西藏班公湖—怒江构造带尼玛盆地构造性质

雅鲁藏布江洋俯冲及印度-欧亚陆陆碰撞导致了强烈的大陆岩石圈挤压变形与青藏高原的隆升。研究青藏高原内部破碎带构造-沉积演化,对理解相关变形如何向欧亚大陆腹地扩展传递至关重要。班公湖—怒江缝合带内发育一系列白垩纪—新生代陆相沉积盆地,保存了关于该时期高原内部构造-沉积演化的丰富信息。针对该类盆地的构造性质和形成机制有走滑拉分盆地、断陷盆地、前陆盆地3类不同观点。若要检定上述观点,需要开展如下工作:(1)查明盆地基底与充填建造变形特征;(2)结合构造背景探究其演化机制。鉴于此,本文对该带内尼玛盆地开展大比例尺地质填图与构造分析,结合前人成果,对盆地构造背景、构造性质和构造演化进行了探讨。主要取得了如下认识:(1)尼玛盆地基底为班公湖—怒江洋闭合形成的软碰撞缝合带内的变质岩与海相沉积岩。基底断裂为近东西走向,倾向或南或北的逆冲断裂。(2)盆地充填建造为上白垩统—新近系多旋回河湖相沉积。其变形样式主要为轴向近东西延伸的非对称褶皱,局部卷入基底断裂变形。多幕次变形自边缘向盆地中心前展式递进发展。(3)盆地可以划分为盆北掀斜隆起、南部推覆扇状隆起两处主要剥蚀物源区、中部基底断片掀斜隆起一处次要剥蚀物源区,以及北部叠瓦状压陷区与南部对冲压陷区两处主要构造沉积单元,其构造格架可以概括为“三隆夹两坳”。(4)尼玛盆地肇始于班公湖—怒江洋闭合导致的南北向地壳缩短。其后,雅鲁藏布江洋北向俯冲与印度-欧亚碰撞所致南北向挤压,导致盆地基底断裂发生周期性活动,伴有多旋回磨拉石建造与递进变形。简言之,尼玛盆地为软碰撞缝合带之上发育的山间压陷盆地。     

基于条件分布模型的气象水文干旱传递分析

气象干旱发展到一定程度可以传递为水文干旱。以潘家口水库流域1961—2010年逐月平均降水数据和潘家口水库的入库径流序列为基础数据,分别计算了1、3、6、12个月时间尺度的标准化降水指数（SPI）和标准化径流指数（SRI）,以表征研究区域的气象干旱和水文干旱。基于条件分布模型,分析了不同时间尺度的气象干旱传递到未来的不同等级和不同的预测期（或滞后期）的水文干旱的概率。结果表明,当SPI时间尺度较短或预测期（滞后期）较短时,其对应的SRI水文干旱等级越倾向于维持与SPI相同的干旱等级;随着SPI时间尺度的增长或预测期（滞后期）延长,其对应的SRI水文干旱等级略低于气象干旱或恢复到正常状态。     

四川盆地中部侏罗系大安寨段含有机质泥质介壳灰岩储层的认识及其意义

四川盆地中部下侏罗统大安寨段可划分为三个亚段,主要由暗色泥页岩、结晶介壳灰岩、泥质介壳灰岩三种岩性构成。暗色泥页岩形成于深湖—半深湖相环境,是主要的烃源岩,滨浅湖高能滩相结晶介壳灰岩一向被认为是主要储层,其储集空间以裂缝为主。露头地质调查、岩心和薄片观察、物性资料及试油资料的分析表明,浅湖—半深湖较低能滩相含有机质泥质介壳灰岩是主要的储集层和产层,单层厚度薄,但累积厚度较大,分布面积广,常夹于暗色泥页岩中,源储一体,更有利于成藏。这类泥质介壳灰岩的壳间孔构成了主要的储集空间,壳间孔平行于壳体的长轴方向排列,并常见黑色有机质充填。认为四川盆地大安寨段的油气勘探方向可由结晶介壳灰岩向含有机质的泥质介壳灰岩拓展,浅湖—半深湖较低能滩沉积相带可成为新的勘探领域。初步预测大安寨段上部的一亚段新增有利勘探面积6 100 km2,中部的一三亚段新增有利勘探面积6 600 km2。     

Vibratory Influential Zoning for Grade-Separated Tunnels Under the Load of Trains

