【作者】 罗业雄；

【导师】 尚守平；

【作者基本信息】 湖南大学 ， 结构工程， 2010， 硕士

【摘要】 无机植筋胶是一种以高性能水泥为主要原料添加一定比例的矿物外加剂拌合而成的具有高强度,微膨胀等特性的无机混合物,能在基础加固等有地下水或潮湿环境下使用,具有很好的耐久性、耐火性和经济性等特点。在砌体加固中,高性能复合砂浆薄层钢筋网条带加固是一种经济、有效、应用范围广的加固方法,采用无机植筋代替传统的穿墙拉结筋能很好的解决单面加固,施工复杂等一系列问题,但是以往的研究主要集中在混凝土中的植筋,并没有在砌体中植筋方面的研究。因此本文对无机植筋在砌体中的抗拔和抗剪性能进行了试验研究,主要工作如下：(1)在传统的无机植筋胶的基础上提出一种新型的无机植筋胶,在以水泥和超细掺和料等为主要原料的无机植筋胶中掺入超细石英砂,形成良好级配的三元混合料,并通过材性试验和在混凝土中的拉拔试验验证了此种无机植筋胶的可靠性。(2)对不同砂浆强度等级的砌体进行了不同植筋深度的植筋拉拔试验,砌体植筋拉拔试验的主要破坏形式为锥体破坏,随着植筋深度的增加抗拔承载力也逐渐提高。施工工艺是保证砌体植筋质量的关键,植筋之前需对砌体进行充分浇水湿润,直到砌体表面没有明显的水析出。(3)对16个剪切试件进行砌体-复合砂浆粘结面抗剪试验,试验结果表明,植筋能显著提高粘结面的抗剪强度,并且随植筋面积增加抗剪强度也随之提高,最大提高幅度为38.5%；植筋深度是影响抗剪强度和破坏形式的另一个主要因素,砌体抗剪植筋最小植筋深度应取10d；由于砌体的材料特性和施工可操作性问题,界面剂对抗剪强度有负面影响,因此用水泥复合砂浆加固砌体结构时可不使用界面剂。(4)应用大型有限元软件ANSYS对试件进行非线性模拟分析,考虑粘结面滑移理论和销钉作用,得到了植筋试件和对比试件在粘结面的应力分布和复合砂浆层的裂缝分布,与试验结果十分吻合；剪切销钉的存在使得粘结面应力重分布,约束了粘结面的滑移,从而到达提高粘结面极限抗剪承载力的效果。(5)在Mattock的钢筋抗剪强度理论的基础上,对试验结果进行拟合得到砌体-复合砂浆粘结面抗剪强度公式,与试验结果吻合良好。并在试验和理论计算的基础上提出了砌体中剪切销钉的构造要求。更多还原

【Abstract】 Inorganic embedded adhesive is a kind of compounds with high strength、micro-expansion and other characteristics, including major material-high performance cement and certain percentage of mixing mineral additives. Inorganic embedded adhesive can be used in the foundation strengthening where the water exists and other humid environment, and is provided with better durability, fire resistance and economy and so on. In the masonry strengthening, strengthening with High Performance Ferrocement Laminate is an economic, effective method with wide application. In this method inorganic embedded, instead of the traditional link bar which penetrates the masonry wall, can solve the anchoring problem of single plane strengthening of masonry wall and complex construction. Previous study has focused on embedded in the concrete, but there is no study about embedded in the masonry. In this article the experimental study about pull-out and shear properties in the masonry is taken, mainly the following:(1) A new inorganic embedded adhesive mix is proposed based on the traditional inorganic embedded adhesive which is mainly composed by high performance cement and superfine mineral additives. A kind of superfine quartz sand is taken into the new adhesive, and forms a ternary mixture of good grading in the size. The inorganic embedded adhesive is proved to be reliable by material test and pull-out experiment in the concrete.(2) The strength levels of masonry mortar and the depth of the anchorage are considered in the pull-out test. The major form of damage in the pull-out test is cone damage of the masonry, and the tensile strength of specimen increases gradually with the addition of depth of the anchorage. Construction process is critical to ensure the quality of anchorage in the masonry, so it is needed to wet the masonry before anchoring of the masonry, but in the surface of the masonry water isn’t allowed apparently.(3) 16 shear specimens including embedded bar parameter through the masonry-mortar bonding surface、different embedded depth and the method of interface finishing are tested in the paper. Test results indicate that there is an independent increase between the area of embedded bar and the shear strength, and the maximum increase rate of the shear strength is 38.5%. Depth of the anchorage is also the main factor to affect the shear strength and failure mode, and when the bar bears the shear stress, the minimum anchorage depth of masonry shall be taken by 10d. Because of the material properties of masonry and feasibility issues of construction, interface agents have a negative impact on the shear strength, so it is suggested that interface agents should not be used in masonry strengthening.(4) The finite element software-ANSYS is applied to simulate the properties of the shear specimens, and the slip between the masonry and the composite mortar and the pin are considered in the analysis. The results of the stress distribution and the crack distribution of composite mortar layer for embedded specimen and no-embedded specimen agree well with the experimental results. The stress of bonding surface is redistubited because of the pin, which also restricts the slip of the bonding surface, and increases the ultimate shear capacity.(5) Based on the shear strength of reinforced of Mattock, the formula of the shear strength of brick-mortar bonding surface is fitted by the experimental results and analysis, and is well agreed with the experimental dates. The construction requirements are proposed in the masonry in view of experimental and theoretical calculation.更多还原