比值参数在高密度电法中的应用     

杨润海  赵晋明  王彬  李正光  卢吉高  曾祥凤 《地震研究》2003,26(2):197-200

探讨了比值参数在高密度电阻率法中的应用；根据工程实例说明比值参数在压制局部干扰和邻近异常分离中有良好效果；将比值参数断面与电阻率反演断面比较研究，能取得较好的异常解释效果。  相似文献   

高水压顶管隧道管节修复装置的设计与应用          下载免费PDF全文

常喜平  贺建群  王乐  李贻浩 《探矿工程》2016,43(6):56-59

富春江顶管工程为例,介绍了一种可快速拆卸的用于深埋顶管隧道对管节局部破损进行修复的装置。装置结构简单、紧凑,易于在圆形截面的隧道中进行快速拼装。该装置最高耐水压力0.8 MPa,可对地下水位以下30~80 m顶管隧道中出现沿轴线长＜0.4 m环状破损的管节进行注浆修复。这种设计能够有效解决深埋顶管隧道小面积局部破损、小范围漏水涌砂等问题,为深埋顶管等方法构筑的圆形隧道提供应急修复保障。  相似文献   

Meteorology and haze structure during AGASP-II,Part 1: Alaskan Arctic flights, 2–10 April 1986     

G. A. Herbert  R. C. Schnell  H. A. Bridgman  B. A. Bodhaine  S. J. Oltmans  G. E. Shaw 《Journal of Atmospheric Chemistry》1989,9(1-3):17-48

The second Arctic Gas and Aerosol Sampling Program (AGASP-II) was conducted across the Alaskan and Canadian Arctic in April 1986, to study the in situ aerosol, and the chemical and optical properties of Arctic haze. The NOAA WP-3D aircraft, with special instrumentation added, made six flights during AGASP-II. Measurements of wind, pressure, temperature, ozone, water vapor, condensation nuclei (CN) concentration, and aerosol scattering extinction (b_sp) were used to determine the location of significant haze layers. The measurements made on the first three flights, over the Arctic Ocean north of Barrow and over the Beaufort Sea north of Barter Island, Alaska are discussed in detail in this report of the first phase of AGASP II. In the Alaskan Arctic the WP-3D detected a large and persistent region of haze between 960 and 750 mb, in a thermally stable layer, on 2, 8, and 9 April 1986. At its most dense, the haze contained CN concentrations >10,000 cm^–3 and b_sp of 80×10^–6 m^–1 suggesting active SO₂ to H₂SO₄ gas-to-particle conversion. Calculations based upon observed SO₂ concentrations and ambient relative humidities suggest that 10⁴–10⁵ small H₂SO₄ droplets could have been produced in the haze layers. High concentrations of sub-micron H₂SO₄ droplets were collected in haze. Ozone concentrations were 5–10 ppb higher in the haze layers than in the surrounding troposphere. Outside the regions of haze, CN concentrations ranged from 100 to 400 cm^–3 and b_sp values were about (20–40)×10^–6 m^–1. Air mass trajectories were computed to depict the air flow upwind of regions in which haze was observed. In two cases the back trajectories and ground measurements suggested the source to be in central Europe.  相似文献   

Multiple scattering of seismic waves in fractured media: Velocity and effective attenuation of the coherent components ofP waves andS waves     

Ian Lerche  David Petroy 《Pure and Applied Geophysics》1986,124(6):975-1019

We show that the multiple scattering by small fractures of seismic waves with wavelengths long compared to the fracture size and fracture spacing is indistinguishable from multiple-scattering effects produced by regular porosity, except for an orientation factor due to fracture alignment. The fractures reduce theP-wave andS-wave velocities and produce an effective attenuation of the coherent component of the seismic waves. The attenuation corresponds to 1000/Q of about unity for a Gaussian spectrum of fractures, and it varies with frequencyf asf ³. For a Kolmogorov spectrum of fractures of spectral index the attenuation is an order of magnitude or so larger and varies with frequency asf ^3-v The precise degree of attenuation depends upon the matrix properties, the fracture porosity, the degree of fracture anisotropy, the type of fluid filling the fractures, and the incidence angle of the wave.For fracture porosities less than about 15% theP-wave andS-wave velocities are decreased by the order of 5–10% with a lesser dependence on the type of fluid filling the fractures (gas, oil, or brine) and with a dependence on both the degree of anisotropy and the incident angle made by the wave. The tendency of fractures to occur perpendicularly to bedding suggests that the best way to measure seismically fractured rock behavior in situ is by using the travel-time delay and reflection amplitude. As both the offset and the azimuth of receivers vary from a shot, the travel-time delay and reflection amplitude should both show an elliptical pattern of behavior—the travel-time delay in response to the varying seismic speed, and the reflection amplitude in response to angular variations in the multiple scattering. Observations of attenuation at several frequencies should permit (a) determination of the spectrum of fractures (Gaussian versus Kolmogorovian) and (b) determination of the contribution of viscous damping to the effective attenuation.  相似文献   

