三峡升船机塔柱横梁混凝土施工技术

三峡升船机船厢室段塔柱承重结构的横梁混凝土浇筑施工难度大、复杂性高、无成熟技术可供参考。本文结合三峡升船机塔柱横梁混凝土浇筑的结构特点以及施工特性,总结了三峡升船机续建工程顶部横梁混凝土的施工技术,即采用分层、分块浇筑的办法,通过科学计算后进行合理的施工机械布置和浇筑施工管理,以保证塔柱横梁混凝土的施工质量。通过对贝雷架支撑系统的监测结果分析可知,贝雷架支撑系统的应力变形、挠度变形以及排架变形均满足施工承载要求,筒体位移亦满足技术要求,贝雷架支撑系统稳定、安全。三峡升船机塔柱横梁混凝土施工实践证明了本技术方案的有效性与可靠性,亦可为类似工程的施工组织设计与现场实施工作提供一定的参考。     

三峡升船机塔柱混凝土温控防裂技术

三峡升船机塔柱结构复杂,属于高层薄壁结构,混凝土温度受环境温度影响较大,其混凝土温控难度极大。在施工实践中,通过优化混凝土配合比、合理布置混凝土冷却系统、科学调控冷却水温度与通水时间,科学调整外部环境温度、同时引进混凝土养护新材料、新工艺,并且加强对温控的施工管理等措施,保证了塔柱混凝土的施工质量,证明了温控方案的科学合理性。三峡升船机塔柱混凝土温控防裂技术对研究国内外升船机工程温控措施技术水平,提高水电工程混凝土施工质量,节省工程造价等具有重要的参考价值。     

三峡升船机塔柱混凝土施工测量技术

针对三峡垂直升船机高薄壁塔柱结构混凝土形体及内置埋件施工精度指标要求,对三峡升船机塔柱混凝土及内置埋件施工测量中的平面、高程基准传递及埋件定位测量方法进行了研究。分别将天顶仪投点、电磁波测距及中心带照准标志的圆柱螺帽型定位装置施工测量技术运用于混凝土结构尺寸控制测量以及内置埋件定位测量。通过对实测数据的统计与分析,证明三峡升船机塔柱混凝土施工测量技术方案具有可靠性和可行性。     

三峡工程齿轮齿条爬升式升船机设计

三峡升船机具有提升重量大、升程高、上下游通航水位变幅大、水位变率快等特点,是目前世界上规模和技术难度最大的升船机。经过方案比选,三峡升船机最终确定采用齿轮齿条爬升式,其设备构造复杂,制造、安装及土建结构施工精度要求很高,并首次采用中德联合设计方式。概要介绍了三峡工程齿轮齿条爬升式升船机的总体布置、以及塔柱结构、重要设备的设计方案与关键技术。     

三峡升船机横梁贝雷架支撑系统荷载试验

在三峡升船机续建工程中,针对塔柱横梁施工支撑体系复杂的特点,在横梁混凝土浇筑前进行荷载试验。试验选取轴1、轴2横梁及其相应的基础梁贝雷架作为模型,按照1∶1进行荷载原型试验,通过布置监测点以及采用合理的检测频率,完成试验数据的采集与分析。本次试验取得以下成果：得出了各类型杆件在加载过程中的最大应力值;随着加载量的增加,横梁、基础梁贝雷架的挠度变化量慢慢增大,模板及排架立杆高程在下降;随着加载量的增加,横梁、基础梁贝雷架都发生了较小的侧向位移,轴2横梁模板左右方向变化量和排架立杆垂直度左右方向变化量均很小;试验监测数据表明,经加强后的贝雷架杆件加载后的各项参数满足安全要求,技术方案可应用于塔柱横梁施工,保证升船机塔柱横梁施工安全。     

三峡升船机贝雷架安装与拆除技术

三峡升船机塔柱横梁贝雷架支撑体系的安装与拆除属于高空立体交叉作业,而且施工场地狭窄、施工强度大,贝雷架的安装与拆除所受到的施工干扰大,是三峡升船机塔柱施工中的难题之一。本文通过对贝雷架施工作业环境的系统分析,根据不同部位的特点与要求,制定了有针对性的包括施工设备布置、吊装单元划分、吊点设置、各部位拆除方案在内的塔柱横梁贝雷架安装及拆除施工技术体系。该技术体系在三峡升船机贝雷架安装及拆除工程中得到顺利实施,塔柱横梁贝雷架支撑系统的施工进度、施工成本及施工安全均实现了良好的效果,表明该技术方案合理可靠。本文中贝雷架的安装与拆除施工技术体系可为类似条件下的贝雷架安装和拆除施工提供参考借鉴。     

