Migratory Patterns and Settlement Experiences of African Australians of Refugee Background in Murray Bridge,South Australia

In the past decade Australian immigration policy has emphasised settlement of refugees/humanitarian entrants in rural and regional locations, in preference to metropolitan areas. The settlement outcomes of a case study of African humanitarian entrants of South Sudanese background in Murray Bridge, a regional centre in South Australia, are examined. These participants were self-settled secondary movers from metropolitan Adelaide. The factors which attracted them were centred on employment. Settlement outcomes for Murray Bridge respondents were better than their urban counterparts, in terms of both housing and employment outcomes. However, some later left Murray Bridge because of a lack of opportunities for tertiary education. The results highlight issues of sustainability of settlement and retention, in regional centres in Australia, and of the fluidity of attraction and retention factors and therefore settlement in regional centres.     

港珠澳大桥西人工岛桥结合段波浪演变数值模拟

近年来海洋极端天气频发,港珠澳大桥西人工岛地处外海,与其相连接的桥梁非通航跨的桥面高程较低,容易受到海浪侵袭,威胁到岛桥功能的正常发挥和结构自身安全。针对西人工岛桥结合部周围的复杂地形条件,采用OpenFOAM^®开源程序,分别对S、SSW和SW三个方向的极端波浪进行了数值模拟。通过数值计算结果与物理模型试验测量值的比较验证了的模型的准确性。分析了不同方向入射波的波高和沿岛体斜坡爬高的变化规律。随着波浪入射角的增大,人工岛南侧斜坡的波浪爬高呈逐渐减小,但在岛体西端靠近桥梁的位置处,波浪爬高逐渐增大;同时也反映了越浪和桥面上水风险的大小。研究旨在为实际工程的管理和设计提供参考。     

挤密砂桩加固水下软土大型原位载荷试验研究

港珠澳大桥岛隧工程水下深厚软土采用挤密砂桩进行加固,设计了一套大型原位载荷试验系统对水下挤密砂桩 （sand compaction pile,SCP）复合地基的力学和变形特性进行研究,通过在水下设置高精度静力水准系统获得了良好的沉降观测结果。试验结果表明,水下挤密砂桩复合地基在同一置换率下的应力分担比与载荷水平以及时间效应密切相关;应力分担比比值随荷载级别的升高表现出先减小后增大的趋势,在同一荷载级别下比值随着时间逐步衰减,并最终趋于某一定值。对比分析了几种散体材料桩复合地基承载力理论的计算结果,表明按被动土压力法得到的复合地基承载力与载荷试验结果较为接近。对于高置换率的挤密砂桩复合地基,采用建筑地基处理技术规范提出的沉降折减系数计算得到的复合地基沉降与实测值最为接近,采用日本经验公式计算得到的沉降量偏大。研究结果对于水下挤密砂桩复合地基的设计计算和深水原位测试具有一定的参考意义。     

Behavior of a seismically isolated bridge crossing a fault rupture zone

The effect of the fault rupture zone traversing a seismically isolated bridge is investigated utilizing a finite element model of a section of the Bolu Viaduct and a set of synthetic broadband strong ground motions simulated for the Bolu Viaduct site due to the 1999 Duzce earthquake. Both the original and a potential retrofit seismic isolation system designs are considered in the analyses. The results show double isolation system demands when fault crossing is considered, as compared to the case where fault crossing is ignored. The pier drift demands, however, remain comparable in both cases. Furthermore, the location of fault crossing along the bridge length, as well as the fault orientation with respect to the bridge longitudinal direction are shown to influence substantially the response of the seismically isolated bridge. Isolation system permanent displacements are greatly influenced by the restoring force capability of the isolation system when fault crossing effects in the excitations are ignored. In the case of fault crossing, the permanent displacements of the isolation system are dominated by the substantial permanent tectonic displacement along the fault trace which is imposed upon the structure. The results of this study contribute to developing a better understanding of how seismically isolated bridges respond when traversed by fault rupture zones. The lack of analyses and design guidelines for bridges crossing faults in international standards renders this study a useful reference for the profession.     

土工合成材料加筋土柔性桥台复合结构的研究现状

土工合成材料加筋土柔性桥台复合结构（GRS-IBS）是美国针对中、小型单跨桥梁的快速更换问题而提出的一种新型技术,是原有GRS桥台技术的优化与提升。到目前为止,美国积累了10多年的工程经验和研究成果,其中有44个州超过250座桥梁采用了GRS-IBS结构形式进行设计和建造。这些成果主要集中在现场工程监测方面,也有一些关于车辆静载试验和数值分析方面的研究。本文收集、整理了40多座GRS-IBS的工程资料和相关研究成果,即从现场工程监测、车辆静载试验和数值分析3个方面,以案例形式对其研究现状进行归纳总结。结果表明,GRS-IBS整体变形协调性能良好、受环境温度变化的影响小,桥跨结构与桥头引道之间无明显的差异沉降及路面裂缝出现;GRS桥台的沉降与侧向变形基本上能在施工阶段完成,工后沉降及变形均很小;GRS桥台墙面处侧向土压力值很小且分布均匀,不符合朗肯土压力理论,筋材受力亦较小且分布均匀;GRS桥台潜在破裂面的下半段与朗肯主动破坏面吻合较好,但上半段偏差较大,破坏包络面远超出朗肯面。此外,通过数值方法进行影响因素分析,发现小加筋间距和高压实度是保证GRS桥台优良性能的关键性因素;填料内摩擦角、筋-土界面摩擦系数越大,GRS桥台的性能越好。     

