汕头至汕尾铁路汕头湾海底隧道设计综述

汕头湾海底隧道为设计时速350 km的单洞双线高铁海底隧道,具有高水压(隧底最大水压力达0.97 MPa)、高侵蚀性(海域段落氯盐侵蚀环境等级L3)和高烈度地震区(8度地震区)的特点。隧道施工工法复杂,涉及矿山法(海域矿山法、陆域矿山法)、盾构法、明挖法、矿山法+盾构空推法。为进一步探究海底隧道的设计施工关键技术,对汕头至汕尾铁路汕头湾海底隧道设计及关键技术进行阐述,有效解决了盾构机整体无损拆解、穿活动断层带抗震抗断、阈值泄压限排、盾构接缝防水、穿越复合地层适应性、防灾疏散救援、隧道全生命周期健康监测等关键技术问题。     

崖州湾中心渔港周边海域岸线修复工程实例

三亚市受台风、暴雨、海水侵蚀等自然因素的影响,沙滩泥化现象日趋严重,海岸线逐渐后退,草坪植被大面积陷落损毁.该市周边部分水上、陆上工程的过度开发建设等人为因素进一步加剧了海岸生态环境的恶化,使崖州湾中心渔港周边海域岸线生态环境受损.以三亚市崖州湾中心渔港周边海域岸线修复工程为例,详细介绍生态底泥疏浚及处理工程、沙滩修复工程、岸线生态修复工程、贝藻礁型丁坝工程四部分内容,完善崖州湾生态整体修复,提升海岸生态功能和防灾减灾功能,解决民生问题,为类似工程提供参考.     

相邻隧道爆破震动波的传播规律研究

针对胶州湾海底隧道青岛端接线工程匝道开挖对主隧道的振动影响,在主隧道内进行爆破振动监测。以实测振速数据为依据,分析主隧道内对应匝道工作面前后震动波的传播规律,得到垂直振速、水平径向振速以及水平切向振速随测点距工作面距离不同的变化规律。分析发现,主隧道内已开挖区爆破振速大于未开挖区振速,未开挖区振速在一定范围内相对稳定。     

粤东大亚湾水沙环境及岸滩演变分析

根据现场实测水文泥沙及地形资料,对大亚湾海域的自然条件、水沙环境特征及岸滩演变特征进行分析,研究结果表明：大亚湾潮差较小,波浪和潮流动力弱,水体含沙量较低,泥沙来源有限,主要来自近岸附近滩面就地搬运的少量泥沙。湾内底质多为黏土质粉砂,呈现淤积质海岸的沉积特点。因此大亚湾海域水清沙少,自然状态下海床长期保持稳定。近期受港口航道建设、围填海等人类活动的影响,部分海床地形出现较大幅度的冲淤变化。湾内港池、航道疏浚开挖后航槽稳定,回淤强度较小。正确认识该海域的水动力条件、泥沙运移及海床冲淤变化,不仅是开展海岸工程开发建设的关键技术问题,也有利于近岸海洋环境保护及资源开发利用。     

杭州湾跨海大桥南岸接线软土特性分析

根据杭州湾跨海大桥南岸接线软土地基试验段的实际数据,详细分析了软土的各项指标及压缩特性,为软基处理提供依据。     

粤港澳大湾区多层次轨道交通 一体化融合研究

针对目前粤港澳大湾区多层次轨道交通发展存在的跨层次、跨制式、跨区域融合不足等问题,采用实证分析方法,从政策制度设计、规划建设、运营主体协同等方面对其深层次影响因素进行研究.在分析粤港澳大湾区多层次轨道交通发展现状与存在问题的基础上,探究国内外城市群多层次轨道交通发展成败得失与经验启示,提出进行一体化融合体制机制与政策规范建设、加强一体化规划建设管理、促进综合交通枢纽一体化融合、完善土地支持政策与投融资配套政策、建立大湾区多层次轨道交通运营企业联盟等对策.研究成果以期为粤港澳大湾区多层次轨道交通一体化融合决策提供参考.     

美国旧金山湾区捷运系统

介绍美国旧金山湾区捷运系统(Bay AreaRapid Transit System,BART)。论述在旧金山湾区使用BART的重要意义,然后从现有线路、拟建线路规划等方面介绍该线路的总体情况,并对BART的车辆性能以及列车控制系统进行说明,最后分析BART在车票、换乘、环保和安全方面的优势。     

Egg production of the copepod Acartia hongi in Kyeonggi Bay, Korea

Many studies of copepod egg production have shown that food availability and temperature are major factors that influence copepod growth. However, coastal environments are complicated ecosystem and the relationships between growth of copepods and influencing factors are not always clear in nature. We conducted a study along an inner–middle–outer bay transect where variations in environmental parameters would be expected to affect the biomass and egg production rate of A. hongi from February 2001 to December 2001. In this study, we investigated the abundance and biomass with developmental stages and egg production rates of A. hongi in relation to various environmental factors. The copepod A. hongi occurred continuously throughout the year, with a peak abundance in May. In general, the variation in egg production rates showed a similar tendency with the variations in chlorophyll-a throughout the study period. This suggests that phytoplankton biomass is an important factor that affects the egg production of A. hongi. In addition, during the warm season, the egg production of A. hongi was also influenced by the ciliates abundance in the middle and outer bay. Consequently, the egg production of A. hongi is generally affected by food availability in Kyeonggi Bay.     

Shoreline development controls and public access to the ocean's edge

Abstract

The San Diego Coast Regional Commission, faced with the responsibility of approving, approving with conditions, or denying permits for development proposed along the scenic coastal bluffs of San Diego county, has adopted guidelines for bluff‐top development which assures retention of scenic vistas and provision of public access while permitting private landowners “reasonable use”; of their property. These unique guidelines delineate certain environmental and aesthetic parameters within which bluff‐top development may take place. Portions of the guidelines are presented, and some of the factors leading to their formulation and adoption are discussed.