地震计保温效能分析     

安全  翟浩  赵铁锁 《地震地磁观测与研究》2019,40(2):131-134

为内蒙古自治区大沁塔拉地震台地震计安装保温罩，利用台基噪声计算软件，计算保温前后地震观测数据PSD概率密度函数，分析保温罩对地震计的效能，结果发现，保温罩安装后，地震计温度变化平稳，地震观测数据质量提高。  相似文献   

宽频带流动地震台站中地震计浅井式安装研究     

刘政一  袁松湧  许卫卫  徐天龙 《地震地磁观测与研究》2019,40(4):130-137

在井下地震观测中，各种地表背景噪声具有显著衰减作用，针对中国地震科学台阵现有大量非专用浅井式设计的Guralp CMG系列地震计，以及目前多个新获批项目在高背景噪声区域的观测需求，设计一种野外实用浅井观测方式，在北京国家地球观象台进行不同深度、不同井壁材质的观测对比实验，分析研究观测数据的背景噪声功率谱密度，结果表明，随着浅井深度的增加，地震背景噪声在垂直、水平向得到改善，改善程度随频率变化有所不同。分析认为，在华北现有地质环境下，6 m浅井是较为经济的观测方式，性价比高、占地小、施工简便，可用于后续多个项目的宽频带流动地震台阵观测。  相似文献   

Season Effects on Subsurface Constructed Wetlands Performance: Role of Radial Oxygen Loss of Phragmites australis     

Qian Wang  Zhenfeng Cao  Yanbiao Hu  Qiang Kong  Fei Xu  Yuanda Du  Congcong Zhao 《洁净——土壤、空气、水》2019,47(8)

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基于主成分分析法和监测数据的阿尔泰山采金废弃矿区人工恢复措施效益分析          下载免费PDF全文

艾沙江·艾力  徐海量  苑塏烨 《干旱区地理》2019,42(2):288-294

本文以阿尔泰山两河源保护区采金废弃矿区为研究区，从地形、土壤、水分和地表植被4个方面出发，结合矿区现有条件，设置11种恢复措施，选取丰富度指数、优势度指数、多样性指数、均匀度指数、生物量、植被盖度、物种数及土石比等7个评价指标，采用主成分分析法，得出不同恢复措施的主成分得分及生态效益排名。结果表明，单一恢复措施，如推平、羊群驻扎、泥浆等基本上是从某一个方面来考虑生态恢复的，存在一定的缺陷，恢复效益排名比较靠后；多种措施相结合，不仅能改善土壤环境，也会引起植物群落多样性格局的变化，生态恢复效益很好；同一种恢复措施，施行年限越长恢复效果越好。  相似文献   

A new bounding surface model for thermal cyclic behaviour          下载免费PDF全文

C. Zhou  K.Y. Fong  C.W.W. Ng 《国际地质力学数值与分析法杂志》2017,41(16):1656-1666

To accurately predict soil volume changes under thermal cycles is of great importance for analysing the performance of many earth structures such as the energy pile and energy storage system. Most of the existing thermo‐mechanical models focus on soil behaviour under monotonic thermal loading only, and they are not able to capture soil volume changes under thermal cycles. In this study, a constitutive model is proposed to simulate volume changes of saturated soil subjected to cyclic heating and cooling. Two surfaces are defined and used: a bounding surface and a memory surface. The bounding surface and memory surface are mainly controlled by the preconsolidation pressure (a function of plastic volumetric strain) and the maximum stress experienced by the soil, respectively. Under thermal cycles, the distance of the two surfaces and plastic modulus increase with an accumulation of plastic strain. By adopting the double surface concept, a new elastoplastic model is derived from an existing single bounding surface thermo‐mechanical model. Comparisons between model predictions and experimental results reveal that the proposed model is able to capture soil volume changes under thermal cycles well. The plastic strain accumulates under thermal cycles, but at a decreasing rate, until stabilization. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

THE INVERSION OF S-WAVE VELOCITY STRUCTURE IN NINGXIA AND ITS ADJACENT AREA USING BACKGROUND NOISE IMAGING TECHNOLOGY          下载免费PDF全文

XIE Hui  MA He-qing  JIAO Ming-ruo  MA Xiao-jun  ZHANG Nan  LI-Qing-mei 《地震地质》2017,39(3):605-622

In this paper, we use seismic waveform data of 90 seismic stations in Ningxia and its adjacent areas recorded between January 2012 and December 2013 to obtain the Rayleigh surface wave group velocity dispersion of the study area according to the noise imaging method and the 3-D S-wave velocity structure of the crust and upper mantle in Ningxia and its adjacent regions. The results show that within the depth range of 10~40km in Yinchuan graben and Liupanshan fault belt there exists a slow anomaly body, and with the increase of the depth this slow anomaly becomes an abnormal slow zone surrounding Lanzhou Basin between the massif arcuate structure of northeastern margin of Tibet Plateau and Alxa block. The 3-D S-wave velocity structure of the crust and upper mantle of the study area presents obvious lateral inhomogeneity. These results have important significance for the study of the dynamics of active tectonic zones and mechanism of strong earthquakes in Ningxia and its adjacent areas.  相似文献   

