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将应变计组实测应变转换为应力与混凝土的应力状态有关。针对高混凝土坝应力作用水平较高,当混凝土的应力超过一定的限度,混凝土将进入塑性徐变阶段,如果仍基于弹性徐变体的应力-应变关系进行实测应变的应力转换,获得的应力与实际情况不符。该文假设混凝土在高应力作用下将产生塑性流动,根据P.Perzyna假设计算黏塑性应变率,首先推导了最大拉应力屈服准则和Hsieh-Ting-Chen屈服准则的黏塑性应变率计算公式,接着推导了考虑塑性徐变的实测应变转换应力的计算公式,进而探讨了考虑塑性徐变的高混凝土坝实测应变转换为应力。实例分析表明:由于将实测应变转换为应力采用增量法进行计算,在转换过程中,某阶段的应力失真,必然导致后续转换应力的真实性,而考虑塑性徐变的实测应变转换的应力更符合实际情况。
The strain gauge strain measured is converted to stress and stress state of concrete. For high concrete dam high level of stress, when the concrete stress exceeds a certain limit, the concrete will enter the stage of plastic creep, if still based on the stress-strain relationship of elastic creep strain measured stress conversion, the obtained stress and The actual situation does not match. This paper assumes that concrete will produce plastic flow under high stress. According to the P.Perzyna assumption, the formula of maximum tensile stress yield and visco-plastic strain rate of Hsieh-Ting-Chen yield criterion are deduced. The calculation formula of the measured strain transformation stress is deduced considering the plastic creep, and then the measured strain of high concrete dams considering the plastic creep is converted into stress. The case study shows that the stress distortion in a certain stage during the conversion process will inevitably lead to the authenticity of the subsequent transformation stress because of converting the measured strain into stress. In line with the actual situation.