冲绳海槽有孔虫壳体的微量元素Sr,Nd同位素地球化学

钙质生物壳的微量元素组合和Sr,Nd同位素组成是识别海底混合源沉积物中生物源物质相对贡献的重要参数.冲绳海槽有孔虫壳体强烈富集Sr,P,Mn和Ba,富集Li,U,Th,Sc,Co,Pb,Zn,Cr,Rb,Y,Sb和轻稀土元素,弱富集V,Ga,Zr,Nb,Cd和中稀土元素,相对贫Ge,Mo,In,Sn,Cs,Hf,Ta,W,Tl,Bi和重稀土元素,海水中微量元素的背景含量和生物活动对微量元素的选择性吸收是有孔虫壳体中微量元素发生富集和贫化的主要机制,冲绳海槽有孔虫壳体的稀土元素配分模式与海水和太平洋有孔虫的有明显差异,表现出中稀土元素相对富集,并具有微弱的负Ce异常.有孔虫壳体的Sr,Nd同位素比值也与大洋海水不同,分别为0.709769和0.512162,前者略高于大洋海水,后者略低于大洋海水,表明冲绳海槽海水明显受大陆河水影响.     

Coupled analysis of nonlinear sloshing and ship motions

A coupled numerical model considering nonlinear sloshing flows and the linear ship motions has been developed based on a boundary element method. Hydrodynamic performances of a tank containing internal fluid under regular wave excitations in sway are investigated by the present time-domain simulation model and comparative model tests. The numerical model features well the hydrodynamic performance of a tank and its internal sloshing flows obtained from the experiments. In particular, the numerical simulations of the strong nonlinear sloshing flows at the natural frequency have been validated. The influence of the excitation wave height and wave frequency on ship motions and internal sloshing has been investigated. The magnitude of the internal sloshing increases nonlinearly as the wave excitation increases. It is observed that the asymmetry of the internal sloshing relative to still water surface becomes more pronounced at higher wave excitation. The internal sloshing-induced wave elevation is found to be amplitude-modulated. The frequency of the amplitude modulation envelope is determined by the difference between the incident wave frequency and the natural frequency of the internal sloshing. Furthermore, the coupling mechanism between ship motions and internal sloshing is discussed.     

海泥环境中阴极保护的边界元计算

根据阴极保护的特点,建立了用于数值计算的模型;采用边界元方法对海泥介质中的阴极保护系统进行了计算,获得了海泥中钢管表面以及海泥介质内部的电位分布。将计算的结果与测量的数据进行比较,两者具有较好的一致性。     

中哈俄阿尔泰稀有金属矿床时空分布、成因及成矿规律

中哈俄阿尔泰发育许多大型—超大型稀有金属矿床,是世界著名的稀有金属成矿省.该成矿省可分为3个稀有金属成矿带,自西南向东北依次为哈萨克斯坦Kalba-Narym、中国阿尔泰和俄罗斯山区阿尔泰等.这3个成矿带稀有金属矿床以伟晶岩型为主,但伟晶岩与花岗岩关系及其伟晶岩成因不一致:在哈萨克斯坦Kalba-Narym成矿带和俄罗...     

平阴县土壤中重金属元素异常成因研究

通过对平阴县周边及其西部农田区采样调查,平阴县周边元素异常具有异常衬度较高,富集系数大等特征,西部农田区异常具有各元素套合关系好,多数异常衬度不高,富集系数小的特点。结果表明,西部农田区异常是以As,Cd为主要成分的异常,元素含量与SiO2,Al2O3,Fe2O3等常量组分间具有显著的相关性,随SiO2含量的增加而降低,随Al2O3,Fe2O3含量的增加而增加,说明土壤常量组分及其所决定的土壤质地是导致异常形成的主要因素;而平阴城区异常是以S,Hg,As,Zn,Mn等元素为主的异常,是典型的人为综合因素（化工烟尘、工厂污水、生活垃圾）产生的异常。     

数字宜昌建设初探

数字地球、数字城市是近几年刚提出来的一个全新的概念 ,但数字城市的建设却以空前的速度向前发展着 ,国务院总理朱熔基在视察宜昌时提出要把宜昌建设成世界级的城市 ,未来的城市数字化程度将是衡量一个城市发达程度的重要指标 ,启动数字宜昌建设是跻身世界级城市 ,提高宜昌市综合竞争力的重要举措     

