Research On Roadbed Subsidence Measurement System Based On Chain-type Camera Network

In the long-term service of railways,bridges,highways and other infrastructures,these structures may be settled due to external loads,causing a safety hazard.At present,the raodbed subsidence measurement generally adopts the traditional contact measurement method.These measurement methods cannot realize continuous measurement and measurement accuracy is low all have.This project aims to develop a roadbed subsidence measurement system based on chain camera structure to realize non-contact,high-precision and rapid subsidence measurement of structures such as roadbed and bridges.Aiming at the large-scale structure features such as roadbed and bridges,the roadbed subsidence measurement method based on the chain camera network structure can realize the long-span,high-precision,fast and multi-point long-term subsidence measurement requirements.The subsidence measurement model of chain network structure is established to calculate formula of settlement displacement of all measurement points in chain structure,with putting forward the assumptions and constraints of the model.The feasibility of chain camera network structure to realize raodbed subsidence measurement is theoretically verified.In this paper the measurement system consists of three parts: the subsidence observation station,the wireless AP base station and the image data processing center.The hardware of the settlement observation station adopts the ARM image processor as the core embedded image acquisition system.The software design is based on the Linux platform.Its main function is to realize the synchronous acquisition of the illuminated target.The wireless AP base station is to build the WiFi wireless for the subsidence measurement system;image data processing center software design uses Qt multi-threading technology to realize real-time communication function with all observing stations,combined with OpenCV open source visual library design marker point coordinate sub-pixel positioning program,and finally calculates the settlement displacement change of the area to be tested.The subsidence measurement simulation experiment was carried out on the optical vibration isolation platform in the laboratory.By means of the manual precision displacement table given the settlement displacement of the measurement node,the error between the settlement displacement value of the measurement node and the set settlement value was calculated to be less than 0.015 mm,verifying that the system has high measurement accuracy and stability.In order to further verify the actual measurement effect of the system in the outdoor environment,this paper conducted two field subsidence measurement experiments with the road in campus and the Nanjing Yangtze River Bridge as objects.The results of subsidence measurement experiments show that the measurement system can perform high-accuracy and multi-point continuous subsidence measurement functions on roads and bridge surfaces,and verify that the subgrade subsidence measurement system has good practicability.