Analysis And Control Of Hydration Heat Of Mass Concrete Anchor Plug Body In Suspension Bridge Of Mountainous Area

In the past 40 years of reform and opening up,China's economy has achieved rapid development,and the scale of bridge construction has become larger and larger.Many large-span suspension bridges have been built.Among them,the suspension bridge caps,anchors or anchor plugs are cast from large-volume concrete,and the temperature cracks caused by hydration heat in concrete during construction and post-conservation are becoming more and more prominent.Adopting reasonable concrete construction schemes and effective temperature monitoring measures to prevent the generation of harmful cracks and ensure the quality of concrete pouring is an urgent problem to be solved in the research of large-volume concrete hydration heat.Based on the anchor anchor plugging project of the Jinan Jinsha River Bridge(Lijiang side),this paper analyzes and controls the hydration heat of the mass concrete anchor plug body of the mountain suspension bridge.The main research contents are as follows:(1)Based on the theory of hydration heat calculation,using the finite element method of the basic equation of heat conduction and the finite element element method of cooling water,using the hydration thermothermal parameter value and calculation empirical evaluation,combined with the construction technology of the actual project with the corresponding anchor plug construction process,the causes of the cracks in the construction process of the anchor plug body,the concrete construction control,the control of the cooling water inlet and outlet,the temperature control and maintenance of the concrete surface are systematically studied.(2)Aiming at the effect of heat transfer on the anchor body and surrounding rock under the action of hydration heat,the finite element software Midas/FEA2017 is used to simulate the surrounding rock of the anchor body,and the concrete is highly layered.Under the condition of no cooling water,the influence of hydration heat temperature on the thickness of surrounding rock provides reference for the modeling thickness of surrounding rock of the same type of anchor plug.(3)Aiming at the influence of ambient temperature change on the surface temperature of anchor plug concrete,the heat conduction theory of concrete contact with air is proposed to derive the influence depth of temperature change on concrete surface thickness.For the problem of concrete interior insulation effect in anchor room,using finite element software,temperature and stress analysis were carried out for different convection coefficients,and the optimal convection coefficient values at normal temperature pouring were obtained.(4)In view of the problem of high-stratification block and concrete internal cooling water control during the construction of anchor plug body,the fifth and sixth construction stages of anchor plug body are selected for stratified block study;the sixth construction stage of anchor plug casting layer is used to discuss cooling water 12 cases of analysis conditions,systematic analysis and analysis of cooling water parameters,the optimal solution under various working conditions.(5)Combining the actual construction of the anchor plug,the system describes the hydration heat monitoring process,and uses the finite element software to simulate the whole hydration heat temperature field of the anchor plug concrete construction,and compare the field measured data with the theoretical data.The variation law and influencing factors of the temperature field of the anchor plug concrete are obtained,and the relevant temperature control results are summarized.The adverse analysis of the unfavorable situation in the construction encounters the cold wave,and the relevant research conclusions are obtained,which is the construction of the later anchor body and the mountainous area.Types of mass concrete temperature control provide a practical and effective reference.