水平排水板真空预压法处理吹填流泥试验研究

常规的竖向排水板真空预压处理新近吹填流泥的压缩量可达30%～40%,呈明显的大变形特征,排水板弯曲变形严重,导致排水板中的真空度沿深度衰减较大,影响最终加固效果。针对吹填流泥的这种工程特性,通过对比试验,研究了水平排水板真空预压法在该类场地的应用。试验结果表明,水平板真空预压取得的沉降变形、孔隙水压力、出水量、含水率、十字板抗剪强度等物理力学指标均好于常规的竖向板真空预压,并分析了水平板真空预压处理吹填流泥的优势。结果表明,水平板真空预压是一种可行的吹填流泥处理方法。     

初始含水率对真空预压加固吹填淤泥影响试验研究

针对传统的真空预压设计和施工方式较为粗放,主要依靠经验进行,缺乏相关的工程参数的问题。设计不同吹填淤泥初始含水率进行了四组室内对比试验,通过分析孔隙水压力,排水量,沉降量,土体的含水率以及十字板剪切强度等指标的变化规律,探究真空预压处理效果与淤泥初始含水率之间的关系。试验结果表明,含水率高的吹填淤泥在靠近排水板处孔隙水压力消散更快;初始含水率越大,排水固结达到稳定的时间越长;初始含水率高的吹填淤泥在真空预压法处理后仍然具有较高的含水率,对应的土体平均强度较低;试验建立了初始含水率与加固后土体强度之间的线性拟合公式。     

惠州荃湾吹填淤泥地基浅表层真空预压处理

浅表层快速加固技术是基于真空预压原理针对新吹填淤泥等超软弱土快速加固的一种新技术。依托惠州港荃湾港区软基处理工程,通过现场试验研究不同排水板间距对浅表层快速加固效果的影响,研究加固过程中膜下真空度、地表沉降和孔隙水压力的变化规律,对惠州荃湾吹填淤泥加固前、后土体的物理力学性质、强度及地基承载力进行分析。     

真空预压地基土体沉降及强度增长特征

结合目前对真空预压的理论认识和工程实践,对某工程真空预压地基土体的孔隙水压力消散、沉降、物性参数、强度参数的变化特征进行分析。结果表明:孔隙负压消散量受土体扰动及沉降导致的排水板弯折和淤堵的影响较大,可能导致其不简单地随深度增大而减小;计算吹填土的沉降量时,经验系数可取大些,下部原位土体的沉降经验系数可适当取小些;加固后的土体物性参数及强度参数明显变好,且在排水板底深度以下仍有强度增长。结合监测数据的分析结果,对真空预压的有效深度和加固效果进行讨论。结果表明:土体的有效加固深度受真空负压和土体排水阻力的综合影响;在排水板深度范围内的土体加固效果明显,而该深度以下的加固效果则随深度增大逐渐降低并最终趋于无。     

新近吹填淤泥现行真空预压技术加固效果不佳原因分析

为探讨现行真空预压技术加固新近吹填淤泥地基时效果不理想的原因,首先分析新近吹填淤泥的工程特性,然后开展不同含水率下新近吹填淤泥的室内真空固结足尺单井模型试验研究。研究结果表明:1)新近吹填淤泥主要由较细颗粒物质和极细颗粒物质组成,其中黏粒含量(黏粒+胶粒)和强亲水矿物含量(伊利石+蒙脱石)均较高;孔隙特征主要以孤立孔隙和粒间孔隙为主;含水率基本在100%以上、均大于1.5倍的液限,孔隙比均大于2.5,塑性指数基本在20以上,液性指数基本大于2.0。2)新近吹填淤泥采用现行真空预压技术加固时,膜下真空度损失程度可高达20%以上;真空度从排水板向周围土体中传递时的径向损失程度严重,真空压力的径向作用范围仅局限于直径约为40 cm的土柱范围内:土柱范围内土体的无侧限抗压强度值不超过35 kPa;土体的有效加固深度和强度增长幅度均较小。这两方面是新近吹填淤泥采用现行真空预压技术进行处理时效果不理想的主要原因,因此,有必要结合新近吹填淤泥的工程特性研发出一种新型加固技术或对现行真空预压技术加以改进。     

