瞬态瑞雷波法在软土地区地基加固检测中的应用     

富锡良  巫虹  沈仁之 《上海国土资源》2008,(1):53-56

碎石桩、预制桩、搅拌桩是软土地区复合地基加固的常见方法,而有效地检测与评价这些方法加固的深度、强度以及复合地基的承载力等质量指标,是工程建设过程中的重要环节。瞬态瑞雷波在上述三种加固检测与评价中的可行性和有效性,同时结合传统的静态的原位检测手段,瑞雷波法检测可以实现快速准确的大面积检测。  相似文献   

世界海洋蒸发波导时空统计规律研究   总被引：3，自引：0，他引：3  

杨坤德  张琪  史阳  何正耀  雷波  韩一娜 《海洋学报(英文版)》2016,35(7):20-29

The statistical features of the evaporation duct over the global ocean were comprehensively investigated with reanalysis data sets from the National Centers for Environmental Prediction.These data sets have time and spatial resolutions of 1 h and 0.313°×0.312°,respectively.The efficiency of the analysis was evaluated by processing weather buoy data from the Pacific Ocean and measuring propagation loss in the Yellow Sea of China.The distribution features of evaporation duct height(EDH) and the related meteorological factors for different seas were analyzed.The global EDH is generally high and demonstrates a latitudinal distribution for oceans at low latitudes.The average EDH is approximately 11 m over oceans beside the equator with a latitude of less than 20°.The reasons for the formation of the global EDH features were also analyzed for different sea areas.  相似文献   

海洋电场采集电极极差自动补偿方法设计     

刘贵豪  刘兰军  黎明  陈家林  牛炯 《海洋技术学报》2016,(1):57-61

针对海洋电磁勘探的低频、微弱电场信号采集中电极与放大采集电路的耦合问题,提出了一种支持直流耦合的电极极差自动补偿放大采集电路设计方法,给出了系统设计实现,详细介绍了电极极差自动补偿放大采集电路和自动补偿控制算法.测试结果表明,所设计的电极极差自动补偿方法可将0.1～0.7 mV的电极极差自动补偿至0.043～0.074 mV,均控制在0.1 mV以内,满足了海洋电场采集直流耦合的需求,降低了电场采集电路对不极化Ag/AgC1电极的极差设计要求,可有效应用于海洋低频电场信号采集.  相似文献   

K型石油钻机井架瞬态研究          下载免费PDF全文

李万昊  段国林  许红静  马红月  张西坤 《探矿工程》2016,43(8):48-52

根据钻机井架实际工作情况建立井架振动模型,通过测试实验得到动态载荷,应用ANSYS软件对K型钻机井架进行瞬态响应分析。研究结果表明：在动载荷作用下,钻机井架各部分变化具有同时性,而达到最大值的时刻不同,说明井架响应具有滞后性;井架以上下振动为主,同时具有一定程度的扭振;位移变化主要发生在井架顶部,而扭转振幅从顶端向下逐渐减弱;最大振动位移、最大弯矩、最大应力分别为108.33 mm、80990.8 N·m、-0.16354E 09 Pa,均满足设计要求。在瞬态振动过程中,振动衰减最快的是扭转,而X向、Y向、Z向振动位移中X向衰减最快,这与实际情况一致。因此,运用实际动载荷对井架进行瞬态分析为井架结构设计以及安全评估提供了参考依据。  相似文献   

江苏及邻近地区地震电磁辐射异常与地震关系   总被引：1，自引：0，他引：1  

卢永  杨军  冯志生  张念孝 《华南地震》2004,24(2):36-46

对这20多年来江苏及其邻区的地震前的电磁波观测资料进行了整理,对出现的异常信息和地震的对应关系进行了统计分析,分析结果表明,电磁波异常信息与地震三要素有一定的对应关系,并对电磁波的性质从电磁波产生的机制和传播方式两个方面进行了探讨。  相似文献   

Relationships between hydraulic parameters in a small stream under varying flow and seasonal conditions     

