Design Of Strain Monitoring System For Miter Gate Based On Fiber Grating

Yangtze River shipping connecting China's southwest,central and East China's three major economic zones,the volume of freight accounted for more than 80%of the national inland waterway transport,known as the golden waterway reputation.The Three Gorges,Gezhouba Dam as an important node in the upper reaches of the Yangtze River water conservancy project in recent years,with the rapid development of the shipping industry,the amount of lock years of rapid growth,the key role of the Yangtze golden waterway shipping function becomes more and more important.But lock perennial working in complicated environment,the interaction of water swell,dynamic load and water under tremendous pressure on both sides of the door body,the miter gate of AB rod,rod,and the back bottom area of the door body water under the water sealing seat plate steel structure repeated local stress concentration in the lock/release.Long term operation at full load or overload conditions may bring devastating effects.So the miter gate stress concentration area,especially the underwater daily maintenance difficult area of stress/strain monitoring,timely detection of gate structure damage and to evaluate its safety,to improve navigation efficiency,guarantee the waterway transportation safety has important significance.Fiber Bragg Grating is a new type of optical passive device.It has good characteristic of anti-electromagnetic interference and is easy to be used to build fiber sensor net.Strain as a non-electrical signal is an important basis for the evaluation of the health of the building structure and Fiber Bragg Grating is sensitive to strain.This paper bring fiber grating sensor into strain monitoring system of miter gate for the first time.The system is used to monitoring strain of 3#gate of Gezhou dam.The main contents of this article are as below.(1)The finite element strain analysis was carried out to simulate the strain situation of the gate under various working condition.During this progress,a three dimension model was built.The simulation was used to analysis the distribution of strain of the gate to help determine the position of sensors.(2)The miter gate monitoring system includes fiber grating strain acquisition module,The strain acquisition module mainly realizes the signal acquisition function.The demodulation module mainly realizes the function of converting the collected optical signal into an electrical signal and converting the analog signal into a digital signal.Software system module mainly control the entire system,also collect,save and contrast data.The display interface and control system of the system are based on Labview,which can display values of sensors of every position.Once the value of a sensor exceeds the threshold,the system will send an alarm to warn the staff.