| 摘要: |
| 为研究冻融劣化混凝土动静态抗剪性能,进行了不同冻融循环次数(0次、10次、25次、35次、50次)后混凝土在不同法向应力下(0MPa、3MPa、6MPa、9MPa、12MPa)的压剪强度试验,混凝土强度等级为C30。研究分析了冻融循环次数和法向应力对混凝土剪切强度、峰值应变和粘聚力与摩擦系数的影响。研究结果表明：①随着冻融循环次数的增加,混凝土在相同法向应力状态下的剪切强度均逐渐降低,而且法向应力越大,剪切强度随冻融循环次数的增加而降低的程度越小；当冻融循环次数相同且法向应力不大于单轴抗压强度50％时,剪切强度随法向应力的增大而增大,且冻融劣化程度会影响该增幅效果；②在法向应力相同时,剪切峰值变形随冻融循环次数的增加呈线性增长趋势,对某一冻融循环次数,法向应力的存在增大了混凝土的剪切峰值变形；③摩擦系数和粘聚力都随冻融劣化程度的加深而降低,粘聚力大幅度降低是由于冻融劣化作用起主导作用所致；④在上述试验分析的基础上,基于八面体应力空间二次抛物线形式的压剪破坏准则,构建了平面应力状态下考虑冻融循环次数的混凝土压剪破坏准则。 |
| 关键词: 关 键 词：混凝土 冻融循环 法向应力 压剪状态 破坏准则 |
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| 基金项目:国家自然科学基金资助项目(51579139,51709155) |
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| Experimental study on mechanical properties and failure criterion of freeze-thaw deteriorated concrete under Compressive-shear Stress |
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SUN Bao1, WANG Qianfeng1, XU Tonglin2, HE Luxiang1
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1.Hubei Key Laboratory of Disaster Prevention and Mitigation China Three Gorges University;2.College of Civil Engineering ＆Architecture, China Three Gorges University
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| Abstract: |
| In order to study the dynamic and static shear properties of freeze-thaw deteriorated concrete, the compressive-shear strength tests of concrete are carried out under different normal stress (0MPa, 3MPa, 6MPa, 9MPa, 12MPa) after different freeze-thaw cycles (0, 10, 25, 35, 50 times), the concrete strength grade was C30. The effects of freeze-thaw cycles and normal stress on the shear strength, peak strain, cohesion and friction coefficient of concrete were studied. The results show that ①with the increase of freeze-thaw cycles, the shear strength of concrete decreases gradually under the same normal stress state. The greater the normal stress is, the smaller shear strength of concrete decreases degree with the increase of freeze-thaw cycles. When the number of freeze-thaw cycles is the same and the normal stress is less than 50％ of uniaxial compressive strength, the shear strength increases with the increase of normal stress, and the deterioration of freezing and thawing will affect the effect of this increase. ②When the normal stress is the same, the shear peak deformation increases linearly with the increase of freeze-thaw cycles. For a certain freeze-thaw cycle, the existence of normal stress increases the shear peak deformation of concrete. ③The coefficient of friction and cohesion decreased with the deepening of the deterioration degree of freeze-thaw, and the reduce of cohesion was due to the dominant effect of freezing and thawing deterioration. ④On the basis of the above experimental analysis, and based on the compression-shear failure criterion in the form of quadratic parabola in octahedron stress space, the compression shear failure criterion of concrete under plane stress state considering freeze-thaw cycle times is established. |
| Key words: concrete freeze-thaw cycle normal stress compression-shear state failure criterion |
