再生骨料及废弃纤维的分布模型研究
发布时间：2019-06-14 17:08
【摘要】：以数值方法模拟混凝土试件的承载力、裂缝扩展过程及破坏形态的细观力学方法已经发展起来,更为直观地反映试件从内部损伤到宏观破坏的机理。作为贯彻可持续发展战略的典型材料：再生混凝土、废弃纤维再生混凝土,从细观角度研究其自身性能是一项前景可观的研究课题。基于此,本文从细观角度研究再生骨料及废弃纤维分布情况对基体混凝土作用机理及力学性能的影响,分别建立了再生骨料分布模型及废弃纤维分布模型。对于再生骨料分布模型,取再生骨料取代率为50%的C30再生混凝土,利用CAD建立20个不同的二维再生混凝土细观骨料分布模型,导入ABAQUS对其进行单轴拉伸数值模拟,定义再生骨料分布均匀性系数α,得到α对再生混凝土单轴受拉性能的影响；对于废弃纤维分布模型,取再生骨料取代率为50%的C30基体再生混凝土,加入体积取代率为0.12%,长度为15mm的废弃聚丙烯纤维,在ABAQUS中建立14个二维废弃纤维再生混凝土分布模型,对其进行单轴拉伸数值试验,定义三个废弃纤维分布系数：分布均匀性系数β、分布聚拢性系数γ、分布角度系数λ,得出β、γ、λ对废弃纤维再生混凝土性能的影响规律。本文主要成果及结论如下：(1)笔者建立的再生骨料及废弃纤维分布模型是首次从细观角度研究再生骨料及废弃纤维的分布情况对基体混凝土抗拉性能的影响,模拟所得结论与现有试验数据或理论相一致,证明该模拟方法具有实际适用性,为进一步完善相关理论提出了新的思路和方向。(2)不同a的再生混凝土受拉开裂作用机理相同：裂缝始于界面,进而向砂浆扩展、延伸,α仅影响裂缝位置及裂缝穿过再生骨料的数量。但再生混凝土抗拉强度及变形能力随着α的改变而呈规律性变化：当再生骨料分布均匀性适中,即α∈[0.338,0.483]时,抗拉强度较高,受拉应力—应变曲线分为弹性阶段、塑性阶段、陡峭下降段、平缓下降段,曲线更为饱满,变形能力更好；当再生骨料分布过于均匀或分散,即a0.338或a0.483时,抗拉强度较低,受拉应力—应变曲线有缺失或不饱满,极限拉应变较小,变形能力较差。(4)不论废弃纤维分布如何,即不论β、γ、λ取何值,废弃纤维再生混凝土受拉开裂作用机理相同：裂缝始于基体混凝土,纤维在裂缝开展过程中起到阻裂作用。但废弃纤维再生混凝土抗拉强度及变形能力随着β、γ、λ的改变而呈规律性变化：抗拉强度随着λ的增大而减小且影响显著,而β及γ对其影响微小,且随着β及γ的增大,抗拉强度平缓减小,即纤维分布越离散、纤维抱团情况越显著,抗拉强度越小；且峰值拉应变随着β、γ的减小而增大,即废弃纤维根数及间距分布越均匀废弃纤维再生混凝土变形能力越好,但λ对受拉峰值应变几乎无影响。
[Abstract]:The meso-mechanical method for simulating the bearing capacity, crack propagation process and failure form of concrete specimens by numerical method has been developed, which can more intuitively reflect the mechanism from internal damage to macroscopic failure of concrete specimens. As a typical material to carry out the sustainable development strategy: recycled concrete and waste fiber recycled concrete, it is a promising research topic to study their own properties from a mesoscopic point of view. Based on this, the effects of recycled aggregate and waste fiber distribution on the action mechanism and mechanical properties of matrix concrete are studied from a meso-point of view, and the recycled aggregate distribution model and waste fiber distribution model are established respectively. For the recycled aggregate distribution model, 20 different two-dimensional recycled concrete meso-aggregate distribution models are established by using CAD to replace C30 recycled concrete with recycled aggregate ratio of 50%. The uniaxial tensile numerical simulation is carried out by introducing ABAQUS to define the uniformity coefficient of recycled aggregate distribution 伪, and the effect of 伪 on the uniaxial tensile properties of recycled concrete is obtained. For the waste fiber distribution model, the C30 matrix recycled concrete with recycled aggregate substitution rate of 50% was selected, and the waste polypropylene fiber with volume substitution rate of 0.12% and length of 15mm was added. Fourteen two-dimensional waste fiber recycled concrete distribution models were established in ABAQUS. The uniaxial tensile numerical test was carried out to define three waste fiber distribution coefficients: distribution uniformity coefficient 尾, distribution cohesion coefficient gamma. The influence of 尾, 纬 and 位 on the properties of waste fiber recycled concrete is obtained by the distribution angle coefficient 位. The main results and conclusions of this paper are as follows: (1) the distribution model of recycled aggregate and waste fiber is the first time to study the influence of the distribution of recycled aggregate and waste fiber on the tensile properties of matrix concrete from a mesoscopic point of view. The simulation results are consistent with the existing test data or theory, which proves that the simulation method has practical applicability. In order to further improve the related theories, a new idea and direction are put forward. (2) the tensile cracking mechanism of recycled concrete with different a is the same: the crack begins at the interface and then extends to mortar. 