Research On Temperature Control Technology Of Mass Concrete Of Suspension Bridge Anchor

The anchor is an important part of the suspension bridge structure system.Due to its huge pouring volume,there are many difficulties in the temperature control of the mass concrete of the anchor.At present,the temperature control of the suspension bridge gravity anchorage and the tunnel anchorage are relatively relative.Few,the temperature control indicators of domestic mass concrete projects also mainly follow the "Construction Code for Mass Concrete".Due to the differences in areas and structures,it is worth studying whether it is suitable for temperature control of some special complex structures.This article takes the anchor ingots on both sides of the Taihong Yangtze River Bridge as the engineering background,and uses a combination of theory and measurement to study the temperature field and temperature stress field of the mass of the anchor ingots of the suspension bridge,and comparatively analyzes the influencing factors.Suggested temperature control.The main research contents and results of this article are as follows:(1)According to the construction plan and site data,the finite element model of the gravity anchor bar C40 anchor part was established using Midas/civil,and compared with the field measured values,it was found that the temperature of the project reached the peak of temperature about 50h after pouring.The surface temperature difference of the structure reaches the peak value about 60h after the concrete is poured.(2)The length of the construction interval will seriously affect the temperature control effect.On the one hand,it is necessary to avoid the interval is too short.The lower concrete has insufficient heat dissipation,which increases the difficulty of temperature control;on the other hand,it is necessary to avoid the temperature of the lower surface falling too low,causing The temperature gradient was too large when pouring the upper concrete.(3)After studying the field measurement data of the tunnel anchor,it is found that the temperature change in the tunnel anchor hole with time is less than the temperature outside the tunnel,and the temperature basically fluctuates around 10℃;in order to make the simulation analysis results as realistic as possible,the anchor The ambient temperature of the plug body in a relatively closed environment can be considered to be 0.7 to 0.9 times the external ambient temperature.When the external temperature is high(such as in the afternoon),0.7 is recommended,and when the external temperature is low(such as midnight),0.9 is recommended.(4)The MIDAS/FEA software was used to establish the finite element model of the anchor plug body for parameter sensitivity analysis.It was found that when the thickness of the anchor plug body was changed from 4m to 2m in the design plan,the peak temperature of the concrete decreased by 1.8℃ and the peak stress decreased by 1.06MPa;For every 10 kJ/(m2·h·℃)decrease of convcction coefficient on the surface of the concrete,the peak temperature increases by 1.0℃,and the peak stress decreases by 0.35MPa;the temperature of each layer of the anchor plug increases by 5℃,and the peak temperature increases by 3.0℃,The peak stress rises by 0.40MPa;compared with ordinary cement,the peak temperature of medium and low heat cement decreases by 4.6℃and 14.9℃ respectively,and the peak stress decreases by 0.40MPa and 1.51Mpa.