关于混凝土钻芯取样法有关标准的讨论

本文对国内不同行业有关混凝土钻总取样方法的标准进行了讨论，供月行在使用和修订相应标准时参考。     

冲击回波法检测隧洞混凝土衬砌厚度

冲击回波法是通过接收、分析在混凝土中传播的回波信号，判断结构混凝土厚度和内部质量的新型无损检测技术。室内试验和工程应用研究表明，该方法为隧洞混凝土衬砌厚度检测提供了一个有效的测试手段。     

钢纤维聚合物混凝土抗压本构关系

钢纤维聚合物混凝土是由聚合物混凝土基体和钢纤维共同组成的纤维增强复合材料，它的力学行为不仅依赖于聚合物混凝土基体的行为，而且与钢纤维的掺量、分散特征以及钢纤维的几何尺寸有关，本文将基于损伤力学原理研究在不同纤维掺量下的钢纤维聚合物混凝土的全程压力-应变曲线及其本构模型。     

Microstructural investigation of long-term degradation mechanisms in GFRP dowel bars for jointed concrete pavement

Steel dowel bar is used to transfer loads in concrete pavement slab. However, once the steel dowel bar corrodes, it may cause faults, such as joint freezing in concrete pavement, level differences resulting from spalling or decreased efficiency of load transfer, etc., which are the same problems experienced by typical reinforcing steel. This study evaluated the applicability of glass fiber-reinforced polymer (GFRP) dowel bar as a substitute for steel dowel bar. A microstructural analysis was conducted to examine the decrease in durability of GFRP dowel bar exposed to deterioration environments. To analyze the deterioration mechanism of GFRP dowel bar, scanning electron microscopy was employed and the porosity was measured by the gas absorption method. It was concluded that the longer the GFRP dowel bar was exposed to deterioration environments, the more the interlaminar shear stress decreased. This result was validated by the microstructural analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

混凝土爆扩桩施工技术

结合工程实例详细介绍了混凝土爆扩桩的成孔、爆扩、混凝土浇筑等施工过程,从施工准备、施工工艺、施工检查及应注意的事项几个方面做了具体阐述,使工程桩达到了设计要求,取得了良好的施工效果。     

State of Practice for Positive Moment Connections in Prestressed Concrete Girders Made Continuous

Precast bridges are often constructed as single span for dead load, but continuous for live load. A diaphragm connection is provided for negative moment continuity. However, the connection may also be subjected to positive moments due to time-dependent effects. Because these moments may be large enough to damage the diaphragm or even the girders, a positive moment connection is often provided. This paper reports on a study to determine the types of positive moment connections used across the country and to identify potential problems with these types of connections. A questionnaire survey was conducted to assess the state of practice for precast prestressed concrete bridges made continuous. The survey provides valuable information on this type of bridge and updates a previous survey on this subject.     

Analytical modeling and experimental study of tensile strength of asphalt concrete composite at low temperatures

In this study, analytical modeling of the tensile strength of hot-mix asphalt (HMA) mixtures at low temperatures was developed. To do this, HMA mixtures were treated as a two-phase composite material with aggregates (coarse and fine) dispersed in an asphalt mastic matrix. A two-phase composite model, which was similar to Papanicolaou and Bakos's [J. Reinforced Plast. Compos. 11 (1992) 104] model with a particle embedded in an infinite matrix, was proposed. Unlike Papanicolaou and Bakos's model, an axial stress was introduced to the fiber end to consider the load transferred from the asphalt mastic the aggregate. Efforts were also made to consider the effect of aggregate gradation, asphalt mastic degradation, and interfacial damage between the aggregates and asphalt mastic matrix on the tensile strength of the HMA mixtures. Experimental investigations were conducted to validate the developed theoretical relations. A reasonable agreement was found between the predicted tensile strength and the experimental results at low temperatures. Parameters affecting the tensile strength of asphalt mixtures were discussed based on the calculated results.     

桥梁高性能混凝土应用

分析比较了混凝土与高性能混凝土的应用情况，介绍了桥梁使用高性能混凝土的必要性和重要性，通过评价高性能混凝土桥梁的寿命、经济性，提出了降低HPC桥梁建设成本的措施。     

砼受压损伤力学本构模型的研究

本文利用ＭＴＳ公司８１５．０２型电液伺服试验系统对砼进行了等应变速率加载控制的应力一应变全曲线试验，应用不可逆热力学和内变量理论的成果建立了砼损伤力学模型，并用概率统计的观点分析了损伤的演化规律。由于考虑了不可逆变形的影响，本文所建本构模型与实验吻合较好。     

龙潭拱坝砼上坝运输方案选择

龙潭拱坝坝高９０ｍ，砼上坝运输是砼施工过程中的中间环节，控制进度的关键，必须因时因地制宜地选择适当的运输机械和运输方案，使砼运输能做到保质、保量、及时和经济，通过论证比较，结合本工程现实情况，砼上坝运输不采用缆机而采用门机方案．