红层泥岩半刚性基床结构动态变形试验研究

高速铁路要为列车的高速行驶提供一个高平顺性和稳定性的轨下基础,而路基作为轨道结构的基础,必须具有强度高、刚度大、稳定性和耐久性好的特性。由于红层泥岩属于软岩,工程稳定性差,以红层泥岩作为基床的填料,其刚度明显不足,所以为了弥补基床表层的不足,在其顶部添加一层水泥稳定级配碎石。为了验证这些措施的效果,以便指导工程设计和施工,通过足尺动态模型试验,模拟在实际荷载条件下基床的动态变形特性,结果表明,采用水泥稳定级配碎石作为基床表层填料,静态变形明显降低,能够大幅降低动荷载作用时的动变形,减少了基床结构的永久变形,增强了轨道结构的稳定性。     

黄河入海泥沙沉积固结过程抗侵蚀性变化研究

河口入海泥沙沉积固结过程中抗侵蚀性的变化直接决定着沉积物的再悬浮和二次迁移,对河口岸滩的稳定具有重要决定作用。在现代黄河三角洲潮滩模拟入海泥沙快速沉积,现场测试不同固结时间沉积物的抗侵蚀性和物理力学指标的变化。研究发现,黄河入海泥沙沉积物的抗侵蚀性随固结时间增长迅速提高,当沉积固结时间达8h时,其临界侵蚀切应力就超过了原状潮滩表层沉积物;新沉积泥沙的临界侵蚀切应力与其重度、贯入阻力、剪切强度呈良好的正相关关系,与含水率呈良好的负相关关系。黄河入海泥沙临界侵蚀流速的试验值随固结时间的增长速率要高于各泥沙起动公式计算值的增长速率,前者是后者的1.5～4.1倍。     

湘赣桂地区加里东期构造变形特征及成因分析

系统解剖了华南早古生代地层出露较好且加里东运动比较典型的地区,包括广西的元宝山、越城岭、大明山、大瑶山、云开大山地区以及湘赣边境等地区。通过对其褶皱、断裂形态的描述与分析发现大明山、大瑶山地区EW向的寒武系褶皱是云开地块在晚寒武世-早奥陶世由南向北推覆挤压的结果,而桂北元宝山、越城岭地区及湘赣边境地区NE-NNE向的早古生代地层的褶皱是由于华夏地块与扬子地块在晚奥陶世-早志留世沿郴州-临武断裂收缩挤压的结果,而且这一收缩挤压是属于陆内造山事件而不是前人所说的洋陆俯冲事件和陆-陆碰撞造山事件,且加里东运动先由南向北、后由东向西逐渐拓展,变形强度由强到弱。     

歧口凹陷歧深地区沙三段层序地层格架及其演化

在对钻井、录井、测井、地震和各种测试资料的综合分析基础上,对沙三段层序地层格架进行了系统的研究。共识别出4个层序界面,3个三级层序,并在各三级层序内识别出低位体系域、湖扩体系域和高位体系域。认为深凹及控凹断裂边缘3个体系域发育完整,而板桥及歧北次凹斜坡带仅发育退积型湖扩体系域和进积型高位体系域。在此基础上,建立了歧深地区层序地层发育模式——陆相单斜断坡带型(西断东缓超)地层格架,为研究区有利储集体的预测提供了基础。     

二维地震在延边凉水煤田勘查中的应用

二维地震勘探比较广泛应用于平原、丘陵等地区,但在地形比较复杂的山区应用比较少。延边凉水煤矿接替区位于吉林省长白山区,该区山高林密,地表施工条件较差,以往勘查资料较少。利用二维地震勘探方法查明了落差较大的断层和勘查区主要煤层的隐伏露头位置,确定煤层的赋存范围和构造形态,取得了一定的成果。     

长江中下游江湖关系演变趋势数值模拟

以长江中下游防洪系统为对象,概述了在大型复杂防洪系统洪水行为数值模拟基础上,成功地将长江中下游洪水演进数学模型转化为面向长江防洪系统防洪规划方案评估需求的长江中下游江湖水沙演变的数学模型.为适应防洪规划方案论证涉及江湖水沙相互制衡相互关联客观情况,建立了面向江湖水沙关系及其演变的数学模型.针对长江中下游江湖水沙运动特点,在水沙数值模拟的范围内侧重对下荆江河道冲刷、荆江三口分流分沙模式、洞庭湖泥沙淤积、江湖耦合等环节进行了讨论,提出了合理可行的数值处理方法.模拟结果较好反映了江湖水沙演变规律,主要成果已应用于长江中下游防洪规划和防汛调度方案中.     

汾河二库蓄水对兰村水源地影响的数值模拟研究

首先建立了汾河二库及其下游地区水文地质概念模型,然后根据地下水水头长观资料识别模型的水文地质参数,运用可视化标准软件Visual Modflow,建立了地下水三维不稳定流模型来刻画汾河二库地下水下游区域流动的基本规律。运用识别后的模型预测了未来2010年和2015年水库不同蓄水位条件下的地下水动态变化。模拟结果表明,汾河二库的建成使周围地下水流动发生了变化,水库蓄水造成流域地下水位的上升,但对兰村水源地的影响有限。     

金昌市WRDMAP项目示点村基线调查数据分析

通过对WRDMAP项目G2A案例研究两个示村基线调查数据的分析,研究石羊河流域具有代表性区域农业投入与种植等综合现状,以水资源开发利用现状基础数据来探讨当地农业生产用水问题,为水资源管理提出切实可行的农业节水与种植建议。     

