重力坝常态混凝土垫层裂缝成因分析

Analysis on Crack Mechanism for Normal Concrete of Bedding Cushion in Gravity Dam

混凝土大坝垫层一般坐落在基岩上,且长厚比很大,施工期开裂很常见.针对单个浇筑块长度40m、层厚2.0m的重力坝垫层混凝土的施工期开裂现象,采用混凝土温度场和应力场的仿真计算方法,考虑水管冷却和表面保温措施,对实际施工过程进行模拟.结果表明,在两个缺陷槽之间的垫层厚度最薄,并受到薄层长间歇、基岩约束大、廊道附近应力集中、局部表面流水等因素的不利影响,导致廊道附近垫层易裂.

Bedding cushion in concrete dam is often located on rock base, and its length to thickness ratio is large. So it is common to crack during construction period. Aim at the crack phenomenon happened to the sin- gle concrete blocks with 40.0m long and 2.0m thick of bedding cushion in gravity dam during construction pe- riod, the actual construction process is simulated based on the method of simulation calculation of temperature field and stress field considering water cooling pipes and surface heat preservation measures. The result shows that around the gallery of bedding cushion, due to some adverse factors such as the thinnest part of defects slot, thin pouring layer and long interval pouring, large bedrock constrains, stress concentration around the gallery, local surface flowing and so on, it is easy to crack.