通仓浇筑常态混凝土和碾压混凝土重力坝的劈头裂缝和底孔超冷问题  

Some Problems of Transverse Cracks and Extracooling of Bottom Outlet in Concrete Gravity Dams without Longitudinal Joint

作　　者：朱伯芳[1] 许平[1] 

机构地区：[1]中国水利水电科学研究院,北京100038

出　　处：《水利水电技术》1998年第10期14-18,共5页Water Resources and Hydropower Engineering

基　　金：国家攀登计划FB-1成果;中国三峡开发总公司资助;国家自然科学基金

摘　　要：不少重力坝在上游面产生了几十米深的严重劈头裂缝，首次指出这与通仓浇筑有密切关系，由于坝内没有纵缝，因而没有接缝灌浆前的二期水管冷却，水库蓄水时，坝内温度仍然很高，而水温较低，产生了较大的内外温差，使得在施工过程中上游面已出现的表面裂缝扩展成为深层劈头裂缝。目前，碾压混凝土重力坝的高度不大，似乎还没有报导过严重劈头裂缝，但碾压混凝土重力坝也是通仓浇筑的，没有二期水管冷却，今后随着坝高的增加，对碾压混凝土重力坝产生劈头裂缝的问题也应给予重视．对于通仓浇筑的常态混凝土重力坝和碾压混凝土重力坝，由于基础约束区域扩大，底孔超冷可能产生巨大的温度应力，并引起严重裂缝．为了防止裂缝，需要采取严格的温度控制措施．针对三峡大坝通仓浇筑方案，进行了详细的计算分析，计算结果证实了上述判断．Many severe transverse cracks had appeared on the upstream face of conventional concrete gravi-ty dams. It is pointed out in this paper that this is due to the fact that there is no longitudingal joints in thesedams and so there is no artifical pipe cooling for joint grouting. When the reservoir is filled, the temperature inthe dam body is still very high, but the temperature of the water is low and the temperature difference betweenthe upstream face and the interior of dam makes the existing superficial cracks extend to large cracks. There isno longitudinal joint in RCC gravity dams, so it is necessary to take precautions against the appearance of largetransverse cracks on the upstream face of high RCC gravity dams- Furthermore, it is pointed out in this paperthat the extracooling of the orifices in the conventional concrete gravity dams without longitudinal joint andRCC gravity dams may introduce severe tensile thermal stress and may promote the appearance of large cracksin the dam.

关 键 词：通仓浇筑 混凝土重力坝 劈头裂缝 底孔超冷 

分 类 号：TV544.7[水利工程—水利水电工程] TV642.3