Grade-separated tunnels are even more vulnerable components in high-speed railway engineering structures. The dynamic characteristics of tunnels under a train load are key indicators that influence the safe operation and durability of the entire line. In this study, with consideration of the major factors influencing grade-separated tunnels for high-speed rails, such as train speed, traffic mode, surrounding rock type, between-tunnel height, and crossing angle, a parameterized finite element model is established based on an orthogonal experimental design. In the proposed model, tensile stress (under which any vibration-induced structural damage is caused) is defined as a main evaluation index, and thus the empirical formula for each influencing factor is obtained. When the index was determined under multiple factors and at different levels, rock height between tunnels is found to be the biggest factor influencing the response of grade-separated tunnels to the vibratory load of the trains, followed by train speed, surrounding rock level, and crossing angle. Finally, based on the relevant standards for concrete stress, the zoning of grade-separated tunnels under the vibratory load of trains is established by multiple factors. Such zoning provides important theoretical references for future structural design, maintenance, and reinforcement of grade-separated tunnels for high-speed rails.     

Oceanic vertical mixing of the lower halocline water in the Chukchi Borderland and Mendeleyev Ridge

Oceanic vertical mixing of the lower halocline water (LHW) in the Chukchi Borderland and Mendeleyev Ridge was studied based on in situ hydrographic and turbulent observations. The depth-averaged turbulent dissipation rate of LHW demonstrates a clear topographic dependence, with a mean value of 1.2×10–9 W/kg in the southwest of Canada Basin, 1.5×10–9 W/kg in the Mendeleyev Abyssal Plain, 2.4×10–9 W/kg on the Mendeleyev Ridge, and 2.7×10–9 W/kg on the Chukchi Cap. Correspondingly, the mean depth-averaged vertical heat flux of the LHW is 0.21 W/m2 in the southwest Canada Basin, 0.30 W/m2 in the Mendeleyev Abyssal Plain, 0.39 W/m2 on the Mendeleyev Ridge, and 0.46 W/m2 on the Chukchi Cap. However, in the presence of Pacific Winter Water, the upward heat released from Atlantic Water through the lower halocline can hardly contribute to the surface ocean. Further, the underlying mechanisms of diapycnal mixing in LHW—double diffusion and shear instability—was investigated. The mixing in LHW where double diffusion were observed is always relatively weaker, with corresponding dissipation rate ranging from 1.01×10–9 W/kg to 1.57×10–9 W/kg. The results also show a strong correlation between the depth-average dissipation rate and strain variance in the LHW, which indicates a close physical linkage between the turbulent mixing and internal wave activities. In addition, both surface wind forcing and semidiurnal tides significantly contribute to the turbulent mixing in the LHW.     

抗差拟合推估在基坑支护结构变形监测中的应用

本文提出了利用二次曲面函数和多面函数法构建基坑监测面变形模型的方法，并将稳健估计应用于监测数据处理中。通过实例分析，指出了二次曲面函数法适合无支撑的苦坑监测面位移模型拟合，多面函数法适合有支撑的基坑监测面位移模型拟合。最后，对如何确定多面函数法的中心点个数作了讨论．得出了有益的结论。     

土木工程专业《测量学》课程教学改革研究

分析了土木工程专业《测量学》课程教学的现状，指出了课程教学改革的必要性和迫切性，提出了重视现代测量技术的测量学教学大纲、多媒体教学的内容和形式、虚拟实习和野外实习相结合的具体内容和措施。     

互联网与中国信息网络城市的崛起

从互联网骨干网络拓扑结构入手,对中国互联网进行了初步的地理学分析,着重考察了基于这种新的信息基础设施架构之上的中国城市体系格局。结果表明：一个由信息网络城市组成的城市网络已在中国浮现,北京、上海和广州之间的互联网骨干连接构成了我国长距离电子通信的核心层次。互联网基础设施建设正在重构城市的竞争优势,而地理区位因素仍在其中起着重要的作用。     

论电离层对GPS定位的影响

电离层是ＧＰＳ定位的主要误差源。本文论述电离层的特征和折射系数,以及电离层的下列影响：电离层码群延、电离层载波相位超前、电离层多普勒频移、振幅闪烁、电离层相位闪烁效应、磁暴对ＧＰＳ定位测量的影响、电离层对差分ＧＰＳ的影响和ＧＰＳ接收机的电离层改正。