重大水利水电工程施工实时控制关键技术及其工程应用

高心墙堆石坝和高混凝土坝的施工质量与施工进度控制是工程建设的重要技术问题。针对常规人工控制手段难以确保高心墙堆石坝施工质量,以及高强度连续施工下高混凝土坝施工进度难以实时控制等问题,提出了高心墙堆石坝填筑碾压质量实时监控技术、坝料上坝运输过程实时监控技术和施工质量动态信息PDA实时采集技术,实现了大坝填筑碾压全过程的全天候、精细化、在线实时监控;在建立高混凝土坝施工进度实时控制数学模型基础上,提出了施工进度实时预警与动态调整方法,为高混凝土坝施工进度的实时预测、适时预警、动态调整与优化提供了分析手段;提出了网络环境下数字大坝系统集成技术,研制开发了数字大坝系统,为大坝竣工验收、安全鉴定及运行管理提供了支撑平台。成果已应用于10余项重大工程,取得了显著的经济效益和社会效益。     

常州高架沥青混凝土施工中碾压质量控制

碾压是沥青路面施工中的最后一道工序,文章从常州高架沥青混凝土施工过程分析了沥青路面压实机理,探讨了沥青路面压实工艺流程,提出碾压施工质量控制措施。     

某水电站大坝斜层碾压混凝土施工技术

碾压混凝土坝是某水电站的主体建筑物。针对某碾压混凝土重力坝的特点,全面应用国内斜层碾压混凝土施工的先进技术,制定了科学合理的施工技术措施,文章详细介绍了某水电站大坝斜层碾压混凝土坝的施工技术。     

水利工程碾压混凝土施工技术的现状及发展

自1974年开始研究碾压混凝土大坝以来,该项技术已取得了巨大进步。现在,在气候条件不同的许多国家中,都在修建碾压混凝土大坝。正在建造的碾压混凝土大坝比其他类型的坝多。碾压混凝土大坝的高度和体积已大大增加。本文阐述了国外碾压混凝土施工技术的现状及发展及我国碾压混凝土筑坝技术的发展历程和特点。     

碾压混凝土坝钻芯检测与分析

论述了碾压混凝土坝钻芯检测工艺流程,以及芯样的获取、编录和标识等过程关键注意事项,分析了芯样的对碾压混凝土坝铺筑过程的再现程度,以及芯样分析对碾压混凝土坝内部质量的可行性评价。     

高心墙堆石坝填筑施工过程实时监控系统研发与应用

文章针对高心墙堆石坝填筑施工特点,建立了过程控制指标体系,确定了过程监控方法,提出了解决方案,研制开发了具有实时性、高精度、自动化、全天候等特点的大坝填筑施工过程监控系统,实现土石料上坝运输过程、坝面填筑碾压过程的实时监控。该系统应用于亚洲第一高土石坝———糯扎渡心墙堆石坝的施工现场,建立了以监控系统为核心的施工过程控制体系,对大坝填筑施工的主要环节实现精细化的全天候实时监控,有效地控制了大坝填筑施工参数,提高了施工过程的质量控制水平与效率。     

碾压混凝土坝施工质量管理

本文主要从试验工作、温控、缝面处理及现场生产管理等几个方面阐述了碾压混凝土坝在施工过程中的质量管理措施和方法。     

水利工程大坝碾压砼的施工分析

将水泥、粉煤灰、粗骨料和砂等的材料进行拌合,由此形成一种不具有塌落度的超干硬性混凝土,这称为碾压混凝土。用碾压机械的强力振动和碾压的共同作用对超干硬性混凝土压实的施工技术称为碾压混凝土的施工技术,用这种方法修筑的坝称为碾压混凝土坝,本文对混凝土的碾压工艺流程、碾压混凝土的施工配合比以及碾压方式、层间处理、养护等水利工程大坝混凝土碾压施工进行了分析。     

混凝土面板堆石坝填筑料碾压方法研究

洪家渡电站混凝土面板堆石坝填筑伊始，本文就该坝填筑施工中使用的自行式振动碾已采用的或将采用的几种碾压方法的施工效率、质量控制、适宜条件等工程指标的分析比较，旨在抛砖引玉为后续施工中针对不同的施工条件及多种压实机械优选合理的、经济的碾压方法和施工参数组织施工。     

多层结构模型在龙滩碾压混凝土坝应力分析中的应用

本文提出一种设想棗采用多层结构模型分析碾压混凝土坝的应力特点。在详细推导多层结构模型弹塑性公式的基础上,制定反映该模型特点的非线性计算方法;针对龙滩大坝的情况,提出碾压混凝土层面法向刚度的确定方法,进而对龙滩大坝的应力进行计算分析。结果表明,多层结构模型在高碾压混凝土坝的应力分析中具有一定的应用前景。     

高心墙堆石坝坝面碾压施工仿真理论与应用

在对高心墙堆石坝坝面碾压系统进行全面分析的基础上,提出了以填筑单元为仿真单位的碾压施工仿真理论,建立了能够反映碾压过程中不确定因素的精细化仿真模型,保证仿真贴近实际施工。研究成果在糯扎渡心墙堆石坝工程的填筑单元中得到了应用,验证了方法的可靠性,对于大坝现场碾压施工具有指导意义,为工程进度控制和管理提供了技术支持。     

Aligning laboratory and field compaction practices for asphalt – the influence of compaction temperature on mechanical properties

The approach used to identify a compaction temperature in the laboratory, based on binder viscosity, provides a single compaction temperature whereas, on-site, a roller operates within a temperature window. The effect on the density and mechanical properties of rolling during a temperature window remains unclear. Consequently, asphalt concrete binder mixtures were compacted in different temperature windows in the laboratory using a Roller Sector Compactor, and the observed phenomena were then related to field study observations. The results show that while similar densities can be achieved in a broad range of temperature windows, other mechanical properties such as fracture energy may decline up to 30% if compacted outside the optimum temperature window. These results indicate that a compaction temperature window should form part of mix design and quality control. The paper proposes specifying a compaction window based on temperatures and the resulting mechanical properties rather than a single compaction temperature.     

