列车振动荷载作用下南京细砂振动累积变形特性试验研究

列车振动荷载作用下松散砂土振密造成的早期路基沉降将对列车的正常运行产生很大的影响。本文以南京地区新近沉积片状细砂为研究对象,采用英国GDS空心圆柱扭剪仪模拟列车振动荷载的实际应力路径,并考虑排水条件、试样围压和加载幅值等因素,初步研究了2000列次(14000振次)列车振动荷载作用下南京新近沉积片状细砂的振动排水特性和竖向累积变形特性。实验结果表明,试样围压对南京片状细砂的竖向累积变形的影响较为明显,同时,当试验围压较小时,加载幅值对试样的竖向累积变形的影响更大。其次,排水条件主要对列车运营前期的路基累积变形产生明显的影响,对后期的累积变形的影响基本可以忽略。最后,根据试验结果,本文也初步给出了排水条件和不排水条件下南京片状细砂的竖向累积应变增长曲线的新预测公式及其参数取值。研究结论对列车振动荷载作用下新近沉积砂性土的动力学特性及其累积变形的计算方法等问题的研究具有很好的参考价值。     

Surface characterization of maize-straw-derived biochars and their sorption performance for MTBE and benzene

Biochars generated at various temperatures might show significant differences in sorption for organic contaminants. In this study, a series of biochars, generated from pyrolyzing maize straws at different temperatures, were systematically characterized. The characterization results showed that with increasing pyrolysis temperature, the surface areas, micropore areas and aromaticity of biochars were enhanced. Batch experiments were conducted to study methyl tert-butyl ether (MTBE) and benzene sorption to biochars. The results indicated that the sorption capacity of benzene to biochars was higher than that of MTBE. The higher pyrolyzed temperature of biochars resulted in a stronger sorption affinity for target compounds, and the dominant sorption mechanisms varied for biochars pyrolyzed at different temperatures. The sorption to biochars pyrolyzed at 700 and 800 °C performed a high adsorption capacity, which indicated that they might be a promising sorbent to remove MTBE and benzene from water. Biochar pyrolyzed at 400 °C showed transitional sorption mechanisms from partition to adsorption for MTBE and benzene. Pore-filling was a possible sorption mechanism to biochars pyrolyzed at high temperature.     

Spatial heterogeneous response of land use and landscape functions to ecological restoration: the case of the Chinese loess hilly region

Ecological restorations over time may have profound effects on ecological and socio-economic systems. However, land-use changes and landscape functions that accompany ecological restorations can have spatial differentiations due to varied biophysical and socio-economic contexts. Therefore, these spatial differentiations caused by ecological restoration must be understood for better planning and management of restoration activities. The Baota District, with 576 villages in the center of the Chinese Loess Plateau, was selected as the study area because of its dramatic transition from cropland to grassland and shrubland from 1990 to 2010. Using the ArcGIS software and a k-means clustering analysis, an approach to identify types of land-use change patterns (TLCPs) at the village level was developed, and four TLCPs were delineated. The analysis indicated a general pattern of cropland decline by 21.6 %, but revealed significant spatial variations between villages in different TLCPs. Vegetation cover and soil retention, which are key proxies for landscape functions, increased by 22.70 and 108 %, respectively, from 2000 to 2010 with significant spatial heterogeneity. The Universal Soil Loss Equation was employed for the assessment of soil retention. The analysis of landscape metrics revealed a major trend of fragmentation and regularity on the county and village scale; however, spatial variations remained. Physical attributes were used to characterize different TLCPs, and notable differences were found. The spatial heterogeneous change in land use and landscape functions on the village scale may be useful for land use and ecological restoration management policy makers.     

基于GIS的南方丝绸之路国内段交通路线网络重建研究

南方丝绸之路交通路线网络的重建与研究,有利于深化历史时期中国西南边疆各区域之间和中国与东南亚、南亚等地区之间经济贸易发展和文化交流与合作的认识。本文利用历史文献资料、历史地理学等研究成果、田野调查资料、当代交通和遥感影像数据、DEM数据等,复原汉晋、唐宋、元、明清4个时期南方丝绸之路国内段的交通路线网络,分析影响古代西南山区交通路线走向的人文和自然因素,对比研究古代交通里程与实测距离之间的比例关系。结果显示：① 南方丝绸之路川滇间的交通网络格局在汉晋时期即已基本形成,两千年来相对较为稳定;云南内部和经云南出境的交通路线网络呈现出更加多元化的趋势。② 中央王朝对西南边疆少数民族地区统治力度的变化等人文因素在不同时期对南方丝绸之路交通路线的整体格局及空间演变起到重要作用。③ 在影响南方丝绸之路交通路线具体走向的自然因素中,海拔2200 m、坡度20°是重要的阈值。④ 历史时期西南山区1古代里约可换算为实测距离0.45 km。     

