巷道支护加钢筋网喷射混凝土破坏过程的数值模拟

确保喷射混凝土支护方式的有效性是喷射支护的关键,如何事先预测喷射混凝土的破坏模式是矿山建设工程中亟待解决的问题。采用三维真实破坏过程分析系统,对加钢筋网喷射混凝土结构在双向拉伸作用下的破坏过程进行数值模拟,直观再现了喷射混凝土结构中应力场分布及裂纹演化过程。分析其破坏机理,并提出了一些建议,对于工程实践有一定的指导作用。     

Effect of stress on abrasive and erosive wear of steels and sprayed coatings

The effect of stress on abrasive and erosive wear was studied for the hypoeutectoid steel, two hypereutectoid tool steels and flame sprayed coatings. In the experiment, the specially designed tester as well as SEM and contact profilometer were applied. Abrasion and erosion remove asperities protruding from the surface of coatings. The imposed stress increased erosive wear of coatings. Application of compressive stress to steels reduces roughness of the wear scar. Compressive stress caused distinct damage localization in abraded and eroded coatings, mean spacing of surface irregularities Rsm observed in erosion test was about 50% larger than in unstressed coatings. Results of fractal analysis confirm stress-induced change in surface topography.     

Support to rock excavations provided by sprayed liners

The support provided to mining excavations by sprayed liners is investigated. A long cylindrical excavation of circular cross-section is considered. Three models to analyse liner mechanisms are presented. In the first model the liner forms a thin cylindrical layer firmly bonded to the surface of the excavation. The rock surrounding the excavation may contain open joints and fractures due to the excavation process. In the second model the liner material penetrates into the fractures to their full extent. In the third model the liner material penetrates some distance into the fractures but the fractures extend well beyond this depth and are taken to extend to infinity. The excavation is subjected to a uniform shear stress at infinity which could represent a perturbation due to mining or a geological disturbance. Two cylindrical regions are considered, an inner region and an outer region which extends to infinity. The stress and displacement in each region are calculated, using plane strain theory of elasticity. In the first model the transfer of stress from the rock to the liner is investigated and the decrease in the stress concentration factor in the rock due to the liner is calculated. In the second and third models the change in the displacement, rotation and stress due to the penetration of the liner material into joints and fractures is investigated. Representative values for the changes in stress and displacement at the surface of the excavation predicted by the three models are presented.     

搪瓷(喷瓷)管道及其连接技术国内外研究现状

搪瓷涂层具有优异的综合耐蚀性,不老化,使用寿命长,是有机涂层的替代产品.介绍了搪瓷管道及喷瓷管道的国内外发展现状和搪瓷(喷瓷)管道的连接技术.俄罗斯率先将搪瓷技术应用于管道防腐,大大提高了管道的耐蚀性,但设备投资巨大、工序繁多、生产效率低,成本相对较高.中国将热喷涂技术应用于搪瓷管道的生产诞生了喷瓷管道,简化了工艺,降低了成本.搪瓷(喷瓷)管道焊接时会破坏接头处瓷层,需要补口.国内外发展了焊接接头内壁牺牲阳极防护法、用综合冶金治理代替焊后补口技术、不锈钢工艺接头连接法、瓷层自熔覆防护法等方法,实现了搪瓷(喷瓷)管道的连接,解决了焊接接头补口问题.     

喷锚网支护在狭小场地深基坑中的应用

通过施工实例 ,介绍了对施工场地狭窄、周围紧邻已有建筑物的深基坑 ,采用喷锚网支护技术的施工方法、施工要点 ,同时也验证了该技术的可行性及经济性     

电弧喷涂铁基防腐涂层在垃圾焚化厂的应用

垃圾焚化厂产生的热量可用于发电和集中供热。一些金属部件,例如热交换器,处于腐蚀性很强的气氛中。基体材料在氯含量很高的气氛中损耗非常快,影响了材料的使用寿命,且带来了高昂的维护费用。在传统的钢材表面喷涂一层防腐涂层,可以显著地改善其表面性能。由于电弧喷涂容易实现并且成本较低,其已成为一种较有成效的喷涂方法。热喷涂镍钴基合金涂层目前已达到先进技术水平,而采用铁基合金作为其替代品则为取得可观的经济效益。最新的研究结果表明在FeCr和NiCr合金的基础上加入硅后可提高其耐腐蚀性能。为了确证这些材料的潜能,本研究制备出不同成分的药芯焊丝并采用电弧喷涂技术进行喷涂。最终在含氯气体环境中测试试样的抗氧化性能。     

喷射钢纤维混凝土性能试验研究

 通过不同的配合比和掺入不同体积率的钢纤维混凝土来进行对比,利用抗压、劈裂抗拉和抗折试验分析钢纤维混凝土的性能。结果表明,水灰比为0.5的钢纤维混凝土抗压、抗折、抗拉强度分别比未加钢纤维混凝土提高了10.3%、9.6%和33.5%,水灰比为0.6的钢纤维分别提高了33.8%、10.8%和8.4%;而对于不同掺量的比较中,掺量较高的混凝土强度提高要高一些。由此可见,在不同的水灰比和不同的掺量下对混凝土的性能会产生不同的影响,但总体看来钢纤维能够提高喷射混凝土的抗压强度和劈裂抗拉强度等性能,能够为地下工程提供更好的支护作用。     

用于海洋环境下活化腐蚀防护的高性能电弧喷涂层

采用铝或锌涂层的活性腐蚀防护是热喷涂技术应用最多的领域.每年大约要消耗20,000吨的喷涂线材,并且未来需求还在增加.热喷涂技术及材料无论是单独还是一起在海洋环境下使用,都有一定的标准.海上风力发电机（OWET）要求维护间隔时间尽可能长,这可以通过使用长寿命的表面涂层来满足使用要求.目前,金属喷涂涂层主要用于OWET的高应力部件,如法兰、框架和安装面.在实验室测试的过程中,研究了多种用于OWET的双涂层体系的抗腐蚀效果,其中金属涂层关注最多.制备了不同厚度和特性的Zn/A1和Al涂层,对部分涂层进行封孔处理,并制备有机涂层形成多层涂层体系.其目的之一是制备地氧含量的防护涂层,并和目前标准的工艺进行对比.依照ISO20340标准[5]对涂层和标样涂层的抗腐蚀性能进行了25周的循环老化测试评价,评估标准为：涂层划痕处的腐蚀和渗透、涂层起泡和锈蚀程度,以及涂层与基材的结合力.测试结果表明,喷涂金属涂层是一种有效的改善材料的抗腐蚀性能方法.采用活性气体作雾化气体的电弧喷涂或冷喷涂制备Zn/A115涂层能够提升涂层的防护效果,并且可以降低涂层的厚度,具有较好的经济前景.     

万家寨引黄工程总干线一、二级泵站防火喷涂项目索赔分析

万家寨引黄工程总干线一、二线泵站防火喷涂项目，在施工过程中，承包商提出了索赔要求，本文介绍了该项目索赔的分析过程，包括索赔证据的确立及索赔费用计算等。     

桥梁钢管疲劳试验

介绍了对专用一级公路上的桥梁钢管进行疲劳试验，用以检验桥梁钢管长期在特定的自然条件下的安全可靠性。