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Analysis of transition from measured strain to stress of concrete dams considering temperature effects
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摘要: 由于混凝土各项性能和水泥水化反应密切相关，因此混凝土热学和力学性能的发展不仅与龄期有关，还与自身温度和温度历程有关，而传统混凝土坝实测应变转换应力计算理论中尚未考虑温度历程的影响，这导致转换获得的拉应力并非真实应力。基于等效龄期理论与变形法基本原理，推导了考虑温度历程的实测应变转换应力公式，并给出了考虑温度历程的实测应变转换应力计算步骤；结合西北地区典型混凝土坝对比分析了考虑温度历程及不考虑温度历程的转换应力，分析表明，西北寒冷地区的典型混凝土坝温度范围为6.4~37.0 ℃，考虑温度历程的拉应力与不考虑温度历程的最大差值为0.49 MPa，且差值峰值出现在早龄期，此时混凝土强度尚未充分发展，若不考虑温度历程影响，则无法进行准确的安全评价。Abstract: Since the performance of concrete is closely related to the cement hydration reaction, the development of the thermal and mechanical properties of concrete is not only related to the age, but also associated with its temperature and temperature history. The influences of the temperature history on the transition from the measured strain to stress are not considered in the traditional theories, which results in an unreal calculated stress. In this paper, the transitional formula from the measured strain to stress in consideration of the temperature process is deduced based on the theory of equivalent age and a deformation method, and the calculation steps are also designed. Based on a typical concrete dam project located in the northwest region, the applicability of the algorithm in this study is verified. Analysis results show that the temperature range is from 6.4 ℃ to 37.0 ℃ in the northwest typical concrete dams, The maximum stress difference is 0.049 MPa whether considering the influences of temperature, so the influences of temperature should not be neglected in this situation. The peak value of the stress differences appears in the early age, and the concrete strength has not yet fully developed at this time. Without considering the influences of the temperature history, an accurate safety assessment can not be carried out for concrete dams.
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Key words:
- concrete dam /
- measured strain /
- temperature process /
- equivalent age /
- stress evaluation
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图 2 实测温度与标准养护温度对比
Figure 2. The contrast of measured temperature and the standard curing temperature
图 3 考虑温度影响和不考虑温度影响下的应力对比分析
Figure 3. Comparison of stress with and without considering of temperature effect
表 1 混凝土材料配合比
Table 1. Proportion of concrete material
强度等级 级配 水胶比 水泥/
(kg·m-3)水量/
(kg·m-3)粉煤灰/
(kg·m-3)砂/
(kg·m-3)粗骨料/
(kg·m-3)减水剂 引气剂 大石 中石 小石 R18020 三 0.53 65 90 105 578 449 599 449 1.528 0.102 
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