圆弧型沉积盆地对平面SH波的散射   总被引：19，自引：0，他引：19  

袁晓铭  廖振鹏 《华南地震》1995,15(2):1-8

采用波函数展开方法给出圆弧型沉积盆地对面ＳＨ波二维散射问题的封闭级数解答。利用外域Ｇｒａｆ加法公式将解答归结为无穷代数方程组的求解。通过截断计算得到解答的数值结果，并通过连续条件的满足程度检验了截断计算的精度。将本文结果已有的近似解析解进行比较，指出了近似解答的误差来源和适用范围。给出一些典型算例说明盆地深度比对地震动的复杂作用。  相似文献   

一种利用积分球原理的日照计新方案   总被引：2，自引：0，他引：2       下载免费PDF全文

王炳忠 《应用气象学报》1995,6(4):436-441

该文提出了一种利用积分球原理设计的新型日照传感器。该传感器由限角挡环、积分球体和光电探测器组成。积分球为一有5个针孔的空心正球体。针孔可阻挡散射光进入球内，而射入球内的直射光，经内壁多次漫反射后，其亮度呈均匀分布。与日照阈值下相应的亮度相比较可确定日照之有无。该日照传感器具有无转动部件、结构简单、无需调整及便于操作等优点。  相似文献   

二维黄金分割法在抗滑桩截面优化设计中的应用   总被引：1，自引：0，他引：1  

李长冬  胡新丽  汤旻烨  董治军 《地质科技情报》2007,26(5):91-94

在对抗滑桩截面宽度和截面高度与抗滑桩费用之间的关系进行综合讨论分析的基础上,引入二维黄金分割法与计算机编程方法,编制了专门的计算软件对抗滑桩截面进行优化设计,以实现满足抗滑要求的前提下使单抗滑桩工程总费用达到最低的优化目的.在三峡库区某工程的实例应用表明,该方法具有良好的社会经济效益,对滑坡的治理设计具有较重要的实际应用价值.  相似文献   

The value of a physically based model versus an empirical approach in the prediction of ephemeral gully erosion for loess-derived soils   总被引：3，自引：0，他引：3  

Jeroen Nachtergaele  J. Poesen  A. Steegen  I. Takken  L. Beuselinck  L. Vandekerckhove  G. Govers 《Geomorphology》2001,40(3-4)

A data set on soil losses and controlling factors for 58 ephemeral gullies has been collected in the Belgian loess belt from March 1997 to March 1999. Of the observed ephemeral gullies, 32 developed at the end of winter or in early spring (winter gullies) and 26 ephemeral gullies developed during summer (summer gullies). The assessed data have been used to test the physically based Ephemeral Gully Erosion Model (EGEM) and to compare its performance with the value of simple topographical and morphological indices in the prediction of ephemeral gully erosion.Analysis shows that EGEM is not capable of predicting ephemeral gully cross-sections well. Although conditions for input parameter assessment were ideal, some parameters such as channel erodibility, critical flow shear stress and local rainfall depth showed great uncertainty. Rather than revealing EGEM's inability of predicting ephemeral gully erosion, this analysis stresses the problematic nature of physically based models, since they often require input parameters that are not available or can hardly be obtained.With respect to the value of simple topographical and morphological indices in predicting ephemeral gully erosion, this study shows that for winter gullies and summer gullies, respectively, over 80% and about 75% of the variation in ephemeral gully volume can be explained when ephemeral gully length is known. Moreover, when previously collected data for ephemeral gullies in two Mediterranean study areas and the data for summer gullies formed in the Belgian loess belt are pooled, it appears that one single length (L)–volume (V) relation exists (V=0.048 L^1.29; R²=0.91). These findings imply that predicting ephemeral gully length is a valuable alternative for the prediction of ephemeral gully volume. A simple procedure to predict ephemeral gully length based on topographical thresholds is presented here. Secondly, the empirical length–volume relation can also be used to convert ephemeral gully length data extracted from aerial photos into ephemeral gully volumes.  相似文献   

曲线坐标在弹性波散射研究中的应用──SH波对不等深度凹陷地形的散射   总被引：1，自引：0，他引：1  

刘殿魁  刘宏伟 《地震工程与工程振动》1996,(2)

本文利用曲线坐标的分析方法研究ＳＨ波对凹陷地形散射的边值问题。首先给出了在曲线坐标系中波动方程解的逼近函数序列，并使此解满足由曲线坐标所描述的具有不同深度的凹陷地形上的边界条件，最后将待解的问题归结为对一组无穷代数方程组的求解．本文提供的方法有如下的特点：（１）可将通常求解凹陷地形对ＳＨ波散射的波动方程的混合边值问题（指在不同边界区域上给出不同的应力分量的边界条件）化为一应力边值问题；（２）本文所使用的曲线坐标，可描述具有不同深度与宽度比的拟半圆形凹陷地形散射问题，并给出一般解；（３）本文方法可推广用于求解Ｐ（－ＳＶ）波对凹陷地形的散射问题。作为算例，本文给出了ＳＨ波对具有不同深度与宽度比的凹陷地形散射的数值结果，并进行了分析比较。  相似文献   

Water clarity modeling in Lake Tahoe: Linking suspended matter characteristics to Secchi depth     

Theodore J. Swift  Joaquim Perez-Losada  S. Geoffrey Schladow  John E. Reuter  Alan D. Jassby  Charles R. Goldman 《Aquatic Sciences - Research Across Boundaries》2006,68(1):1-15

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