南沙港区软土固结孔压特性试验研究

根据南沙港区主要地层土的室内试验和现场测试成果,分析固结过程中土体孔隙水压力变化特性。结果表明：三轴试验固结过程中,淤泥、淤泥质土和粘质粉砂孔隙水压力消散相同百分数的固结时间存在数量级差别,淤泥质土和粘质粉砂的渗透系数不能由时间-沉降曲线确定;三轴不排水剪切过程中,粘质粉砂中孔隙水压力随剪应变先增大后减小,表现出密实砂的孔隙水压力变化特性;该区域地基真空预压加固过程中吹填层、粘质粉砂层和淤泥质土层中的孔隙水压力随膜下真空压力增加而迅速降低,而淤泥层中孔隙水压力缓慢下降,地基土层具有明显的成层特性。     

不同加载方式下真空加固吹填软土的现场试验与数值模拟*

吹填软土在真空负压作用下发生排水固结时,其强度和变形特性与真空负压的加载方式关系密切。首先对吹填软土进行了真空预压现场加固试验,通过对地表沉降、真空度跟踪监测,研究并比较不同负压加载方式下地基沉降规律及加固效果;然后采用FLAC3D建立三维弹塑性数值模型,对软土地基采用不同加载方式进行数值模拟,并与现场试验的实测数据进行对比,深入探讨加载方式对软土地基固结影响的细观机理。研究结果表明：采用真空预压法加固吹填软土地基时,慢速加载方式比瞬时加载方式更有利于土体的加固,建议在实际工程中采用分级加载方式施加真空荷载。     

真空-堆载联合预压法处理吹填淤泥试验研究

真空-堆载联合预压法的实质是将真空预压法的负压固结理论与堆载预压法的正压固结理论进行联合,使得土体固结达到最大化通过理论分析,论述了真空-堆载联合预压下基于孔隙水压力和沉降的平均固结度计算方法.结合大面积吹填淤泥软基处理的工程实际,通过对孔隙水压力、沉降等进行观测,提出了有效地控制加载速率与加载周期的方法;研究了孔隙水压力变化规律,并结合工程实际进行了平均固结度的验算分析,表明该计算方法存在一定的合理性.     

等压下真空-堆载联合预压法与真空预压法对比试验研究

对于温州地区的吹填土,当使用普通真空预压法处理时难度较大、真空度传递欠缺、空隙水压力消散过慢、土体深层加固效果较差,因此需要堆载进行联合处理。在等压条件下,设置纯真空预压和真空-堆载联合预压室内试验对照组,在抽真空至土体表层沉降稳定后对真空-堆载预压联合组以4kPa/d的堆载速率进行堆载,与普通真空预压法的表层沉降量、真空度、孔隙水压力、抗剪强度、含水率等指标对比表明,真空-堆载联合预压法处理后土体的物理指标均优于普通真空预压处理的土体,说明真空-堆载联合预压法能够有效地提高软土地基的加固效果。     

真空预压新技术加固吹填超软土的现场试验研究

针对沿海吹填超软土特性,通过广东惠州荃湾港区现场试验,采用真空预压新技术加固吹填超软土,包括新型超软土浅层预处理技术、新型高效节能抽真空技术、新型防淤堵塑料排水板技术等。试验区分别通过浅层预处理和真空联合堆载预压深层处理试验评价真空预压新技术加固吹填超软土的效果。根据加固前后现场监测与检测结果,从真空度、沉降量、孔隙水压力、十字板剪切试验、静力触探试验和室内土工试验成果等指标分析吹填超软土加固效果,证实真空预压新技术在沿海吹填超软土地基处理中具有良好的加固效果及经济性。     

Errata

正In the paper"Influence of Fouling Assemblage on the Corrosion Behaviour of Mild Steel in the Coastal Waters of The Gulf of Mannar,India"in Vol.12,No.4,Page:509,References were lost,and the two authors’biographies were identical.The correct text is shown below.We apologize to the authors and our readers for any inconvenience caused by the errors.     

Journal of Marine Science and Application 2014 Sum. Contents

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第34届海洋、离岸及极地工程国际会议(英文)

正St.John's,Newfoundland,Canada,May 31-June 5,2015 OMAE2015 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to: meet and present advances in technology and its scientific support;     

33rd International Conference on Ocean,Offshore and Arctic Engineering （OMAE2014）

正San Francisco,California,June 8-13,2014.OMAE 2014 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to:·meet and present advances in technology and its scientific support;·to exchange ideas and experiences whilst promoting technological progress and its application in industry·to promote international cooperation in ocean,offshore and arctic engineering.In line with the tradition of excellence of previous OMAE conferences,more than 900 technical papers are planned for presentation.Outreach for Engineers Specialty Forum This Specialty Forum is designed for students and professionals who may not be familiar with the Ocean and Offshore industry,as well as those who have just recently specialized in this field.     

