Dynamic Response of Foundations during Startup of High-Frequency Tunnel Equipment

The specialized equipment utilized in long-line tunnel engineering is evolving towards large-scale,multifunctional,and complex orientations.The vibration caused by the high-frequency units during regular operation is supported by the foundation of the units,and the magnitude of vibration and the operating frequency fluctuate in different engineering contexts,leading to variations in the dynamic response of the foundation.The high-frequency units yield significantly diverse outcomes under different startup conditions and times,resulting in failure to meet operational requirements,influencing the normal function of the tunnel,and causing harm to the foundation structure,personnel,and property in severe cases.This article formulates a finite element numerical computation model for solid elements using three-dimensional elastic body theory and integrates field measurements to substantiate and ascertain the crucial parameter configurations of the finite element model.By proposing a comprehensive startup timing function for high-frequency dynamic machines under different startup conditions,simulating the frequency andmagnitude variations during the startup process,and suggesting functions for changes in frequency and magnitude,a simulated startup schedule function for high-frequency machines is created through coupling.Taking into account the selection of the transient dynamic analysis step length,the dynamic response results for the lower dynamic foundation during its fundamental frequency crossing process are obtained.The validation checks if the structural magnitude surpasses the safety threshold during the critical phase of unit startup traversing the structural resonance region.The design recommendations for high-frequency units’dynamic foundations are provided,taking into account the startup process of the machine and ensuring the safe operation of the tunnel.

Towing characteristics of large-scale composite bucket foundation for offshore wind turbines

In order to study the towing dynamic properties of the large-scale composite bucket foundation the hydrodynamic software MOSES is used to simulate the dynamic motion of the foundation towed to the construction site.The MOSES model with the prototype size is established as the water draft of 5 and 6 m under the environmental conditions on site.The related factors such as towing force displacement towing accelerations in six degrees of freedom of the bucket foundation and air pressures inside the bucket are analyzed in detail.In addition the towing point and wave conditions are set as the critical factors to simulate the limit conditions of the stable dynamic characteristics.The results show that the large-scale composite bucket foundation with reasonable subdivisions inside the bucket has the satisfying floating stability.During the towing process the air pressures inside the bucket obviously change little and it is found that the towing point at the waterline is the most optimal choice.The characteristics of the foundation with the self-floating towing technique are competitive for saving lots of cost with few of the expensive types of equipment required during the towing transportation.

Design of Large-Scale Prestressing Bucket Foundation for Offshore Wind Turbines

The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads. The finite element model of a large-scale prestressing bucket founda- tion for offshore wind turbines is set up and the structural characteristics of the arc transition structure of the founda- tion are analyzed for 40-60 channels(20-30 rows) arranged with prestressing steel strand under the same ultimate load and boundary conditions. The mechanical characteristics of the key parts of the foundation structures are illus- trated by the peak of the principal tensile stress, the peak of the principal compressive stress and the distribution areas where the principal tensile stress is larger than 2.00 MPa. It can be concluded that the maximum principal tensile stress of the arc transition decreases with the increasing number of channels, and the amplitude does not change signifi- cantly; the maximum principal compressive stress increases with the increasing number of channels and the amplitude changes significantly; however, for the distribution areas where the principal tensile stress is larger than 2.00 MPa, with different channel numbers, the phenomenon is not obvious. Furthermore, the principal tensile stress at the top of the foundation beams fluctuantly increases with the increasing number of channels and for the top cover of the bucket, the principal tensile stress decreases with the increasing number of channels.

One-Step-Installation of Offshore Wind Turbine on Large-Scale Bucket-Top-Bearing Bucket Foundation

In 2010,the first offshore wind turbine with integrated installation was established in Qidong sea area of Jiangsu Province,China,which led to the implementation phase of one-step-installation technique based on the design and construction of large-scale bucket-top-bearing (LSBTB) bucket foundation.The critical technique of LSBTB bucket foundation included self-floating towing,penetration with adjustment of horizontal levelness,removability and one-step-installation.The process of one-step-installation included the prefabrication of LSBTB bucket foundation in onshore construction base,installation and debugging of wind power,overall water transportation of foundation and wind power system,and installation of foundation and offshore wind turbine on the appointed sea area.The cost of one-step-installation technique was about 5 000 Yuan/kW,which was 30%-50% lower than that of the existing technique.The prefabrication of LSBTB bucket foundation took about two months.During the one-step-installation process,the installation and debugging of wind power and overall water transportation need about one to two days in sea area within 35 m depth.After the proposed technique is industrialized,the cost will be further reduced,and the installation capacity is expected to be up to 500 wind turbines per year.

