冻融循环作用下混凝土抗冲磨性能研究#br#

寒冷地区水工构筑物长期承受着河流冲刷及冻融循环的循环作用。两者耦合作用下，混凝土力学性能及耐久性能将出现更大程度的劣化。该文对冻融循环作用下的混凝土抗冲磨性能进行研究，根据理论分析和试验结果，研究了冻融侵蚀作用下混凝土冲磨损伤规律。该文主要研究工作如下：①设计一种新的混凝土冲磨试验方法。考虑引气剂、冻融次数等因素，进行混凝土试件的冻融试验，得到冻融混凝土的动弹模、相对质量和抗压强度变化规律；进行冻融混凝土在不同流速下的冲磨试验。试验表明，混凝土在冻融和冲磨耦合作用下，耐久性退化比单一因素的作用严重2~3倍；②结合混凝土冻融损伤模型和冲磨模型，建立冲磨作用下冻融混凝土的磨蚀率理论模型。该模型计算结果与试验数据有良好的吻合；③建立有限元模型，对我国北方地区混凝土桥墩进行分析，在考虑冻融和冲磨交替作用下，混凝土桥墩表面年均磨蚀厚度在4.7~5.7mm之间。河流流速越大，冲磨程度越高。

Research on the anti-abrasion capacity of concrete under freeze-thaw cycle

Hydraulic structures in cold regions subject to abrasion and freeze-thaw effect in the long term. Under the coupling freeze-thaw effect, the mechanical properties and durability of concrete may experience a greater degradation. In this work, the anti-abrasion capacity of concrete under freeze-thaw cycle is investigated, and the abrasion-induced damage law of concrete under freeze-thaw cycle was studied on the basis of the experimental data and theoretical analysis. The main research work is summarized as: (1) A new abrasion test method for concrete was designed. With the factors of air-entraining agent and freeze-thaw cycles considered, the freeze-thaw tests of 48 specimens were conducted, and the change laws of dynamic elastic modulus, relative mass and compressive strength of concrete under freeze-thaw cycles were attained. The experimental results show that under the coupling action of freeze-thaw cycle and abrasion, the durability degradation of concrete is 2 or 3 times more serious than that under the single action. (2) Based on the freeze-thaw damage model and the abrasion test, the theoretical attrition rate model of freeze-thaw concrete under the abrasion action was established, and a good agreement between the calculated results and the experimental results could be achieved. (3) A finite element model was established based on the theoretical model, and then it was used for the analysis of a concrete pier located at the north part of China. It was found that the annual abrasion depth was calculated to be 4.7-5.7mm under the coupling effect of abrasion and freeze-thaw cycle. The more rapid the stream is, the more serious the abrasion of concrete is.