Investigation of the pressure field of an underground explosion by the piezophotographic method

Zusammenfassung Es wurde versucht, mit Hilfe der piezophotographischen Methode das Druckfeld in der Nähe einer Untergrundsprengung zu untersuchen. Kugelförmige Ladungen von 5 kg TNT wurden 3 m unter die Oberfläche im konsolidierten Sandboden angebracht. Piezophotographische Druckaufnehmer mit Messbereich 1,5–250 bar und 15–2500 bar wurden sowohl statisch, als auch dynamisch geeicht und ihre Richtungscharakteristik bestimmt. Es wurden insgesamt 5 Druckfelduntersuchungen vorgenommen, wobei die Druckmessungen in einem orthogonalen Netz von Messpunkten, das sich bis in die Entfernung von 40 Ladungshalbmessern ausdehnte, durchgeführt wurden. Die entwickelte Messtechnik wird eingehend beschrieben. Auf Grund der erhaltenen Ergebnisse konnte unmittelbar für jeden Versuch die Druckverteilung in vertikalen und horizontalen Netzprofilen festgelegt werden. Das Druckfeld wurde danach durch den Isobarenverlauf in der untersuchten Ebene abgebildet.     

爆炸地震波作用下地下结构动力响应数值分析

爆炸地震波荷载类似于天然地震波荷载，但又不完全相同。基于有效应力动力分析法，运用二维显式有限差分程序FLAC对地下结构在竖向和水平爆炸地震波荷载作用下的动力响应进行数值分析。编制了周围土体介质分析模型的程序模块并与FLAC接口。考虑了水平和竖向爆炸地震波荷载对地下结构的耦合效应，得出了一些定性的结论。     

Statistical determination of the law of dispersion of marking material in the shattered zone

Studia Geophysica et Geodaetica -     

地下核爆炸地震波二次源特征

层裂是地下核爆炸震源物理过程中最重要的非球对称源过程.对其机制的研究,多基于面波资料,本文基于远场体波资料,利用经验格林函数方法,消除路径及接收场地效应,利用地下核爆炸远场地震波P波数据对震源时间函数进行了反演,结果显示明显的双脉冲特征,该二次源特征不随方位角及震中距变化,说明它源自震源本身,其双脉冲特征与层裂机制相符.     

地下爆炸Rg波低谷点激发机理

目前普遍认为Rg_S散射是地下核爆炸短周期Lg波的主要能量来源,其主要依据为由线性偶极补偿源（CLVD）激发的Rg波谱的低谷点随深度变化的特征与区域震相Lg波谱的低谷点随深度变化的特征具有一致性. 本文利用简正振型理论,分析了Rg波谱中低谷点的形成机理,给出了各种速度模型下CLVD源深度与低谷点频率之间的关系,并分析了利用公式hCLVD=V/(16fNull)估计震源深度的局限性. 本文的研究结果进一步支持了CLVD源是激发Lg波的主要因素的观点,并得到重要结论：CLVD源形式下的本征位移函数及其导数的叠加所形成的极小值,即源的空间分布特征,是形成Rg波低谷点的原因,而不能仅用水平向基频本征位移函数过零点来解释.     

Estimation of long wave radiation by an empirical method

Summary Utilising two years data collected at two tropical coastal stations, Madras (13°04N, 80°15E) and Waltair (17°42N, 83°18E) and for one tropical continental station, Nagpur (21°09N, 79°07E), the authors have re-evaluated the constants ofBrunt's regression equation. Analyses of the observations for Waltair and Nagpur show good correlation coefficients (r) between the values of the effective emissivity of the atmosphere (the effective emissivity is the ratio of incoming long-wave sky radiation at the surfaceR _s , to black body radiation T ⁴) and the square root values of surface vapour pressuree (mb). The value ofr for Waltair from radiometer observations is 0.98. It is also determined for Waltair and Nagpur from Ångström compensation pyrgeometer observations as 0.83 and 0.91 respectively. A low correlation co-efficient 0.56 is obtained for Madras. It might be due to higher surface vapour pressure values at Madras than at Waltair and Nagpur. The applicability of the reduced regression equations are examined for different years for the different stations. The agreement between the computed values with the new regression equations and the observed long-wave sky radiation at the surface seems to be quite good.     

地下核爆炸Lg波的激发机制

地下核爆炸Lg波的激发机制,目前尚未十分清楚.其中主要观点之一是源区附近由补偿线性矢量偶极源（CLVD）激发的Rg波的散射形成的S波是Lg波能量的主要来源.本文利用理论地震图模拟方法,基于东哈萨克斯坦地区速度模型,分析比较了东哈萨克斯坦地壳速度模型下的爆炸源、张裂源及CLVD源对区域震相Lg波的影响.结果表明,从能量的角度来看,CLVD源是激发Lg波的主要因素.模拟计算结果也进一步证实了CLVD源激发的Lg波振幅谱具有低谷点的特征源自于该震源所激发的Rg波;在此基础之上,检验了Patton提出的估算震源埋藏深度的经验公式.结果发现,该公式仅适用于震源埋藏深度较浅的情况（<500m）.这些结果对于进一步理解及更好地利用Lg波具有重要理论指导意义.     

