Pile response in submerged lateral spreads: Common pitfalls of numerical and physical modeling techniques     

《Soil Dynamics and Earthquake Engineering》2013

A three dimensional dynamic numerical methodology is developed and used to back-analyze experimental data on the seismic response of single piles in laterally spreading slopes. The aim of the paper is not to seek successful a-priori (Type A) predictions, but to explore the potential of currently available numerical techniques, and also to get feedback on modeling issues and assumptions which are not yet resolved in the international literature. It is illustrated that accurate simulation of the physical pile–soil interaction mechanisms is not a routine task, as it requires the incorporation of advanced numerical features, such as an effective stress constitutive soil model that can capture cyclic response and shear-induced dilation, interface elements to simulate the flow of liquefied ground around the pile and proper calibration of soil permeability to model excess pore pressure dissipation during shaking. In addition, the “conventional tied node” formulation, commonly used to simulate lateral boundary conditions during shaking, has to be modified in order to take into account the effects of the hydrostatic pore pressure surplus that is created at the down slope free field boundary of submerged slopes. A comparative analysis with the two different lateral boundary formulations reveals that “conventional tied nodes”, which also reflect the kinematic conditions imposed by laminar box containers in centrifuge and shaking table experiments, may underestimate seismic demands along the upper part of the pile foundation.  相似文献   

SPATIAL VARIABILITY OF MIDTROPOSPHERIC CIRCULATION PATTERNS AND ASSOCIATED SURFACE CLIMATE IN THE UNITED STATES DURING ENSO WINTERS     

Michael J. Keables 《自然地理学》2013,34(4):331-348

Numerous studies have documented that the Pacific/North American (PNA) pattern is the dominant extratropical response to ENSO forcing affecting the circulation over North America. However, the PNA is not the sole pattern that occurs during ENSO events. This study identifies the dominant synoptic circulation patterns and associated temperature and precipitation departures that occur during ENSO winters. Using standardized departures of 500 mbar heights over North America and the North Pacific Ocean, a subjective classification of the anomaly maps for winter months identified as warm ENSO events identifies three basic categories of 500 mbar standardized anomaly patterns: Variations of the PNA pattern, the reverse PNA pattern, and patterns with no PNA signature. Composite standardized anomaly maps of the synoptic categories of 500 mbar heights as well as composites of standardized temperature and precipitation departures for the contiguous United States were constructed. Three variations of the PNA, accounting for nearly half of the ENSO winters, are presented, identifying various configurations of the 500 mbar anomaly field and their effect on precipitation and temperature distribution. Similar composites are presented for reverse PNA and non-PNA winters. [Key words: climatology, climate change, El Nińo/Southern Oscillation, troposphere.]  相似文献   

钻杆内螺纹接头摩擦热裂原因探讨          下载免费PDF全文

刘永刚  练章华  李齐富  李鹏 《探矿工程》2012,39(Z1):97-99

钻杆内螺纹接头摩擦热裂失效事故随着近年来深井、超深井和水平井等复杂工况井的增加而时有发生,已成为钻杆内螺纹接头失效的一种重要形式。本文对钻杆内螺纹接头摩擦热裂纹的宏观失效形式,微观断面特征和材料组织相变特征进行了分析,从钻杆接头受力,钻杆接头材料进行了失效机理研究,并从钻杆使用,材料性能和表面处理等方面提出了预防失效的建议和措施。  相似文献   

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潘国荣  宋蕴璞  李怀锋  张鹏 《大地测量与地球动力学》2012,32(2):78-81

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Linear monitoring for cast-in-place reinforced concrete arch bridge construction     

ZHENG Yifeng  CAO Yu  WANG Yuanyuan 《世界地质(英文版)》2012,15(2):145-150

Linear monitoring is an important link of bridge construction control,which is conducted in key processes of construction to ensure the security of bridge in construction procedure. Combining with main arch construction monitoring program of No. 2 bridge in north district of Changbai international tourism resort,main content and key technologies are recommended. Considering the various influential factors during the construction process,linear adjustment is handled to ensure that the stress and linear of main arch meet design requirements.  相似文献   

