某水利枢纽工程纵向围堰坝段混凝土温控防裂要点研究

Study on key temperature control and anti-cracking points for concrete longitudinal cofferdam section of a water control project

水利枢纽工程中,纵向围堰坝段作为永久性挡水建筑物,两个侧面分别具有提前挡水和长期暴露的特点,开裂风险较大,需要有针对性的防裂措施。以某水利枢纽工程混凝土纵向围堰坝段为例,采用有限元仿真的分析方法,就其过流面、暴露面温控防裂要点进行重点分析。结果表明:无温控措施时,侧面最大应力达2. 82 MPa,安全系数仅为0. 59;设置纵缝及24℃中期冷却后,过流面、暴露面最大应力分别为1. 22 MPa、1. 18 MPa,安全系数分别为1. 37、1. 41;进一步对过流侧进行25. 00 m高程以下堆渣、对暴露侧进行保温后,过流面、暴露面最大应力分别降低为0. 85 MPa、0. 71MPa,安全系数分别提高到1. 96、2. 35,均满足1. 65的设计标准。因此,对于提前过流侧面的针对性防裂措施为,设置纵缝、过流侧过流前中期冷却及堆渣;暴露面一侧由于长期暴露,易遭遇寒潮影响,其主要防裂措施为,设置纵缝、中期冷却及保温。

Taking the longitudinal cofferdam section of a water control project as the study case, the key temperature control and anti-cracking points of its overflow surface and exposed surface are analyzed with the method of finite element simulation analysis. The result shows that the maximum lateral stress is 2.82 MPa and the safety factor is only 0.59 when no any temperature control measures are adopted. After arranging longitudinal joint and making the mid-term cooling at 24 ℃, the maximum stresses of both the overflow surface and the exposed surface are 1.22 MPa and 1.18 MPa, while the safety factors are 1.37 and 1.41 respectively. After slag-piling made for the overflow side below the elevation of 25.00 m and the insulation made for the exposed side, the maximum stresses of both the overflow surface and the exposed surface are lowered to 0.85 MPa and 0.71 MPa respectively, while the safety factors are enhanced to 1.96 and 2.35 respectively as well, and then all of them meet the design standard of 1.65. Therefore, the targeting anti-cracking measures for the in-advanced overflow side are the arrangement of longitudinal joint, mid-term cooling and slag-piling before the overflow of the overflow side, while the main anti-cracking measures for the side of the exposed surface are the arrangement of longitudinal joint, mid-term cooling and insulation due to the long-term exposure and being prone to be impacted by cold-wave.