长白山区暗棕壤成土作用地球化学特征

以代表性暗棕壤垂直剖面土壤地球化学数据为依据,研究了长白山区特定的森林景观条件下成土过程中元素的分异与富集特征。研究结果表明,在岩石风化过程中主要以CaO、 Na2 O、 Sr淋溶为主,有机酸淋溶过程中SiO2、 Al2 O3、 K2 O部分被淋溶,部分游离铁下渗到土体中下部氧化成铁锰胶膜;微量元素在风化过程中被次生黏土矿物吸附,不同程度地富集,在腐殖质积累过程中Cd、 Zn、Pb、 Mo、 Hg、 Co、 Mn、 Cr等亲生物元素进一步富集于表层土壤, Ce、 Ni、 Sb、 Ti、 V、 Y、 Zr在表生环境中地球化学性质稳定,残留富集于土壤表层。母质层继承和保留了基岩元素地球化学分布的基本特征。     

马超营断裂带地质及地球化学特征

根据对马超营断裂带系统进行的地质—地球化学剖面研究，探讨了该带断裂构造活动及其元素地球化学迁移富集规律与构造地球化学分异之间的关系；分析了蚀变、矿化与成矿的关系，认为早期面型蚀变伴有成矿元素的活化和迁移，但无矿化富集，后期带状蚀变伴有金的富集成矿且以硅化、绢云母化为主要标志。从而，为马超营断裂带这一重要的以金为主成矿带的进一步工作、研究，提供了地球化学方面的依据。     

FEM for stability analysis against overturning of portal water injection sheet pile

Portal water injection sheet pile （PWISP）, as a retaining wall, appeared in seashore engineering in 2000. Although there have been many systematic methods addressing the issue, there are very few focusing on the new structure because of the difficulties in defining the earth pressure between the two piles. A new method is proposed in this paper to obtain the earth pressure between the PWISPs. Stability analysis against overturning follows as a consequence. Using Finite Element Analysis （FEA） software ANSYS, both the nonlinear characteristics of the soil and those of the contact elements are taken into account to obtain the earth pressure distribution on the contact surface. Based on the results of the FEA, Rankin＇s theory and the slip plane theory, the formula of the earth pressure on the inner surfaces between the piles is given. Assuming the PWISP as the analysis object and the earth pressure as an outside force acting upon it, the equation of stability against overturning of the PWISP is presented. Finally, some parameters are discussed about the stability of the PWISP against overturning, such as the embedded depth of the front pile, the distance between the two rows of piles, the internal friction angle and the cohesion of the earth. The results show that the increase of the cohesion and the internal friction angle will decrease the distance and the embedded depth, and therefore enhance the stability against overturning. Specifically, when the distance is 1/3-2/3 of the maximal excavation depth, the two rows of piles give the best performance in stability.     

Incremental elastoplastic FEM for simulating the deformation process of suction caissons subjected to cyclic loads in soft clays

This paper presents an incremental elastoplastic finite element method (FEM) to simulate the undrained deformation process of suction caisson foundations subjected to cyclic loads in soft clays. The method is developed by encoding the total-stress-based bounding surface model proposed by the authors in the ABAQUS software package. According to the model characteristics, elastoplastic stress states associated with the incremental strains of each iteration are determined using the sub-incremental explicit Euler algorithm, and the state parameters describing the cyclic accumulative rates of strains are updated by setting state variables during the calculations. The radial fallback method is also proposed to modify the stress states outside the bounding surface to the surface during determination of the elastoplastic stress states. The stress reversals of soil elements are judged by the angle between the incremental deviatoric stress and the exterior normal vector at the image stress point on the bounding surface to update the mapping centre and state variables during cyclic loading. To assess the general validity of the method, the reduced scale model tests and centrifuge tests of suction caissons subjected to cyclic loads are simulated using the method. Predictions are in relative good agreement with test results. Compared with the limit equilibrium and quasi-static methods, the method can not only determine the cyclic bearing capacity, but can also analyse the deformation process and the failure mechanisms of suction caisson under cyclic loads in soft clays.