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Analysis of influences of humidity on stress deformation of thin-wall aqueduct
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摘要: 混凝土力学特性受湿度影响，且存在湿胀特性。混凝土薄壁渡槽与水接触面积大，输水时间长，故其内部湿度变化会影响自身性能。基于Fick第二定律建立湿度扩散模型，应用物理试验率定了饱和湿度扩散系数。考虑到混凝土弹性模量随湿度的变化和湿胀效应，建立渡槽湿度场和应力场分析模型，以研究分析渡槽槽壁湿度不同扩散深度对渡槽变形及内力性能的影响规律。结果表明，随着输水时间延长，槽壁内湿度扩散深度沿厚度方向呈非均匀分布。湿度扩散深度会影响渡槽变形和应力分布。随湿度扩散深度增加，渡槽纵向挠度有所增加，横向变形有所减小，横向效应大于纵向影响程度。湿度增加使渡槽槽壁内侧压应力增大，外侧拉应力增大，这有利于渡槽结构整体安全，但不利于外侧抗裂。Abstract: The mechanical properties of concrete are affected by the humidity, and the hydraulic concrete usually has the characteristics of wet expansion. Because of the large water contact area and long water conveyance time, the internal humidity change in the concrete thin-walled aqueduct will affect its working performance. Based on Fick's second law, a humidity diffusion model is established, and the concrete saturated humidity diffusion coefficient is calibrated by using a physical model. Considering the variation of concrete elastic modulus with humidity and the effects of the wet expansion, an analytical model of the humidity field and stress field of the aqueduct is established to analyze the influences of different diffusion depths of humidity along the aqueduct wall thickness on the deformation and internal force performance of the aqueduct. The analysis results show that with the increase of water transfer time, the diffusion depth is non-uniformly distributed along the wall thickness of the aqueduct, and the diffusion depth of the humidity will affect the deformation and stress distribution of the aqueduct. With the increase of the humidity diffusion depth of the aqueduct wall, the longitudinal deflection of the aqueduct increases, the transverse deformation decreases, and the transverse influence is greater than that of the longitudinal effect. The compressive stress on the inner side of the aqueduct wall increases and the outer tensile stress increases because of the increase in humidity. The humidity is favorable for the aqueduct structure safety, but it is unfavorable for the outer crack resistance.
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Key words:
- humidity /
- concrete /
- aqueduct /
- diffusion coefficient /
- deformation /
- internal force
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图 3 渡槽沿厚度方向相对湿度变化
Figure 3. Variation in relative humidity along wall thickness direction of aqueduct
图 6 跨中及端肋断面应力分布(单位：MPa)
Figure 6. Stress distribution of transverse section in mid-span and end bearing (unit: MPa)
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