Stability of the Guiding Dike in Yangtze Estuary Under the Wave Load

1 .IntroductionIt has beenrealizedthat constructing gravitystructures onsoft soil foundations is a difficult task,especiallyinthe marine area where boththe geological and environmental conditions are severe .Thisisnot only because the bearing capacity of the soft foundation is relatively low, but also because thestrength of the soft soil will befurther weakened bythe waveloading (Andersenet al .,1988 ;Ander-sen and Lauritzsen,1988 ; Yasuhara ,1988) .The strength weakening may cause serious d…     

南海东北部两种软珊瑚

金黄编笠软珊瑚Morchellana boleliformis(Ridley)和黎明编笠软珊瑚Morchellana auroro(Ridley)隶属于棘软珊瑚科Nephtheidae编笠软珊瑚属Morchellana,于1979—1983年采自南海东北部水域。     

Pathways to sustainable landscape management: peer recognition as an indicator of effective ‘soft’ actions

New Zealand is a food producer and exporter that combines neoliberal policy with performance-based environmental management, using ‘soft’ governance and actions where possible. Voluntary environmental farm awards are analysed to identify the landscape management activities recognised as best practice by peers at a farm level. Results highlight the importance of whole farm system management. However, the efficacy of reliance upon voluntary mechanisms is coming under increasingly critical scrutiny, as environmental conditions in intensive agricultural landscapes continue to decline. The research question this poses is whether whole farm plans can be practically and formally connected in three concurrent ways – to supply chain management, and to statutory planning frameworks and environmental regulations and to local landscape co-management – while still maintaining flexibility of action for the farmer.     

Stone pillar rockfall in Danxia landform area,Mt. Langshan,Hunan Province,China

A typical Danxia stone pillar, Leipishi I, in the World Natural Heritage site at Mt. Langshan, China, collapsed on 2 November 2009. To understand the mechanism controlling this rockfall event, uniaxial compressive strength, tensile strength, resistance against sulfuric acid, and freezing and thawing properties were analyzed from 44 sandstone and conglomerate cores collected from the Lanlong Formation, the only exposed formation on Mt. Langshan. In addition, four rock slices were created for analysis under a polarizing microscope. A detailed reconstruction of the geometry and restraint conditions of the stone pillar in place before the rockfall occurred permitted an estimation of the stress state before collapse using 3D finite-element code. The results show that the rapid retreat of soft, intercalated rock layers due to weathering can profoundly change the stress state within the rock body, causing compressive or tensile stresses to rise above compressive or tensile strengths in specific sections of a rock body, and causing partial or complete collapse.     

加劲桩配合工法桩在软土基坑中的支护效果评价

以嘉兴晶辉广场深基坑工程为背景,研究了旋喷加劲桩在软土深基坑中的支护效果。结合监测数据,利用FLAC 3D有限差分软件,对旋喷加劲桩配合SMW工法桩(劲性水泥土搅拌桩)这种组合结构在基坑各个开挖工况下的受力情况以及深层土体水平位移变化情况进行模拟计算。结果表明:深层土体水平位移曲线呈"鼓肚状",最大水平位移安全合理,位于基坑开挖底面以上1m~2m处;SMW工法桩所受剪力随开挖深度的加深而增大;三排加劲桩所受拉力呈现为越接近基坑开挖底面越大的规律。模拟结果与实际监测结果基本一致,且均在安全范围内。说明旋喷加劲桩在软土基坑中的支护效果较好,此次模型的建立较合理,为今后类似基坑工程的设计计算提供了参考。     

