通水冷却对碾压混凝土消力池温度应力的影响

Influence of Water Cooling on Temperature Stress of Roller Compacted Concrete Stilling Pool

针对碾压混凝土施工普遍存在的温度裂缝问题,以某水利枢纽工程碾压混凝土消力池为例,采用三维有限元浮动网格法对其全过程温度场和应力场进行仿真研究,计算过程中考虑了冷却水管间距、通水水温、通水时间、混凝土水化热温升及弹性模量等对消力池温度场和应力场的影响,对比分析了不同方案的温度及应力变化规律。结果表明,施工期对高温季节浇筑混凝土埋设冷却水管进行通水冷却,可将最高温度降低4~6℃,最大温度应力降低0.38~0.47MPa,通水冷却效果明显;在不改变通水时间和通水水温的条件下,冷却水管水平间距减小0.5m,可将基础混凝土最高温度降低0.6℃左右,最大温度应力降低0.11~0.13 MPa;在不改变通水时间和冷却水管间距的条件下,混凝土大层浇筑完毕通3d10℃的制冷水、7d14℃的制冷水和20d的河水相比单一的通30d河水,可将基础弱约束区混凝土最高温度降低1.5℃左右,最大温度应力降低0.3MPa左右。

Aiming at the problem of temperature cracks that commonly exist in RCC construction,this paper takes the roller compacted concrete stilling pool of a certain hydro-junction engineering as an example.A simulation study is made on the whole construction process of the stilling pool with three-dimensional finite element method,in which the impacts from water cooling,hydration heat temperature rise of concrete,elastic modulus on both the temperature and stress of the stilling pool are considered in the calculation.And then the temperature stress of the stilling pool under different schemes are comparatively analyzed.The results show that during the construction period,the maximum temperature of stilling pool can be reduced by about 4-6℃and the maximum temperature stress can be reduced by about 0.38-0.47 MPa in high temperature season by water cooling and burying concrete cooling pipes.Therefore,the effect of water cooling is obvious.Without changing the duration and temperature of water,if the horizontal distances between cooling water pipes are reduced by 0.5 m,the maximum temperature of foundation concrete can be reduced by about 0.6℃and the maximum temperature stress can be reduced by 0.11-0.13 MPa.Without changing the duration and the distance between cooling pipes,it is a new way that passing cooling water at 10℃for 3 days immediately after pouring of large concrete floors,passing 7 days of cooling water at 14℃and passing the river water for 20 days.Compared with the old way that only river water is passed for 30 days,the maximum temperature of concrete in weak confinement zone of foundation can be reduced by about 1.5℃and the maximum temperature stress can be reduced by about 0.3 MPa.