Recent progress on wave induced loading measurements in warships

Recent measurements of wave induced hull strain and flexure in RN warships are presented together with the derivation of the current design criteria for extreme hull girder bending loads. The history of the development of the shipboard instrumentation used is given and recent developments to improve the quality and ease of analysis of the data are described. An unexpectedly high transverse asymmetry in the longitudinal strains measured in destroyers is shown to be the result of a combination of vertical and lateral bending in oblique seas. Finally recent theoretical comparisons between the loading of Deep-Vee hulls and conventional UK rounded bilge hulls are presented which demonstrate the higher loading experienced by this type of hull form.     

联合作战计划和执行系统

全球指挥控制系统(GCCS)实施当前美国海军网络中心战信息基础设施的联合计划网络。联合作战计划和执行系统(JOPES)支持GCCS实现联合计划。JOPES有两类计划：时间不限的精密预案计划生成作战计划、方案计划或职能计划；时间敏感的危机行动计划生成作战命令或战役方案。前者在和平时期创建的作战计划是后者的计划基础，加速应付危机的能力。     

The 11th International Conference on Hydrodynamics (ICHD 2014)

正19–24 October 2014 SingaporeCONFERENCE THEMES The overall aim of the ICHD Conference is to provide a forum for participants from around the world to review,discuss and present the latest developments in the broad discipline of hydrodynamics and fluid mechanics.The first International Conference on Hydrodynamics(ICHD)was initiated in 1994 in Wuxi,China.Since then,9 more ICHD conferences were held subsequently in Hong Kong,Seoul,Yokohama,Tainan,Perth,Ischia,Nantes,Shanghai and St Petersburg.Evidently the ICHD conference has become an important event among academics,researchers,engineers and operators,working in the fields closely related to the science and technology of hydrodynamics.The 11th ICHD will be held in Singapore in 2014.     

第十二届深水操作会议和展览会(英文)

正November 4-6,2014Moody Gardens HotelConvention Center/Galveston,TX The Deepwater Operations Conference and Exhibition is celebrating its 12th anniversary this year.This growing event will continue the tradition of excellence in addressing operational challenges involved in developing deepwater resources.We will return to the Moody Gardens Hotel and Convention Center on November 5-7,2014 in Galveston,Texas.     

Eastbound or westbound ?

In terms of equal sailing distances, where is the inflexion when ships depart from ports in the Asian Continent to New York via Suez and/or Panama？
The answer is China South Port Group （Hong Kong, Shenzhen and Guangzhou）.     

Impact of regulation on the performances of long-distance transport services: A comparison of the different approaches in Sweden and Norway

Despite the many socio-economic similarities between Sweden and Norway, differences in jurisdiction, organisation, cooperation, and financing of long-distance passenger train and coach services have led to the development of four distinctively different ways of serving the markets. This paper describes how the train and coach markets have developed in the two countries, with emphasis on regulatory and industrial structure and a couple of performance variables.Looking at passenger rail, both countries separated infrastructure from operation over a decade ago. However, while Norwegian rail is characterised by an almost monopoly supplier, rail services in Sweden are partly decentralised to the responsibility of county authorities and are widely subjected to competitive tendering. The rest of the network is about to be opened up for on-the-track competition. Swedish Rail (SJ) has spent the last decades consolidating its core business (passenger rail) and sold out its other businesses. In contrast, the Norwegian state rail (NSB) has expanded its business to become a major bus operator and property owner, with extensions also into the Swedish market.The coach industry was more recently deregulated in both countries. The Swedish coach market is dominated by privately owned companies operating services to and from Stockholm. In Norway, state-owned NSB is a major coach operator on medium distance routes, and is also the largest partner of Nor-Way Bussekspress which totally dominates long-distance coach services. Further, the Norwegian coach market is characterised by cross-ownership and cooperation which has enabled an extensive route network which covers most of Norway.We find distinct differences in achievements in the two modes and in the two countries. Swedish rail services have succeeded in winning market shares and in renewing and developing both infrastructure and service levels to a greater extent than the Norwegian model. On the other hand, the Norwegian coach market seems to be more developed and efficient compared to its Swedish counterpart.The paper concludes with a discussion on the possible links between the different approaches and the performance observed, with the aim to stimulate further and more detailed research on some important issues.