大瑞铁路澜沧江大桥工程边坡稳定性三维数值模拟分析

采用现场调查、工程地质分析和三维数值模拟方法,对在建大瑞铁路工程澜沧江大桥边坡稳定性进行了综合分析研究。澜沧江大桥是在建大瑞铁路的控制性工程之一,由于多种因素的综合作用,桥址岸坡发育延伸较长的顺坡向节理和近垂直的陡倾节理。右岸桥位工程开挖区位于一组较大型顺坡结构面的下方,岸坡稳定性直接关系到桥位的适宜性。综合研究表明,工程开挖后,右岸桥位上部岩体极易在顺坡向结构面的控制下发生滑移–拉裂式破坏,沿外倾结构面产生较大的位移,甚至可能失稳,需要进行专门的工程治理。左岸边坡岩体结构相对稳定,工程开挖后,位移将主要集中在开挖面附近的浅表层部位,不仅变形较小,影响范围也相对较小。      

Particle Swarm-Based Translation Control for Immersed Tunnel Element in the Hong Kong-Zhuhai-Macao Bridge Project

Immersed tunnel is an important part of the Hong Kong-Zhuhai-Macao Bridge (HZMB) project. In immersed tunnel floating, translation which includes straight and transverse movements is the main working mode. To decide the magnitude and direction of the towing force for each tug, a particle swarm-based translation control method is presented for non-power immersed tunnel element. A sort of linear weighted logarithmic function is exploited to avoid weak subgoals. In simulation, the particle swarm-based control method is evaluated and compared with traditional empirical method in the case of the HZMB project. Simulation results show that the presented method delivers performance improvement in terms of the enhanced surplus towing force.     

The effects of uniform and nonuniform pile spacing variations on local scour at pile groups

Pile groups are frequently used to support bridge decks. Scour in the vicinity of piles is the main cause for the bridges failure. In this research, to address the effects of uniform and nonuniform pile spacing on the equilibrium scour depth, laboratory experiments were carried out under steady clear-water conditions. For this purpose, scour depth produced by pile group with various pile spacing and arrangement was investigated using a laboratory flume. Flume bed was covered by uniform sediments with a median size of 0.9?mm and 0.2?m thickness. Flow discharge and velocity as well as scour depth were recorded in each experiment and the data were analyzed. The results showed that the pile spacing influences the local scour depth and with increase in uniform and transverse (perpendicular to the flow) spacing, the maximum scour depth was reduced. The pile spacing variation in line with the flow has a minor effect on scour depth. In addition, the pile spacing perpendicular to the flow was with the most influences on scour depth. The results of this research can be used by engineers to optimize the design of bridges.     

春、秋季东海大桥海上风电场水域鱼类群落结构

为探明工程建设后东海大桥风电场水域鱼类群落结构特征,作者利用等级聚类和多元统计等方法对该水域鱼类种类组成、优势种及群落结构进行分析。春、秋季共发现18种鱼类,隶属6目9科15属;鲈形目鱼类所占比例最高(50%),其中又以虾虎鱼科鱼类最高(44.4%)。春季优势种为短吻红舌鳎(Cynoglossus joyneri)、棘头梅童鱼(Collichthys lucidus)、矛尾虾虎鱼(Chaeturichthys stigmatias)和孔虾虎鱼(Trypauchen vagina),秋季优势种为棘头梅童鱼、龙头鱼(Harpadon nehereus)和凤鲚(Coilia mystus);棘头梅童鱼为春、秋季共同优势种。等级聚类和非度量多维标序排序表明,东海大桥风电场水域鱼类群落可分为春季和秋季2个组群,相似性检验(ANOSIM)显示2个组群差异极显著(R=0.851,P0.01)。生物与环境相关分析(BIOENV)表明温度和盐度是影响东海大桥风电场水域鱼类群落结构的最主要环境因子,两者结合因子与鱼类群落的相关系数为0.791。本研究发现,东海大桥风电场水域是棘头梅童鱼、凤鲚、龙头鱼等多种鱼类的育幼和索饵场所,群落结构具有典型的季节特征。     

