锚筋与混凝土粘结锚固问题的数值模拟研究

发布时间：2018-07-12 21:52

本文选题：锚筋 + 粘结材料　；参考：《中国海洋大学》2015年硕士论文

【摘要】：锚固技术是通过埋设在土层中或岩石中的锚杆,将结构物与地层紧紧地锁在一起,依赖锚杆与周围地层的剪应力传递结构的拉力或使地层自身得到加固,以保持结构物和岩体的稳定。在岩体工程中采用锚固技术,能够提高岩体自身的强度和稳定性、节约工程材料、缩小结构物的尺寸和减轻构件自重。锚固技术已经成为提高岩体工程稳定性和解决复杂的岩体工程问题的有效方法之一。随着锚固技术在岩土工程领域的推广和应用,考虑到问题的相似性,广大工程技术人员将岩土工程锚固技术应用到混凝土结构中,从而使得混凝土后锚固技术得到了广泛的应用。本文采用数值模拟的分析方法研究锚筋、砂浆、混凝土三相介质界面粘结问题。利用ANSYS有限元计算软件,对由锚筋、粘结材料、混凝土三种材料组成的复合体以及复合体中不同材料间的界面选取并使用合适的力学模型进行计算分析。本文选取了一系列不同粘结界面本构关系、粘结层厚度和混凝土外围尺寸的模型进行计算,研究这些因素对锚固体系统起裂荷载、极限荷载、粘结应力分布的影响,并与已有的解析结果进行对比分析。主要研究成果如下：(1)基于ANSYS有限元软件建立了一种由界面粘结滑移破坏控制的锚筋-砂浆-混凝土三相介质锚固体中的极限抗拔力。通过对算例的计算结果分析表明,本文所建立的模型能够比较准确的反应锚固系统的受力特性。(2)通过控制模型几何尺寸相同的情况下,根据第一组算例改变锚固系统中粘结界面的本构关系,通过计算结果表明,锚固系统起裂荷载的大小随粘结界面剪切刚度的增大而降低,极限荷载、临界裂缝长度的大小随界面断裂能的增大而增加。(3)通过控制粘结界面本构关系相同的情况下,根据第二组算例即保持锚杆直径与混凝土外围尺寸不变,变化开孔直径(或粘结层厚度),通过计算结果表明,锚固系统的起裂荷载随粘结层厚度的增加略有降低,极限荷载基本不变。(4)通过控制粘结界面本构关系相同的情况下,根据第三组算例即保持锚杆直径与粘结层厚度不变,变化混凝土外围尺寸,通过计算结果表明,起裂荷载与极限荷载均保持不变。(5)将数值模拟分析计算的结果与以往解析模型计算时仅将砂浆层作为剪滞模型的结果进行比较分析,通过计算结果表明,中间粘结层是存在轴向应力的,解析结果与数值模拟结果当粘结界面的剪切刚度比较大时起裂荷载差距较大,当断裂能比较小时极限荷载差距较大,其中产生的差异是由粘结层的轴向变形引起的,由此说明以往提出的解析计算方法在界面剪切刚度较小且断裂能较大时才对起裂荷载以及极限荷载均适用。
[Abstract]:The anchoring technology is to lock the structure and the stratum tightly together by the anchor rod embedded in the soil layer or rock, depending on the tensile force of the shear stress transfer structure between the anchor rod and the surrounding strata or to strengthen the stratum itself. To maintain the stability of the structure and rock mass. Anchorage technology used in rock mass engineering can improve the strength and stability of rock mass, save engineering materials, reduce the size of structure and reduce the weight of components. Anchorage technology has become one of the effective methods to improve the stability of rock mass engineering and solve complex rock engineering problems. With the popularization and application of anchoring technology in geotechnical engineering field, considering the similarity of the problems, geotechnical engineering anchoring technology is applied to concrete structure. As a result, the post-anchoring technology of concrete has been widely used. In this paper, the interfacial bond problem of anchor bar, mortar and concrete three-phase medium is studied by numerical simulation. The finite element analysis software ANSYS is used to calculate and analyze the interface of the composite composed of anchor bar, bond material and concrete, and the interface between different materials in the composite, and the appropriate mechanical model is used to calculate and analyze it. In this paper, a series of models of different bond interface constitutive relations, thickness of bond layer and external size of concrete are selected to calculate the effects of these factors on the initial crack load, ultimate load and bond stress distribution of Anchorage system. The results are compared with the existing analytical results. The main research results are as follows: (1) based on ANSYS finite element software, a kind of ultimate pull-out force in the anchor bar, mortar and concrete three-phase medium Anchorage body controlled by interfacial bond-slip failure is established. The results of numerical examples show that the model established in this paper can accurately respond to the mechanical characteristics of the anchoring system. (2) by controlling the model with the same geometric size, According to the first set of examples, the constitutive relation of the bond interface in the Anchorage system is changed. The calculation results show that the initial crack load of the anchoring system decreases with the increase of the shear stiffness of the bond interface, and the ultimate load is limited. The critical crack length increases with the increase of the interface fracture energy. (3) by controlling the bond interface constitutive relation is the same, according to the second set of examples, the diameter of the anchor rod and the external size of the concrete are kept unchanged. The calculated results show that the initial crack load of the anchoring system decreases slightly with the increase of the thickness of the bond layer, and the ultimate load is basically unchanged. (4) under the same constitutive relation of the bond interface, the initial load of the anchoring system decreases slightly with the increase of the thickness of the bond layer. According to the third group of examples, the diameter of anchor rod and the thickness of bond layer are kept constant, and the outer size of concrete is changed. The calculation results show that, The initial crack load and ultimate load remain unchanged. (5) the results of numerical simulation and calculation are compared with those of the previous analytical model only when the mortar layer is used as the shear lag model. There is axial stress in the intermediate bond layer. The analytical results and numerical simulation results show that the gap of initial crack load is larger when the shear stiffness of the bond interface is large, and the limit load difference is larger when the fracture energy is small. The difference is caused by the axial deformation of the bond layer, which shows that the analytical calculation method proposed in the past is suitable for both the initiation load and the ultimate load when the interface shear stiffness is small and the fracture energy is large.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU37

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