层状组合结构轴拉条件下的裂缝饱和度分析与应用

Crack Saturation Analysis and Applications of Layered Composite Structures under Axial Tension Condition

基于裂缝扩展机理分析了裂缝扩展过程中的饱和现象,建立了层状组合结构的数值模型,分析了轴拉条件下裂缝中心区域的应力分布特征,论证了裂缝饱和度存在的客观性,探讨了荷载边界条件、材料参数与上覆压力对裂缝饱和度的影响,结合钢衬混凝土组合结构工程特性,研究了裂缝饱和度的基本规律。结果表明,轴向拉伸荷载边界条件不影响裂缝饱和度,裂缝层材料的弹性模量和泊松比越大,或相邻层材料的弹性模量和泊松比越小,裂缝饱和间距越大;上覆压力对裂缝饱和间距的影响较小。对于钢衬混凝土组合结构,轴拉条件下的裂缝饱和间距主要取决于外包混凝土厚度;布筋对钢衬混凝土组合结构的裂缝饱和度有显著影响,钢筋的埋入,相当于降低了混凝土裂缝层的有效厚度,可起到控制裂缝最大宽度的效果,建议将钢筋布置在混凝土层中部,以期增加潜在的裂缝条数,而不会出现宽度过大的裂缝。

Based on the theory of crack propagation,the saturation phenomenon in the process of crack propagation is discussed,and a numerical model of layered composite structure is established.Then the characteristics of stress distribution in the central zone between adjacent cracks are studied under axial tension condition,which contributes to demonstrating the existence of crack saturation.The effects of load boundary condition,material parameters and the overburden loading on the crack saturation are discussed.According to the practical engineering structures such as steel-lined concrete,the basic law of crack saturation is studied.The results show that the load boundary condition which is perpendicular to the direction of crack propagation does not affect the crack saturation.Moreover,the larger the elastic modulus and Poisson's ratio of the cracked layer material,or the less the elastic modulus and Poisson's ratio of the neighboring layers material,the greater the saturate spacing of cracks;Overburden pressure has little impact on the saturate spacing of cracks;For the steel-lined concrete composite structure,the crack saturated spacing depends mainly on the thickness of concrete layer;The reinforcement installment has a significant impact on the crack saturation of the steel-lined concrete composite structure;The embedding of rebar is equivalent to reducing the effective thickness of the concrete layer,achieving the effect on controlling the maximum crack width.Therefore,it is recommended that the rebar arranged in the middle of the concrete layer can increase the potential number of cracks,and the large width cracks will not appear.