探地雷达探测地下目标时的波速估计

在利用探地雷达(GPR)进行工程检测过程中，电磁波在地下介质中的传播速度是影响埋深计算精度的关键参数之一。本文通过吸取几种波速求取方法的优点，给出一种精度高、操作性强的波速求取法——刚性界面反射系数法；并利用此法，由LTD探地雷达实测数据求得整条测线的速度曲线。经检验，借助于少量钻芯数据，利用此法可使公路面层厚度检测的相对误差小于5％。     

Substorm fields in and near the auroral zone

During the last few years, the study of both temporal and spatial variations of substorm fields has rapidly expanded, mainly because of the relationships which exist between polar magnetic substorms and magnetospheric phenomena. Also during these years, proposed current systems believed to be responsible for substorm variations have evolved into complex three-dimensional systems with field-aligned and magnetospheric currents coupled to the eastward and westward electrojets. Recent model studies show that substorm variations in and near the auroral zone can easily be modelled using both two and three-dimensional current systems. In these studies, induction effects were simulated by assuming the Earth to be infinitely conducting at some depth below the surface.The use of magnetometers distributed along magnetic meridians has resulted in a better understanding of the complex current patterns making up the electrojets. For example, during the expansive phase of substorms, the westward and poleward progression of the overall westward electrojet was discovered to take place through the sequential development of a series of westward electrojets.     

Dependence of seismic wave amplitudes on the size of shot-hole explosions

Summary The paper presents relations experimentally determined between seismic wave amplitudes and the charge size in the immediate vicinity of the shotpoint ( 800 m), on the one hand, and at a more distant station ( 22.5 km), on the other hand. Whereas close to the shotpoint the amplitudes observed sometimes display a considerably degree of scatter, as well as a change in character of the P-wave record due mainly to the change in position of the holes in the area of the shotpoint, this effect was not observed at the more distant station. Since the charge size was changed in the course of the measurements, the observed amplitudes will be reduced to a unified charge size of Q=1,200 kg, according to Eq. (8), in which the exponent n has the following values: n_Pg=0.77, n_Sg=0.92 and n_Lm=1.51. The values of the exponent n for P-waves are very close to the values given in [4–9].     

On the propagation of spherical waves due to large underground explosion

Summary When a high explosive pressure acts on the boundary of a spherical cavity in an elastic medium, the material in a region around the charge behaves plastically and thereafter an elastic wave is propagated. Not only that but the elastic plastic boundary moves also with a certain velocity which is less than the elastic wave velocitySabodash [3]²). In this paper, firstly the case when the elastic plastic boundary moves with a velocityV ₀. (V ₀<c) has been dealth with. The pressure in the elastic medium on this boundary has been assumed to be constant and equal toP ₀. Secondly the case when the elastic plastic boundary moves with an exponentially decaying velocity has been considered. The pressure in the elastic medium on this boundary has also been assumed to be of exponential character.     

利用背景噪声研究郯庐断裂带北段沈阳附近地区横波速度结构

郯庐断裂带是贯穿中国东部的一条巨型断裂带,总体呈NNE向延伸,总长度达 2400 km,南起长江北岸湖北广济,经安徽庐江、江苏宿迁、山东郯城和渤海,过沈阳后分为西支的依兰—伊通断裂带和东支的密山—敦化断裂带.郯庐断裂带北段是中国大陆历史强震活跃区和现今地震重点危险区之一.前人从地震地质、地球物理及地震活动性等方面开展基...     

近地空中爆炸作用下钢框架结构冲击响应

采用多物质欧拉与拉格朗日耦合算法,对框架结构和混凝土地面采用Lagrange单元、空气和炸药采用多物质ALE单元,建立流固耦合有限元模型,对一个五层的钢框架结构在近地爆炸作用下冲击压力波的传播过程、结构冲击响应和变形以及破坏过程进行了数值模拟.数值模拟分析结果表明,拉格朗日-欧拉耦合算法较好地模拟了爆炸冲击波在介质中的传播和作用在结构上的爆炸荷载效应.在爆炸近区,空气爆炸冲击波的衰减速率快;爆炸产生强烈的冲击波首先使钢框架结构正面的柱和梁柱节点区产生很大的塑性变形,钢框架柱在发生爆炸的瞬间失去承载能力,最终导致建筑物整体倒塌.考虑结构变形和流体荷载间的相互影响可以较真实地模拟结构在爆炸荷载作用下的连续倒塌过程,为研究结构在爆炸荷载作用下的连续倒塌提供了有效手段.     

