西北强风沙环境混凝土冲蚀磨损与防护材料试验研究

发布时间：2018-03-25 15:10

本文选题：冲蚀磨损　切入点：混凝土　出处：《兰州交通大学》2016年博士论文

【摘要】：已经开通的兰新高速铁路沿线穿越五大强风区,风区地段风力强劲、风期长,强风携带的沙粒对风区地段的混凝土桥梁的梁体、墩身和铁路路基产生了严重的冲蚀磨损,造成如桥梁墩身表面的水泥剥落以及水泥与骨料之间微裂纹的产生,这些损伤可能进一步加剧混凝土结构的其他病害和损伤,大大降低混凝土结构的耐久性。混凝土结构耐久性的降低不仅影响其设计寿命,同时造成庞大的维修费用,也给列车的行车安全造成了重大的隐患。关于混凝土结构材料的冲蚀磨损,目前人们重点研究含沙水流对水工混凝土结构材料的冲蚀磨损,主要研究了试验方法、冲蚀磨损机理、评价指标和抗磨措施,并取得了一些进展。而对于风沙环境(气固两相流)下,混凝土结构材料冲蚀磨损的试验方法、冲蚀磨损机理和防护、修补材料的研究还鲜见报道。为此,本文采用气流挟沙喷射法,模拟戈壁风沙环境,对混凝土、改性环氧树脂、环氧树脂基复合材料及水泥基防护、修补砂浆进行冲蚀磨损试验,分析其冲蚀磨损行为和冲蚀磨损机理。结合现场试验和室内试验探讨了改性环氧树脂基复合材料作为强风沙流地区混凝土结构冲蚀磨损防护材料的可行性。主要研究内容和结论如下:(1)依据ASTMC418-2005《混凝土冲蚀磨损标准试验方法》研发了冲蚀磨损试验机,该试验机由供气系统、供沙系统、喷枪和喷嘴系统及试样室等4个部分构成;分析了现场收集沙的粒径分布,确定了室内试验沙的粒径范围;校核了气流速度和压力的关系,以便确定试验速度。(2)研究了冲蚀速度、冲蚀角度、冲蚀时间和沙流量等参数对混凝土试样冲蚀磨损的影响,试验发现各试样的冲蚀率和风沙流速度满足幂指数关系,拟合速度指数在2.0-3.2之间,符合脆性材料的冲蚀磨损规律;各试样在90°冲蚀时冲蚀率高,而在45°冲蚀时冲蚀率低,与脆性材料的冲蚀规律相一致;混凝土试样的冲蚀率随沙流量的增大先降低后增大;混凝土材料的冲蚀磨损机制为:表面层水泥石的开裂脱落和次表面层的选择性磨损。(3)采用沥青、纳米SiO2和改性脂肪胺固化剂对双酚A型环氧树脂进行增韧改性,研究了其耐久性和抗冲蚀磨损性能。试验发现沥青、纳米SiO2和改性脂肪胺固化剂提高了环氧树脂的力学性能、耐久性和冲蚀磨损性能,其冲蚀时表现出半塑性材料的冲蚀特征,最大冲蚀率出现在45°冲蚀角,且冲蚀抗力相比于混凝土有了极大的提高;改性环氧树脂的冲蚀是冲蚀能量法向分量和切向分量共同作用的结果,法向分量使材料表面产生裂纹和破碎,切向分量使材料表面产生切削。(4)制备了玻璃(碳)纤维增强环氧树脂复合材料,研究了含胶量、纤维取向、纤维布类型和冲蚀参数等对复合材料冲蚀磨损性能的影响。试验发现环氧树脂基复合材料的冲蚀行为表现出半塑性材料的冲蚀特征,最大冲蚀率出现在45°~60°;对于单向纤维增强环氧树脂复合材料,在冲蚀角为45°时,其冲蚀率与冲蚀速度呈指数关系,速度指数为2.1-2.8;在相同的冲蚀条件下,单向纤维增强环氧树脂复合材料垂直冲蚀的冲蚀率比平行冲蚀的高,含胶量越高复合材料的冲蚀抗力就越高;复合材料的主要冲蚀磨损机制为微裂纹的产生、纤维的弯曲断裂、纤维与基体剥离以及基体的显微切削。(5)制备了不同的水泥基防护、修补砂浆,研究了砂浆强度等级、砂子级配、丙乳含量、纤维类型和含量对水泥基防护、修补砂浆冲蚀磨损性能的影响。试验发现水泥石和水泥基防护、修补砂浆的冲蚀率均随着风沙流速度的增大而增加;PP和PVA纤维增强砂浆的冲蚀率随冲蚀角度的增加呈锯齿状变化,其余砂浆的冲蚀规律与脆性材料相一致;砂浆的强度等级越高,其冲蚀抗力也越高;砂子级配越大,砂浆的冲蚀抗力越高;达到一定掺量的丙乳能在砂浆中形成聚合物膜特殊结构,提高砂浆的韧性和冲蚀抗力;适宜量的PP和PVA纤维能对砂浆起到增强和增韧作用,从而能够提高砂浆的冲蚀抗力,特别是高角度冲蚀时的冲蚀抗力。
[Abstract]:Lanzhou Xinjiang has been opened along the high-speed railway passing through five strong wind area, wind area of strong wind, wind period, strong wind carried sand concrete girder bridge on the wind section of the pier and railway roadbed caused serious erosion, such as caused by micro cracks between the cement surface and spalling of bridge pier cement and aggregate, these injuries may further exacerbate other diseases and damage of the concrete structure, greatly reduce the durability of the concrete structure. To reduce the durability of concrete structure not only influences the design life, and caused huge maintenance costs, but also to the running safety of train caused significant risks. On the erosion wear of concrete structure material. At present, people focus on sediment erosion of material of hydraulic concrete structure wear, mainly studied the test method, the erosion mechanism, evaluation index and Anti-wear measures, and made some progress. But for the sand environment (gas-solid two-phase flow), test method of erosion wear of concrete structure material, erosion mechanism and protection of repair materials is rarely reported. Therefore, the sediment air injection method, simulation of Gobi sandy environment, concrete, change epoxy resin, epoxy resin composite materials and cement mortar protection, erosive wear test, analysis of the erosion wear behavior and erosion wear mechanism. Combined with the field test and laboratory test of modified epoxy resin based composite material as the wind sand flow erosion area of concrete structure wear protection material feasibility is discussed. The main research contents and the conclusions are as follows: (1) on the basis of ASTMC418-2005< concrete erosion wear test method standard > developed erosion test machine, the test machine comprises a gas supply system for sand spraying system The 4 part of the gun and nozzle system and sample room; analyzes the collected sediment particle size distribution, the indoor test sediment