| The amount of large-volume concrete poured at one time has increased from the initial hundreds of cubic meters to the current tens of thousands of cubic meters,making the construction process more difficult and the quality risk also increasing.If the quality control is not in place,concrete cracks are likely to occur.With global warming,hightemperature construction in summer may become the norm.In order to avoid cracking of the bearing platform due to excessive temperature difference between the inside and outside,it is necessary to adopt a combination of internal and external quality control methods to solve the problem.There are many maintenance methods at present,and it is impossible to use multiple methods at the same time to compare the maintenance effects of the same cap.From the perspective of saving time and cost,this thesis conducts numerical experiments on multiple maintenance methods for the same cap.In this thesis,the main pier cap of a continuous rigid frame bridge is studied based on the project.First,the maintenance parameters of the large-volume concrete cap under high temperature are studied,and the correctness of the numerical analysis method in this thesis is verified by the field measurement data.Various maintenance techniques for large-volume concrete caps under high-temperature environment are studied.The main research work of this thesis is as follows:(1)The thesis studies the maintenance of large-volume caps from the aspects of high temperature environment parameters,internal maintenance parameters and external maintenance parameters.Among them,the high temperature environment parameters are mainly ambient temperature parameters;the internal maintenance parameters include cement hydration heat,thermal conductivity and specific heat capacity,adiabatic temperature rise,pipe cooling system and other parameters;the external maintenance parameters are related to the maintenance method,mainly involving the heat conduction equation and boundary conditions and other parameters.(2)This thesis introduces the on-site intelligent temperature control monitoring technology for large-volume caps.By sorting out and analyzing the internal measured data of the 192-meter-high pier caps of a bridge after construction and maintenance,and comparing them with the numerical analysis results,the reliability of the numerical analysis method in this thesis is verified.effectiveness.(3)Starting from the research on the internal maintenance of large-volume concrete caps,and centering on the characteristics of high-temperature environment parameters,the caps are studied with different mold entry temperatures,and the interior of the caps with different cold water pipe inflow temperatures,cold water pipe diameters,and cold water pipes.The crossing work conditions under the arrangement spacing are analyzed,and the reasonable setting scheme of the internal tube cooling system of the cap under high temperature is obtained.(4)Carry out research on the maintenance of the external covering insulation layer,and on the basis of internal maintenance measures,conduct numerical research on different types of external soil covering maintenance and water storage maintenance,and analyze the effects of different maintenance methods on the rise in internal temperature,surface temperature and inner surface of the cap.The effect of temperature difference.(5)Numerical analysis was carried out on the composite maintenance technology and dynamic maintenance technology of large-volume concrete caps,the maintenance effect of the caps under composite maintenance was studied,and the sensitivity of the temperature of the caps to the curing of different thicknesses of soil was studied,and the form of dynamic maintenance scheme for covering soil was proposed. |
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