Lateral distributions of EAS muons (Eμ>800 MeV) measured with the KASCADE-Grande Muon Tracking Detector in the primary energy range 1016–1017 eV     

《Astroparticle Physics》2015

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Analysis of soil resistance on laterally loaded piles based on 3D soil–pile interaction     

Youngho Kim  Sangseom Jeong 《Computers and Geotechnics》2011

The load distribution and deflection of large diameter piles are investigated by lateral load transfer method (p–y curve). Special attention is given to the soil continuity and soil resistance using three-dimensional finite element analysis. A framework for determining a p–y curve is calculated based on the surrounding soil stress. The appropriate parametric studies needed for verifying the p–y characteristic are presented in this paper. Through comparisons with results of field load tests, the three-dimensional numerical methodology in the present study is in good agreement with the general trend observed by in situ measurements and thus, represents a realistic soil–pile interaction for laterally loaded piles in clay than that of existing p–y method. It can be said that a rigorous numerical analysis can overcome the limitations of existing p–y methods to some extent by considering the effect of realistic three-dimensional combination of pile–soil forces.  相似文献   

Longitudinal dunes can move sideways   总被引：3，自引：0，他引：3  

Patrick Hesp  Robert Hyde  Virginia Hesp  Qian Zhengyu 《地球表面变化过程与地形》1989,14(5):447-451

Longitudinal dunes occur in all major sand areas in the world. Their dominant mode of migration or extension is considered to be either prevailing- or resultant wind-parallel, the dunes extending downwind via accretion of the terminal nose. In the Qaidam Pendi in Northwest China a series of active longitudinal dunes extend downwind at 5–10 m yr^?1. Internal sedimentary structures examined in the dunes, however, display beds dipping in one direction rather than two opposed directions as is expected. Analysis of aerial photographs confirms that these dunes migrate laterally up to three metres per year, whilst maintaining a symmetrical longitudinal dune morphology.  相似文献   

京津唐张地区地壳上地幔三维P波速度结构   总被引：33，自引：15，他引：33  

朱露培  刘福田 《地球物理学报》1990,33(3):267-277

采用作者最近新提出的频谱参数化方法,对北京电信传输台网2447个远震P波到时残差数据进行了反演,说明新的参数化方法能有效地应用于实际数据.反演结果表明,京津唐张地区深部100多km内存在明显的速度横向不均匀性;50 km以上部分的结构与地表的地质构造有较好的对应关系:在燕山隆起区下部表现为高速异常区,而凹陷区下部则呈现低速异常区;深度100 km以下,地表构造的痕迹逐步消失,异常蝠度也相应降低.研究区域范围内存在三个大的低速异常块体,其中以天津、唐山附近的水平尺度为100 km左右的低速异常区幅度最大,向下一直延伸到约100 km的深度,而且在100 km以下存在一低速异常构造与之对应.研究区域内发生的强震大部分都位于低速异常区边缘向高速区过渡的梯度带上.  相似文献   

一种反演地幔横向密度差异的方法          下载免费PDF全文

叶正仁 《地球物理学报》1988,31(1):65-72

重力位球谐系数及板块运动速度是两种独立的地球物理观测资料,但二者同时又是地幔内横向密度差异及与之相联系的地幔流动的结果,从而,中长波重力异常与板块运动的观测提供了探索地幔横向非均匀的一条途径。本文根据适合于低雷诺流动的最小粘滞损耗原理,利用张量场及矢量场的标量分解与传播子解的数学方法,将观测的重力位球谐系数和板块运动速度作为约束条件,发展了一种反演地幔横向密度差异的方法。  相似文献   

The role of thrust ramp reactivation in pull-apart mechanism of the Erzincan basin,North Anatolian Fault Zone,Turkey     

《Geodinamica Acta》2013,26(3):219-228

The new field data obtained from the southwestern margin of the Erzincan pull-apart basin located on the eastern segment of North Anatolian Fault Zone indicate that the opening of the basin is not only controlled by pull-apart mechanism but also by a lateral ramp structure associated with SSE-NNW Late Miocene thrusting along the Sivas Basin. The fault bordering the southwestern margin of the basin is the lateral part of the Karada thrust that is the roof thrust of the Sivas fold-thrust system, rather than a segment of the North Anatolian Fault Zone. The Erzincan basin was nucleated as a lateral ramp basin during the Pliocene on the lateral ramp-related folds and expanded by the pull-apart opening mechanism between two segments of the North Anatolian Fault Zone. The WSW-ENE pull-apart opening of the basin was recorded by the Pliocene lacustrine-fluvial sediments and Quaternary volcanics as listric normal faulting.  相似文献   

