沙河渡槽施工期温度场分析

Temperature Field Analysis During Construction of Shahe River Aqueduct

根据热传导理论,对渡槽槽身在蒸汽养护条件下施工期的温度场进行了分析。结果表明:预养期,混凝土内外温差相对较小,且混凝土弹性模量较小,槽身不会产生较大的温度应力;升温期,混凝土温差多为外层温度高于内部温度,主要产生压应力,可适当放宽该时段温差要求;恒温期,受水化热影响内部温度继续上升,内外温差逐渐减小,一般由负温差转为正温差,有些工况会出现温差进一步加大现象,大多数工况都能满足15℃温差限值的要求;降温期,降温结束后混凝土内外温差不能满足15℃限值的要求,降温期混凝土外层会产生较大的拉应力,因此应采用较慢的降温速度,并且应延长混凝土在蒸汽养护蓬中的静置时间。

Base on the heat conduction theory,the temperature field of the constructing aqueduct body under the steam-cured conditions was analyzed.The results show that,during pre-cured period,the temperature difference between exterior and interior of the concrete is relatively small.Moreover,the elasticity modulus of the concrete is very low and there is no large temperature stress in aqueduct body.During heating-up period,the exterior temperature of the concrete is higher than the interior temperature and the compressive stress is prevailing,so the range of temperature difference can be broadened.During the constant temperature period,the interior temperature of the concrete is rising due to the hydration heat and the temperature difference is decreasing.Meanwhile the value of temperature difference is increased from negative to positive and the value is further increased under some conditions.The 15 ℃ limitation of temperature difference can be met in many conditions.During the cooling period,the 15 ℃ limitation can＇t be met at the end of this period and the larger tensile stress is prevailing in the outer concrete.So a lower cooling rate should be introduced and the standing time of aqueduct body in the steam-curing chamber should be extended.