Opening and Sharing of Large-scale Instruments and Equipment in Agricultural Research Institutes:A Case Study of Environment and Plant Protection Institute of Chinese Academy of Tropical Agricultural Sciences

The article introduces the main practices and achievements of the Environment and Plant Protection Institute of Chinese Academy of Tropical Agricultural Sciences in promoting the sharing of large-scale instruments and equipment in recent years,analyzes the existing problems in the management system,management team,assessment incentives and maintenance guarantee,and proposes improvement measures and suggestions from aspects of improving the sharing management system,strengthening management team building,strengthening sharing assessment and incentives,improving maintenance capabilities and expanding external publicity,to further improve the sharing management of large-scale instruments and equipment.

Research of Personnel Operational Ability Evaluation of Large-scale Complex Equipment

The level of personnel operation ability determines the expected effectiveness of large-scale complex equipment. Firstly, this paper constructs the personnel operational ability evaluation index system and analyzes the data source of index. Secondly, the weight of index is determined and the fuzzy comprehensive evaluation model is proposed. Finally, results of instance analysis show that the evaluation model is feasible and effective.

Vibration Isolation Characteristics of Impedance-balanced Ship Equipment Foundation under Unbalanced Excitation

A new type of impedance-balanced ship equipment foundation structure based on the principle of impedance balancing using a“discontinuous panel-vibration isolation liquid layer-foundation structure”is proposed to solve the problem of poor low-frequency vibration isolation of the foundation under unbalanced excitation of shipboard equipment.Based on the finite element method,the influence of characteristic parameters of the foundation panel structure on its vibration reduction characteristics under unbalanced excitation is explored.The results show that the vibration isolation level of the impedance-balanced foundation is 10 dB higher than the traditional foundation in the low-frequency band of 10-500 Hz when subjected to combined excitation of concentrated force and moment.Increasing the thickness of the impedance-balanced foundation panel can enhance the isolation effect.Increasing the number of sub-panels can effectively reduce the vibration response of the foundation panel and enhance the isolation performance of the foundation.The connection stiffness between sub-panels has a small effect on the isolation performance of the foundation.

European Offshore Wind Gravity Foundation

The development history of the offshore wind gravity foundation in Europe is briefly introduced.Sumnarized in which the equipment relates to offshore wind power installation,including ships and special equipment related to wind power installation.And the installation method and technology of gravity foundation are analyzed.The development trend of the offshore wind power gravity foundation is put forward.

精密设备防微振基台动力特性分析与研究

电子制程产业属于高投入、高产出的技术密集型行业,其精密工业设备对微振动环境要求较严格,因此防微振基台尤为重要。基于有限元分析与工程实测方法,分析基台板厚对防微振基台结构固有频率、动刚度等动力特性的影响,并结合精密设备容许振动标准对不同厚度基台振动响应进行振动评估,为精密设备防微振基台设计提供理论依据和制程。

热缩型纤维调控大体积混凝土抗裂性能研究

研究了高模量热缩型纤维与具有高微细连通孔的内养护集料协同作用对大体积混凝土力学性能、抗裂性能、收缩性能的影响,并进行了微观机理分析。结果表明:复掺热缩型纤维和内养护集料对大体积混凝土力学性能影响较小,但能明显提高大体积混凝土的抗裂性能并降低收缩变形,最大裂缝宽度和单位面积的总开裂面积较基准组分别降低了85.7%、94.9%,干燥收缩值降低了47.6%。SEM分析表明,热缩型纤维及内养护集料与胶凝浆体紧密结合、界面致密,从而提高了大体积混凝土的抗裂性能。

过程设备机械设计基础与制图集中教学改革探索

过程设备基础、制图、课程设计通常以分散教学模式面向工科学生,存在学生难以发现知识之间的内在联系、知识体系受限、学习兴趣不高等问题,而集中教学模式可以提高教学知识的丰富度和关联度。依托华东理工大学机械与动力工程学院教学优势,开展了过程设备基础、制图、课程设计三合一集中教学,实现了由简入繁的课程衔接,形成了紧密配合的教学进度,改革教学效果评价方式,提高了学生的学习兴趣,加深了专业知识的教学深度,为全国同类课程的改革实践提供了借鉴。

