碾压混凝土重力坝通水冷却温控效果研究

Study on temperature control effect of water cooling for roller compacted concrete gravity dam

对碾压混凝土坝采取合理可行的温控措施,对于降低温控费用和防止温度裂缝尤为重要。以某碾压混凝土重力坝为例,采用三维有限元浮动网格法模拟大坝施工进度安排,考虑混凝土弹性模量和水化热温升随龄期变化、通水冷却时长、通水温度等因素,对该碾压混凝土重力坝进行温控仿真研究,分析了通水冷却效果和坝体温度、应力变化规律。结果表明:通水时间为20 d,冷却水温从20℃降低到15℃时,可使各区最高温度降低0. 6~0. 7℃,最大温度应力降低0.08~0. 13 MPa。冷却水温为20℃,通水时间从15 d增加到20 d,可使各区最高温度降低1. 0℃,最大温度应力降低0. 11~0. 15 MPa。控制混凝土浇筑温度为25℃,采取通水温度20℃、通水时长20 d、全坝段通水冷却温控措施,坝体最高温度和最大应力均满足控制标准。研究成果为该碾压混凝土重力坝的通水冷却温控设计和施工管理提供了重要依据,对类似工程的温控设计具有参考意义。

Reasonable and feasible temperature control methods for the roller compacted concrete(RCC)dams are of great importance to reduce temperature control costs and to prevent temperature cracks.Taking a RCC gravity dam as an example,the three-dimensional finite element floating grid method was used to simulate the dam construction schedule.The temperature control simulation study of the concrete gravity dam was carried out by considering the change of the elastic modulus of the concrete and the temperature rise of the hydration heat with age,the length of the cooling time and the temperature of the water.The cooling effect of water cooling and the change regulation of temperature and stress were analyzed.The results showed that:when the water cooling days were 20 days and the cooling water temperature reduced from 20 to 15℃,the maximum temperature in each area can be reduced by 0.6~0.7℃,and the maximum temperature stress can be decreased by 0.08~0.13 MPa.When the water cooling temperature was 20℃and the days of cooling water increased from 15 days to 20 days,the maximum temperature of each district reduced by 1.0℃and the maximum temperature stress reduced by 0.11~0.15 MPa;The maximum temperature and maximum stress of the dam body meet the temperature and stress control standard by controlling the concrete with pouring temperature25℃and taking the cooling water temperature 20℃for 20 days in the whole dam.This study provides an important basis for the temperature control design of water cooling and construction management of the RCC gravity dam,and can guide the temperature control design of similar projects.