水工隧洞衬砌混凝土通水冷却控温最佳时机

Research on Time Control for Water Cooling Lining Concrete of Hydraulic Tunnel

大坝混凝土通水冷却时机控制的成功经验,不能很好适用于薄壁衬砌结构控温控裂。以水工隧洞为例,采用有限元法仿真计算,深入分析衬砌混凝土内部最高温度、最大内表温差、最大拉应力、最小抗裂安全系数及温降速率等温控特征值与通水时间的关系。结果表明:通水冷却控温最佳时机是混凝土覆盖冷却水管开始通水、最大内表温差出现后瞬间终止。在白鹤滩水电站1#泄洪洞上平段144~145单元进行现场试验,并结合有限元法仿真,验证了其控温控裂的科学性和经济有效性,可供实际工程采用。

The successful experience of controlling the timing of water cooling for dam concrete cannot be well applied to temperature control and crack control of thin-walled lining structures.Taking the lining concrete of hydraulic tunnel as an example,the Finite Element Method was applied to study the relationship between the maximum inside temperature,the maximum inner surface temperature difference,the maximum tensile stress,the minimum crack resistance safety factor,the cooling rate and cooling time.The results indicate that the best time for water cooling and temperature control is when the concrete covers the cooling water pipe and the water starts to flow,and the maximum internal surface temperature difference occurs and ends immediately.Field tests were carried out in units 144-145 of the upper flat section of the 1#spillway tunnel of Baihetan Hydropower Station,and combined with Finite Element Method simulation,the scientific and economic effectiveness of temperature control and crack prevention was verified,which can be applied in practical engineering.