滇中红层软岩微观结构及水理特性试验研究

滇中红层软岩具有成岩作用差、易产生较大变形、遇水易软化、易崩解等特征,本文采用环境扫描电镜试验和水理特性试验,对红层软岩的微观结构特征,崩解、膨胀、软化等水理特性进行了研究。试验结果表明,红层软岩矿物粒间空隙大多被粘土矿物填充,粘土矿物以伊利石和蒙脱石为主,为混层结构,结晶程度相对较差,多数有蚀变的痕迹。具有微小裂隙的红层软岩在1~2次充分饱水烘干后,崩解性开始显现;随着干湿循环次数增加,岩样的质量变化呈减小趋势;干湿循环次数继续增加,崩解性指数趋于平缓。红层软岩由于风化作用影响程度和自然含水率的差异,岩体内部崩解张力具有明显不均匀性。经过自由浸水48h后,红层软岩的单轴抗压强度降低29.83%~58.47%,各地层软化系数在0.4~0.7之间,遇水后呈现显著软化效应。这些结果为红层软岩地区公路工程建设的工程地质研究提供了一定参考。     

常用软土路堤沉降预测方法的评价与应用

在软土地基上修筑路堤,最突出的问题是路堤的稳定与沉降。为掌握软土路堤在施工期中的变形动态,就必须进行动态观测和沉降预测,一方面保证路堤在施工中的安全与稳定,另一方面能正确预测工后沉降。而众多的预测方法给实际应用选择带来一定的困难,如何更科学合理地选择预测方法是工程技术人员面临的难题。就几种常用的曲线拟合预测方法的适用性进行分析,以期针对具体工程选取更为合适的预测方法,有效控制工后沉降并保证路堤施工和运营期的安全。     

Characteristics of deformation of saturated soft clay under the load of Shanghai subway line No. 2

Shanghai subway Line No. 2 passes through the center of Shanghai from Songhong Road station in the west to Zhangjianggaoke station in the east. The total length of Shanghai subway Line No. 2 is 25 km. The tunnel mostly lies in the saturated soft clay and the environment issue can not be ignored. The response frequency and response stress of soil around the tunnel are monitored when the subway train passes through. The cyclic triaxial test of the saturated soft clay around the subway tunnel is conducted using the data monitored. The characteristics of deformation of the saturated soft clay of Shanghai under the subway load are analyzed. The results show that when the subway train Line No. 2 begins to run, a small and vertical rebound first occurs in the saturated soft clay at the side wall of the tunnel. Although a large deformation does not occur in the saturated soft clay at the side wall of the tunnel when the subway train has run for a period of time, yet with the lapse of time, a perceptive and non-uniform deformation will still occur. The vertical rebound is transitory and a plastic deformation occurs immediately in the saturated soft clay at the bottom of the tunnel, the large deformation at the bottom of the tunnel is 30 times that of the saturated soft clay at the side wall of the tunnel. An erratum to this article can be found at     

CFG复合桩在软弱地基处理中的应用

某工程采用CFG复合桩对软弱地基土进行处理,持力层为粉质粘土,设计单桩承载力标准值180kPa,复合地基承载力标准不低于220kPa,采用沉管法施工。成桩后进行桩间土的力学性质测试发现,施工前后桩问土的强度没有提高,土的挤密度不明显;运用单桩静力载荷试验分析发现,I区的l号桩发生刺入破坏,单桩承载力标准值按比例荷载计算为105kPa,远低于理论预估值,Ⅱ区单桩承载力标准值按比例荷载计算为185kPa,与设计值相近。用单桩动测试分析发现原因是由于桩间土的差异及施工桩身的施工质量问题所致。     

21世纪中国城市未来的软规划与生态文明建设

文章旨在通过理念性的探讨,试就“中国在日益深入地参与全球贸易和投资中所面临的主要挑战”这一议题激发大家的讨论。文章论述了当代城市化理论现状、城市化和可持续发展之间的关系对中国国家发展目标的影响以及中国21世纪面临的发展挑战,认为：1）中国应注重基于本土发展经验的理论知识构建,以指导自身的城市化道路。特别地,中国需要平衡经济增长与可持续发展之间的关系,充分利用和部署生态资本,推动生态文明建设;2）以部署生态资本为重心的“软规划”在未来规划中将占据更重要的地位,为此需要进行体制改革、机构重组以及加强政府部门与私营部门和民间社会之间的合作;3）扩展型都市区可在生态文明建设中发挥更大作用,努力打造一个可持续的、宜居的和有经济活力的体制性框架,从而为“一带一路”倡议提出的国际贸易和投资深化发展提供基础。