悬索桥塔柱混凝土水化温度效应分析与控制研究

Analysis and Control Research of Hydration Heat of Suspension Bridge Tower Column

采用数值模拟方法研究了风速、热量、拆模龄期、气候条件以及模板条件对塔柱混凝土水化温度应力的影响规律。首先基于调研,建立塔柱混凝土温度场与应力场的计算模型;其次,以背景工程常规塔柱为例,考虑不同的风速、热量、拆模龄期、气候条件以及模板参数,对施工过程中的水化温度以及应力效应进行模拟,研究表面应力发展规律;最后,提出常规节段的控制建议。分析结果表明:风速增大会提高开裂风险水平,但在保温条件较好的情况下,高风速的影响有限;表面最不利拉应力、开裂风险与绝热温升近似呈线性增长的比例关系;早龄期拆模时,表面仍有较高的拉应力,与瞬时效应组合后显著提高了开裂的可能性;冬季抗拉强度上升缓慢,开裂风险显著高于夏季;采用散热较好的钢模板时,会增大前期的受拉效应,防护措施作用较小;建议从降低热量、增加前期保温等方面入手,以最大程度降低表面开裂风险水平。

The influence of wind speed,heat,climate,time of formwork removal and formwork condition on the temperature stress of tower column are studied by numerical simulation. Firstly,the numerical model of temperature field and stress field of tower column are established based on the investigation.Secondly,based on the conventional column of the practical project,the hydration heat and stress effect in the construction process are simulated,and the development law of surface stress is studied by considering different wind speeds, heat, time of formwork removing, climate and the formwork parameters. Finally,the control suggestions are proposed. The results show that the increase of wind speed will increase the risk of cracking,but the effect of high wind speed is limited in the case of better insulation conditions. The maximum tensile stress and cracking risk are linearly increased with adiabatic temperature rise. When the formwork remove at early age,the surface still has a high tensile stress,which increases the possibility of cracking after combination with instantaneous effect. In winter,the tensile strength increases slowly,and the risk of cracking is significantly higher than that in summer.When the steel plate with better heat dissipation is adopted,the pre-tension effect can increase,at the meanwhile the protective measures is less effective. It is suggested that the risk level of surface cracking should be reduced by reducing the heat and increasing the heat preservation in the early stage.