GPS-RTK与数字测深仪在玉环县漩门湾水下地形测量中的应用     

刘云波  吴吕稳  许茵 《测绘与空间地理信息》2012,(7):215-216

探讨了GPS-RTK与数字测深仪集成技术在水下地形测量中的原理和作业流程,并结合工程实例,使其高精度、高效率、低成本的优势得以体现。  相似文献   

相邻基坑有限宽度土条主动土压力的计算     

岳树桥  左人宇  陆钊 《岩土力学》2016,37(7):2063-2069

同步开挖的相邻基坑间有限宽度土条不同于以往的邻近既有建筑基坑的有限土条,其破坏方向未知,破坏形式多样,土条两侧的主动土压力计算不能沿用以往的研究成果来扩展应用。借鉴筒仓受力原理应用于相邻基坑间的土条分析计算,通过力学平衡分析和微分方程求解,得出基坑开挖中两侧均为支护结构的有限宽度土条（砂土和黏性土）的主动土压力计算公式,该公式输入参数少、假设条件少,使用方便。对比朗肯主动土压力计算公式和有限元数值模拟计算结果,该计算公式与有限元模拟计算结果基本一致,在相同深度处计算的土压力远小于朗肯土压力。  相似文献   

板块运动地球动力学机制探究     

方曙 《大地测量与地球动力学》2016,36(9):775-783

对前人提出的多种地球动力学机制特别是地幔对流说进行剖析,提出板块运动地球动力来源于地转离极作用和旋转半径变化造成的地转不同步作用,并受到刚性岩石圈板块应力平衡作用、惯性作用和弹性作用等内在规律的制约,另外规律性的固体潮作用和偶然性的陨石撞击作用是影响板块运动的附加应力因素。  相似文献   

Dynamic stiffness of monopiles supporting offshore wind turbine generators     

《Soil Dynamics and Earthquake Engineering》2016

Very large diameter steel tubular piles (up to 10 m in diameter, termed as XL or XXL monopiles) and caissons are currently used as foundations to support offshore Wind Turbine Generators (WTG) despite limited guidance in codes of practice. The current codes of practice such as API/DnV suggest methods to analysis long flexible piles which are being used (often without any modification) to analyse large diameter monopiles giving unsatisfactory results. As a result, there is an interest in the analysis of deep foundation for a wide range of length to diameter (L/D) ratio embedded in different types of soil.This paper carries out a theoretical study utilising Hamiltonian principle to analyse deep foundations ($L/D\ge 2$) embedded in three types of ground profiles (homogeneous, inhomogeneous and layered continua) that are of interest to offshore wind turbine industry. Impedance functions (static and dynamic) have been proposed for piles exhibiting rigid and flexible behaviour in all the 3 ground profiles. Through the analysis, it is concluded that the conventional Winkler-based approach (such as p–y curves or Bean-on-Dynamic Winkler Foundations) may not be applicable for piles or caissons having aspect ratio less than about 10 to 15. The results also show that, for the same dimensionless frequency, damping ratio of large diameter rigid piles is higher than long flexible piles and is approximately 1.2–1.5 times the material damping. It is also shown that Winkler-based approach developed for flexible piles will under predict stiffness of rigid piles, thereby also under predicting natural frequency of the WTG system. Four wind turbine foundations from four different European wind farms have been considered to gain further useful insights.  相似文献   

平均海面同步改正传递法的误差分析          下载免费PDF全文

许军  暴景阳  刘雁春  于彩霞 《海洋测绘》2012,(4):22-24

给出了平均海面同步改正法中异步效应及余水位引起的误差的表达式。对中国沿海3组典型验潮站进行了数值计算,统计分析了异步效应与余水位引起的误差的量值与规律。  相似文献   

大震前水氡同步异常变化及其预测意义探讨   总被引：2，自引：0，他引：2  

张昱  刘小凤  常千军  陈瑶  刘宝勤 《地震研究》2010,33(3)

分析了1990年4月26日青海共和7.0级地震、2000年9月12日青海兴海6.6级地震、2001年11月14日昆仑山口西8.0级地震和2008年5月12日四川汶川8.0级地震前青海、甘肃以及四川北部地区部分水氡观测点的资料变化情况,发现这些测点的观测资料存在同步或准同步的变化,而且变化时间早,持续时间长。共和地震前,距震中越近的测点,出现的趋势性异常所占的比例越高,异常时间越早。昆仑山口西地震的异常持续时间更长,多数异常点距震中更远。随着时间的推移,异常点从西北向东南迁移。兴海地震个别测点出现异常。汶川地震的异常的同步性更好,而且多数测点的同震效应非常明显。这些地震的异常的恢复时间均无明显的规律,有些是在地震前恢复,有些是在地震后恢复。  相似文献   