Influence of different roller compaction modes on asphalt mix performance

This study aims to investigate the relationship between different roller compaction modes and resulting mechanical performance. In order to accomplish these objectives, a trial asphalt pavement section was observed and monitored both during the paving and compaction processes. Asphalt mix was sampled from the paver to be used later in laboratory and evaluate the differences between compaction in-field and laboratory. Asphalt concrete mixes were prepared and compacted in the laboratory using a steel roller compactor, with varying factors that influence compaction in terms of compaction modes (static, vibratory and a combination of both), as well as effort and temperatures in order to attempt to simulate field compaction conditions. The identification of a harmonised compaction procedure for specimen fabrication able to produce mixtures with stiffness properties resembling field compacted mixtures was also investigated based on the performance-based test results.     

水平激振模式下压实系统动力学过程及响应特性研究

针对智能振动压路机水平激振特点,根据压实进程中土壤参数变化,按工况分阶段建立二自由度动力学模型,研究纯滚动、滑转、纯打滑三种工况下振动轮与土壤相互作用的动力学过程。以XG6133D型智能振动压路机为例,仿真分析压实系统时频响应特性。结果表明,随压实进程振动轮水平运动发生由单周期至倍周期变化,其时域波形波峰、波谷产生锯齿状、平顶状畸变,频谱呈现除基波外仅含丰富奇次倍谐波。时频响应特性研究可为预测压实状况及提高压实性能提供理论依据。     

碾压混凝土内时损伤本构模型

本文应用内时理论和损伤力学建立了碾压混凝土压剪及压压剪状态下的内时损伤本构模型。其特点是：混凝土的弹塑性特性由内时理论描述，而破坏由损伤力学来描述。前者使本构模型摆脱了一般弹塑性中屈服面的概念，从而简化了非线性计算过程；后者使微裂纹引起的软化、体积膨胀等都可由损伤变量来考虑；从而既反映了混凝土的本质特性，又使模型的参数和基本方程大大减少。应用本文建议的模型分析碾压混凝土压剪及压压剪状态剪应力－应变关系，所得计算结果与试验数据相符合，可作为碾压混凝土重力及拱坝设计的依据。     

碾压混凝土坝的等效连续本构模型

本文根据变形等效的基本原理，导出了一个等效连续的本构模型，并给出了碾压混凝土层间真实应力的估算式，为复杂成层结构的应力分析提供了一条系统的简化计算技术路径．     

The Effect of Agglomeration Methods on the Micromeritic Properties of a Maltodextrin Product, Maltrin 150™

Maltrin M150 is a fine powder of maltodextrin which is a carbohydrate product made by controlled hydrolysis of corn starch. Agglomerated Maltrin was prepared using a fluidized bed granulation process and a roller compaction method, respectively. The micromeritic properties of these two granular products were compared. Three different sizes of granules (20/30, 40/50 and 80/100 mesh size) were used in the evaluation. Granules produced by the fluidized bed method showed a relatively low bulk density as compared to the roller compacted granules. As the granule size was reduced, the roller compacted granules showed a decrease in bulk density while an increase in bulk density was seen in the fluidized bed granulated product. A better flowability of the roller compacted granules was demonstrated by a higher flow rate and a lower compressibility index. For a given compression pressure, roller compacted granules produced compacts with a lower tensile strength. A significant work-hardening effect was exhibited by the roller compacted product.     

A process model for the compaction and saturation of partially impregnated thermoset prepreg tapes

Automated manufacturing of composite materials is key to reducing cost and improving consistency in part quality. Modeling of manufacturing processes can identify influential material, geometric, and process variables, while providing a framework for their optimization and control. A process model has been formulated to describe the compaction and saturation of partially impregnated thermoset prepreg tapes during their placement, using a roller compaction and vacuum consolidation. The roles of various parameters that characterize the initial prepreg tape state and the final prepreg tape state are investigated. The model yields the degree of resin saturation in the tape with changes in its thickness after being compacted, due to an external pressure. The results estimate the degree of dry fiber region within the tape, which can provide vacuum pathways for air or volatile removal before consolidation and cure. The model can be adapted for different material constitutive relationships of tape compaction and saturation.     

Modification of α-lactose monohydrate as a direct compression excipient using roller compaction

Abstract

Roller compaction was used to prepare a direct-compressed lactose excipient using crystalline α-lactose monohydrate. The effect of various roller compaction process parameters (compaction pressure, compaction repetition, and speed ratio) on the characteristics of compacted α-lactose monohydrate was investigated. Results were compared with data obtained using industrial spray-dried lactose and lactose samples with different degrees of crystallinity. XRPD analysis revealed that roller compaction reduced the crystallinity of α-lactose monohydrate, and the resulting material is similar to spray-dried lactose in behavior as a direct compression excipient. Roller compaction introduced desirable characteristics to the raw α-lactose monohydrate by inducing changes in crystallinity and particle morphology. Scanning electron microscopy results indicated that the compaction process converted some of the original torpedo-shaped crystals of α-lactose monohydrate into a more cylindrical shape with rounded edges. Compaction pressure and repetition of compaction have a significant effect on the modification of the crystallinity of the processed, raw α-lactose monohydrate.