發(fā)布時間：2018-06-15 02:26

  本文選題：低溫環(huán)境 + 碾壓瀝青混凝土��； 參考：《新疆農業(yè)大學》2014年碩士論文

【摘要】：水工瀝青混凝土具有防滲性能好、適應變形能力強等特點，已廣泛用于心墻壩中。目前，大部分瀝青混凝土心墻都是在常溫環(huán)境條件下進行碾壓施工的。新疆寒冷地區(qū)施工工期短，在施工中也經常遇到機械故障等因素造成工期滯后，為滿足來年防洪度汛高程需要適當延長施工工期，考慮在低溫環(huán)境下進行碾壓瀝青混凝土的施工。而瀝青混凝土心墻在低溫環(huán)境下施工能否碾壓密實、碾壓層面溫度過低時能否有效結合是一項急需解決的問題。 本文采用室內試驗和現(xiàn)場試驗相結合的研究方法，根據常溫下的基礎配合比確定了低溫環(huán)境下的配合比；現(xiàn)場對低溫環(huán)境下施工的心墻碾壓瀝青混凝土進行密度、孔隙率、滲透系數的測定，并鉆取芯樣進行力學性能試驗，對比分析低溫環(huán)境下由于瀝青用量增加后瀝青混凝土的物理、力學性能的變化；通過制作不同溫度的下層料與上層熱料結合的瀝青混凝土試件，進行了結合面的劈裂抗拉試驗、抗剪斷試驗、小梁彎曲試驗、拉伸試驗，分析不同結合面溫度下抗拉性能的變化規(guī)律；通過室內試驗量測上層熱料攤鋪后對不同溫度下層料的加熱效應，施工現(xiàn)場對碾壓瀝青混凝土結合面附近的溫度變化進行觀測，并對心墻越冬層的溫度變化過程進行了監(jiān)測。主要得到了以下結論： （1）試驗用原材料各項技術指標均滿足設計規(guī)范要求，低溫環(huán)境下為提高瀝青混凝土的施工性能，配合比參數的取值為：最大粒徑為19mm、級配指數為0.38、填料用量為14%、瀝青用量由6.6%提高到7.0%。 （2）現(xiàn)場檢測表明低溫環(huán)境下碾壓瀝青混凝土心墻的密度、孔隙率、滲透系數均能滿足規(guī)范要求；由于瀝青用量的增加使瀝青混凝土的強度略有降低，適應變形能力增大，能夠滿足設計規(guī)范要求。 （3）對不同結合面溫度試件進行試驗后，劈裂抗拉強度、抗剪斷強度、抗彎強度、拉伸強度均隨結合面溫度降低而呈下降趨勢，結合面溫度為30℃時與本體（一次成型試件）相比分別下降了10.6%、8.1%、4.5%、6.2%，下降幅度均較小，能夠滿足規(guī)范要求。 （4）結合面溫度低于30℃時，試件斷面較平整，，試件逐漸呈現(xiàn)脆性破壞，而結合面溫度高于30℃時，試件斷面粗糙不平，層間有大顆粒骨料相互嵌入，試件逐漸呈現(xiàn)延性破壞，表明隨著結合面溫度的降低對瀝青混凝土的層間結合質量有一定影響。 （5）越冬期間利用電熱毯加熱心墻可起到保護心墻的作用，熱砂加熱法對越冬層加熱效果顯著。上層熱料對下層瀝青混凝土結合面加熱效果明顯，當160℃左右的熱料攤鋪到30℃的下層瀝青混凝土后，通過熱傳遞結合面以下10mm處溫度可達到規(guī)范要求的70℃以上。 （6）試驗表明：結合面溫度從現(xiàn)行規(guī)范要求的70℃降低到30℃后，瀝青混凝土能夠碾壓密實，并且結合面力學性能沒有明顯下降，碾壓層面結合質量良好。
[Abstract]:Hydraulic asphalt concrete has been widely used in core dam because of its good impermeability and strong adaptability to deformation. At present, most asphalt concrete core walls are rolled under ambient conditions. In the cold area of Xinjiang, the construction period is short and the construction period is often delayed due to mechanical failure. In order to meet the flood control elevation in the coming year, it is necessary to extend the construction period appropriately. Considering the construction of roller compacted asphalt concrete in low temperature environment. Whether the asphalt concrete core wall can be compacted under low temperature and whether it can be effectively combined when the rolling layer temperature is too low is an urgent problem to be solved. In this paper, the combination of indoor test and field test is used to determine the mixture ratio at low temperature according to the basic mix ratio at room temperature, and the density and porosity of the core wall roller compacted asphalt concrete under the low temperature environment are carried out in the field. The permeability coefficient is measured and the core sample is drilled for mechanical performance test. The physical and mechanical properties of asphalt concrete under low temperature environment are compared and analyzed because of the increase of asphalt content. The split tensile test, shear test, trabecular bending test and tensile test of the bonding surface were carried out by making the asphalt concrete specimens with different temperatures of the lower layer and the upper hot material. The variation law of tensile performance at different bonding surface temperature is analyzed, and the temperature change near the interface of roller compacted asphalt concrete (RCC) is observed at the construction site through indoor test measuring the heating effect of the upper layer of hot material after spreading the lower layer material at different temperature. The temperature variation process of wintering layer of core wall was monitored. The main conclusions are as follows: (1) each technical index of raw materials for test meets the requirements of design code. In order to improve the construction performance of asphalt concrete under low temperature environment, The maximum particle size is 19mm, the gradation index is 0.38, the filler content is 14, and the asphalt content is increased from 6.6% to 7.0.The field test shows that the density and porosity of the RCC core wall under low temperature environment is higher than that of the RCC core wall. Due to the increase of asphalt content, the strength of asphalt concrete is slightly reduced, and the deformation ability is increased, which can meet the requirements of design code. The splitting tensile strength, shear strength, flexural strength and tensile strength decreased with the decrease of the temperature of the bonding surface. When the temperature of the bonding surface was 30 鈩

本文編號：2020149