风环境对大体积混凝土水化程度与孔结构变化的影响研究

Study on the influence of the wind environment on the hydration degree and pore structure change of massive concrete

摘要：采用现场监测的方法研究了风环境轻轨大体积混凝土桥墩施工水化程度与孔结构的影响。首先，测试大体积混凝土桥墩不同面的风速，根据自然对流影响及结构表面温差的表面放热系数通用公式计算得到各表面放热系数，利用有限元软件AN-SYS中的热分析模块计算出不同风速下桥墩各表面的水化热温度；同时模拟桥墩混凝土配合比，进行相同风速的养护试验，研究不同风速对混凝土孔结构变化的影响，应用孔结构测试仪进行了气泡数目、气泡弦长、硬化混凝土空气含量观测。分析结果表明：相对于背风面，迎风面温度受风环境的影响更加明显。而对于内侧，风速影响不大，几种风况下温度基本一致。风向对混凝土表面放热系数的影响基本可以忽略。在风速为16m／s，龄期为8d的气泡弦长小于20nm，而龄期为8d的气泡弦长在50～60nm3之间；风速为16m/s的含气量、气泡平均半径均比风速为2,6、8m／s的要低；在风速为8m／s的混凝土气孔比表面积最大；风速为2m/s混凝土硬化后气泡间距指数要比风速为16m／s的分别要大8．03％（8d）、22．84％（32d）。

The influence of wind environments on light rail mass concrete pier construction and hydration degree of pore structure is in- vestigated by using on-site monitoring.Firstly, the mass concrete pier of different surface wind speed were tested.The surface heat transfer coefficient is obtained by calculation according to general formula of surface heat transfer coefficient of the effect of natural convection and surface temperature ,the calculated under different wind speed of bridge pier on the surface of hydration heat temperature using the thermal analysis module of finite element software ANSYS.Also simulation concrete piers formula, the same wind speed and different curing ex- perimental, effects of different wind speed of concrete pore structure change, using pore structure measurement instrument were the num- ber of bubbles, bubble chord length and hardening air content of concrete observation.The analysis results show that compared to the lee- ward,windward surface temperature is affected by the wind environment is more obvious.For the inner side,the wind speed has little ef- fect, and the temperature is basically the same under several wind conditions.The influence of wind direction on the surface heat transfer coefficient of concrete can be ignored.In wind speed up to 16 m/s,the age for 8 d bubble chord length is less than 20 nm,and age for 8 d bubble chord length between 50-60 nm.Wind speed is 16 m containing volume,average bubble radius are than the wind speed for 2,6,8 m/s to low.At a wind speed of 8 rn/s of concrete pore specific surface area is the largest.Wind speed for the 2 m/s of concrete hardening of the bubble is 8.03%（8 d） and 22.84%（ 32 d） greater than spacing index the wind speed of 16 m/s.