干熄焦锅炉炉管失效机理分析

通过对干熄焦锅炉炉管及腐蚀产物开展系统研究，提出炉管失效原因为氧化/硫腐蚀＋高温粉尘冲刷。长寿命炉管仅耐磨层发生了较为严重的氧化及硫腐蚀，而近基体层发生了轻微氧化及硫腐蚀，基体只发生了轻微氧化；短寿命炉管耐磨层、近基体层以及基体裂纹内均发生了较为严重的氧化及硫腐蚀，且存在珠光体球化、内表面产生全脱碳层等缺陷。推测短寿命炉管存在超温现象，而超温可加剧氧化及硫腐蚀反应。此外，短寿命炉管遭受了较为严重的高温粉尘冲刷，不仅可造成炉管减薄，还会导致炉管表面温度升高。因此，减少循环气体中粉尘量尤其是大颗粒，可有效减弱冲刷以及控制炉管表面温度，是提高炉管使用寿命的关键。     

桥渡冲刷计算方法分析

对各类冲刷公式建立的依据以及公式的适用条件进行了分析,介绍了公式发展历史,并提出现在应用这些公式所面临的问题以及解决方法,为桥下河槽冲刷的进一步研究提供了理论基础。     

Management of bridges with shallow foundations exposed to local scour

Abstract

The Serbian road network includes a large portion of bridges with shallow foundations vulnerable to local scour as tragically demonstrated during the extreme flooding in May 2014. Currently, the bridge management procedures in Serbia and worldwide do not comprehensively account for a risk of bridge failure due to flooding and fail to provide sufficient information for the decision-making. Thus, a novel methodology for quantitative vulnerability assessment is suggested as a tool to identify the most vulnerable bridges in a network. Herein, the essential task is evaluation of the conditional probability of a bridge failure due to local scour in a flooding event of a certain magnitude. To apply this approach on a network level, there is a dire need to establish precise practice-ready guidelines on an optimal set of information to be used and/or collected in situ, which is discussed on an example of the Serbian bridge database. The vulnerability of a bridge to local scour may be used as a comprehensive indicator of a bridge performance in a flooding event. For a network level, the vulnerability maps with respect to flooding of different magnitudes will give road operators crucial information to apply adequate quality control plans to vulnerable bridges.     

三峡库区奉节河段库岸蓄水再造研究

通过二维水流泥沙数模计算，分析了三峡库蓄水后棒节河段的泥沙淤积量、流场、近岸流速及浪高等的变化；探讨了岸坡可能的3种再造形式；冲刷塌岸、整体滑移、岩坡崩塌；建立了库岸冲刷塌岸的预测模型，并进行了预测；计算分析了不同水位、冲刷淤积、地震等工况下典型滑坡的稳定性变化规律；最后，对库岸再造的工程防治措施提出了建议。     

Scour evaluation for foundation of a cable-stayed bridge based on ambient vibration measurements of superstructure

This study develops a foundation scour evaluation method merely using the ambient vibration measurements taken from the superstructure of a cable-stayed bridge. Various modal frequencies of girder and those of the local pier are first identified for Kao-Ping-Hsi Bridge. The finite element model of this bridge is then constructed to perform the modal analysis with original design parameters. Combining the above results, this work further determines the best boundary support conditions for the model to fit the identified modal frequencies of bridge girder. According to this globally best fitted model, the optimal soil stiffness is first decided by fitting the critical bridge frequencies with a known deposit height at the pylon. Subsequently, the scour depth at a pier can be estimated by varying the depth of its supporting soil to fit the two sensitive frequencies of local pier modes. Finally, a direct measurement scheme is carried out to verify the estimated scour depth.     

预应力小箱梁水文计算分析

结合滦河镇大桥工程概况,简述了桥梁截面形式及截面尺寸,根据设计流量进行了小箱梁水文计算,包括冲刷计算及桥孔长度计算,从而为确定桥梁跨径是否合理提供了参考。     

苏通大桥索塔深水群桩基础冲刷防护工程的设计与施工

从苏通大桥深水群桩基础结构方案出发,分析了冲刷及防护对大桥安全性的影响,进而从防护工程理念、结构设计与施工、防护效果监测等方面阐述了苏通大桥基础冲刷难题的解决方法.     

管道穿河埋深综合判定

管道穿河的埋深问题一直是岩土工程勘察的重点问题，埋深过浅会导致洪水来临时，管道被冲刷露出，造成安全问题；埋深过深会增加不必要的经济浪费。但是对于埋深计算，一直没有相关规范出台，实际应用中多是相关经验公式粗略估计。这些经验公式常由于假设或使用条件的限制，存在较大的差异。在综合考虑各公式计算前提的基础上，评判该前提条件对计算结果的影响，并依此锁定埋深计算的上下限之间的差值，为最终可靠的断定埋深提供了重要的参考。     

Flow measurement around scoured bridge piers using Acoustic-Doppler Velocimeter (ADV)

Recently flow investigation around cylindrical obstacles has attracted much attention considering its application to river and offshore environment. Scour around obstacles is the major cause of their foundation failure. This failure occurs in extreme cases of unsteady flows interacting with a given structure and with changing bed condition. In order to reduce the tremendous amount of expenses involved in either over-designing those foundations or rebuilding damaged structures, precise flow measurement instrument is essential. In the present study, the Acoustic-Doppler Velocimeter (ADV) has been utilized in the laboratory to investigate the flow characteristics around cylindrical piers on a scoured bed under various wave-current combinations. Some of these results are reported in this paper and the suitability of the ADV in this field is explained.     

新型地锚扶壁式泥石流格栅坝基础冲刷计算方法研究

泥石流格栅坝工程安全稳定的关键是基础,相比外露结构的计算,基础遭冲刷掏空的问题更值得引起重视。在提出新型地锚扶壁式泥石流格栅坝的基础上,将格栅坝基础冲刷分为初期和中后期两个阶段,初期冲刷主要以坡面冲刷为主,中后期冲刷主要考虑冲坑的变化发展。基于能量法,推导了格栅坝基础冲刷深度的计算公式,通过算例分析了不同流深下的冲刷深度,并与其它公式的计算结果做了对比。结果表明:推导公式计算的冲刷深度比其它公式计算的结果都大,初期冲刷的影响在设计中应当予以重视。