particle size range; the relationship between flow velocity and pressure check, in order to determine the test speed. (2) studied the impact velocity, impact angle, erosion time and sand flow parameters on the influence of concrete specimen erosion test, found that the sample erosion rate and sand flow velocity exponential fitting, velocity index between 2.0-3.2, with the erosion of brittle material of each specimen in 90 DEG; erosion erosion rate is high, and in the 45 degree erosion erosion rate is low, consistent with erosion behavior of brittle materials; erosion of concrete specimens increases with the flow rate of sand decreased first and then increased; the concrete material erosion wear mechanism is that wear cracking surface layer of cement stone falling and secondary surface layer (3) used. Asphalt, nano SiO2 and modified aliphatic amine curing agent for toughening modification of bisphenol A type epoxy resin, study its durability and anti erosion performance. Experiment results showed that asphalt, nano SiO2 and modified aliphatic amine curing agent to improve the mechanical properties of epoxy resin, durability and erosion resistance, the erosion show the erosion characteristics of semi plastic material, the maximum erosion rate in the 45 degree angle erosion and erosion resistance, compared to the concrete has been greatly improved; the erosion of modified epoxy resin as a result of the erosion energy method to the component and tangential component interaction, the normal component of the surface crack and breakage the tangential component of the material, surface cutting. (4) (c) were prepared by glass fiber reinforced epoxy resin composite material of rubber content, fiber orientation, fiber type and erosion parameters on the composite erosion wear resistance. Ring. Experiment results showed that the erosion behavior of epoxy resin composites exhibit erosion characteristics of semi plastic material, the maximum erosion rate appeared at 45 DEG ~60 DEG; for unidirectional fiber reinforced epoxy resin composite material, the erosion angle is 45 degrees, the erosion rate and erosion rate exponentially, the speed index was 2.1-2.8; in the same conditions of erosion, erosion of unidirectional fiber reinforced epoxy resin composite vertical erosion rate than parallel erosion, erosion resistance of rubber content higher composite material is higher; the main composite material erosion wear mechanism is micro cracks, bending fracture of fiber, fiber and matrix stripping and matrix micro cutting. (5) preparation of cement based protection, different mortar strength grade of mortar, sand gradation, emulsion content, protective fiber type and content on the cement mortar, repair erosion performance Effect of cement and cement. Experiment results showed that base protection, erosion repair mortar rate increases with the increasing of sand flow rate; PP and PVA fiber reinforced serrated change increase of mortar erosion rate with the erosion angle, consistent with the erosion law of mortar brittle materials; mortar strength grade is higher, the erosion resistance is also higher; the greater the sand gradation, erosion resistance of mortar is higher; reach a certain dosage of acrylic emulsion can form special polymer film structure in mortar, improve the mortar toughness and erosion resistance; appropriate amounts of PP and PVA fiber to enhance and improve the toughness of the mortar, which can improve the erosion the resistance of mortar, especially the erosion resistance of high angle erosion.

【学位授予单位】：兰州交通大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TV431

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