【摘要】：以數(shù)值方法模擬混凝土試件的承載力、裂縫擴(kuò)展過程及破壞形態(tài)的細(xì)觀力學(xué)方法已經(jīng)發(fā)展起來,更為直觀地反映試件從內(nèi)部損傷到宏觀破壞的機(jī)理。作為貫徹可持續(xù)發(fā)展戰(zhàn)略的典型材料：再生混凝土、廢棄纖維再生混凝土,從細(xì)觀角度研究其自身性能是一項(xiàng)前景可觀的研究課題�；诖�,本文從細(xì)觀角度研究再生骨料及廢棄纖維分布情況對(duì)基體混凝土作用機(jī)理及力學(xué)性能的影響,分別建立了再生骨料分布模型及廢棄纖維分布模型。對(duì)于再生骨料分布模型,取再生骨料取代率為50%的C30再生混凝土,利用CAD建立20個(gè)不同的二維再生混凝土細(xì)觀骨料分布模型,導(dǎo)入ABAQUS對(duì)其進(jìn)行單軸拉伸數(shù)值模擬,定義再生骨料分布均勻性系數(shù)α,得到α對(duì)再生混凝土單軸受拉性能的影響；對(duì)于廢棄纖維分布模型,取再生骨料取代率為50%的C30基體再生混凝土,加入體積取代率為0.12%,長度為15mm的廢棄聚丙烯纖維,在ABAQUS中建立14個(gè)二維廢棄纖維再生混凝土分布模型,對(duì)其進(jìn)行單軸拉伸數(shù)值試驗(yàn),定義三個(gè)廢棄纖維分布系數(shù)：分布均勻性系數(shù)β、分布聚攏性系數(shù)γ、分布角度系數(shù)λ,得出β、γ、λ對(duì)廢棄纖維再生混凝土性能的影響規(guī)律。本文主要成果及結(jié)論如下：(1)筆者建立的再生骨料及廢棄纖維分布模型是首次從細(xì)觀角度研究再生骨料及廢棄纖維的分布情況對(duì)基體混凝土抗拉性能的影響,模擬所得結(jié)論與現(xiàn)有試驗(yàn)數(shù)據(jù)或理論相一致,證明該模擬方法具有實(shí)際適用性,為進(jìn)一步完善相關(guān)理論提出了新的思路和方向。(2)不同a的再生混凝土受拉開裂作用機(jī)理相同：裂縫始于界面,進(jìn)而向砂漿擴(kuò)展、延伸,α僅影響裂縫位置及裂縫穿過再生骨料的數(shù)量。但再生混凝土抗拉強(qiáng)度及變形能力隨著α的改變而呈規(guī)律性變化：當(dāng)再生骨料分布均勻性適中,即α∈[0.338,0.483]時(shí),抗拉強(qiáng)度較高,受拉應(yīng)力—應(yīng)變曲線分為彈性階段、塑性階段、陡峭下降段、平緩下降段,曲線更為飽滿,變形能力更好；當(dāng)再生骨料分布過于均勻或分散,即a0.338或a0.483時(shí),抗拉強(qiáng)度較低,受拉應(yīng)力—應(yīng)變曲線有缺失或不飽滿,極限拉應(yīng)變較小,變形能力較差。(4)不論廢棄纖維分布如何,即不論β、γ、λ取何值,廢棄纖維再生混凝土受拉開裂作用機(jī)理相同：裂縫始于基體混凝土,纖維在裂縫開展過程中起到阻裂作用。但廢棄纖維再生混凝土抗拉強(qiáng)度及變形能力隨著β、γ、λ的改變而呈規(guī)律性變化：抗拉強(qiáng)度隨著λ的增大而減小且影響顯著,而β及γ對(duì)其影響微小,且隨著β及γ的增大,抗拉強(qiáng)度平緩減小,即纖維分布越離散、纖維抱團(tuán)情況越顯著,抗拉強(qiáng)度越小；且峰值拉應(yīng)變隨著β、γ的減小而增大,即廢棄纖維根數(shù)及間距分布越均勻廢棄纖維再生混凝土變形能力越好,但λ對(duì)受拉峰值應(yīng)變幾乎無影響。
[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 偽, and the effect of 偽 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, 緯 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. 偽 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 偽: when the distribution uniformity of recycled aggregate is moderate, that is, 偽 鈭，

本文編號(hào)：2499543