对新型螺杆灌注桩的受力特征与破坏性状的探讨

螺杆灌注桩是一种承载力高、造价低、施工方便、无环境污染的新桩型。根据螺杆桩的静荷载试验资料,深入分析了螺杆桩竖向荷载的传递机理,探讨了螺杆桩的受力特征和破坏性状,为今后螺杆桩的设计和施工提供可靠的依据。     

Hurricanes Ivan, Jeanne, Karl (2004) and mid-latitude trough interactions

Summary Singular vectors (SVs) constructed from the adjoint model of the U.S. Naval Operational Global Atmosphere Prediction System (NOGAPS) for three Atlantic hurricanes in 2004, Ivan, Jeanne and Karl, are examined to understand interactions between them and a mid-latitude trough system. By optimizing the perturbation energy localized in a small region centered at the 48-hour projected position of a tropical cyclone, the initial time singular vector represents the sensitive region to the final state within the specified region for a specified optimization period. For hurricane Ivan, the SV analysis reveals the merging of a shortwave mid-latitude trough and Ivan to form a new trough system. This new trough system impacted the evolution of hurricane Jeanne in subsequent time through the upstream flow of the trough that moved toward Jeanne. This is consistent with previous studies on the sensitivity of tropical cyclone prediction using SV diagnostics. The SV associated with Jeanne at later stage shows that Jeanne influenced the third hurricane Karl through the trough system as Karl went through extratropical transition and became part of the trough. This effect is magnified when the SV is computed using the moist adjoint system containing large scale precipitation. Detailed diagnostics of the SVs for individual components at different levels show that the sensitivity associated with the trough is very similar for those optimized for Jeanne and Karl, respectively, thus providing evidence that the mid-latitude trough impacted Jeanne and Karl at the same time. This study demonstrates the capability of singular vector in diagnosing complicated interactions among a mid-latitude trough and three co-existing tropical cyclones.     

地铁工程勘察现状与技术研究课题

地铁勘察的特点:一是没有征地的勘察,二是地下系统工程的勘察;我国地铁勘察经历了探索、积累和规范化的历史发展时期,各时期按照可行性研究、初步勘察、详细勘察、施工勘察四个勘察阶段进行工作;根据地铁设计要求和地质条件采取多样化的测试手段,勘察内容全面,技术逐步完善,具有明显的专业特色;今后应结合地铁施工方法和设计要求,研究和总结特殊设计指标的测试技术,解决地铁结构在第四系饱和砂层中的抗震设计问题,加强施工新技术和新方法在不同地质条件下的适应性研究,在安全、快速施工和降低造价等方面不懈努力。     

Linking the Sulu UHP belt to the Korean Peninsula: Evidence from eclogite, Precambrian basement, and Paleozoic sedimentary basins

Considerable debate on whether and how the Sulu Orogenic Belt extends eastward to the Korean Peninsula has remained over the past decade. New results reported here include the following: (1) an eclogite and retrograded eclogite-bearing complex (Hongseong Complex) is discovered in South Korea, in which the eclogite occurs as lenses in circa  810–820 Ma granitic gneiss. SHRIMP zircon dating of the eclogite yields  230 Ma for the metamorphic age and  880 Ma for the protolith age; (2) The basement of the Rangnim, Gyeonggi and Yeongnam massifs have affinities to the basement of the North China Block (NCB). However the Gyeonggi Massif encloses a minor amount of large or small slabs of the Hongseong Complex that are similar to the rocks of the Sulu Belt. (3) Two main Paleozoic basins within the Rangnim and Gyeonggi massifs have a similar Paleozoic tectono-stratigraphy to the NCB. (4) The Imjingang and Ogcheon belts do not exhibit any metamorphic characteristics of collisional orogenic belts. Based on these facts, we propose a crustal-detachment and thrust model and suggest that the collision belt between the Yangtze Block (YB) and NCB (Sino–Korea Craton) is preserved along the western margin of the Korean Peninsula. The lower part of the UHP metamorphosed lithosphere of the YB was subducted under the Korean Peninsula and not uplifted to the surface. The lower crust of the YB (the Hongseong Complex) was detached from the subducted lithosphere and thrust over the Korean Peninsula, and inserted into the basement rocks of the Gyeonggi Massif. The upper crust of the YB possibly was detached from the lower crust and overthrusted along the Honam and Chugaryong shear zones. The Imjingang and Ogcheon belts possibly represent the detached upper crust of YB and their present occurrences are controlled by a Mesozoic strike–slip shear structure. All these detached lower and upper crustal slabs were strongly deformed during the Late Jurassic and Early Cretaceous tectonic event leading to their present geological distribution and characteristics.     

