结构特征及场地类别对复合隔震结构地震反应的影响

对并联复合隔震结构的地震反应性能进行了分析。通过有限元软件模拟并联复合隔震结构试验确定了软件分析所需的一些参数,利用这些参数建立了并联复合隔震结构工程模型,并对其进行了时程分析。结果表明,复合隔震结构的基底剪力和位移在不同结构特征、不同场地类别和不同地震烈度下反应不敏感,说明其在设计与应用时非常有利。     

青海湖近岸现代沉积滩坝主要类型及沉积特征*

滩坝是隐蔽油气藏最重要的沉积储集层类型之一,已成为陆相断陷盆地油气勘探的重要领域。现代沉积滩坝的研究是深入认识滩坝沉积相的有效手段。环湖考察研究发现青海湖近岸滩坝类型多样,主要发育了废弃三角洲前缘处滩坝、三角洲侧缘处滩坝、湖岸线拐弯处滩坝、开阔滨浅湖处滩坝和冲积扇改造处滩坝5种类型。通过对各种类型滩坝剖面的详细分层及沉积物室内矿物组成分析等,发现不同类型滩坝砂体沉积特征存在很大差异。整体而言,青海湖近岸滩坝沉积物粒度较粗,黏土含量低,结构成熟度较高,沉积构造多见平行层理、交错层理和冲洗交错层理,垂向上表现出上粗下细的反韵律特征。同时,选取了青海湖南岸规模较大的坝相,分别对坝主体、坝间和坝侧缘进行详细的探槽剖面分析,得出坝主体单旋回厚度较坝间和坝侧缘大,沉积物粒度也相对较粗,黏土含量最低,分选性也最好,是发育为隐蔽油藏最有利的区域。     

基于改进线性光谱解混和 SCS-CN 模型的广州主城区降雨产流模拟

城市降雨产流特征的定量研究对于城市雨水资源开发利用、科学规划和管理具有十分重要的意义。以广州市主城区为研究对象,提出一种改进的线性光谱解混方法提取遥感影像的不透水面、植被和土壤盖度,并结合SCS-CN 产流模型进行城区降雨径流模拟。首先利用线性光谱解混方法提取 2015-10-18 Landsat 8 OLI 遥感影像的不透水面、植被和土壤盖度;然后利用归一化建筑物指数和归一化植被指数进一步优化解混结果;最后结合优化的不透水面、植被和土壤盖度计算合成的 CN 值,并应用 SCS-CN 产流模型分析研究区在不同降雨重现期的降雨产流分布特征。结果表明：改进的线性光谱解混方法能较好地提高不透水面、植被和土壤盖度的提取精度;不透水面盖度越高的区域,CN 值越高;CN 值对地表径流深模拟有显著的影响;在不同重现期降雨条件下,研究区地表径流深空间分布格局差异显著;总体上,降雨量越大,不透水面盖度越高,形成的地表径流深越深,内涝发生的可能性越大。     

Changes in SOC and nutrients under intensive tillage in two types of slope landscapes

The net effect of tillage erosion on soil properties would be associated with the spatial variation in soil constituents,and therefore plays an important role in ecological agriculture.We conducted a consecutive tillage by hoeing 15 times during a period with no rainfall in the two slope landscapes(a linear slope and complex slope) of the Yangtze Three Gorges reservoir areas,to examine the relationship between soil erosion rates and the variations in soil chemical properties and compare the effects of soil redistribution on SOC and nutrients between the linear and complex slopes.After the simulated tillage,notable changes in 137 Cs inventories of the soil occurred in the summit and toeslope positions on the linear slope,while there were significant changes in 137 Cs inventories at convex and concave positions on the complex slope.Soil profile disappeared at the summit slope boundary,with the exposure area of 16.0% and 7.6% of the experimental plot,respectively,for the linear and complex slopes due to no soil replacement.Soil organic C and nutrients were completely depleted with the disappearance of soil profiles at soil eroding zones,whereas a remarkable increase in SOC,total N and available nutrient concentrations of the post-tillage surface soil and a decrease in total nutrient concentrations(P and K) were found at depositional zones on the linear slope.For the complex slope,however,changes in SOC and nutrient concentrations of the post-tillage surface soil exhibited a patterndifferent from that on the linear slope,which showed a remarkable decrease in SOC and total nutrient concentrations but a slight increase in available nutrient concentrations after tillage in the toeslope position.Due to the gradual increase in soil depth from top to bottom of the slope,SOC and nutrient inventories in the soil profiles were significantly correlated with soil redistribution rates on both the linear and complex slopes.Tillage causes remarkable changes of soil chemical properties in the surface soil layer and soil profile,and increases SOC and nutrient inventories for the soil profile downslope in steeply sloping landscapes.     

