network, etc. Writing conversion program between analog and digital signals, the sending and receiving procedures of nodes. In network layer, from gateway function, the perspective of the protocol stack and rate matching, analyzed feasibility of ZigBee and GPRS gateway. The node of ZigBee sensor uses CC2430as the monolithic processor, GPRS module uses MC52i module. The user can remote control via terminal operation, and then it can obtain the sensor information and control sensor nodes.Finally, real-time monitoring of metro tunnel construction applied in practical engineering, example of the vibration string stress gauge, realized stress gauge embedded and protection, wireless transmission of segment inner force monitoring data. The results can be seen form monitoring, with the continuous excavation of the tunnel, the value of steel stress is increasing; Tunnel segments maximum tensile stress and the maximum compressive stress appeared at the dome and the side wall of tunnel, and its value is less than the value of ultimate tensile strength, segment has sufficient security reserve.Combined with field monitoring data, use of the Flac3D software simulated on the metro tunnel construction process. The numerical results showed, when three times the hole width away form the KA14+930working face, spatial effects disappeared basically, the value of steel stress gradually stabilized; segment maximum tensile stress exceeds the ultimate tensile strength of concrete, concrete may cracking, crack resistance capacity meet the requirement of crack resistance during normal use.