Mechanism And Modeling Of Early Age Transverse Cracking In Continuously Reinforced Concrete Pavement With Active Crack Control

Continuously reinforced concrete pavement(CRCP)does not have transverse shrinkage joints.It is affected by temperature and humidity stress at the initial stage of pouring,and transverse cracks are inevitable.However,the evenly distributed transverse cracks with fine crack width do not affect the performance and performance of CRCP.Durability.Existing studies have shown that the typical structural failure of CRCP—thrust failure,mostly occurs at dense cracks.Therefore,controlling CRCP thrust failure should reduce the occurrence of unfavorable crack distribution such as dense cracks.The control of transverse cracks at the initial stage of CRCP pouring can prevent impact.Breaking damage plays a positive role in promoting.In response to this problem,this paper adopts the secondary development of ABAQUS to accurately simulate the temperature field and humidity field of the early-age CRCP pavement.Considering the development and change of the early-age concrete mechanical properties with the maturity,the construction includes the bond slip of the reinforced concrete interface.The virtual crack model in the cohesive zone of the migration effect is used to study the early-age CRCP pavement transverse crack propagation time history curve.According to the analysis results of the CRCP pavement crack propagation law of different spacing induced cracks,the cracking risk and the optimal prefabricated crack spacing are studied.The main research contents and results of this paper are as follows:(1)Based on the ABAQUS finite element calculation platform,FORTRAN is used to compile a series of pavement temperature and humidity field subprograms that consider the effects of environmental heat convection,solar radiant heat,road radiant heat and cement hydration heat: FILM,DFLUX,USDFLD and HETVAL,The simulation results of the above subroutines are verified by relevant test results and calculation examples respectively.The development law of temperature and humidity characteristics of cement concrete pavement during the construction period is explored.The calculation results show that the CRCP pavement has a higher temperature rise due to the violent hydration reaction in the initial 20 hours.It is fast,and there is obvious hysteresis effect of temperature change from top to bottom in the structural layer.At the same time,night construction can greatly reduce the internal temperature gradient of the concrete pavement slab and reduce the possibility of pavement cracking;the concrete slab only has a greater effect on the shallower surface.Humidity gradient,the humidity drops rapidly,and the internal humidity changes very little.(2)Establishing USDFLD subroutine development to obtain a concrete maturity development model,considering the thermodynamic parameters of concrete and the changes in strength with maturity,and obtaining a prediction model of various mechanical parameters of concrete at early ages;based on fracture mechanics,it is established to consider the interface between steel and concrete The virtual crack model of the cohesive concrete cohesive zone is verified by three-point bending test.At the same time,the five stages of cracking of reinforced concrete beams are analyzed according to the P-CMOD curve.(3)Using sequential coupling,apply the stress field calculated sequentially from the temperature field and the humidity field to the actual CRCP pavement model,and consider the influence of the relative mechanical parameters of the early-age concrete that develops with age to obtain a continuous precast crack Propagation of transverse cracks on reinforced concrete pavement;change the spacing between prefabricated cracks to obtain a more reasonable spacing between 1000 mm and 1500 mm.In this interval,dense transverse cracks can be better avoided,and at the same time,erosion can be better prevented.Broken destruction.