长距离GPS/BDS参考站网多频载波相位整周模糊度解算方法     

祝会忠  李军  蔚泽然  张凯  徐爱功 《测绘学报》2020,49(3):300-311

长距离网络RTK是实现GPS/BDS高精度实时定位的主要手段之一,其核心是长距离参考站网GPS/BDS整周模糊度的快速准确确定。本文提出了一种长距离GPS/BDS参考站网载波相位整周模糊度解算方法,首先利用GPS双频观测数据计算和确定宽巷整周模糊度,同时利用BDS的B2、B3频率观测值确定超宽巷整周模糊度。然后建立GPS载波相位整周模糊度和大气延迟误差的参数估计模型,附加双差宽巷整周模糊度的约束,解算双差载波相位整周模糊度,并建立参考站网大气延迟误差的空间相关模型。根据B2、B3频率的超宽巷整周模糊度建立包含大气误差参数的载波相位整周模糊度解算模型,利用大气延迟误差空间相关模型约束BDS双差载波相位整周模糊度的解算。克服了传统的使用无电离层组合值解算整周模糊度的不利影响。采用实测长距离CORS网GPS、BDS多频观测数据进行算法验证,试验结果证明该方法可实现长距离参考站网GPS/BDS载波相位整周模糊度的准确固定。  相似文献   

基于LAIC电场渗透和SAMI2模拟的地震-电离层扰动现象研究     

刘祎  周晨  赵正予  赵庶凡  张学民  孔建 《地震》2018,38(1):74-83

地震会造成电离层电子密度扰动。 基于三维电场渗透模型和SAMI2模型, 模拟地震发生前产生的异常电场对电离层电子密度的影响。 模拟结果表明, 地震前形成的附加电流会引起电离层产生异常电场, 且异常电场值与地震震级和地震发生时间有着明显的相关。 同时异常电场会使电子产生E×B漂移, 造成电子密度扰动。 随着时间的推移, 电子密度扰动逐渐减小且扰动区域会向着靠近磁赤道方向或远离磁赤道方向漂移。  相似文献   

四川盆地西南缘龙马溪组泥岩地球化学特征及物源区和构造背景分析   总被引：1，自引：0，他引：1  

张茜  肖渊甫  王晓飞  余谦  王剑  赵安坤  门玉澎  周业鑫 《地质论评》2020,66(5):1393-1410

本文对川西南荥经地区龙马溪组泥岩的岩石学、矿物学及元素地球化学开展了研究，探讨了龙马溪组沉积环境、物源区属性及构造背景。结果表明，研究区龙马溪组泥岩砂质、钙质含量较高，指示其沉积水体较浅。稀土元素特征及及A—CN—K图解说明龙马溪组泥岩组成较少受成岩及交代作用影响，样品较完整地保存了物源和风化作用信息。K2O、Rb、Al2O3 /TiO2含量较高及Eu负异常指示其母岩为偏酸性的长英质岩、花岗岩类，推测主要来自康滇古陆新元古代早期地台盖层。ICV值大于1，CIA平均值为66，Th/U与地壳UCC值相近，Rb/Sr值明显低于PAAS，指示其物源为近源初次旋回的快速沉积产物，受化学风化作用较小，沉积环境为干燥、寒冷环境。La/Yb、LREE/HREE及Sc/Cr等值均与被动大陆边缘值相近，结合Sc/Cr—La/Y等判别图解，说明研究区沉积构造背景主要为被动大陆边缘。  相似文献   

Tidal effects on intra-continental earthquake initiation in the Tibetan Plateau and its adjacent areas*          下载免费PDF全文

Guannan Liu  Zhi Wang  Cunxi Liu 《地震科学（英文版）》2020,33(4):209-219

To investigate the tidal effects on intra-continental earthquake initiation in the Tibetan Plateau and its surrounding areas, we selected over 1,500 focal mechanism solutions of inland earthquakes (epicenter locates at least 100 km to the coastlines) from Global Centroid Moment Tensor (GCMT) project and analyzed the p-values of tidal normal and shear stress as well as tidal Coulomb failure stress. For Coulomb failure stress calculation, we used Coulomb 3.40 software. We find that: (1) p-values of tidal stress change suggests a high tidal correlation of earthquake imitations with tidal normal stress change; (2) when tidal normal stress reached the local maximum values of compression and when tidal shear stress were closed to the positive peaks, earthquakes generated more frequently; (3) particular seismogenic environments such as strong continental plate interactions and the existence of fluids or rheologic substance possibly raise the tidal correlations and (4) higher sensitivity of earthquake initiation to earth tide presents along with higher seismicity, suggesting the rate of rain energy accumulation somehow has a dominating effect on the tidal correlation of earthquake initiation.  相似文献