非金属声屏障单元板的轻质优化及力学研究

非金属声屏障因其良好的吸隔声性能、力学性能、耐候性能以及耐久性能迅速成为高速铁路降噪工程中的首选产品。针对非金属声屏障的制作工艺及力学性能,通过总结对比提出优化方案,使用轻质混凝土作为主要材料,将非金属声屏障单位面积内的重量极大降低,并通过有限元软件ANSYS14.5进行改良后产品的力学性能模拟分析,对其在极端情况下的可行性进行验证。     

新型金属声屏障单元板工作性能研究

设置声屏障是缓解交通噪声污染问题的主要途径之一,一种新型无铆型金属声屏障单元板可有效改善现有声屏障单元板的主要缺陷。根据国家标准和行业规范对此种无铆型金属声屏障单元板的声学性能和力学性能进行研究,结果表明此种声屏障单元板在承受7 kPa的均布荷载时,单元板上产生的最大变形远小于规范限值且最大应力远小于材料的屈服强度及疲劳强度。承受疲劳荷载后,声屏障单元板整体保持完好,各组分间保持有效连接。填充了吸声材料的声屏障单元板的降噪系数可达0.79,远高于规范中的规定值。以上结果均表明此种无铆型金属声屏障单元板完全符合实际工程应用要求。     

Freeze-thaw Durability of Recycled Aggregate Concrete:An Overview

The characteristics of surface appearances,mass loss,relative dynamic modulus of elasticity and strength loss of different recycled aggregate concretes(RAC) exposed to freeze-thaw cycles were analyzed.It was found that the freeze-thaw resistance of RAC could be determined by the recycled aggregate compositions and admixtures.Both the saturation degree and the air void structure were the key factors influencing the freeze-thaw damage on concrete.Some major proposed freeze-thaw deterioration mechanisms were utilized to interpret the freeze-thaw damage on recycled aggregate concrete.Meanwhile,some potential measures to enhance the freeze-thaw resistance of concrete were summarized and discussed.