An empirical method to estimate shear wave velocity of soils in the New Madrid seismic zone

In this study, a set of charts are developed to estimate shear wave velocity of soils in the New Madrid seismic zone (NMSZ), using the standard penetration test (SPT) N values and soil depths. Laboratory dynamic test results of soil samples collected from the NMSZ showed that the shear wave velocity of soils is related to the void ratio and the effective confining pressure applied to the soils. The void ratio of soils can be estimated from the SPT N values and the effective confining pressure depends on the depth of soils. Therefore, the shear wave velocity of soils can be estimated from the SPT N value and the soil depth. To make the methodology practical, two corrections should be made. One is that field SPT N values of soils must be adjusted to an unified SPT N′ value to account the effects of overburden pressure and equipment. The second is that the effect of water table to effective overburden pressure of soils must be considered. To verify the methodology, shear wave velocities of five sites in the NMSZ are estimated and compared with those obtained from field measurements. The comparison shows that our approach and the field tests are consistent with an error of less than of 15%. Thus, the method developed in this study is useful for dynamic study and practical designs in the NMSZ region.     

松嫩盆地井下摆记录到的地方震地表反射波

地震波在地球表面的反射波PP、SS由于需经地球表面的一次反射,因此属于远震记录观测到的震相。本文利用井下摆观测数据,对2003年吉林松原震群和2005年黑龙江林甸地震震相进行认真研究,根据台站附近的测井资料确定的上地壳速度模型,对选定的地表反射点进行地震波的走时计算,初步判定在特定的震中距内井下摆可以记录到地方震的地球表面反射波。为和远震记录的PP和SS震相相区别,本文暂定此震相为PgPg,SgSg。     

基于GNSS数据的朝鲜核爆电离层效应观测研究

本文分析了电离层对2009年、2013年和2016年朝鲜核试验中地下核爆(Underground Nuclear Explosion,UNE)的响应.利用南北半球IGS站的GNSS-TEC观测数据,发现了在3次核试验期间的磁共轭电离层扰动现象.观测结果表明,3次UNE所产生的电离层扰动分别以228m·s^-1、173m·s^-1和147m·s^-1的速度从核试验爆心地区径向传播.本文研究提出,UNE所产生的电离层TEC扰动是岩石圈-大气层-电离层耦合(Lithosphere-Atmosphere-Ionosphere Coupling,LAIC)电场渗透到电离层高度引发电动力学过程的结果.此外,LAIC电场可以沿磁力线映射到共轭半球,从而在共轭地区造成电离层TEC扰动.因此,在核试验地区附近以及其对应的磁共轭地区,UNE所产生的LAIC电场在电离层TEC扰动的形成中起着关键性的作用.     

基于波场梯度法研究安宁河—则木河断裂带速度结构

不同尺度的密集台阵为波场梯度法的发展提供了条件,与其他成像方法相比,波场梯度法在拓展应用上还相对较少.本文将波场梯度法应用于小区域的相对高频的地震波形获得高分辨率的速度结构.首先将台站数据网格化,利用网格点上波形数据得到相速度、方位角变化、几何扩散和辐射花样.研究区域为安宁河—则木河断裂带上的冕宁—西昌—越西区域,采用波场梯度法获得了该区域5~15 s Rayleigh面波的相速度,并反演出上地壳S波速度结构.结果显示沿断裂带浅层地壳的低速异常与张裂断陷沉积形成的昔格达地层特征相一致.安宁河断裂带附近有明显的高速异常,在不同深度高速异常都有着明显的变化,与研究区域花岗岩的分布相对应.不同深度高速体的分布可能与花岗岩体在上地壳的侵入有关.西昌地区上地壳的低速异常反映了较厚的沉积层.速度结构与实际地质构造基本吻合,表明利用波场梯度法可以有效地计算小区域高分辨率三维速度结构.本文将速度结构与不同深度的地质构造资料和震源分布相结合,为该研究区域上地壳的构造研究提供了可靠参考.

     

昆仑山断层围陷波的分析和研究

对2001年昆仑山口西MS8.1级地震产生的断层带,布设了沿断层和横跨断层的两条人工地震测线.通过对观测资料的定量分析和处理,求得了昆仑山断层带内部的细结构.分析工作包括从S波震相开始的振幅谱计算、速度频散计算、群速度测量,并用面波频散方法反演S波速度结构,用振幅谱比的方法估计断层带的Q值.野外试验结果表明,S波震相与围陷波组的时间差随炮点与台站之间距离增大而增加,在断层带外的测点上观测到与断层带相关的场地效应.最后得出昆仑山断层带宽度为250m、速度结构为断层内低速的分层结构和Q值为15（断层内）和30（围岩）.虽然昆仑山口西地震的震级比美国加州Landers地震的震级（MS7.6）大,且地震产生的破裂带长度长得多,但是这两个地震断层带的宽度却相差不大.