Time-domain wave diffraction of two-dimensional single and twin hulls     

Sangita Maiti  Debabrata Sen 《Ocean Engineering》2001,28(6):171

The nonlinear diffraction of 2D single and twin hulls are studied by employing a mixed Eulerian–Lagrangian model based on a higher-order cubic-spline boundary element solver. Two types of simulations are considered. In the first, waves are generated by a piston-type wave-maker in a rectangular tank and in the second case a nonlinear incident wave is assumed to exist in the tank in which the body is introduced. For the application of this model, the full nonlinear diffraction problem is recast in terms of a perturbation wave-field. Computations are performed for rectangular and triangular hull geometries. Computed results show significant nonlinearities, particularly in the heave force. The twin hull results show the influence of wave interference on the diffraction forces. This interference influences the surge force considerably, but heave force is less affected.  相似文献   

寒区隧道保温设防长度工程实践与研究进展综述北大核心CSCD     

庞小冲  朱小明  穆彦虎  张坤  张力杰  郑波  李凌洁 《冰川冻土》2022,44(3):998-1010

保温法是目前寒区隧道建设中应用最为广泛的一种冻害防治方法。通过敷设保温材料可以减缓隧道结构、围岩体与洞内空气的热量交换过程,进而减小或避免衬砌与围岩体内的季节冻融,实现冻害防治的目的。在工程设计中,隧道保温段的敷设长度和厚度是两个关键参数,其中敷设厚度相对容易确定,但是敷设长度的确定目前缺乏统一的标准和简便可靠的方法,给隧道保温设计带来了一定的难度和不确定性。基于此,对包括现有铁路和公路规范要求、经验公式、工程类比法、理论解析法、数值模拟法等寒区隧道保温段敷设长度确定方面的工程实践、研究进展和挑战进行了系统的总结,并在此基础上提出保温设防设计用气象数据的选取方法、保温设防长度确定的依据、隧道进出口的差异性,以及季节冻土与多年冻土区隧道的差异等未来工程实践和科学研究仍需解决和研究的重点,以期能够为寒区隧道保温防冻工程设计难题的解决提供参考。  相似文献   

杭州某顶管下穿钱江二桥的施工影响分析     

吕斌 《中国勘察设计》2010,(3):58-61

杭州某污水处理厂双线圆形管道拟采用顶管隧道施工方案,分别用plaxis软件进行有限元分析和经验法计算得到顶管隧道穿越钱江二桥铁路桥梁引起的地面变形、桩基变形、桩基承载力影响大小数据。结果证明顶管穿越铁路桥,对桥梁影响较小。  相似文献   

San Diego–Tijuana: Not quite a binational city or region     

Glen Sparrow 《GeoJournal》2001,54(1):73-83

The cities of San Diego and Tijuana have faced each other across the international boundary for over 100 years. The question raised by this article is whether they comprise a binational city or region. After a brief comparison of their histories, economies and political systems, a review of some indications of cross border attitudes and a discussion of binational regionalism as it is impacted by continentalism, it is concluded that the relationship between these cities is driven by factors of economics not friendship or trust. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

中国晚新生代碱性玄武岩中贯穿双晶贵橄榄石          下载免费PDF全文

穆治国  刘如曦 《地质科学》1994,29(4):399-403

B80年代至今,在研究我国北方晚新生代碱性重武岩过程中,首先在内蒙的达里诺尔和黑龙江的科洛火山岩中观察到具贯穿双晶的贵橄榄石,最初认为是一种偶然现象。  相似文献   

Paleostress fields from calcite twins in the Pyeongan Supergroup, South Korea     

Seong-Seung  Kang  Jun-Mo  Kim  Bo-An  Jang 《Island Arc》2005,14(2):137-149

Abstract   Paleostress fields of the Late Paleozoic to Early Mesozoic Pyeongan Supergroup that is distributed along the northeastern part of the Ogcheon Belt in South Korea were investigated using the calcite strain gauge (CSG) technique. Combining the results of this study with those of other studies investigating the relationship between twin strain, twin density and width, which are used as indicators of deformation conditions in the natural low-temperature deformation of limestone, it was estimated that calcite twins in the study area were probably formed at temperatures lower than 170°C. From two samples, two different principal paleostress directions were inferred from calcite twins, while only one direction was inferred from two other samples. This result suggests that deformation occurred during two or more different tectonic events in the Pyeongan Supergroup during the Mesozoic era. The maximum shortening axis was oriented in two directions, northeast–southwest and northwest–southeast, respectively, which coincide well with the paleostress directions inferred from the stress inversion for many fault sets. Combining the results of the paleostress analysis from this and other studies, we hypothesize that the directions of the maximum shortening axis in the Pyeongan Supergroup changed from northeast–southwest during the pre-Daebo orogeny period (Late Triassic period) to northwest–southeast during the syn-Daebo orogeny period (Early Jurassic to Early Cretaceous period) in the Mesozoic era.  相似文献   

圆梁山隧道施工期间增加辅助坑道的设计与施工          下载免费PDF全文

曾蔚  张民庆 《探矿工程》2005,32(5):56-59

在圆梁山隧道修建期间，为解决进口车站大跨段的快速施工以及施工中所遇到的2、3、4和5号溶洞的涌水涌砂难题，创造性地新增设了3条横通道、1条地质探洞、2条迂回导坑和4条泄水洞共10条辅助坑道。主要介绍了施工期间增设的10条辅助坑道的设计与施工。  相似文献   

一种反条纹长石的形成机制及其冷却史     

薛纪越  张富生  胡梅生 《岩石学报》1988,4(4)

对承德黑山苏长岩中反条纹长石进行显微镜研究表明,钾长石条纹具乳滴状和细脉状两种形式。前者在成核后的生长中,或多或少趋向等轴状,是一种非共格的离溶作用,而后者对主晶有确定的取向。在透射电镜下,此类条纹与其主晶界面的应变能,说明它是半共格离溶的。斜长石主晶是‘e斜长石’组成的两相交生体,即所谓Bφggild交生。本文还讨论了它的冷却史及由它表明的地质环境。  相似文献   

沉管隧道抗震研究   总被引：1，自引：0，他引：1  

陈贵红  高波  赵玉光 《地震研究》2006,29(1):60-64

以南京长江沉管隧道为例,利用动力有限元法对沉管隧道进行抗震分析;对埋深、地质条件、水等因素对沉管隧道地震反应的影响进行分析,并从中得出了一些有益结沧,供有关人员进行抗震设计和抗震分析参考。  相似文献   

隧道掘进机施工条件下的隧洞围岩分类方法探讨     

何文君  张兵 《贵州地质》2006,23(1):66-68

针对隧道掘进机(Tunnel Boring Machine--TBM)施工隧洞中的围岩分类问题,指出TBM施工条件下的隧洞围岩分类应针对围岩的可钻掘性,充分考虑影响TBM掘进效率的主要工程地质因素,提出了在《工程岩体分级标准》围岩稳定性基本分级的基础上,依据岩石的单轴抗压强度、岩石的耐磨性和岩体的完整性将TBM施工条件下的隧洞围岩分为A(好)、B(一般)、C(差)3个级别的围岩分类新方法。  相似文献