藏北羌塘中部日湾茶卡地区花岗闪长岩LA-ICP-MS锆石U-Pb年龄与地球化学特征

报道了藏北羌塘中部日湾茶卡地区花岗闪长岩体锆石U-Pb年龄和岩石地球化学特征。该花岗闪长岩位于龙木错—双湖—澜沧江板块缝合带西段。岩石样品中的锆石具有较好的晶形,可见典型的岩浆振荡环带结构,具有较高的Th/U值,为典型的岩浆成因锆石。样品锆石LA-ICP-MS技术测得的锆石年龄为211.0Ma±1.8Ma,表明其时代为晚三叠世。全岩地球化学分析表明,该花岗闪长岩具有高SiO2、Al2O3,富碱,低TFe2O3、TiO2的特征,A/CNK值为0.97~1.04,为准铝质—弱过铝质岩石。稀土元素配分模式显示,配分曲线右倾,伴随较弱的Eu负异常;微量元素蛛网图表现出Nb、Ta、Ti、P亏损和Rb、Th、U、K、Pb富集的特征;样品点在构造环境判别图解上均落入碰撞型花岗岩区。初步分析,其岩浆来源可能为幔源岩浆底侵使古老地壳发生熔融。此碰撞型花岗闪长岩对龙木错—双湖—澜沧江洋碰撞的时限提供了一定的岩石学约束,为龙木错—双湖—澜沧江洋的演化提供了基础地质资料。     

Effects of engineering geological condition on response of suspension bridges

The geological condition may vary largely from one support to another for a long span bridge. The effect of geological variability and spatial variation produced by propagation and coherence loss of seismic ground motion on the response of long span suspension bridges is investigated in this article. The case of Jiangyin Yangtse River Bridge, a suspension bridge with a main span of 1385 m, is studied in detail. Numerical results show that the geological difference at the supports has a significant effect on the seismic response of long span suspension bridges and, that it is unacceptable to neglect the difference. The effect of the propagation of seismic ground motion on the response of long span suspension bridges is far more important than that of the coherence loss. The response of bridges varies greatly with the horizontal apparent velocity in a very complex way, and there is a critical horizontal velocity for a given response quantity.     

Creep of saturated materials as a chemically enhanced rate‐dependent damage process

Material behaviour that exhibits characteristics of creep induced by a spontaneous mineral dissolution enhanced by material damage is studied. It is believed that the characteristic rates of the chemical processes involved determine the time‐rate dependence of the resulting strain. A basic model of a combined chemo‐plastic softening and chemically enhanced deviatoric strain hardening for saturated geomaterials is presented. Chemical softening is postulated to occur as a consequence of the net mass removal resulting from dissolution and precipitation of specific minerals occurring at the damage‐generated inter‐phase interfaces. Closed and open systems are discussed. In the former case, deformation at constant stress results entirely from a local compensation mechanism between the chemical softening and strain hardening. The classical three stages of creep are interpreted in terms of mechanisms of dissolution and precipitation, as well as the variation in the reaction surface areas involved in the mass exchange. In an open system, the above local mechanism is enhanced by the removal of mass via diffusion of species affecting the mass balance. Such a system is addressed via a boundary value problem as shown in an example. Copyright © 2007 John Wiley & Sons, Ltd.     

A new Voronoi diagram-based approach for matching multi-scale road networks

Journal of Geographical Systems - Object matching is a key technology for map conflation, data updating, and data quality assessment. This article proposed a new Voronoi diagram-based approach for...     

Isolation of protoplasts from <Emphasis Type="Italic">undaria pinnatifida</Emphasis> by alginate lyase digestion

The aim of this study is to isolate protoplasts from Undaria pinnatifida. Protoplasts of the alga were isolated enzymatically by using alginate lyase, which was prepared by fermenting culture of a strain Vibrio sp. 510. Monofacterial method was applied for optimizing digestion condition. The optimum condition for protoplast preparation is enzymatic digestion at 28°C for 2h using alginate lyase at the concentration of 213.36 U (8 mL) every 0.5g fresh thalline with NaCl 50 and at the shaking speed of 150 r min⁻¹ during digestion. The protoplast yield can reach 2.62±0.09 million per 0.5 g fresh leave under the optimum condition. The enzyme activity is inhibited by Ca²⁺ and slightly enhanced by Fe²⁺ and Mn²⁺ at concentrations of 0.05, 0.08 and 0.10 mol L⁻¹.     