浅层地震勘探数据拟同步采集时差分析与实践   总被引：2，自引：1，他引：1       下载免费PDF全文

朱德兵  平利姣  朱自强 《地球物理学进展》2008,23(6):1958-1962

理想的地震勘探数据采集,其硬件系统采用多道同步方式实现,保证多路信号的时间或相位一致性.理论时差分析表明,就地震信号的初至时刻来看,多路同步采集系统也存在系统误差.浅层地震勘探数据记录道数少,采用单个A/D模数转换器件通过逻辑系统控制实现少量地震道的多路循环分时采集,在满足采样定理所需采样频率和不增加地震信号初至系统误差的前提下,可以以较少的硬件成本实现浅层地震信号的有效采集,这种采集方式我们称之为有效拟同步采集;通过实践证明了其采集方式的有效性.  相似文献   

广东天气雷达组网策略及在台风监测中的应用   总被引：2，自引：1，他引：1  

白玉洁  胡东明  程元慧  胡胜 《热带气象学报》2012,28(4):603-608

天气雷达是台风监测的重要探测工具,雷达资料实际应用过程中经常遇到多雷达运行不同步、资料采集不及时等问题的困扰。采用区域雷达服务器中央控制运行模式能有效解决这些问题。以0606号台风"派比安"为例,介绍了广东省新一代多普勒天气雷达网在台风监测方面的策略和运行模式。多雷达拼图大大拓展了雷达的监测范围,双多普勒雷达风场反演技术能够揭示台风环流的中尺度三维结构。  相似文献   

A SUPER-DYNAMIC DEFORMATION MEASUREMENT SYSTEM WITH LONG-TIME PARALLEL CONTINUOUS ACQUISITION          下载免费PDF全文

LI Shi-nian  QI Wen-bo  LIU Li-qiang 《地震地质》2019,41(6):1529-1538

In the simulation experiments of earthquakes in laboratory, the instability slip or rupture events are obtained through steady state loading to simulate earthquake processes. In the experiments, steady-state deformation and unstable sliding occur alternately. It is hard to determine the origin time and duration of the instability event of fault, and there may be many instability events in one experiment. Therefore, in order to ensure that sufficient data is obtained at the extremely short instability moment to analyze the mechanical process of the earthquake source, the data acquisition system is required to continuously collect data at high-speed from the beginning of the experiment until the end, and the lasting time can be more than ten hours, so it requires huge storage space. Although the upper frequency limit of the instability signal is unknown exactly, but the previous experiments have shown that the frequency of the signal will reach hundred to several kilohertz, so the sampling frequency of the data acquisition should be above megahertz. In this case of long-time continuous high-frequency data acquisition, it is still necessary to maintain a high signal-to-noise ratio. Furthermore, previous studies have proved that the source mechanics field has a complex spatial structure, which is difficult to describe with a few measuring points, and it is necessary to perform simultaneous measurements of the source mechanics field for dozens or more measuring points. The combination of long-term continuous recording, high-resolution high-frequency sampling and multi-point simultaneous measurement poses a huge challenge to the technical indicators of the observing system. With the method for composing distributed synchronous acquisition machine group by using multiple high-resolution high-frequency sampling computers, a super dynamic deformation measurement system of high signal-to-noise ratio, which features 64-channel, 16-bit resolution, 4MHz sampling frequency, and parallel continuous acquisition with tens of hours was developed. This system can realize the synchronous acquisition of various signals, such as strain, acoustic emission, electromagnetic waves and displacement, so it is convenient for analyzing the conversion relationship between various physical quantities.  相似文献   

上天、入地、下海:极端条件下矿物学研究     

束今赋 《地学前缘》2020,27(3):133-153

上天、入地、下海,进行极端条件下的矿物学研究,研究微矿物,发现新矿物。主要利用金刚石压机,结合使用国内外同步辐射X-光源、中子源,以及其他多种物理的、化学的、光学的测试手段(如岩石矿物化学分析,光薄片测定,电子探针,离子探针,扫描电镜,透射电镜,红外、紫外、拉曼光谱,激光加热等),对来自天外的陨石、陨石坑样品、地球深处地幔源矿物以及海底甲烷水合物进行了一些研究。模拟不同温度和压力下各种不同成分的矿物材料的晶体结构、物理和化学性质。文章着重研究从地球内核到地壳海底的各种不同组分在不同温度、压力极端环境下形成的各种各样的典型矿物:从金属固体内核和金属液体外核中的ε-Fe到核幔边界(CMB)地球D″层的后钙钛矿(Post-Perovskite)结构(ppv)镁铁硅酸盐(Mg,Fe)SiO₃,从下地幔中的铁磁性钙钛矿(Perovskite)结构(pv)镁铁硅酸盐布里奇曼石(Bridgmanite)(Mg,Fe)SiO₃、镁铁氧化物(Fe,Mg)O和后尖晶石(Post-Spinel)结构的含Fe³⁺毛河光矿(Maohokite)(HP-Mg$Fe^{3+}_{2}O_{4}$)到过渡带、上地幔和地壳中的镁铁硅酸盐、硅氧化物、铬铁氧化物和金刚石及其内含物以及甲烷水合物(CH₄·H₂O)等。进行高温高压极端条件下的矿物学研究,为探索地球结构性质、形成动力和发展历史提供了新的窗口。  相似文献