Rocking vibrations of a rigid embedded foundation in a poroelastic half‐space     

X. Q. Hu  Y. Q. Cai  G. Y. Ding  J. Wang 《国际地质力学数值与分析法杂志》2010,34(13):1409-1430

This paper presents an analysis of the rocking vibrations of a rigid cylindrical foundation embedded in poroelastic soil. The foundation is subjected to time‐harmonic rocking excitation and is perfectly bonded to the surrounding soil. The soil underlying the foundation base is represented by a homogeneous poroelastic half‐space, whereas the soil along the side of the foundation is modeled as an independent poroelastic stratum composed of a series of infinitesimally thin layers. The behavior of the soil is governed by Biot's poroelastodynamic theory. The contact surface between the foundation base and the poroelastic soil is assumed to be smooth and either fully permeable or impermeable. The dynamic interaction problem is solved by employing a simplified analytical method. Some numerical results for the nondimensional rocking dynamic impedance and nondimensional angular displacement amplitude of the foundation are presented to show the effect of nondimensional frequency of excitation, poroelastic material parameters, hydraulic boundary condition, depth ratio and mass ratio of the foundation. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Nutrient export via overland flow from a cultivated field of an Ultisol in southern China     

Linhong Wei  Xunqiang Cheng  Yuanfeng Cai 《水文研究》2013,27(3):421-432

Understanding the influence of complex interactions among hydrological factors, soil characteristics and biogeochemical functions on nutrient dynamics in overland flow is important for efficiently managing agricultural nonpoint pollution. Experiments were conducted to assess nutrient export from Ultisol soils in the Sunjia catchment, Jiangxi province, southern China, between 2003 and 2005. Four plots were divided into two groups: two peanut plots and two agroforestry (peanut intercropped with citrus) plots. During the study period, we collected water samples for chemical analyses after each rainfall event that generated overland flow to assess nutrient export dynamics. The concentrations of potassium (K) and nitrate‐N (NO₃^––N) in overland flow were higher during the wetting season (winter and early spring). This reflects the solubility of K and NO₃^––N, the accumulation of NO₃^––N during the dry season and an increase in desorption processes and mixing with pre‐event water caused by prolonged contact with soil in areas with long‐duration, low‐intensity rainfall. In contrast, concentrations of total nitrogen (TN) and total phosphorus (TP) were higher during the wet season (late March to early July) and during the dry season (mid‐July to the end of September or early October). This was due to the interaction between specific hydrological regimes, the properties of the Ultisol and particulate transport processes. Variations in nutrient concentrations during storm events further identified that event water was the dominant source of total nitrogen and total phosphorus, and pre‐event water was the dominant source of NO₃^––N. In addition, the results obtained for the different land uses suggest that agroforestry practices reduce nutrient loss via overland flow. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

An example of enhanced tephra deposition driven by topographically induced atmospheric turbulence     

Sebastian F. L. Watt  Jennie S. Gilbert  Arnau Folch  Jeremy C. Phillips  Xiaoming M. Cai 《Bulletin of Volcanology》2015,77(5):1-14

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通过断层气氢探测新郑-太康断裂的浅层位置     

马兴全  王志铄  孙杰  李涛  李源  蔡颖哲  夏修军  赵显刚 《震灾防御技术》2017,12(2):354-362

新郑-太康断裂隐伏于河南省东部平原下，是一条规模较大的北西向断裂带，曾于2010年发生太康4.7级地震，确定该断裂准确的浅层位置对防震减灾具有重要意义。根据深部石油勘探资料，应用德尔格X-am 7000型多气体检测仪，在新郑地区布置2条与断裂走向近垂直的地球化学测线进行土壤氢气浓度测试，结果发现解放路和马庄村-前宫村测线异常点位处氢气浓度分别为背景值的16-33倍和40-50倍。2条H₂浓度曲线同步解释出一条倾向变化、宽约150m的走滑断裂带，位置与石油勘探资料吻合良好。此次研究表明利用断层气氢探测隐伏断裂的浅层位置在该区具有较好的可行性。  相似文献   

吉林松原5.8级震群震相特征     

卢燕红  张洪艳  刘轶男  陈聪  陈闯  蔡宏雷 《地震地磁观测与研究》2017,39(1):67-72

选取2013年松原5.8级震群23个M_S≥3.0地震事件，通过地震波的振动持续时间、速度、周期、振幅等，进行震相识别，综合分析发现：该区域土层较厚，且震源相对较浅，面波较发育，波列的振动持续时间较长；地震震相主要以Pn、Sn、Pg、Sg、PmP、SmS为主：其中PmP、SmS震相在震中距70—110 km范围内较易识别；Pn、Sn震相在震中距150 km以上可较清晰的识别，随着震中距增大，Sn震相在震中距350 km以上将不易识别。  相似文献   

