Research And Control On Crack Of Twin-block Ballastless Track On Subgrade

The main structure of ballastless track is reinforced concrete structure. The ballastless trackendures various long-term loads from the outside, which brings the crackles or other defects.In the process of high speed railroad construction and operation, the ballastless track usuallysuffers from the existence of crackles. Even the reinforced concrete structure of ballastlesstrack can work with crackles, the roadbed slab crackles will appear and then extend to causetragic events with exogenous process like train load, temperature load, the axial temperatureload and so on.This paper is based on the crackles appear in the double-block type ballastless trackstructure in the process of real operation and combined the real features of double-typeballastless track in China. The essay classified various crackles according to the position ofthe crackles and analyzed the reasons of the appearance of crackles with the assistance ofknowledge on concrete. Through the analysis mentioned above, the author determined theresearch target: considering the crackles on roadbed slab under the action of reinforcedconcrete slippage cementation and the action of train load, temperature load, the axialtemperature load.By the application of large general finite element software ANSYS, the author presumedthe construction and operation situation of double-type ballastless track. The author analyzedthe influence of temperature stress on track structure’s stress distribution. Then the authorconsidered the interruption of actual construction and operation condition and constructeddouble-type ballastless track ANSYS model about the roadbed of track board rebar andreinforced concrete slippage cementation which is based on the fracture mechanics theory. Inthis way, the unsteady extension length of different depth of crackles can be inferred.Therefore, the author can put forward the critical value of unsteady extension length ofdouble-type ballastless track considering the effect of reinforced concrete slippagecementation. Based on the above analysis, the author applied the software of applied statisticsSPSS to operate the data fitting and made a prediction on the fatigue life of surface cracklesof different depth. The result shows that the axial temperature load has much greater influencethan that of temperature gradient load and train load on the fatigue longevity.At last, according to the result of theory research, the paper explained the necessaryprevention and control measures on crackles in the process of design and construction andthereafter from various aspects.