一种获取Klobuchar电离层改正模型的新方法

介绍了利用松弛搜索法对Klobuchar模型的参数进行拟合，并利用IGS提供的IONEX格式对全球电离层数据进行试验分析，获得了可靠的结果。     

冈底斯南缘打加错地区竟柱山组沉积特征及其时代

竟柱山组地层出露于西藏昂仁县打加错东地区,是一套以砂岩、砾岩为主的陆相碎屑岩建造,通过野外剖面测制、样品采集、分析测试及同位素年代学研究,分析了竟柱山组地层、沉积环境、沉积相、岩石地球化学特征等,认为该组地层为一套红色磨拉石建造,其形成于打加错断陷湖盆的河流—湖泊相沉积环境。竟柱山组上部安山岩透镜体中锆石U-Pb同位素年龄89. 97 ± 0. 7 Ma,其地层时代为晚白垩世。     

胶东金矿成矿深度的构造校正测算及成矿预测

成矿深度测算对于矿床学理论研究和深部找矿都有重要意义。经典的成矿深度“压力/比重”计算方法,缺乏考虑构造应力在成矿过程中的影响。前人按照“压力/比重”的计算方法,提出胶东蚀变岩金矿是6 000~8 000 m深的元古宙成矿,石英脉型金矿是深度在3 000 m左右的中生代成矿,并据此建立了金矿垂直五层楼的分带模式。依据该模式指导的深部预测勘查效果不好。“成矿深度构造校正测算”是近几十年逐渐成长起来的一个新方法,即先减去“构造附加压力”后再进行成矿深度测算。本文介绍“成矿深度构造校正测算”的计算方法,指出其应用条件和预测意义。开展成矿深度构造校正测算需要以下条件:(1)确定成矿模式;(2)开展野外构造变形岩相测量;(3)测量岩石矿物应变,恢复成矿构造应力场,计算构造附加静水压力;(4)测算成矿深度。根据“成矿深度构造校正测算”方法已经获得胶东多个典型金矿成矿深度的测算结果:(1)夏甸金矿成矿深度为-1 979.51~-3 014.72 m;(2)焦家金矿成矿深度为-1 632.4~-2 331.6 m;(3)大尹格庄金矿成矿深度为-2 775.4~-4 164.5 m;(4)新城金矿成矿深度为-1 781.29~-2 750.0 m;(5)玲珑金矿成矿深度为-720.55~-3 454.97 m。根据以上典型金矿成矿深度的测算结果,本文认为胶东金矿属于深-1 000~-4 500 m的浅成热液剪切带型矿床,由此推断胶东典型金矿矿体主要部分仍然赋存在深部。按照“构造校正测算”方法得到的成矿深度,结合地质、物探和化探信息,预测金矿发育“深部第二富集带”,已经得到胶东金矿勘查工作的证实。     

基于IDA的层间隔震结构失效模式研究

层间隔震结构是由基础隔震结构发展而来的一种新型隔震结构。为研究层间隔震结构的倒塌,需先研究不同层间隔震结构的不同失效模式和失效位置,文章建立了3个不同结构参数的层间隔震结构有限元模型,选取20条与抗震规范反应谱吻合的地震动,采用增量动力分析（IDA）方法,分别对其失效模式和失效位置进行研究。研究表明:基于不同的结构参数,层间隔震的基本失效模式有三种,即隔震层水平位移超限导致结构失效、下部结构层间位移角超限导致结构失效、隔震层拉压应力超限导致结构失效;隔震层下部结构和隔震层最外边缘支座为结构的薄弱位置,应引起更多关注。此方法不仅可以研究结构的不同失效模式,还可以确定失效位置,可为下一步层间隔震结构的抗倒塌分析提供理论基础。     

库车坳陷克拉苏构造带协同变形机制及盆山耦合关系

克拉苏构造带构造非常复杂,经过30余年的油气勘探开发,构造规律不清楚、构造圈闭不落实的问题仍然非常突出。本文通过大量三维地震资料的构造解释、建模及实钻资料验证,发现克拉苏构造带在剖面上呈分段分层变形、平面上呈雁列式展布特征。提出克拉苏构造带两种协同变形机制,较好地解释了在膏盐层调节作用下盐上、盐层、盐下3个构造层的差异变形现象。结合遥感影像及重力异常影像分析了盆山耦合关系,提出了南天山造山带的差异隆升推覆作用,南部温宿、新和、牙哈古隆起的阻挡作用和古近系膏盐层的调节作用是变形的3个主要影响因素,并据此较好地解释了克拉苏构造带构造圈闭平面展布格局。     

空间分析技术在研究传染病时空传播规律中的应用

以手足口病为例,介绍了地理信息的空间统计技术在传染病时空传播规律研究中的应用,包括传染病空间分布模式研究、传染病聚集性分析、传染病扩散传播模式分析、传染病发病率空间自相关分析及传染病发病率空间回归模型预测方面的研究,为传染病防治决策提供科学依据,具有一定的实用性。