Geological analysis and FT dating of the large-scale right-lateral strike-slip movement of the Red River fault zone

Tectonically, the large-scale right-lateral strike-slip movement along the Red River fault zone is char-acterized at its late phase with the southeastward extension and deformation of the Northwestern Yunnan normal fault depression on its northern segment, and the dextral shear displacement on its central-southern segment. Research of the relations between stratum deformation and fault movement on the typical fault segments, such as Jianchuan, southeast Midu, Yuanjiang River, Yuanyang, etc. since the Miocene Epoch shows that there are two times dextral faulting dominated by normal shearing occurring along the Red River fault zone since the Miocene Epoch. The fission track dating (abbrevi-ated to FT dating, the same below) is conducted on apatite samples collected from the above fault segments and relating to these movements. Based on the measured single grain’s age and the con-fined track length, we choose the Laslet annealing model to retrieve the thermal history of the samples, and the results show that the fault zone experienced two times obvious shear displacement, one in 5.5 ± 1.5 MaBP and the other in 2.1± 0.8 MaBP. The central-southern segment sees two intensive uplifts of mountain mass in the Yuanjiang River-Yuanyang region at 3.6―3.8 MaBP and 1.6―2.3 MaBP, which correspond to the above-mentioned two dextral normal displacement events since the late Miocene Epoch.     

An 8.1Ma calcite record of Asian summer monsoon evolution on the Chinese central Loess Plateau

Carbonates in loess-red clay sequences consist mainly of calcite and dolomite. The EDTA analysis of carbonates in different size fractions and magnetic susceptibility reveal that calcite is a sensitive index of summer monsoon. The chemical analysis of carbonates and calcite from an 8.1 Ma loess-red clay sequence at Chaona on the Chinese central Loess Plateau shows that the evolution of the Asian summer monsoon experienced four stages, namely 8.1―5.5 Ma, 5.5―2.8 Ma, 2.8―1.5 Ma and 1.5―0 Ma, with increasing intensification and fluctuation, suggesting a possible combining impacts of uplift of the Tibetan Plateau and global changes on the Asian summer monsoon.     

修正的莫尔-库仑理论的解析和验证

根据主应力可分解为静水应力和偏应力,以及它们在应力莫尔圆和变形方面的相关性,推导出修正的莫尔-库仑理论的数学表达式。从理论上解决了库仑理论和莫尔理论存在的许多缺陷,特别是中间主应力对材料抗剪强度的影响。它的四参数准则的计算结果与一些混凝土的试验数据相当吻合。     

西秦岭天水尹道寺中生代酸性火山岩锆石U-Pb定年和元素地球化学研究

对天水尹道寺酸性火山岩进行了LA-ICPMS锆石U-Pb定年、全岩主量和微量元素分析.结果表明,本区酸性火岩熔岩均为流纹岩,SiO2、Na2O K2O含量高,TiO2含量低,主体为亚碱性系列,轻稀土高度富集,Eu负异常明显.微量元素原始地幔标准化分配模式及洋中脊玄武岩标准化分配模式分别与大陆板内火山岩或大陆板内花岗岩的分配模式一致,Ba、Sr、P、Ti显著亏损.锆石U-Pb同位素定年揭示了流纹岩的岩浆结晶年龄为印支末期(211Ma).流纹岩具有富集放射性Pb同位素的特点,其源区可能为北秦岭基底岩石.依据稀土元素和微量元素分配模式对比研究,认为流纹岩浆为地壳下部部分熔融的产物.源区物质可能为下元古界秦岭岩群中的黑云角闪斜长片麻岩,源区的残留物主体可能为斜长石,含有角闪石,岩浆演化过程中存在少量的碱性长石和黑云母的分离结晶.印支末期秦岭地区处于由陆内碰撞造山阶段开始向深部地幔调整和岩石圈减薄阶段转变,特殊的构造背景使得陆内挤压、剪切走滑和推覆构造较为发育,西秦岭尹道寺地区特定的构造背景与断裂构造的结合,形成了该地区独特的流纹岩浆喷发.     

南宁市大气能见度变化特征及影响因子分析

对2000至2006年的南宁市能见度资料进行统计分析。分析表明,南宁市近7a能见度年均值在13～17km之间,总体呈下降趋势。一年之中,能见度最小值主要出现在1至3月,最大值出现在6至7月,汛期能见度明显好于非汛期。一日之中,能见度的日变化为：08时〈02时〈20时〈14时。能见度与气象因子的相关分析表明,能见度与温度、风速成正比,与压强、降水、湿度成反比。与污染物的相关分析表明,能见度与PM10浓度的相关性较强,达到-0.58。     

内蒙古夏季干旱的水汽输送特征分析

对于大气中水汽的定性、定量测量是提高内蒙古干旱研究与预测的有效手段。利用NCEP再分析资料和内蒙古地区实测降水资料（1961-2000年），定性、定量地分析东亚水汽分布、水汽输送与内蒙古夏季干旱的关系。得出内蒙古地区上空低层大气的含水量偏少是内蒙古夏季干旱的一个重要因素。由于青藏高原大地形作用，孟加拉湾和南海的水汽北上受阻，不能达到内蒙古高原是形成内蒙古干旱的又一原因。受大气环流影响，内蒙古高原水汽辐合偏弱是内蒙古夏季干旱的重要原因。青藏高原的水汽通量与内蒙古东西部降水都存在明显负相关；孟加拉湾至内蒙古西部是内蒙古西部地区降水的水汽通道，南海至中国东北地区为内蒙古东部降水的水汽通道。