三峡升船机船厢室段混凝土浇筑设备布置研究

本文详细介绍了三峡升船机船厢室段混凝土施工设备的选型过程,包括船厢室段混凝土施工特性分析,投标阶段浇筑设备选型论证,施工阶段对设备选型的系统调整和优化。施工设备的工程实践效果表明,三峡升船机船厢室段混凝土浇筑设备布置方案有效覆盖了所有浇筑面,满足浇筑高峰期混凝土入仓强度的要求,施工进度、成本、安全均得到有效控制。三峡升船机船厢室段混凝土浇筑设备经过前期的合理规划,以及后期的系统调整与优化,对三峡升船机工程的顺利完建发挥了重要作用,具有较高的推广应用价值。     

三峡升船机船厢室施工程序研究

针对三峡升船机船厢室平衡重和船厢荷载的施加顺序对塔柱埋件结构部位变形的影响,对船厢室的施工顺序和设备安装顺序方案进行了研究,解决了船厢和平衡重荷载的施加顺序对螺母柱、齿条和纵向导向变位影响的施工技术难题。根据对塔柱结构进行的仿真计算结果,分析了船厢与平衡重荷载施加顺序分别对螺母柱、齿条、纵向导向部位横河向、顺河向和竖向变形的影响,通过对施工程序优化提出了合理的升船机船厢室的施工程序以及施工总进度计划安排。该施工程序能够使螺母柱、齿条、纵向导向、船厢结构与塔柱在各工况下的位移满足安全要求,并且基于该施工程序的施工进度满足升船机试运行要求。工程实践证明了本文所建立的三峡升船机船厢室施工程序的合理性与科学性,确保了三峡升船机船厢室的顺利施工,保障了升船机的安全运行,可为类似升船机船厢室的施工提供参考。     

水工高精混凝土施工技术创新与实践

本文以三峡工程升船机中的高精混凝土施工为背景,阐述了水工高精混凝土的涵义、施工技术要点以及施工实践。详细介绍了三峡升船机高精混凝土施工的主要精度控制标准、高精度测量技术、高精混凝土施工技术和混凝土形体检测结果。     

三峡升船机塔柱横梁支撑系统设计

本文介绍了三峡升船机塔柱横梁混凝土施工支撑系统的实施方案,从贝雷架支撑体系所承受荷载要求、结构强度要求以及变形稳定性要求出发,通过科学计算制定出合理的贝雷架支撑系统的支座系统设计方案、结构设计方案以及上部钢管排架设计方案,并对贝雷架支撑系统以及相应的塔柱混凝土墙体结构在混凝土浇筑前后以及混凝土浇筑过程中的应力（应变）、变形、位移进行了监测。监测结果表明,横梁支撑系统满足了横梁浇筑支撑要求,施工质量优良,安全可靠,设计与施工方案可行。     

国内结构混凝土疲劳性能研究现状

对国内结构混凝土疲劳性能的研究动态进行了较为全面详细的阐述。着重阐述了应用较多的钢筋预应力混凝土、高强混凝土、高性能混凝土、纤维混凝土的疲劳研究,同时简单介绍了活性粉末混凝土和多孔混凝土疲劳性能的研究。通过对国内各类结构混凝土疲劳性能研究现状分析,以期对国内研究者以后研究混凝土疲劳性能有所帮助。最后提出研究结构混凝土在多重环境因素耦合作用下疲劳性能的必要性。     

Polyolefin fiber-reinforced concrete enhanced with steel-hooked fibers in low proportions

Over the past few years, polyolefin fiber reinforced self-compacting concrete has shown high performance in both fresh and hardened state. Its fracture behavior for small deformations could be enhanced with a small amount of steel-hooked fibers, obtaining a hybrid fiber-reinforced concrete well suited for structural use. Four types of conventional fiber-reinforced concrete with steel and polyolefin fibers were produced on the basis of the same self-compacting concrete also manufactured as reference. These concrete mixtures were manufactured separately with the same fiber contents being subsequently used for two more hybrid mixtures. Fracture properties, in addition to fresh and mechanical properties, were assessed. The research showed both synergies (with the two types of fibers working together in the fracture processes) and an improvement of the orientation and distribution of the fibers on the fracture surface.     

某厂房地面工程混凝土裂缝病害分析

正确检测、分析混凝土结构裂缝的性状、成因及发展趋势,是鉴定结构安全性、实用性和耐久性及制定处理决策的技术依据。地面工程中混凝土结构易出现裂缝问题,大多由配合比、施工方法、环境等多种因素共同作用导致。本文结合工程实例,对某厂生产车间地面工程裂缝原因进行鉴定和分析,为其他类似工程防治裂缝与施工提供借鉴和参考。     

建筑结构中混凝土的裂缝分析、特征与控制

混凝土的裂缝是一个普遍存在的问题，是建筑工程中确保工程质量不容忽视的重要环节之一。本文从一般的理论和多年的现场经验，通过观察及查阅有关资料，对混凝土裂缝产生的原因、特征及控制措施进行阐述。     

