The Durability Assessment And Lifetime Analysis Of Existing Railways Slab Culvert

Daqin railway, as China’s "Western coal shipped East" one of the most important channels, 2010 reached a total volume of 400 million tons, is the design year traffic 4 times, while Daqin railway train axle are also rising, far beyond the design criteria.Now operating on Daqin line situation, along the route of slab culvert in overload condition, durability of slab culvert down serious affect the safe operation of lines.Therefore, to the durability of the Daqin railway slab culvert became a serious problem.Fatigue factors and the external environmental factors of railway slab culvert by combination of slab culvert durability degradation.Through field investigation, laboratory testing and modeling analysis of slab culvert analysis of durability and service life, study says:(1) For Daqin railway slab culvert field measurement tests include concrete strength, carbonation depth, chloride ion content of concrete cover thickness, and so on, the investigation shows that the existing slab culvert strength decreases Carbonation depth, chloride ion penetration depth is greater than.(2) Study of 25 t, 27 t, 30 t axle fatigue properties of the lower cover plate.Obtained by experiments, steel and concrete strain increment and load the basic linear relationship;Reinforcing steel bar and concrete of strain and strain amplitude fatigue law from fast to slow the development of the times, about 50,000 times the growth rate slowed; the early increase.Fatigue loads for the 27t/30 t, beam mid-span deflection exceeds allowable value of standard values.Based on the test results, calculation and analysis of fatigue life under various axle cover plate, axle load on the cover plate fatigue life of great impact.(3) By learning vector quantify(LVQ) neural network evaluation method and the finite element analysis of slab culvert for durability assessment;And use the S-N curve of materials, calculation of probability limit state and based on Fick’s second law of chloride ion corrosion life prediction model for life prediction of slab culvert.Obtained corrosion of great influence on the behavior of slab culvert;Slab culvert assessment results other than the intensity was good;With the increase in axle weight, sharp drop in fatigue life of steel bars and concrete, percentage lower than fatigue life of reinforced concrete;25T axle load slab culvert under the remaining life expectancy of 48 years;25T axle load slab culvert under chlorion erosion remaining life for 13.5 years.Calculation method of slab culvert under considering only a single factor life and for loads and environment under the combined influence of slab culvert life provide a reference.