D. R. Hart  P. J. Mulholland  E. R. Marzolf  D. L. Deangelis  S. P. Hendricks 《水文研究》1999,13(10):1497-1510

Twenty conservative tracer injections were carried out in the same reach of a small woodland stream in order to determine how variation in discharge and leaf accumulation affect stream hydraulic parameters. The injections were made at various discharge rates ranging from 2·6 to 40 l/s. Five of the injections were made during late autumn, when there were large accumulations of leaves in the stream. Estimates of hydraulic parameters were made by fitting a transient storage solute transport model to conservative tracer concentration profiles. Velocity increased almost linearly with increasing discharge, indicating a decline in the Darcy friction factor. Dispersion also increased with increasing discharge, especially for the lower flow injections. The relative size of the storage zone was small (∽0·1). There was no definable relationship between discharge and the relative storage zone size, but the rates of exchange between the storage zone and the main channel increased markedly with increasing discharge. The presence of large accumulations of leaves had a clear effect on the hydraulic characteristics of the stream, producing much higher friction factors, larger storage zone sizes and lower velocity than would have been predicted by discharge alone. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Dynamic soil–structure interaction analysis using Lanczos vectors with adaptive time integration technique     

R. Venugopala Rao  N. S. V. Kameswara Rao 《国际地质力学数值与分析法杂志》1999,23(11):1141-1158

An analytical procedure to obtain the response of soil–structure interaction problems, time domain is described. The procedure makes use of large domain for descritization along with co-ordinate transformation using Lanczos vectors. The responses are obtained in time domain using an adaptive direct integration method. The scheme has the ability to estimate errors due to temporal discretization as well as co-ordinate transformation. The procedure has been applied to half-space problems and non-convex domains for validation of the scheme, and the scheme obeys causality condition in both the situations. The present method has all the advantages of time domain scheme which is local both in space and time with small computational effort. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

天然电场选频测深法在地下水勘探中的异常理论分析与实践应用     

杨天春  陈卓超  梁竞  戴世鑫  周林  杨追 《地学前缘》2020,27(4):302-310

选频法是音频大地电场法的进一步应用与发展。本文通过实践应用说明选频法在浅层地下水勘探中的有效性,并对选频法测深极距(MN)与地下水埋深之间的关系开展对比分析和初步理论研究。首先,采用水平交变电场、交变磁场共同作用下的均匀半空间中低阻导电球体简化地质地球物理模型,对选频法测深曲线开展正演计算;然后,对选频法在广西“十二五”农村饮水安全工程应用中的131口钻井出水量情况进行统计,并对其中98口钻井的钻探情况开展详细列表统计分析,对比研究测深曲线异常处MN极距大小与实际钻探出水深度之间的关系。理论分析与实践应用表明,选频法在浅层地下水勘探中效果明显,是一种确定浅层地下水井位的有效方法;同时,实践统计结果表明,选频法测深法异常曲线处MN极距的大小与实际钻探出水深度之间存在1∶1的近似关系,验证了理论模拟计算结果的正确性;另外,本文的研究成果表明,在浅层(<200 m)天然电磁法勘探中,天然电场观测值的大小除了与大地的电阻率、信号的频率有关外,还与电极距大小是相关的。  相似文献   

瞬态信号高分辨力谱分析——富里叶变换插值法   总被引：1，自引：0，他引：1  

李正斌 《煤田地质与勘探》1995,23(6):51-54

在介绍提高谱线分辨力的2种数字处理方法(BSFA和移频低通滤波)的基础上,根据谱线间隔Δf=1/(NΔ),要提高谱线分辨力,不仅增大Δ,增大N同样也可以降低Δf,提出了富里叶交换(FFT)插值法。但N值的增大不是由原始采样数据补充零来实现,而是根据在频谱图上选取感兴趣的频域范围作为富氏变换的输入,将谱线的谱添加若干零后再作反富氏变换,得到放大2倍的谱线。该方法在多组信号相关谱分析中尤其适用。   相似文献   

半航空瞬变电磁自适应正则化-阻尼最小二乘算法研究     

杨聪 《地质与勘探》2020,56(1):137-146

反演问题一直是地球物理的重点研究问题之一。本文以长导线源半航空瞬变电磁为例,对时间域半航空数据进行一维反演研究。将自适应正则化(ARIA)反演方法和阻尼最小二乘(LM)反演方法相结合,提出一种改进的反演方法:自适应正则化-阻尼最小二乘(ARIA-LM)反演算法。本文选用三层理论模型对比阻尼最小二乘算法、自适应正则化反演算法与本文方法,并使用四层理论地层模型来验证算法的有效性和可靠性。结果表明:该算法在一定程度上对高阻分辨率增强,能有效提高反演的精度及稳定性。  相似文献