白鹤滩水电站导流洞衬砌混凝土温控限裂技术研究
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摘要
温度裂缝严重影响水工衬砌结构的耐久性和安全性。白鹤滩水电站导流洞导流任务重、使用时间长、尾水段与尾水洞结合为永久结构。为限制温度裂缝,使用低热水泥、预冷混凝土、通水冷却、冬季挂帘等综合温控措施,使混凝土裂缝大幅减少。通过统计现场监测数据及裂缝特征,论证了温控措施的合理性,分析了裂缝的一般规律。利用有限元法分析裂缝影响因素的敏感性,结果表明,大量裂缝出现在冬季昼夜温差变化较大时;低温季节当气温变化幅度较小,选择自然入仓也能满足温控要求;断面尺寸越小、分仓长度越短、分期施工对限制混凝土裂缝有利;围岩越完整,约束作用越强,衬砌混凝土开裂风险越大。研究成果可为类似工程提供参考和借鉴。
Temperature cracks seriously affect the durability and safety of hydraulic lining structure.Diversion tunnel of Baihetan hydropower station has some characteristics,such as heavy task of diversion,long time use,and combination of tail water part with tailrace tunnel as permanent structure.To prevent temperature crack,some comprehensive measures for control of temperature including use of low thermal cement,precooling concrete,water cooling,winter hanging curtain were taken to reduce concrete crack substantially.Through analyzing the field-monitoring data and the crack characteristics,the rationality of the temperature control measures has been demonstrated and the law of the cracks is found.And then the finite element method was used to make sensitivity analysis of crack's influencing factors.The results show that most of cracks appear in winter especially when diurnal temperature varies greatly.In low temperature season,when the change of temperature is mall,the concrete placing can meet temperature control requirements.The section size is smaller,dividing length of concrete placing is shorter,separate pouring of side wall and top arch can make the more benefit for controlling the concrete crack.When the integrity of surrounding rock is better,the constraint of rock mass is stronger,the risk of concrete lining crack is greater.The results of this paper can provide reference for similar projects.
Temperature cracks seriously affect the durability and safety of hydraulic lining structure.Diversion tunnel of Baihetan hydropower station has some characteristics,such as heavy task of diversion,long time use,and combination of tail water part with tailrace tunnel as permanent structure.To prevent temperature crack,some comprehensive measures for control of temperature including use of low thermal cement,precooling concrete,water cooling,winter hanging curtain were taken to reduce concrete crack substantially.Through analyzing the field-monitoring data and the crack characteristics,the rationality of the temperature control measures has been demonstrated and the law of the cracks is found.And then the finite element method was used to make sensitivity analysis of crack's influencing factors.The results show that most of cracks appear in winter especially when diurnal temperature varies greatly.In low temperature season,when the change of temperature is mall,the concrete placing can meet temperature control requirements.The section size is smaller,dividing length of concrete placing is shorter,separate pouring of side wall and top arch can make the more benefit for controlling the concrete crack.When the integrity of surrounding rock is better,the constraint of rock mass is stronger,the risk of concrete lining crack is greater.The results of this paper can provide reference for similar projects.
引文
[1]邹开放,段亚辉.溪洛渡水电站导流洞衬砌混凝土夏季分期浇筑温控效果分析[J].水电能源科学,2013,31(3):90-93,138.
[2]施正友,曹周生,韦灿强,等.低热硅酸盐水泥在三峡工程大体积混凝土中的研究及应用[J].混凝土,2007(12):84-87.
[3]段寅,袁葳,岳朝俊.低热水泥混凝土温控特性及在地下工程适用性研究[C]//第24届全国结构工程学术会议论文集(第Ⅱ册).北京:2015:560-563.
[4]樊启祥,段亚辉.水工隧洞衬砌混凝土温控防裂技术创新与实践[M].北京:中国水利水电出版社,2015.
[2]施正友,曹周生,韦灿强,等.低热硅酸盐水泥在三峡工程大体积混凝土中的研究及应用[J].混凝土,2007(12):84-87.
[3]段寅,袁葳,岳朝俊.低热水泥混凝土温控特性及在地下工程适用性研究[C]//第24届全国结构工程学术会议论文集(第Ⅱ册).北京:2015:560-563.
[4]樊启祥,段亚辉.水工隧洞衬砌混凝土温控防裂技术创新与实践[M].北京:中国水利水电出版社,2015.