基于国普数据的芦山县地震应急基础数据更新及其应用研究     

申源  蔡晓燕  张莹  郭红梅 《震灾防御技术》2017,12(4):893-901

通过研究地理国情普查数据和四川省芦山县地震应急基础数据库的数据类型、数据结构及二者间的关系，完成了地理国情普查数据向芦山县地震应急基础数据的转换与更新；并以芦山地震为例，利用城镇地震应急快速评估系统验证了更新后数据的可靠性。  相似文献   

Hybrid absorbing boundary condition for three-dimensional elastic wave modeling     

Xin Liu  Yang Liu  Zhi-Ming Ren  Xiao-Hui Cai  Bei Li  Shi-Gang Xu  Le-Kai Zhou 《应用地球物理》2017,14(2):270-278

Edge reflections are inevitable in numerical modeling of seismic wavefields, and they are usually attenuated by absorbing boundary conditions. However, the commonly used perfectly matched layer (PML) boundary condition requires special treatment for the absorbing zone, and in three-dimensional (3D) modeling, it has to split each variable into three corresponding variables, which increases the computing time and memory storage. In contrast, the hybrid absorbing boundary condition (HABC) has the advantages such as ease of implementation, less computation time, and near-perfect absorption; it is thus able to enhance the computational efficiency of 3D elastic wave modeling. In this study, a HABC is developed from two-dimensional (2D) modeling into 3D modeling based on the 1st Higdon one way wave equations, and a HABC is proposed that is suitable for a 3D elastic wave numerical simulation. Numerical simulation results for a homogenous model and a complex model indicate that the proposed HABC method is more effective and has better absorption than the traditional PML method.  相似文献   

Processes of initial collision and suturing between India and Asia   总被引：6，自引：0，他引：6  

Lin Ding  Satybaev Maksatbek  FuLong Cai  HouQi Wang  PeiPing Song  WeiQiang Ji  Qiang Xu  LiYun Zhang  Qasim Muhammad  Baral Upendra 《中国科学:地球科学(英文版)》2017,60(4):635-651

The initial collision between Indian and Asian continents marked the starting point for transformation of land-sea thermal contrast, uplift of the Tibet-Himalaya orogen, and climate change in Asia. In this paper, we review the published literatures from the past 30 years in order to draw consensus on the processes of initial collision and suturing that took place between the Indian and Asian plates. Following a comparison of the different methods that have been used to constrain the initial timing of collision, we propose that the tectono-sedimentary response in the peripheral foreland basin provides the most sensitive index of this event, and that paleomagnetism presents independent evidence as an alternative, reliable, and quantitative research method. In contrast to previous studies that have suggested collision between India and Asia started in Pakistan between ca. 55 Ma and 50 Ma and progressively closed eastwards, more recent researches have indicated that this major event first occurred in the center of the Yarlung Tsangpo suture zone (YTSZ) between ca. 65 Ma and 63 Ma and then spreading both eastwards and westwards. While continental collision is a complicated process, including the processes of deformation, sedimentation, metamorphism, and magmatism, different researchers have tended to define the nature of this event based on their own understanding, an intuitive bias that has meant that its initial timing has remained controversial for decades. Here, we recommend the use of reconstructions of each geological event within the orogenic evolution sequence as this will allow interpretation of collision timing on the basis of multidisciplinary methods.  相似文献   

福建地区波速比分布特征     

蔡杏辉  巫立华  张丽娜  段刚  许振栋 《地震地磁观测与研究》2017,38(3):23-29

选取福建地震台网"十五"观测系统2009—2015年记录的748个M_L≥1.0地震事件,采用多台和达法计算福建区域波速比值和泊松比值,并绘制二者空间等值线图,分析其分布特征,讨论波速比值高低与震级大小和震源深度的关系,结果发现,波速比大小与二者关系不大。  相似文献   

光纤光谱仪的研制及其在海水营养要素检测中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

李彩  曹文熙  程远月  孙兆华  杨跃忠 《热带海洋学报》2010,29(2):12-16

基于交叉非对称的czerny-Turner结构, 研制了一种微型光纤光谱仪, 采用光栅分光、线阵CCD探测光, 基于复杂可编程逻辑器件及PC104设计CCD数据采集电路, 采样结果通过PC104总线上传至PC104工控机, 光谱仪及数据采集电路集成为一光谱仪模块, 约为96mm(宽)×104mm(长)×18mm(高), 该模块与PC104工控机之间通过PC104总线以“针”和“孔”形式层叠连接, 在具有体积小、功耗低、采样速度快等优点的同时还具有极好的抗震性, 非常适合于野外恶劣工作环境下的在线使用。将其应用于海水中铁等痕量元素及营养盐在线检测仪, 试验结果良好。  相似文献