| The construction of long-span anchored suspension bridges often encounters the construction of large-scale anchorage and bearing platform.When pouring these large-volume concretes,not only the construction period is long but also the structure is affected by many external factors such as the environment.When concrete pouring is completed,the large amount of heat generated during the solidification process is difficult to be released in time,while the heat of the outer surface of the concrete structure is easily released,which easily forms a large internal and external temperature difference.At the same time,when the mass concrete is bounded and restricted by the boundary and structure,it will easily cause uneven tensile stress inside and outside the structure.When the tensile stress exceeds the tensile stress of concrete,it will cause cracking of the concrete,making the structure waterproof,impermeability,use function,as well as durability and safety performance decline,therefore,large-volume concrete needs to be hydration heat control in the construction process.The thesis relies on the construction of the mass concrete anchorage and bearing platform of Wujiang’s extra-large Bridge,through the feasibility and temperature control measures of one-time pouring of large-capacity concrete bearing platform by optimizing the concrete mix ratio,improving on-site construction technology and combining finite element analysis,the final construction plan was implemented.In addition,combined with the engineering practice,the construction monitoring of the gravity-type anchor raft layering was carried out,and the developmental variation law of the theoretical calculation temperature and the measured temperature when the pouring layer height was 2m was analyzed.The main work of this paper is as follows:(1)The heat conduction theory of concrete,thermal properties and hydration heat of cement are introduced,and the steps of using finite element program to solve the temperature field are presented.(2)Mainly from layer thickness pouring and pipe cooling related factors to analyze the degree of impact on the hydration heat of mass concrete.And the concrete curing measures and countermeasures when temperature control indicators exceeded the limit were briefly analyzed.(3)The solid model of the large-capacity concrete tower is established.The theoretical calculation results are compared with the measured results to study he temperature field and stress field distribution of the mass concrete of cushion cap one-time pouring,and finally implemented.(4)Using the finite element software Midas/civil to establish the hydration heat analysis model of gravity anchor mass concrete,and study its influence on the pouring layer height of 2m and temperature control from the aspects of mix design and pipe cooling arrangement.Methods and results are available for engineering reference. |
