淮河入海水道二河新建水闸混凝土温控防裂研究

Study on concrete temperature control and crack prevention of Erhe new sluice on Huai River canal diverting flood into see

针对新建水闸闸墩混凝土早期易出现竖向"上不着顶,下不着底"的裂缝问题,用三维有限元仿真计算法,对该水闸施工期混凝土的温度场和应力场进行了多方案的计算分析,其中包括施工过程仿真、温控措施仿真、环境条件仿真、施工方案比较等,以揭示了这类裂缝产生的机理。建议混凝土底板与1m高闸墩底部混凝土同时浇筑,改善闸墩变形约束条件,降低底板强约束区部位闸墩拉应力,以不出现裂缝。工程实践表明,这一建议是正确的。此外,对第V联中墩内埋冷却水管的温度削峰效果也进行了模拟计算,给出了这种冷却措施的效果和特点。

<Abstrcat>Concerning the common phenomenon that there often exist the vertical cracks in new sluice piers at early-age concrete, which are almost vertical and could not propagate to the top or the bottom of the piers, with the simulative technique of 3-D finite element method the authors did the analysis of the thermal and stress results from a few of calculation cases about Erhe Sluice, which is new built and located on the Huai-River canal diverting flood into see. In the numerical simulation the concrete construction process, engineer measures for thermal control, environmental conditions, and different construction schemes were taken into account. From the comprehensive analysis the cracking mechanism is cleared, some correct measures for cracking prevention were suggested and the project is totally not cracked during the construction and the operation up to now over 2 years. The main measure is the 1-meter high bottom segment of the piers was constructed just directly after the concreting of the bottom slab of the sluice in order to eliminate the deformation restrain between the piers and their bottom slabs and to reduce the tension stresses. In addition, in the pier No.5 the embedment of two water-cooling pipes were suggested to reduce the highest temperature in the pier and the effectiveness of the two pipes were numerical simulated and the results of temperature from the strict numerical calculation and the in-situ measurement are fitted very well. The measure of water-pipe cooling should also be a very good alternative solution to preventing from cracking.