Research On Composite Frame Bridge Safety Monitoring And Evaluation In Subsidence Area

Composite frame bridge as a new type of bridge structure has been widely applied inrailway and highway engineering in mining subsidence area as its adaption to larger surfacesubsidence. As the severe surface subsidence caused by mining becomes enormous, thebridges will severely damage and even collapse. In order to make sure the normal productionand living and to promote the sustainable development of the mining area, it is necessary tomonitor the safety of the composite frame bridges accurately and timely to discover thedisease and to issue early warningsThis thesis is settled in safety monitoring and evaluation on the influences of miningsubsidence on bridge culverts. By the means of numerical simulation and theoretical analysis,the evolution law of inner stress of composite frame bridge under the influence of miningsubsidence is calculated. The changing laws of high stress area, the value and direction ofprincipal stress of bridge with curvature and incline deformation are obtained. Thedetermination method of safety monitoring threshold of bridge culverts subsidence is studiedin this thesis. That is, on the influence of curvature and incline deformation, the roof, the floor,the1/4or1/2of the side wall and the center and edge of the tuck corners of the box framebridge are stress concentration areas, and the largest tensile and compressive stress appears onthe surface of the structure. Generally, the angle between the principal stress direction andlengthways or vertically (X or Y) direction is less than4degrees. When the curvature radiusis larger than2000m, the center position of the curvature circle has no influence on the bridgestructure.Based on the results of numerical simulation and other evaluation methods, the safetyevaluation model of composite frame bridge in mining subsidence area is established andpresent establishing evaluation criteria and level indicators including special structure, grounddeformation and so on are proposed. As a result, this study provides the model and method tomonitor bridge culverts safety in the mining area.On account of safety evaluation model and structure healthy monitoring technology, thesafety monitoring system consists of sensors, data acquisition and transmission and evaluation.The workflow, content and range of applications of the system are determined. The miningbridge culverts safety monitoring and evaluation system is developed based on Visual Basic6.0. The functionality of Graphical display, safety pre-warning and safety assessment can beachieved. The study on safety monitoring and evaluation has been applied into some mine ofHuainan which validates the feasibility of the safety monitoring system and evaluationmethod.