伪 only affects the crack position and the number of cracks passing through recycled aggregate. However, the tensile strength and deformation ability of recycled concrete change regularly with the change of 伪: when the distribution uniformity of recycled aggregate is moderate, that is, 伪 鈭，
本文编号：2499543
[Abstract]:The meso-mechanical method for simulating the bearing capacity, crack propagation process and failure form of concrete specimens by numerical method has been developed, which can more intuitively reflect the mechanism from internal damage to macroscopic failure of concrete specimens. As a typical material to carry out the sustainable development strategy: recycled concrete and waste fiber recycled concrete, it is a promising research topic to study their own properties from a mesoscopic point of view. Based on this, the effects of recycled aggregate and waste fiber distribution on the action mechanism and mechanical properties of matrix concrete are studied from a meso-point of view, and the recycled aggregate distribution model and waste fiber distribution model are established respectively. For the recycled aggregate distribution model, 20 different two-dimensional recycled concrete meso-aggregate distribution models are established by using CAD to replace C30 recycled concrete with recycled aggregate ratio of 50%. The uniaxial tensile numerical simulation is carried out by introducing ABAQUS to define the uniformity coefficient of recycled aggregate distribution 伪, and the effect of 伪 on the uniaxial tensile properties of recycled concrete is obtained. For the waste fiber distribution model, the C30 matrix recycled concrete with recycled aggregate substitution rate of 50% was selected, and the waste polypropylene fiber with volume substitution rate of 0.12% and length of 15mm was added. Fourteen two-dimensional waste fiber recycled concrete distribution models were established in ABAQUS. The uniaxial tensile numerical test was carried out to define three waste fiber distribution coefficients: distribution uniformity coefficient 尾, distribution cohesion coefficient gamma. The influence of 尾, 纬 and 位 on the properties of waste fiber recycled concrete is obtained by the distribution angle coefficient 位. The main results and conclusions of this paper are as follows: (1) the distribution model of recycled aggregate and waste fiber is the first time to study the influence of the distribution of recycled aggregate and waste fiber on the tensile properties of matrix concrete from a mesoscopic point of view. The simulation results are consistent with the existing test data or theory, which proves that the simulation method has practical applicability. In order to further improve the related theories, a new idea and direction are put forward. (2) the tensile cracking mechanism of recycled concrete with different a is the same: the crack begins at the interface and then extends to mortar. 伪 only affects the crack position and the number of cracks passing through recycled aggregate. However, the tensile strength and deformation ability of recycled concrete change regularly with the change of 伪: when the distribution uniformity of recycled aggregate is moderate, that is, 伪 鈭，
本文编号：2499543
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