大跨度门式起重机在受限空间宽大基坑中的改造与应用

门式起重机因其结构合理、安全可靠、稳定性好、适应性强等优点,在很多深基坑工程被广泛应用。结合在城市交通繁忙路段宽大深基坑工程施工的实例,针对基坑施工时面临的周边环境复杂、实施空间狭小、吊装作业量大等问题,提出两种垂直运输方式,经方案综合比选,深基坑垂直运输设备采用跨度62m的大跨度门式起重机。通过门式起重机的改造设计、荷载分析及受力验算,结果均满足要求,经现场安装与使用,提出总结了安装和使用过程中的控制要点,为后续类似受限空间工程设计采用门式起重机作为垂直运输设备,提供了一定的借鉴。

市政桥梁钢箱梁梁段安装施工技术分析

为进一步探究市政桥梁钢箱梁安装施工技术要点,文章结合某地市政桥梁工程的实际案例展开研究,讨论了施工准备阶段的地基处理和设备选型,后从节段划分、吊装、合龙与焊接四个环节着手,详细探讨了市政桥梁钢箱梁梁段安装施工技术的具体流程与应当遵循的要点,并对此次施工效果进行评价。结果显示,此次施工作业各项主要指标均符合预期,因此此次施工作业所总结的经验具有一定的参考价值。

生物质电厂特殊振动设备基础振动分析浅探

针对生物质等电厂各类动力设备振动而引起的基础问题,结合实际的动力荷载,通过对设备及其基础在满负荷条件下的振动检测对比分析,了解其时域、频域特征等动力特性,明确现有基础的振动水平与特性。实测和研究结果表明,桩基对于水平、竖向振动均有良好的抑制作用。

液压挖掘机改装设备在浅层加固施工中的应用研究

研究以液压挖掘机改装软土地基浅层加固设备为对象,结合工程实例,探讨了施工准备、施工方法和工艺、就地固化质量检测等方面的内容。通过对原材料的严格检测、施工方法的详细描述以及就地固化处理层厚度、强度和承载性能的测试,确保了工程质量和持久性达到设计要求,其可为日后的路面使用提供可靠保证。

山地光伏升压汇集站施工技术研究

针对山地光伏升压汇集站的施工技术展开研究,旨在提高施工效率和质量,确保光伏发电系统安全可靠运行。通过分析山地光伏升压汇集站施工的特殊性,结合具体案例,提出了针对设备基础、电气安装、站区道路以及站区围墙的施工技术优化方案。

储能设备基础侧壁基于全过程因素的选型分析

基础侧壁的做法选型对储能土建工程有重要影响,合理的基础侧壁选型关系工程的施工经济性、及时履约性、质量可靠性。文章结合实际工程,从设计合理性、造价成本、施工工期、质量控制全过程因素等方面出发,对储能设备基础侧壁的两种选型方案进行了量化分析,为优化工程管理目标、降低土建作业运营决策风险提供了方向与指导,可供实际工程参考应用。

桩基础掘进装备施工工艺分析与控制系统开发

电网建设关系社会民生,系统推进“六精四化”工作,有助力促进产业竞争力,而机械化是其进程中难度高、开展阻力大、技术融合度高的一项工作,文中在前期完成的桩基础掘进装备样机基础之上,剖析结构组成及工作原理,深入分析施工作业过程中的工作轨迹与工艺参数,采用先进的模糊控制理论与PID算法相结合的控制技术,开发出一套适用于多地质结构的控制系统,实验表明,此控制系统能满足种类桩基础条件的施工作业,有助于为电力系统桩基础施工提供实际工程应用价值。

大型竖井凿井大临工程快速施工实践与探讨

在山东黄金集团焦家金矿朱郭李家副井井筒凿井大临工程施工中,采用整体钢结构组合模板进行井架基础施工,利用砖砌墙支撑设备整体浇筑和凿井井架整体吊装。通过合理地布置施工顺序、优化基础施工方法和科学管理等措施,在工期、质量和安全等方面取得了非常好的效果,实现了立井大临工程快速优质施工的目标。

地铁上盖大型机械设备基础施工关键技术

地铁交通这类速度快、舒适性高、换乘方便的交通方式正逐渐成为各大城市基础设施建设的重点。地铁交通的建设往往留下大量的地铁上盖空间,大型机械设备基础如何克服地铁上盖这一不利条件,在保证安全的前提下更好地为地铁上盖空间的开发服务,成为一个亟待解决的问题。本文从塔吊设备基础的设计、连接节点做法、基础短柱加强等方面,提出一种针对地铁上盖大型机械设备基础施工关键技术,可为其他同类型地铁上盖项目的大型机械设备基础提供借鉴。