钢箱梁典型病害分析及其检测与维护技术研究   总被引：3，自引：0，他引：3  

姜竹生  瞿涛  吕磊  吉伯海 《地震学刊》2011,(5):572-577

基于对我国钢箱梁桥的钢箱梁病害调查,总结出我国钢箱梁典型病害的类型,分析各种钢箱梁典型病害产生的机理及导致其破坏的原因,提出了钢箱梁病害的日常检测与维护技术。针对钢箱梁的涂装劣化、钢材腐蚀、结构性损伤等病害,给出了日常检测与维护的主要项目,介绍了人工目视检测、超声波检测、磁粉检测及涡流检测等主要的检测方法的工作原理、优缺点和适用范围。  相似文献   

水平向不均匀土对箱基动力阻抗的影响     

文学章  尚守平 《地震工程与工程振动》2009,29(6)

采用薄层元素法和有限单元法,建立了地基-箱形基础动力相互作用的三维分析模型,该模型可考虑箱形基础周围土的不均匀性影响.利用该模型,分析了水平方向不均匀土对箱形基础的水平和摇摆阻抗的影响.分析了水平方向不均匀土的厚度、剪切弹性模量以及材料阻尼比的影响.分析结果表明:水平方向不均匀土使得箱形基础的各种阻抗均降低,特别是阻抗的虚部.水平方向不均匀土对摇摆阻抗的影响较大.水平方向不均匀土的剪切弹性模量的影响较大而其材料阻尼的影响较小.随着水平方向不均匀土的厚度的增加和基础埋深的增加,其影响增大.  相似文献   

苏通大桥结构健康状态评估技术研究与应用（3）：主梁损伤定位     

邓扬  李爱群  丁幼亮  姚蓓  杨军  周建华 《地震学刊》2010,(3):336-340

为提高基于模态参数的损伤识别方法的损伤敏感性和噪声鲁棒性,将多源数据融合技术引入到苏通大桥主梁损伤定位方法中。基于D-S证据理论对模态柔度和模态应变能指标进行数据融合,并以苏通大桥扁平钢箱梁为分析对象,对融合后损伤定位指标的应用效果进行了讨论。结果表明：基于数据融合的损伤定位方法具有较强的损伤敏感性,只需要较少的低阶模态信息就能识别主梁的早期损伤;数据融合后,损伤定位指标可以在较强的噪声环境下准确地识别斜拉桥钢箱梁的损伤,具有较好的工程实用性。  相似文献   

中扬子地区震旦系陡山沱组页岩储层孔隙结构特征     

徐祖新  郭少斌 《现代地质》2015,29(1):206-212

通过氩离子抛光-SEM技术,分析了中扬子地区震旦系陡山沱组页岩储层孔隙类型、孔隙形态、孔径和面孔率特征,探讨了这些孔隙的油气地质意义。研究认为,陡山沱组页岩储层发育有机质孔隙、粒间孔隙、粒内孔隙和微裂缝4种孔隙类型。页岩孔隙形态可分为不规则多边形孔、圆形或椭圆形孔、复杂网状孔、串珠状孔、长条形孔、线状孔6种类型,其中复杂网状孔的连通性最好,有利于压差传递,可提高页岩气的解吸效率和储层的渗透率。页岩孔径为10~2 000 nm,主体范围为20~200 nm,平均面孔率为1.4%~6.2%。不同类型的孔隙能够为页岩气的赋存提供不同尺度的储集空间,微裂缝和粒间孔隙对页岩气的运移最为有利。  相似文献   

胶州湾北部水层生态动力学模型与模拟 Ⅰ.胶州湾北部水层生态动力学模型   总被引：1，自引：0，他引：1  

俞光耀  吴增茂  张志南  陆贤昆  奚盘根  娄安刚  张新玲 《中国海洋大学学报(自然科学版)》1999,(3)

建立了一个包括浮游植物、浮游动物、无机氮和磷、溶解态与悬浮有机物及溶解氧七状态变量的浅海水体生态动力学箱式模型,并且考虑了海面太阳辐照度变化、海水与底泥温度变化以及营养盐海底溶出和陆源流入的影响。初步分析了在胶州湾北部浮游生态系统演变的几个特征时期动力学方程中的物流动态特征。结果是比较合理的。  相似文献