深圳―中山跨珠江通道对珠江三角洲地区可达性的空间效应

借助可达性分析模型,以深圳―中山跨珠江通道（简称“深中通道”）为案例,采用加权平均旅行时间、覆盖度指数、经济潜能指数分析深中通道建设后对珠江两岸地区可达性的影响和空间分布,并采用可达性变化均衡指数分析深中通道建设对区域可达性公平性变化的影响。结果表明：深中通道建设将显著提升珠三角区域南部的可达性,珠江口西岸地区的可达性提升高于东岸地区。中山市、珠海市 1 h 等时圈内的人口增加最大。珠江口东岸的深圳市、香港特别行政区和西岸的中山市和江门市的经济潜能得到较大的增长。中山市、东莞市和佛山市内部可达性呈现均衡化趋势,可达性公平性得到提升。最后,提出了完善深中通道周边交通运输网络布局和推进珠江口两岸产城互动融合等有针对性的政策建议。     

藏东八宿怒江桥—邦达一带嘉玉桥群研究的新进展

在西藏八宿怒江桥—邦达一带嘉玉桥群中发现较丰富的化石,其中腕足类有：Ｎｅｏｓｐｉｒｉｆｅｒ,Ｓｙｒｉｎｇｏｔｈｙｒｉｓ？Ａｓｙｒｉｎｘｉａ,Ｓｐｉｒｉｆｅｒ;牙形石：Ｐａｌｍａｔｏｄｅｌａｄｅｌｉｃｕｔｕｌａ,Ｐａｌｍａｔｏｌｅｐｉｓｇｒａｃｉｌｉｓｓｉｇ ｍｏｉｄａｌｉｓ,Ｓｐａｔｈｏｇｎａｔｈｏｄｕｓｃｆ．Ｓｔａｂｉｌｉｓ,Ｐｏｌｙｇｎａｔｈｕｓｐｕｒｕｓ;孢子：Ｌｅｉｇａｔｏｓｐｏｒｉｔｉｓｖｕｌｇａｒｉｓ,Ｃｒａｓｉｓｐｏｒａｔｒｙｃｈｅｒａ,Ｓｕｌｃａｔｉｓｐｏｒｉｔｅｓｏｖａｔｕｓ,Ｌｉｍｉｔｉｓｐｏｒｉｔｅｓ,Ｌｅｉｏｔｒｉｌｅｔｅｓ等。据此对嘉玉桥群的划分和时代进行了重新厘定。     

新亚欧大陆桥新疆沿线的孕灾环境及成灾过程分析

以新亚欧大陆桥新疆段为研究对象,从区域地质地貌条件、生态环境等方面详尽阐述了新亚欧大陆桥新疆段的孕灾环境及其在灾害形成过程中对致灾因子的放大作用和成灾过程中各种变异的强化作用。结合2年来野外实地考察资料,系统性分析了新亚欧大陆桥新疆段环境灾害的致灾过程、受灾过程和成灾方式,揭示了区域各类环境灾害间的促进、诱发、转化等相互关系。     

Finite element analysis of structure-borne vibration from high-speed train

Finite element analyses were used to investigate the behavior of the building vibration induced by high-speed trains moving on bridges. The model includes the bridge, nearby building, soil and train. Finite element results indicate that trainload frequencies are more important than the natural frequencies of bridges and trains for building vibrations. If the building natural frequencies approach to the trainload frequencies, which equal an integer times the train speed over the compartment length, the resonance occurs and the building vibration will be large. Moreover, the vibration shape is similar to the mode shape of the resonance building frequency. To isolate the building vibration induced by moving trains, this paper investigates three common types of foundations, which include the extension of retaining walls, pile foundation and soil improvement around the building. Soil improvement around the building is the best way to reduce the building vibration both in horizontal and vertical directions.     

整体桥高性能混凝土桩−土相互作用试验研究

高性能混凝土（高性能复合水泥基材料engineered cementitious composite,简称ECC与超高性能混凝土ultra-high performance concrete pile,简称UHPC）桩基具有良好的抗开裂性能和较高的承载能力,能较好地满足整体桥纵桥向变形。开展了砂土中高性能混凝土桩低周往复拟静力试验,得到了桩基的破坏特点、抗开裂能力以及极限承载力,分析了其桩身变形、桩侧土抗力以及桩身应变等分布规律,并与钢筋混凝土（RC）桩进行了比较。在此基础上,讨论了几种常用规范的适用性。试验结果表明,ECC、UHPC材料能有效减轻桩基的破坏程度、提高桩基的抗开裂能力以及水平承载力;相比RC桩基,高性能混凝土桩基的破坏位置更深,桩基的有效桩长更大,抗震性能更好;其中,ECC桩基的抗开裂能力最强,开裂荷载可达5.8 kN,开裂位移可达15 mm。试验结果还表明,高性能混凝土桩基的变形沿埋深方向不断的减小,埋深1.5 m以下位置基本为0;桩侧土抗力先增大后减小,桩底土抗力和变形量为0;桩身应变分布较为对称,且呈“橄榄”形,在埋深4D～6D（D为桩径）区间内桩身应变较大。分析计算表明,当桩顶位移在10 mm以内时,“m”法与API新规范法均能较好地计算高性能混凝土桩的桩身变形;当位移超过10 mm后,“m”法与实际数值相差较大。“m”法与API新规范法均不能较好地计算桩身弯矩,适用性不高;桩侧土抗力建议采用API新规范法。