临夏盆地晚新生代沉积特征与青藏高原隆升

临夏盆地是青藏高原东北边缘的一个新生代断陷盆地,盆地中的新生代沉积蕴含了丰富的环境演变等信息,并具鲜明的特征,其演化及宏观地貌结构特征的形成具有深刻的构造、气候演变及区域性特征背景,其中构造背景－青藏高原的隆升对其的影响尤为突出,其中发生了3．2MaB.P.、5.3.MaP.P.、2.4MaB.P和1.6MaB.P.的几次强烈的构造运动对于其现代地貌格局与特征的形成具有重要意义。一系列重大地质事件,如黄河于1．6MaB．P．在盆地中出现、河流阶地系列的形成和风成黄土的沉积等青藏高原的阶段性整体隆升密切相关。     

基于首次超越理论的高层隔震结构基础提离易损性分析

针对基础隔震的高层建筑,基于首次超越理论,计算了各个隔震支座在非平稳随机激励下发生基础提离破坏的易损性曲线。隔震结构采用三维有限元建模,隔震支座采用Bouc-Wen模型,经过等效线性化后,应用虚拟激励法求得结构的随机响应。讨论了隔震支座的阻尼比、屈服力以及地震动输入方向对隔震支座易损性曲线的影响。研究发现:增加隔震支座的阻尼比或是增加隔震支座的屈服力都会使得隔震支座发生基础提离的破坏概率增加,地震动的输入方向对隔震支座基础提离易损性曲线影响十分显著。     

走滑断裂分段叠置区物理模拟及构造差异性解析——以塔里木盆地顺北1号断裂为例

走滑断裂分段叠置区通常包括拉分叠置区和挤压叠置区,其形成及演化与油气藏关系密切,其内部构造特征对油气运聚具有重要影响。塔里木盆地顺托果勒地区顺北1号断裂叠置区分段发育特征明显,油气勘探表明,拉分叠置区和挤压叠置区对油气运聚的控制能力有一定差异。在分析构造特征的基础上,对走滑断裂拉分叠置区和挤压叠置区开展了物理模拟实验研究,结果显示,拉分叠置区内发育有多组里德尔（R）剪切和压剪性（P）剪切,在叠置区内多组断裂组成一套平面范围较小、垂向断距较大的雁列地堑系统;挤压叠置区内仅发育一组R剪切、P剪切及单条共轭里德尔（R'）剪切,并在叠置区内形成平面范围较大、垂向断距较小的地垒。因此认为,基底断裂的几何形态、运动性质是控制叠置区发育类型的关键因素。叠置区内断裂发育的数量、规模均受控于总走滑量,并与之呈正相关。相较于挤压叠置区,拉分叠置区的断层数更多,分布更密且地层破碎变形程度更高。在构造特征及力学机制上,拉分叠置区均表现出更强的油气富集潜力。     

FISSION TRACK AGES AND UPLIFT RATES OF THE SOUTH XIZANG (TIBET) REGION

The geological ages of Lhasa, Kangmar and Gaowu rock bodies of Xizang (Tibet) have been determined by fission track method. The results are: 25.5—27.2, 10.7—11.5, 8.06—9.19 Ma respectively. It is found that the fission track (FT) age of apatite increases with the elevation of sample. Calculated by the ages-topographic altitude method, the uplift rates of the above three rock bodies are 0.25, 0.45, and 0.49 mm/a respectively. On the basis of the fission track age and the published isotopic age data, the uplift rates of other regions have been calculated by the mineral pair-blocking temperatures method. The lowest is 0.08 mm/a and the highest 2.4 mm/a. We found that the uplift rates of different regions in the same period are distinet, and the uplift rates of different geological times in the same region also are not alike. This situation shows that the Xizang region has a complex geological and unroofing history due to the collision of the India and Eurasian plates.     

Seepage underneath barrages with downstream subsidiary weirs

A subsidiary weir with a sloping middle apron may be constructed downstream from each of the existing barrages on the River Nile in Egypt to secure its stability against the increase in effective heads. The problem is mathematically solved by a conformal mapping technique. Formulas are obtained to calculate the uplift pressures acting on the existing barrage and the subsidiary weir. Also formulas are derived to calculate the exit gradients along the intermediate filter and the downstream bed. We calculate the seepage characteristics for a wide range of boundary conditions, plot the results in the form of curves, and analyze them.     

Mesozoic cooling history of the “Bachu Uplift” in the Tarim Basin,China: Constraints from zircon fission-track thermochronology

We applied zircon fission-track analysis to outcrop and borehole samples to study the Mesozoic cooling history of the Bachu Uplift, the Central Uplift of the Tarim Basin. Zircon fission-track (ZFT) ages of 182 Ma – 249 Ma are younger than the sample depositional ages indicating substantial post burial thermal annealing and can effectively reveal cooling events in the Bachu Uplift. The strong correlation between single grain ZFT age and U content indicates that most of the zircon grains represent ages that have been partially annealed and so the age is not directly indicative of the time of cooling. The youngest ZFT age populations with modal peak ages of 151 ± 8 Ma (Well HT1 samples), 126 ± 6 Ma (Well T1 samples) and 192 ± 10 Ma (Xiaohaizi Reservoir profile samples) from the decomposition of the ZFT single-grain ages represent the onset of cooling events in the Bachu Uplift, which were related to the collisions of the Qiangtang Terrane and Lhasa Block with the southern margin of the Eurasia continent, respectively. This study provides new insights into the tectonic and sedimentary evolution of the Tarim Basin and even Central Asia by constraining the higher temperature (c. 250–180 °C) part of the basin thermal history.     

无锚固储液罐提离的流-固多种非线性耦合的三维移动边界问题统一分析格式*

本文建立了在地震作用下无锚固储液罐提离的流-固多种非线性耦合的移动边界问题的统一格式的三维分析方法,其中建立了任意四边形标薄板壳拟协调非线性有限元的列式和分析移动边界问题的线性互补方程;提出了在ALE标架下用带压力项的时间分裂步法求解储液罐内含自由液面大幅晃动(移动边界问题)的非定常的三维粘性流体(N-S)问题的方法;其中没有利用轴称性和梁式模态假定等条件及未曾利用势函数理论;该方法适用于一般板壳-流体多种非线性耦合的多种移动边界问题.     

模型储液罐提离的非线性振动的频率与阻尼的研究

本文介绍了铝制储液罐模型在水平地震台上用多种波形激励下的提离非线性振动的频率和阻尼的实验研究，揭示了提离对罐—液多种移动边界和多种非线性耦合结构的动力特性的影响，同时也考虑了基础特性，液面浮顶条件和多种输入波形的影响。     

尼泊尔波迪·科西水利枢纽三维渗流分析

针对尼泊尔波迪·科西水电工程首部枢纽布置和软土坝基的岩性条件和渗透特征 ,通过对混凝土防渗墙深度、灌浆帷幕长度、混凝土渗透性、地基渗透性的敏感性分析 ,确定出防渗墙和防渗帷幕的优化方案 ,并对三种库水位工况下的三维渗流场进行了详细的计算分析 ,为工程优化设计提供依据.