基于模糊层次分析法对“一带一路”重要区域地质灾害危险性评价——以关中经济区为例

在“一带一路”沿线区域开展地质灾害危险性评价与区划具有重大意义。本文以关中经济区为例,综合考虑地质灾害特点、分布规律与孕灾环境等要素,基于坡度和地形起伏度的组合,提出了地质灾害安全区域与非安全区域的初步识别方法。在此基础上,采用模糊层次分析法和GIS空间分析方法对地质灾害各孕灾因子进行了危险性等级评价,并分别进行了单因子和多因子综合制图与结果验证。研究结果表明：1）地质灾害安全区域与非安全区域的初步判识,对灾害风险管理和降低防灾减灾成本有重要参考价值,也大大提高了地质灾害评价区域的针对性和准确性。2）研究区地质灾害安全区域面积占比22.9%（17054.5km²）,非安全区域占比77.1%（57462.6km²）,轻度危险区、低危险区、中危险区和高危险区面积分别占非安全区域面积的17.2%、32.2%、32.0%、18.6%,以中、低危险性为主（64.2%）。高危险性区域集中分布在关中经济区的西北、西南、东南部,而轻度危险性区域集中分布在关中平原以南地区,呈现出东西走向的“条带状”。3）共计3230个灾害点中,仅有3.3%（106个）的灾害点分布在安全区域中,其余96.7%（3124个）的灾害点均分布在非安全区域之中。分布在轻度危险、低危险、中危险和高危险区域中的分别有328个（10.2%）、765个（23.7%）、1007个（31.2%）、1024个（31.7%）,这与危险性等级区划结果具有很好的一致性。表明本文提出的地质灾害安全区域识别方法和地质灾害危险性区划方法具有一定的科学性和准确性。

     

钛酸镧烧结物中游离氧化镧的测定

本文研究了La(Ⅲ)与甲基百里酚蓝和溴化十六烷基吡啶在pH7.8—11.0的NH_4OH-NH_4Cl介质中生成紫色络合物的显色反应,λ_(max)=628nm,ε=8.1×10~4,La量在0—90μg/25ml范围内遵循比尔定律,烧结物中一些常见的离子不干扰测定。本法用于烧结物中游离氧化镧的测定,结果满意。     

Characterization of the mechanical properties of a claystone by nano-indentation and homogenization

Based on the analyses of mineralogical compositions by X-ray diffraction and microstructure by optical microscopy, the Young’ modulus and hardness of a claystone were characterized by the nano-indentation technique and homogenization method. Three distinct microstructural zones are identified in the claystone: clay matrix, a composite matrix of clay and small mineral grains and imbedded quartz grains. The elastic modulus and hardness of different zones were determined by nano-indentation testing. Based on the statistical analysis of nano-indentation results, the spatial mappings and frequency distributions of elastic modulus and hardness of the different zones were obtained. The elastic moduli of main constituent phases of the claystone are then estimated from the nano-indentation tests. These values were further used for the determination of the macroscopic elastic modulus of the claystone using two different homogenization schemes: the dilute scheme and Mori–Tanaka scheme. The predicted values by the homogenization schemes are compared with experimental data obtained from conventional uniaxial compression tests.     

长江三峡及邻区地震活动的灰色预测

根据历史地震记载和现今地震观测数据，运用灰色系统理论，建立了长江三峡及邻区下一个地震活跃期及活跃期内可能发生的最大地震的震级的灰色预测模型。预测结果表明，下一个地震活跃期将持续７９ａ，活跃期内的最大地震震级不会超过５．２级。这对三峡地区地震问题的评价与防患提供了重要的依据     

离子类土壤固化剂对高温冻土工程性质改良试验研究

为了研究离子类土壤固化剂对青藏高原高温冻土工程性质的改良效果,分别选用酸性和碱性离子类土壤固化剂对冻结青藏粉质黏土进行了改良测试。塑性指数测试表明,两种固化剂的最优含量为0.2%。固化剂含量小于0.3%时,冻结温度相对原状土样没有明显的下降。对不同含量碱性和酸性固化土力学性质进行了测试,无侧限单轴抗压强度相对原状土样整体增大,碱性和酸性固化土抗压强度最大分别提高了78.7%和46.6%,最优配比（0.2%）的碱性和酸性固化土体积压缩系数随养护龄期增大而减小,两种固化土的体积压缩系数相对原状土样最大分别下降了80.0%和38.5%,固化效果明显。碱性固化土力学性质变化更显著,说明其更适合对青藏黏土进行改良。