A model of submarine channel-levee evolution based on channel trajectories: Implications for stratigraphic architecture   总被引：3，自引：0，他引：3  

Zoltán SylvesterAlessandro Cantelli 《Marine and Petroleum Geology》2011,28(3):716-727

Channel-levee systems are frequently interpreted as having a long history of cut-and-fill by channel-shaped features of different scales. Results from a simple geometric model based on a centerline migration algorithm combined with a vertical channel trajectory show that an incising-to-aggrading trajectory of a single channel can produce realistic morphologies similar to systems observed on the seafloor and subsurface, including features such as a basal erosional surface, coeval inner and outer levees, internal erosional boundaries, and terraces draped by inner levee deposits. Channel migration results in composite erosional surfaces that are distinct from topographic surfaces, and their formation does not require larger than usual erosional flows. Many submarine channels interpreted as underfit were probably carved by flows similar to the ones that eroded and deposited the entire channel system. We suggest that the features of most submarine channel-levee systems do not require large temporal variations in flow magnitude but can be explained by a simpler model whereby incision, migration and aggradation of a single channel form over time results in an apparently complex system.  相似文献   

四种地下结构抗震设计简化分析方法对比     

徐琨鹏  景立平  宾佳 《震灾防御技术》2019,14(2):281-292

在地下结构抗震设计简化分析方法中,强制反应位移法将土层变形施加在有限元模型侧边界模拟地震作用,反应加速度法将土层加速度施加到整个有限元模型上模拟地震作用,此外还有仅将土层加速度施加到土层模型上模拟地震作用的方法。上述方法均规避了反应位移法中关于弹簧刚度的取值问题,提高了计算效率。本文以1个双跨箱形结构为例,用动力时程分析的计算结果作为校核,分析了强制反应位移法、反应加速度法和仅将土层加速度施加到土体中的简化分析方法在不同侧边距条件下的计算精度,再结合常用的反应位移法,对比分析了4种简化分析方法的误差。分析结果表明:使用强制反应位移法时,侧边距取为1倍结构宽度导致的误差最小,反应加速度法和仅在土体施加加速度的简化方法对侧边距取值不敏感,反应位移法在角点造成的误差最大。  相似文献   

简正模频率的地壳改正效应          下载免费PDF全文

张凌云  徐建桥  孙和平 《地球物理学报》2020,63(4):1332-1339

该文通过对CRUST2.0+PREM 16200个区域一维地球模型简正模频率的计算,得到简正模非线性地壳改正效应.结果表明:地壳改正的非线性化改正不可或缺,对于低频简正模,其影响较小;对于高频简正模,其影响较大,这一变化遵循能量密度函数分布规律.此外,该文将CRUST2.0网格数据展开成球谐函数,并在此基础上计算了地壳侧向非均匀导致的二阶谱峰分裂系数.将其与地幔对应系数比较得出:前者造成的简正模谱峰分裂通常远远小于后者;地壳造成的二阶谱峰分裂主要贡献来自于间断面地形起伏(地壳厚度等)而非地壳的侧向非均匀参数扰动;在反演地幔结构时必须扣除地壳对简正模谱峰分裂系数的影响.  相似文献   

深反射大炮揭示的青藏高原侧向碰撞带地壳骨架结构          下载免费PDF全文

酆少英  李秋生  邓小娟  李井元  熊小松  卢占武  李文辉  王晓冉  吴庆宇  石金虎 《地球物理学报》2020,63(3):828-839

青藏高原东南缘处于印度板块与欧亚板块碰撞的侧翼,揭示该地区的岩石圈结构有助于完整理解青藏高原碰撞造山的动力学过程,对构建大陆碰撞成矿理论框架至为关键.本研究对横过青藏高原侧向碰撞带的一条深反射地震剖面的15个大炮资料,进行了针对性静校正、去噪等处理和单次叠加成像,结果剖面显示了侧向碰撞带岩石圈结构的骨架特征:(1)双程走时(TWT)8～10s的强反射(Tc)将地壳分为上、下两层;Tc可能是大型滑脱构造的拆离面,其存在使上地壳的变形与下地壳解耦;(2)Moho间断面反射(Tm)为3～4个同相轴的窄带反射波组,横向不连续,与深大断裂交汇处被错断,但断距不大;(3)在兰坪—思茅地块下方TWT21s和扬子克拉通西缘下方TWT22～24s存在相向倾斜的反射波组(TL);以Tc、Tm和TL构成的骨架结构,定性地描绘出剖面下方岩石圈地幔以汇聚为主、地壳块体以侧向滑移为主和上地壳为薄皮逆冲或滑脱的分层动力学模式.该岩石圈变形样式明显不同于以正向碰撞挤压、地壳缩短垂向增厚为主的"冈底斯模式".  相似文献