亚洲中部干旱区气候变化与丝路文明变迁研究:进展与问题

亚洲中部干旱区是对全球气候变化响应最为敏感的地区之一,也是水文变化剧烈和生态环境脆弱的地区。该地区包括了古丝绸之路的主体,在东西方交流和丝路文明兴衰历史中发挥了关键的作用。科学评估全球增温背景下亚洲中部干旱区人类社会可持续发展面临的风险,是广受关注的重大科学问题。东西方交流和丝路文明发展历史及其与气候环境变化关系的研究,可为认识该地区不同时间尺度人地关系演变的规律提供科学依据。通过总结东西方交流与丝路文明兴衰历史、亚洲中部干旱区全新世气候变化过程、多时间尺度气候一水文变化机制以及人与环境相互作用的过程与规律等领域的研究进展,提出目前亚洲中部干旱区全新世气候环境变化时空格局和丝路文明演化的过程,以及人与环境相互作用机制的研究存在明显不足。破解亚洲中部干旱区气候变化和文化演化研究区域不均衡问题,加强地学与考古学等多学科交叉研究,是推进气候变化与丝路文明变迁研究的有效途径。这对理解该地区人地关系演化规律、应对气候变化带来的挑战、服务国家“一带一路”倡议具有重要的科学价值和现实意义。     

川西新元古代苏雄组层型剖面SHRIMP锆石U-Pb年龄及其地质意义

对采自川西新元古代苏雄组层型剖面中上部的英安岩进行SHRIMP锆石U-Pb定年,获得了两组谐和年龄值:838±9 Ma(n=9,MSWD=0.80)和780±12Ma(n=5,MSWD=1.2)。其中780±12 Ma解释为苏雄组英安岩的喷发时限,代表康滇裂谷盆地强烈扩张时期的构造岩浆热事件;而838±9 Ma则可能代表康滇裂谷盆地开启前的构造岩浆热事件。综合研究认为,苏雄组位于康滇裂谷半地堑盆地的调节带,为华南新元古代幕式岩浆活动的产物;火山活动和沉积记录均表明,扬子周缘发育与地幔柱相关的裂谷盆地系统,且华南可能是Rodinia超大陆裂解的重要组成单元。     

Discovery of the Surface Rupture Zone on the South of Helishan in Gaotai,Gansu Province

According to a new investigation in the northern Hexi corridor,the remains of two surface rupture zones were discovered on the southern margin fault of the Helishan. One rupture has a length of approximately 7km and the other 10km. The two surface rupture zones might have been produced by the latest earthquake event. On the surface rupture is continuous scarp and free face caused by the rupture. The scarp is about 1 ～ 1. 5m high and on some sites,nearly up to 2m. According to the OSL results,the latest T1 terrace and higher flood plain forming in 3000a B. P. are dislocated by the fault. The above reveals the rupture age to be later than the T1 terrace. However,in the historical data and earthquake catalogue,we didn't find related information about the fault and surface rupture in this area. The 180 A. D. Biaoshi M8. 0 earthquake and the 756 A. D. Zhangye-Jiuquan M7. 0 earthquake are documented in historical data. It is inferred by textual research that the two earthquakes are related to the northern marginal fault of Yumushan in the south of the basin. Due to a lack of reliable evidence,there are still many arguments on this inferred conclusion. Thus we hold that the two surface rupture zones were produced by one of the two large earthquakes or other unrecorded historical event. The research on the activity and surface rupture of this fault can offer valuable information for the tectonic study and strong earthquake risk estimates of this region in the future.     

兴安-东蒙块体中强地震空间迁移特征分析——黄金分割法

地震是一种自然现象,地震的发生遵循自然节律。前人曾将黄金分割法应用于地震发震时间的研究,个别学者将其应用于地震时空特征的分析。在多次尝试的基础上,发现将黄金分割法应用于兴安-东蒙块体M_L 5.0以上中强地震空间迁移特征的研究效果比较明显。按照时间先后顺序发生的3次中强地震,在一定空间范围内形成黄金三角,过结束地震和对边的黄金分割点构成了黄金分割线,该黄金分割线可能是未来地震的震中轨迹线,多条黄金分割线的交汇区域可能是未来地震的危险区;该方法预测未来地震在一年内发震的概率为86%,可以应用于中短期地震的预测;超过2年视为缺震黄金分割线,而多条缺震黄金分割线的交汇区可以应用于中长期地震危险区的判定。本文阐述了一种现象,造成这种迁移规律的物理机制和动力源有待于深入研究。但该方法的研究丰富了黄金分割理论在地震学中的应用,无疑为地震分析预报空间图像的研究提供了新思路。     

中强地震空间分布“X”图像及其含义

基于西太平洋板块向欧亚大陆板块下俯冲产生的推挤,造成黑龙江亚板块地下的地幔物质上涌,使其上覆岩石圈受到垂直方向上涌力的作用。通过分析"X"节理的形成、与断层的关系、火山群"X"型断裂构造的特点,对黑龙江亚板块1999年以来中强地震空间分布进行研究,呈网格化特征分布。根据构造类比法和历史地震比拟法,网格化交汇处缺震区未来几年或更长时间存在发生中强地震的背景,即内蒙古扎兰屯,通辽和黑龙江五大连池,绥化历史老震区;尤其是2008年6月10日内蒙古扎兰屯附近(阿荣旗境内)发生M 5.2地震后该地区可能再次成为未来地震的危险区。本文研究结果对区域地震危险区的判定有借鉴意义。