本文選題：機(jī)制砂　切入點(diǎn)：骨料形狀　出處：《浙江大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著我國城鎮(zhèn)化進(jìn)程的不斷加深以及基礎(chǔ)設(shè)施建設(shè)的日益發(fā)展,近年來不少地區(qū)天然砂資源逐漸匱乏。機(jī)制砂作為天然砂的良好替代物,正受到越來越高的重視。然而,機(jī)制砂在顆粒粒形、級配與石粉含量等方面與天然砂存在顯著差異,機(jī)制砂一般級配較差、細(xì)度模數(shù)偏大,且表面粗糙、顆粒尖銳有棱角,這些都導(dǎo)致了其對混凝土力學(xué)性能的影響與天然砂相比存在巨大差異。本文選取了浙江省地區(qū)常用的三種機(jī)制砂和一種天然砂,從各自特性入手,根據(jù)現(xiàn)行規(guī)范評定了其質(zhì)量等級。同時(shí),定義了三種形狀參數(shù)并利用數(shù)字圖象處理技術(shù)比較了不同種類砂之間的形狀差異,并由此建立了特定形狀參數(shù)骨料組成的混凝土模型,利用有限元數(shù)值模擬方法研究了骨料形狀差異對混凝土力學(xué)性能的影響。本文還針對每一種砂制作了混凝土試塊和鋼筋混凝土試驗(yàn)梁,通過試驗(yàn)研究了機(jī)制砂對混凝土工作性能、力學(xué)性能、干縮性能、梁受彎性能、梁受剪性能等的影響,得到如下主要結(jié)論:(1)本文采用的細(xì)骨料樣品中,工程用臺州精品機(jī)制砂(機(jī)制砂C)為Ⅰ類中砂,臺州普通機(jī)制砂(機(jī)制砂B)為Ⅲ類中砂,富陽產(chǎn)卵石機(jī)制砂(機(jī)制砂A)不符合現(xiàn)行規(guī)范的規(guī)定,但由于目前有工程尚在應(yīng)用,仍列為研究目標(biāo),杭州地區(qū)普通河砂(天然砂)為Ⅱ類中砂;(2)本文利用數(shù)字圖像技術(shù)獲取了細(xì)骨料圖像并分析了其形狀參數(shù),結(jié)果表明天然砂總體上形狀較機(jī)制砂更平整圓潤。不同機(jī)制砂中,機(jī)制砂A的各項(xiàng)形狀參數(shù)略好于另外兩種機(jī)制砂,說明卵石母巖的機(jī)制砂其形狀相對碎石母巖的機(jī)制砂略光滑圓潤;(3)本文提出了一種隨機(jī)骨料單元生成方式,其特征是能夠生成特定形狀參數(shù)的骨料單元。本文參照了骨料形狀參數(shù)的實(shí)測結(jié)果,建立了混凝土細(xì)觀模型,然后結(jié)合有限元數(shù)值模擬方法分析了不同種類細(xì)骨料混凝土的抗壓強(qiáng)度;(4)本文制作了混凝土試塊并進(jìn)行了工作性試驗(yàn)、力學(xué)性能試和體積穩(wěn)定性試驗(yàn),結(jié)果表明良好的細(xì)骨料顆粒形狀是保證其混凝土工作性的重要因素,且由合格的機(jī)制砂制作的混凝土其強(qiáng)度和長期干縮性能能夠達(dá)到甚至超過天然砂混凝土;(5)本文通過鋼筋混凝土梁試驗(yàn)研究發(fā)現(xiàn),機(jī)制砂及天然砂梁的受彎、受剪性能總體上非常相似,由天然砂梁的設(shè)計(jì)方法計(jì)算得到的機(jī)制砂梁受彎、受剪極限承載力也均滿足工程要求。但是,從試驗(yàn)結(jié)果中發(fā)現(xiàn),天然砂鋼筋混凝土梁抗裂能力略優(yōu)于機(jī)制砂鋼筋混凝土梁,特別是由現(xiàn)行方法計(jì)算得出的機(jī)制砂鋼筋混凝土梁開裂荷載偏于不安全,建議對機(jī)制砂鋼筋混凝土梁的開裂荷載設(shè)計(jì)進(jìn)行適度調(diào)整。
[Abstract]:With the deepening of China's urbanization and the development of infrastructure construction, natural sand resources in many areas have been gradually scarce in recent years. As a good substitute for natural sand, machine-made sand is receiving more and more attention. There are significant differences in grain shape, gradation and stone powder content between machine-made sand and natural sand. The general gradation of machine-made sand is poor, the fineness modulus is large, the surface is rough, and the grain is sharp and angular. All of these results in a great difference between the mechanical properties of concrete and the natural sand. In this paper, three kinds of machined sand and one kind of natural sand which are commonly used in Zhejiang Province are selected, starting with their respective characteristics. The quality grade is evaluated according to the current specifications. At the same time, three shape parameters are defined, and the shape differences among different kinds of sand are compared by digital image processing technology, and a concrete model composed of aggregates with specific shape parameters is established. The influence of the shape difference of aggregate on the mechanical properties of concrete is studied by using finite element numerical simulation method. In this paper, concrete test blocks and reinforced concrete test beams are made for each kind of sand. The effects of machine-made sand on the working properties, mechanical properties, dry shrinkage properties, flexural properties of beams and shear properties of beams are studied. The main conclusions are as follows: 1) in the sample of fine aggregate used in this paper, The fine machined sand of Taizhou (machine-made sand C) is class 鈪，

本文編號：1631558