玄武质岩石的单颗粒锆石U-Pb年龄谱

报道了托云、东浮山、羊角、雪花山和山旺5处新生代玄武岩的SHRIMP锆石U-Pb测年结果。位于西南天山造山带的托云新生代玄武岩的14个测点年龄值十分发散,最大值与最小值分别为857.1和203.4Ma,它们与其余4件玄武岩样品49个SHRIMP锆石测点年龄一同构筑了涵盖各个地质时期几乎贯穿整个地质时间的复杂年龄谱。位于华北克拉通中部区域南太行山造山带的东浮山、羊角和雪花山新生代玄武岩3件样品累计36个锆石测点形成的锆石年龄谱相对简单,其中35个测点的年龄集中在1719.9～2641.6Ma,唯一的古生代年龄(311.3Ma)出现在雪花山玄武岩7.1测点。位于华北克拉通东部裂谷带内山旺玄武岩6件样品27个测点的单颗粒锆石年龄构筑的锆石年龄谱形成3个集中时间段,分别为新太古代—古元古代(2595.4～1852.2Ma)、古生代(385.8～271.1Ma)和中生代(109.4Ma)。3个年龄谱中大部分单颗粒锆石U-Pb年龄均能在各自所处区域内发现与之对应的岩浆-热事件,部分单颗粒锆石年龄可能暗示所在区域至今未发现的岩浆热事件,托云、东浮山-羊角-雪花山、山旺新生代玄武岩的复杂单颗粒锆石年龄谱再造了各自所处区域的地质演化史。3个锆石年龄谱的复杂程度与各自区域地表出露岩浆岩的规模和期次复杂程度相关,天山造山带内岩浆岩发育,托云玄武岩锆石年龄普最复杂,记录了天山造山带的演化,而华北克拉通中部区域南太行山造山带地表零星出露岩浆岩,东浮山-羊角-雪花山玄武岩的锆石年龄普最简单。处于后期遭受破坏改造的华北克拉通东部裂谷带内的山旺玄武岩的单颗粒锆石年龄谱,其复杂程度明显低于托云玄武岩的年龄谱,而又高于东浮山-羊角-雪花山玄武岩的年龄谱。鉴于玄武质岩浆同化混染围岩过程中能量消耗和地球化学印记以及玄武质岩浆上升的耗时限制,认为托云、东浮山、羊角、雪花山和山旺新生代玄武岩中具有复杂年龄信息的锆石捕掳晶不是玄武质岩浆在快速上升过程中从围岩中捕获的,而是在岩石圈拆沉过程中进入软流圈地幔中,随着具原生岩浆性质的玄武质岩浆喷发到达地表。     

Zircon U–Pb ages and tectonic implications of Paleozoic plutons in northern West Junggar,North Xinjiang,China

North Xinjiang, Northwest China, is made up of several Paleozoic orogens. From north to south these are the Chinese Altai, Junggar, and Tian Shan. It is characterized by widespread development of Late Carboniferous–Permian granitoids, which are commonly accepted as the products of post-collisional magmatism. Except for the Chinese Altai, East Junggar, and Tian Shan, little is known about the Devonian and older granitoids in the West Junggar, leading to an incomplete understanding of its Paleozoic tectonic history. New SHRIMP and LA-ICP-MS zircon U–Pb ages were determined for seventeen plutons in northern West Junggar and these ages confirm the presence of Late Silurian–Early Devonian plutons in the West Junggar. New age data, combined with those available from the literature, help us distinguish three groups of plutons in northern West Junggar. The first is represented by Late Silurian–Early Devonian (ca. 422 to 405 Ma) plutons in the EW-striking Xiemisitai and Saier Mountains, including A-type granite with aegirine–augite and arfvedsonite, and associated diorite, K-feldspar granite, and subvolcanic rocks. The second is composed of the Early Carboniferous (ca. 346 to 321 Ma) granodiorite, diorite, and monzonitic and K-feldspar granites, which mainly occur in the EW-extending Tarbgatay and Saur (also spelled as Sawuer in Chinese) Mountains. The third is mainly characterized by the latest Late Carboniferous–Middle Permian (ca. 304 to 263 Ma) granitoids in the Wuerkashier, Tarbgatay, and Saur Mountains.As a whole, the three epochs of plutons in northern West Junggar have different implications for tectonic evolution. The volcano-sedimentary strata in the Xiemisitai and Saier Mountains may not be Middle and Late Devonian as suggested previously because they are crosscut by the Late Silurian–Early Devonian plutons. Therefore, they are probably the eastern extension of the Early Paleozoic Boshchekul–Chingiz volcanic arc of East Kazakhstan in China. It is uncertain at present if these plutons might have been generated in either a subduction or post-collisional setting. The early Carboniferous plutons in the Tarbgatay and Saur Mountains may be part of the Late Paleozoic Zharma–Saur volcanic arc of the Kazakhstan block. They occur along the active margin of the Kazakhstan block, and their generation may be related to southward subduction of the Irtysh–Zaysan Ocean between Kazakhstan in the south and Altai in the north. The latest Late Carboniferous–Middle Permian plutons occur in the Zharma–Saur volcanic arc, Hebukesaier Depression, and the West Junggar accretionary complexes and significantly postdate the closure of the Irtysh–Zaysan Ocean in the Late Carboniferous because they are concurrent with the stitching plutons crosscutting the Irtysh–Zaysan suture zone. Hence the latest Late Carboniferous–Middle Permian plutons were generated in a post-collisional setting. The oldest stitching plutons in the Irtysh–Zaysan suture zone are coeval with those in northern West Junggar, together they place an upper age bound for the final amalgamation of the Altai and Kazakhstan blocks to be earlier than 307 Ma (before the Kaslmovian stage, Late Carboniferous). This is nearly coincident with widespread post-collisional granitoid plutons in North Xinjiang.