纳米材料在混凝土中的研究与应用 第十三届全国结构工程学术会议特邀报告

介绍了纳米材料的一些特性,讨论了纳米SiO2及硅粉对混凝土强度和耐久性能的改善作用。纳米SiO2及硅粉作为外掺料可制备高性能混凝土.纳米材料作为外掺抖还可用以制备具有特殊功能的混凝土。例如,添加纳米金属氧化物可制备智能混凝土和环保混凝土。添加纳米金属粉末可制各电磁屏蔽混凝土等。     

Measurement of Workability of Fresh Concrete Using a Mixing Truck

The main objective of this study is to evaluate the workability of fresh portland cement concrete while it is still in the mixing truck by determining fundamental rheological parameters (plastic viscosity and yield stress). Nine concrete mixtures with different values of yield stress and plastic viscosity were tested in a concrete truck. The measurements made with the truck were based on the typical method of determining the flow behavior in a traditional fluid rheometer; that is, the shear rate in the mixing truck was swept from high to low by varying the rotation speed of the drum. The results of these experiments are discussed and compared with data provided by the ICAR rheometer, a portable rheometer designed for measuring concrete rheology. The test results indicate that the mixing truck equipment is sufficiently sensitive to detect differences in yield stress, slump, and plastic viscosity. However, the plastic viscosity determined by the truck measurement did not correlate with plastic viscosity as measured by the ICAR rheometer, while the yield stress determined by the truck measurement did correlate well with the measured slump and the ICAR rheometer resultsSuggestions are given on how to improve the mixing truck for better use as a rheometer.     

Creep behaviour of FRP-reinforced polymer concrete

Polymer concrete is a kind of concrete where natural aggregates such as silica sand or gravel are binded together with a thermoset resin, such as epoxy. Although polymer concretes are stronger in compression than cementitious concrete, its tension behaviour is still weak. The reinforcement of polymer concrete beams in the tension zone with pultruded profiles made of epoxy resin and glass fibers are a good compromise between stiffness and strength. In this paper it is reported an investigation of the creep behaviour of polymer concrete beams reinforced with fiber-reinforced plastics (pultruded) rebars. Four-point bending creep test were performed. An analytical model was applied to verify the experimental results.     

Polymers in concrete: a vision for the 21st century

Polymers in concrete have received considerable attention over the past 25 years. Polymer-impregnated concrete (PIC) was the first concrete polymer composite to receive widespread publicity. PIC has excellent strength and durability properties, but it has few commercial applications. Polymer concrete (PC) became well known in the 1970s and is used for repair, thin overlays for floors and bridges, and for precast components. Polymer-modified concrete (PMC) has been used primarily for repair and overlays. Several limitations have slowed the use of concrete polymer materials. However, there are many current and future uses for these materials that will effectively use their unique properties. Improved, automated repair methods, improvements in materials, replacements for metals, structural applications, and architectural components will prove to be popular uses of concrete-polymer materials.     

Constitutive modeling of reinforced concrete and prestressed concrete structures strengthened by fiber-reinforced plastics

A batch of constitutive models for steel reinforcing bar, prestressing tendon, concrete and fiber-reinforced plastic are proposed for the nonlinear finite element analysis of reinforced concrete structures, prestressed concrete structures, reinforced concrete structures strengthened by fiber-reinforced plastics and prestressed concrete structures strengthened by fiber-reinforced plastics. These material models have been tested against series of experimental data and good agreements have been obtained, which justifies the validity and the usefulness of the proposed nonlinear constitutive models.     

Two-layer pre-stressed beams consisting of normal and steel fibered high strength concrete

The paper is focused on analysis of two-layer bending pre-stressed beams consisting of steel fibered (SF) high strength concrete (HSC) in compressed zone and normal strength concrete (NSC) in tensile zone. Investigation of such beams is important for RC structural design, because calculation of fibers volume ratio is significant, like that of reinforcing steel bars for usual RC elements. In other words, such elements are made of high performance concrete (HPC). There is a growing tendency that more effective HPC structures replace NSC ones, first of all in pre-stressed elements. Definition of the HSC class lower limit, to be used in the compressed zone of a two-layer pre-stressed beam, is given. It was demonstrated that SF have little effect on the beam elastic deflections. However, the ultimate deflections of the section increase because additional potential for plastic energy dissipation (PED) in the bending element. NSC, used in the section tensile zone, contributes additionally about 20% to the section’s PED potential compared to one-layer HSC beams. In order to guarantee sufficient section’s ductility of the pre-stressed beams, required to withstand dynamic loadings, a minimum SF ratio is proposed to be considered. The fibers take the tensile stresses, yielding cracks in the concrete matrix. A design method for calculation of the SF volume ratio, as a function of required ductility, is proposed. A numerical example, illustrating the efficiency of this method is presented.