料石砌体基本力学性能研究

发布时间：2018-01-20 17:24

本文关键词： 料石砌体抗压承载力抗剪承载力破坏形态力学分析有限元分析　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：在我国东南沿海地区,料石砌体依然应用广泛。但是现有的料石砌体结构存在严重的安全隐患。针对该地区料石砌体结构的特点,本文开展了料石砌体抗压承载力和抗剪承载力试验,并结合力学分析和有限元分析,三者相互对比、相互印证,为料石砌体结构的应用提供了依据。本文通过7组(共21个)试件的抗压试验,研究了料石砌体在竖向荷载作用下的破坏过程及砂浆强度、灰缝厚度对料石砌体抗压承载力的影响。试验结果表明：其破坏过程主要分为三个阶段,弹性阶段、裂缝开展阶段和破坏阶段,为脆性破坏,粗料石砌体的脆性破坏更加明显；其抗压承载力很高,随着砂浆强度的提高而提高,随着灰缝厚度的增加而降低,细料石砌体抗压承载力的离散性小于粗料石砌体。通过力学分析得：因料石和砂浆材料性能的差异,在竖向荷载作用下,料石水平向受拉、砂浆水平向受压,它们的水平向应力主要受砂浆强度、料石和砂浆厚度比的影响。在此基础上提出了粗细料石统一的抗压承载力计算公式,综合考虑了砂浆强度、料石强度、料石和砂浆厚度比的影响,较真实地反映了料石砌体抗压承载力与砂浆水平向应力的关系,可供规范修订参考。通过有限元分析得到了料石砌体在竖向荷载作用下的应力云图,在竖向灰缝与上下两皮料石的连接处,存在应力集中现象,与试验过程中试件该部位首先开裂相吻合：料石和砂浆的水平力大小、方向及其影响因素,与力学分析得到的结果基本一致。本文开展了6组(共18个)试件的抗剪试验,利用液压伺服系统(MTS)加载,直接得到了粘结强度和摩擦强度。试验结果表明：当试件发生剪摩破坏时,其破坏过程主要分为三个阶段,弹性阶段,粘结力消失阶段和摩擦耗能阶段；其粘结强度随着砂浆强度的提高而提高,摩擦强度随着竖向压应力的提高而提高。充分考虑它们离散性的差异,本文提出了抗剪强度标准值和设计值的计算公式。结合试验结果、力学分析和有限元分析得到：随着轴压比的增大,料石砌体的破坏部位依次为料石和砂浆的粘结面、砂浆、料石,其破坏形态依次为剪摩破坏、剪压破坏和斜压破坏。通过力学分析得到了在剪压复合作用下,料石和砂浆的三个主应力大小和方向,并分析其变化。在此基础上提出了一种新的剪压相关曲线理论：变粘结强度法,使得该曲线在剪摩破坏和剪压破坏交点处光滑,用数学方法证明了其正确性。通过有限元分析得到了在不同轴压比下砂浆和料石各自的应力云图,与力学分析相对比,相互验证了其合理性。
[Abstract]:In southeast coastal areas of China, stone masonry is still widely used. However, the existing masonry structure has serious safety risks. In view of the characteristics of the masonry structure in this area. In this paper, the compressive bearing capacity and shear bearing capacity of stone masonry are tested, and combined with mechanical analysis and finite element analysis, the three are compared with each other to verify each other. In this paper, the failure process and mortar strength of stone masonry under vertical load are studied through compressive tests of 7 groups (21 specimens). The test results show that the failure process is divided into three stages, elastic stage, crack development stage and failure stage, which is brittle failure. The brittleness failure of coarse stone masonry is more obvious. Its compressive capacity is very high, which increases with the increase of mortar strength and decreases with the increase of ash seam thickness. The discreteness of compressive bearing capacity of fine stone masonry is smaller than that of coarse stone masonry. Through mechanical analysis, it is concluded that under vertical load, stone is pulled horizontally and mortar is compressed horizontally because of the difference of material properties between stone and mortar. Their horizontal stresses are mainly affected by mortar strength, the ratio of aggregate to mortar thickness. On this basis, a unified formula for calculating the compressive capacity of coarse and fine materials is proposed, which considers the strength of mortar and the strength of aggregate and stone. The effect of the thickness ratio of aggregate to mortar reflects the relationship between the compressive capacity of masonry and the horizontal stress of mortar. Through the finite element analysis, the stress cloud diagram of stone masonry under vertical load is obtained. The stress concentration phenomenon exists in the joint of vertical gray joint and upper and lower leather stone. It is consistent with the first crack of the specimen during the test: the horizontal force, direction and influencing factors of the aggregate and mortar. In this paper, the shear tests of 6 groups (18 groups) of specimens are carried out and loaded with hydraulic servo system (MTS). The bond strength and friction strength are obtained directly. The experimental results show that the failure process is divided into three stages: elastic stage, adhesive disappearance stage and friction energy dissipation stage when the specimen is subjected to shear and friction failure. The bond strength increases with the increase of mortar strength, and the friction strength increases with the increase of vertical compressive stress. In this paper, the calculation formulas of the standard value and design value of shear strength are put forward. Combined with the test results, the mechanical analysis and finite element analysis show that: with the increase of axial compression ratio. The failure position of masonry is the bond surface of aggregate and mortar, mortar and aggregate in turn, and the failure modes are shear friction failure, shear compression failure and baroclinic failure in turn. Through mechanical analysis, the composite action of shear and compression is obtained. On the basis of the analysis of the three principal stresses and directions of aggregate and mortar, a new theory of shear compression curve is proposed: variable bond strength method. The curve is smooth at the intersection of shear failure and shear-compression failure, which is proved to be correct by mathematical method. The stress cloud diagram of mortar and stone under different axial compression ratio is obtained by finite element analysis. Compared with the mechanical analysis, the rationality of the method is verified.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU522.3

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