武汉长江二桥的复测监理工作

介绍武汉长江二桥的规模与结构，总结４年来对该桥的平面与高程施工控制网和正桥０￣１６号桥台、Ｈ型塔柱、墩位的复测监理工作，以及所取得的成效。     

新亚欧大陆桥东端城市群空间结构规划构想

基于陆桥经济理论,着眼陆桥经济带东部崛起,分析了当前新亚欧大陆桥东端淮海城市群空间结构特点,指出当前陆桥经济发展带来的新的挑战和机遇。通过淮海城市群中心城市职能指数和经济联系强度的相互验证计算,进一步明确徐州作为本区域的中心性城市地位,提出了新亚欧大陆桥东端淮海城市群"一心五轴六组团"的总体空间规划构想,以及实施规划的三大措施,即建设具有强大辐射力的区域性特大中心城市、实施淮海城市群核心区一体化、推动淮海城市群规划上升为国家战略。     

可液化场地桥梁桩基改进m值法研究

为了合理分析可液化场地桥梁桩基侧向承载力进行了改进m值法的研究。基于振动台试验和m值法,建立了桩-土相互作用体系有限元分析模型;引入反映可液化砂层侧向承载力衰减状态的孔压比指标值Ru;将不同时刻对应墩顶配重惯性力作为体系外部激励施加于墩顶;通过不断试算液化过程中砂土的m值,保证桩的弯矩计算值与试验值吻合较好。建立了考虑孔压比效应的砂土m值衰减因子p与Ru之间关系式。最后,推荐给出可液化场地桥梁桩基侧向承载性能分析的改进m值法。     

新西海桥的非线性地震响应分析

本文讨论了日本第一座公路钢管混凝土拱桥——主跨230m的新西海桥的非线性地震响应特性。采用三维有限元计算模型,用纤维单元法考虑钢管混凝土的材料非线性,用P-δ效应考虑几何非线性,讨论了在纵桥向地震作用、横桥向地震作用以及纵、横桥两方向同时作用情况下该桥的非线性地震响应特性和抗震性能。计算表明,在纵桥向地震作用时轴力的作用显著,拱脚附近产生的内力较大;而横桥向地震作用时轴力和面外弯矩作用显著,拱脚以及拱肋与桥面连接附近产生的内力较大;横向地震响应远大于纵向地震响应;应考虑纵、横桥向地震力共同作用的影响。     

利用振动法测量预应力体外索的索力

为了能够利用振动法测量316国道洪塘大桥预应力体外索的索力,本文根据理想弦的振动方程以及梁的横向振动方程,建立起有灌浆预应力体外索索力的计算模型,该计算模型中含有两个权重系数λ1、λ2。利用该桥体外预应力索的模型实验数据,通过最小二乘法拟合出系数λ1、λ2并得到体外索索力的计算公式。误差分析表明该体外索索力计算公式误差小,可以用于洪塘大桥体外索索力计算以及该桥体外索长期健康监测。     

Local scour around two side-by-side cylindrical bridge piers under ice-covered conditions

In the current study, 108 flume experiments with non-uniform, cohesionless sediments have been done to investigate the local scour process around four pairs of side-by-side bridge piers under both open channel and ice-covered flow conditions. Similar to local scour around bridge piers under open channel conditions and a single bridge pier, it was observed in the experiments that the maximum scour depth always occurred at the upstream face of the pier under ice-covered conditions. Further, the smaller the pier size and the greater the spacing distance between the bridge piers, the weaker the horseshoe vortices around the bridge piers, and, thus, the shallower the scour holes around them. Finally, empirical equations were developed to estimate the maximum scour depth around two side-by-side bridge piers under both open channel and ice-covered flow conditions.