Research On Monitoring Of Rail Transit Engineering Based On Optical Fiber Sensing Technology

Rail transit engineering is a combination of all kinds of high level complex engineering,such as civil engineering,construction,geotechnical engineering and mining engineering.Stable,reliable and efficient monitoring technology is an important means to ensure the safe construction of rail transit engineering.However,the traditional monitoring technology is more and more difficult to adapt to the rapid development of rail transit engineering safety monitoring requirements in the long-term use process.The optical fibre sensing monitoring technology developed in recent years has become an ideal monitoring method in the rail transit engineering monitoring industry by virtue of its strong anti-interference ability,high accuracy,good stability,waterproof and moistureproof,long durability,long distance and large range distributed monitoring,good integration and other advantages.At present,the optical fibre sensing monitoring technology is mostly in the laboratory experiment stage,and fails to fully integrate into the actual engineering monitoring operation of rail transit engineering.In the actual engineering application,there are practical problems such as low survival rate and low matching degree between the layout method and the actual engineering.To this end,this paper,based on the current demand of urban rail transit project construction monitoring and the shortage of the traditional monitoring technology,relying on Jin Yi east inter-city railway engineering,rail transit construction in foundation pit retaining structure as the research object and shield tunnel segments,solves the fibre optic sensing monitoring technology in the palisade structure and deformation of shield tunnel segments of the engineering application problem,the main research content and conclusions include the following aspects:(1)Research on the performance of optical fibre sensors:basic performance analysis of optical fibre sensors made based on optical fibre sensing technology,research on their packaging methods and sensing characteristics,and understand their monitoring physical quantity.The strain and temperature sensing coefficients were calibrated.(2)Research on monitoring technology of deep horizontal displacement of pile based on optical fibre sensing technology(BOTDA):Lumbar beam structure in foundation pit engineering retaining structure in the presence of the two kinds of bored piles of deep horizontal displacement monitoring,improved under the waist beam structure is difficult to live single U monitoring technology,and puts forward some corresponding u-shaped monitoring technology,principle and mechanics of materials based on the Angle method,strain transformation principle of displacement of u-shaped layout algorithm was deduced,and designed the beam with PVC pipe as the carrier of indoor model test,and in the actual project compared with the monitoring results of traditional dip pipe,experiment and practical engineering results show the validity of the more U monitoring technology and the reliability of the optical fibre sensing technology,It solves the problems of the inclinometer tube monitoring accuracy is insufficient and the sensor is deactivated under the waist beam structure.(2)based on fibre optic sensing technology(BOTDA,FBG)concrete support stress deformation monitoring technology research:based on the principle of mechanics of materials,concrete support of lattice column contains generalized force model solving,solved the sensor installation parameters and stress calculation method for the ambiguous problem,through the practical engineering compared with traditional steel bar meter monitoring effect,illustrates the BOTDA and FBG monitoring effect is superior to the traditional steel bar meter monitoring effect,further verify the validity of the model;(3)based on fibre optic sensing technology(BOTDA)deformation monitoring technology research of shield tunnel segments:in the two dimensional distribution of the original Z displacement monitoring technology on the basis of the combination of shield tunnel segment of threedimensional deformation model,diamond design based on the distributed optical fibre sensor layout 3 d displacement monitoring technology,and deduced the corresponding three displacement calculation method,design the board as the carrier of the segment 3 d displacement of indoor model test,verify the validity of the diamond monitoring technology,solved the Z monitoring technology and the segment does not match the actual displacement problem.