九江-瑞昌5.7级地震余震的S波分裂研究

利用在九江-瑞昌MS5.7地震震中附近架设的丁家山台(DJS)、狮子洞台(SZD)和武蛟台(WUJ)的地震波形资料,采用S波分裂系统分析方法,对余震进行了S波分裂分析。结果表明,震中距较小、台站附近断层分布复杂的丁家山台(DJS)的慢波时间延迟相对较大,快波偏振方向不太集中。台站附近断裂分布单一的武蛟台(WUJ)快波偏振优势方向与断裂走向角度相差约35°,与区域主压应力方向也不一致。台站附近无断层通过的狮子洞台(SZD)快波偏振优势方向接近区域主压应力方向。慢波时间延迟大小与震源深度没有明显的规律性关系。     

1597年10月6日ldquo;珲春-汪清深震区rdquo;Mge;8地震触发的湖震和火山喷发

探讨了1597年10月6日（明万历二十五年八月二十六日）地震的烈度特征,地震伴随的湖震和火山喷发,以及地震类型与规模．结果表明, 1597年10月6日地震为可能发生在ldquo;珲春——汪清深震区rdquo;的一次Mge;8深源地震;地震在中国东部地区产生了广泛的湖震,其多种形态可与1775年葡萄牙里斯本地震产生的湖震比拟;地震触发了望天鹅火山的一次中小规模爆发式喷发,其地点在中国吉林省长白县境内．      

近震信号检测参数设置研究

地震信号检测是进行各种地震数据分析和处理的首要任务,STA/LTA方法具有算法简单、便于实时处理等特点,被广泛应用于地震信号检测.结合实际震例数据研究STA/LTA方法进行地震信号检测的各种影响因素,得到该方法进行检测时最合理的参数设置范围.     

Finite element analysis of steep excavation slope failure by CFS theory

The distribution of Coulomb failure stress (CFS) change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation (stress loading and unloading processes), the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.     

乌加河地震台地电阻率干扰形态识别

选取乌加河地震台2015-2018年地电阻率观测资料,分析数据异常变化,结合观测环境及实地调查,发现存在降雨、雷电、金属管线、农田灌溉、设备漏电等影响因素,对比分析并总结各类干扰曲线形态、变化幅度、影响时间、干扰频次等特征,以便正确认识并排除地电阻率干扰,为地震异常信息识别提供帮助。     

Geospatial-temporal analysis of land-use changes in the Yellow River Delta during the last 40 years

Research on land use/land cover changes (LUCC)has been the core project of the Global EnvironmentalChanges since the 1990s[1—6]. Scientists at home andabroad have been laying emphasis on integrationstudies on land-use change by “space and process”features[7—10] as researches on LUCC are in a greatdeal. It is of paramount important for us to studyLUCC at various spatial-temporal scales and build aquantitative assessment of land-use conversion by in-tegrated spatial-temporal features. …     

Advances in research on earthquake fluids hydrogeology in China: a review

Monitoring of subsurface fluid (underground fluid) is an important part of efforts for earthquake prediction in China. The nationwide network, which monitors groundwater level, water temperature, and radon and mercury in groundwater, has been constructed in the last decades. Large amounts of abnormal fluid changes before and after major earthquakes have been recorded, providing precious data for research in earthquake sciences. Many studies have been done in earthquake fluid hydrogeology in order to probe the nature of the earthquake. Much progress in earthquake fluid hydrogeology has been made in the last decades. The paper provides a review of the advances in research on earthquake fluid hydrogeology over the last 40 years in China. It deals with the following five aspects: (1) an introduction to the development history of monitoring networks construction; (2) cases of different subsurface fluid changes recorded before some major earthquakes which occurred in the last decades; (3) characteristics of subsurface fluid changes following major earthquakes; (4) mechanism of subsurface fluid changes before and following earthquakes; (5) application of earthquake fluids in the hydrogeology field.     

Research on the imaging of concrete defect based on the pulse compression technique

When the synthetic aperture focusing technology (SAFT) is used for the detection of the concrete, the signal-to-noise ratio (SNR) and detection depth are not satisfactory. Therefore, the application of SAFT is usually limited. In this paper, we propose an improved SAFT technique for the detection of concrete based on the pulse compression technique used in the Radar domain. The proposed method first transmits a linear frequency modulation (LFM) signal, and then compresses the echo signal using the matched filtering method, after which a compressed signal with a narrower main lobe and higher SNR is obtained. With our improved SAFT, the compressed signals are manipulated in the imaging process and the image contrast is improved. Results show that the SNR is improved and the imaging resolution is guaranteed compared with the conventional short-pulse method. From theoretical and experimental results, we show that the proposed method can suppress noise and improve imaging contrast, and can also be used to detect multiple defects in concrete.     

金沙江支流黑水河松新电站短须裂腹鱼（Schizothorax wangchiachii）过坝后上溯行为

鱼类过坝后的上溯行为对鱼类寻找适宜的产卵、索饵等功能性栖息地至关重要。现阶段我国大多数研究聚焦于鱼类上溯通过鱼道的游泳行为量化,而过坝后的上溯行为分析鲜有报道。本研究在金沙江下游支流黑水河松新坝址处利用PIT(passive integrated transponder)遥测技术对松新电站过鱼对象短须裂腹鱼(Schizothorax wangchiachii)过坝后的上溯行为开展监测,考虑监测过程中水文情势变化对过坝后上溯行为的影响,采用生存分析方法,构建了耦合多因素(流量、水温、河道涨落水率、昼夜节律、肥满度等)的Cox风险比例回归模型,利用AIC模型准则筛选出最优模型参数,识别了影响鱼类过坝后上溯成功率的关键因素。结果表明:(1)短须裂腹鱼在松新鱼道的上溯效果显著优于河道;(2)水温及河道涨落率是影响短须裂腹鱼过坝后上溯效果的关键因素;(3)水温与短须裂腹鱼过坝后河道上溯成功率呈负相关,当水温超过短须裂腹鱼最适温度后,河道上溯成功率随着温度的上升呈递减趋势;河道涨落水率与短须裂腹鱼过坝后河道上溯成功率呈正相关,其中涨水情势下短须裂腹鱼河道成功上溯的概率高于落水,河道上溯成功率随着涨...     

金沙江下游支流黑水河松新电站幼鱼下行过坝研究

梯级小水电的开发一定程度上破坏了河流连通性并阻碍了鱼类洄游通道。黑水河流域松新坝址为了满足鱼类上行产卵修建了松新鱼道,然而作为洄游物种生命周期中的关键行为,鱼类下行洄游的需求也同等重要。为了寻求一种可行、高效、低损伤的下行过鱼方式,了解河流中不同环境因素对鱼类下行效率的影响,本研究在金沙江下游支流黑水河松新水电站补水通道开展鱼类下行过坝效果评估研究。针对两种鲤科鱼类(棒花鱼Abbottina rivularis和短须裂腹鱼Schizothorax wangchiachii)幼鱼和两种鳅科鱼类(短体副鳅Paracobitis potanini和红尾副鳅Paracobitis variegatus)幼鱼各放鱼90尾,定量分析鱼种、水体透明度、放鱼位置、流量、水温、水位等因素对鱼类下行效率的影响。结果表明:棒花鱼、短须裂腹鱼、短体副鳅、红尾副鳅的下行率依次为22.22%(20尾)、28.89%(26尾)、8.89%(8尾)、15.56%(14尾);幼鱼下行成功率与上游河道水温呈正相关趋势,且放鱼位置、鱼种、上游河道水温和流量均对鱼类下行成功率有显著影响。通过构建二元Logistic回归模型识...