【作者】 王敏；

【导师】 王应军； 孙明清；

【作者基本信息】 武汉理工大学 ， 固体力学， 2015， 硕士

【摘要】 聚乙烯醇(PVA)—应变硬化水泥基复合材料(简称SHCC)是目前发展迅速的一种超高延性纤维增强水泥基复合材料,通过在特制水泥砂浆中掺入一定量的PVA纤维制成,在承受拉伸荷载时,表现出多缝稳定开裂和应变硬化特征,从而在许多发达国家的不同领域已经得到了工程应用,但却鲜有SHCC管道方面的研究。本课题在国家863计划——《多基结构材料复合技术及在高压管制造中的应用》(2013AA031306)项目资助下开展SHCC管道的相关研究。本文通过实验手段研究SHCC管道在平压荷载作用下的应变、位移以及裂纹的变化;再通过理论计算SHCC管道的极限承载力及其影响因素,并对SHCC管刚度进行探讨。主要工作如下:(1)开展了SHCC单轴拉伸实验和三支承下的SHCC管平压试验,研究表明,SHCC材料与管环的失效过程大致分为:弹性阶段、开裂阶段、强化阶段和破坏阶段等,在SHCC管底、管腰和管顶等观察到多条细裂纹,与内径相同的普通混凝土管相比,SHCC具有厚度更薄以及承载力更高的优势;(2)建立了SHCC管道平压状态下的力学分析模型,分别以最大压应变和最大弯矩为控制参量计算得出SHCC管的极限承载力,并与测试结果进行了比较,讨论了结构几何尺寸以及材料力学参数对结果的影响,研究表明以最大压应变为控制参数计算极限承载力能较准确的得到SHCC管的极限承载力,此方法中SHCC受压时的极限弹性应变对结果影响最大;以最大截面弯矩为控制参数计算极限承载力时能较准确的反映出SHCC管平压试验的过程,此方法中SHCC的极限拉伸强度对结果影响最大;(3)基于国内外结构管刚柔性的相关理论分析了SHCC管刚度,结果表明:SHCC管在进入开裂阶段后直至最终破坏,其刚度随着管顶荷载的增加,明显下降;本文围绕SHCC管研究展开,对发展新型抗裂混凝土管道将起到推动作用。更多还原

【Abstract】 As one of the most developing Fiber Reinforced Concrete,Polyvinyl AlcoholStrain Hardening Cement-based Composites(PVA-SHCC or SHCC for short) is a new type of concrete. By mixing the PVA fibers,flyash,and quartz into cement-based concrete,the toughness of the SHCC could be improved significantly. When bearing the tensile load,SHCC showed the features of multi-cracking and strain hardening. A increasing number of developed countries had used this new material in projects,but there is few research focus on the SHCC pipe. This paper made some research on SHCC pipe based under the support of National 863 Plan(2013AA031306).Focused on problems in the application of the SHCC pipe,this paper analyzed the strain,deflection and cracking behavior of the SHCC pipe under the flat load based on lots of experiments. Furthermore,the ultimate bearing capacity and stiffness of the SHCC pipe have been discussed. The contributions are showed as follows:(1) Based on the uniaxial tensile test and flat crushing test,the failure process of the SHCC could be divided into 4 stages:elastic stage,cracking stage,strengthening stage and failure stage. This paper analyzed the test result of each stage and concluded that:comparing to the common cement-based concrete pipe,the SHCC pipe has the advantages of thiner wall,lighter mass and higher strength.(2) This paper built a new mechanical model for SHCC pipe under the condition of flat crushing. Based on the theories of the maximum compressive strain and maximum moment,the ultimate load bearing capacity of the SHCC has been calculated and analyzed by each theory. Moreover, we discussed the advantages and disadvantages for both theories.(3) The analysis for the stiffness of the SHCC pipe under the conditioni of flat crushing showed: the stiffness of the SHCC pipe was changing from the cracking stage,and with the increasement of the flat crushing load,the changing trend was becoming faster.All contributions proposed in this paper was centred on the SHCC pipe. And,to some extent,the conclusions improved the basic theory of the SHCC and may promote the application of the SHCC pipe.更多还原