酸溶法测定硫铁矿中的全硫

在野外地质队实验室仪器少的条件下,用酸溶的方法分析硫铁矿中全硫,简单、快速、易操作,取得良好的结果。     

Lateral dynamic response of a pipe pile in saturated soil layer

This paper presents an analytical solution for the lateral dynamic response of a pipe pile in a saturated soil layer. The wave propagations in the saturated soil and the pipe pile are simulated by Biot's three‐dimensional poroelastic theory and one‐dimensional elastic theory, respectively. The governing equations of soil are solved directly without introducing potential functions. The displacement response and dynamic impedances of the pipe pile are obtained based on the continuous conditions between the pipe pile and both the outer and inner soil. A comparison with an existing solution is performed to verify the proposed solution. Selected numerical results for the lateral dynamic responses and impedances of the pipe pile are presented to reveal the lateral vibration characteristics of the pile‐soil system. Copyright © 2015 John Wiley & Sons, Ltd.     

Bearing capacity of strip foundations reinforced with geogrid sheets by using upper bound finite‐element limit analysis

By using the upper bound finite‐elements limit analysis, with an inclusion of single and two horizontal layers of reinforcements, the ultimate bearing capacity has been computed for a rigid strip footing placed over (i) fully granular, (ii) cohesive‐frictional, and (iii) fully cohesive soils. It is assumed that (i) the reinforcements are structurally strong so that no axial tension failure can occur, (ii) the reinforcement sheets have negligible resistance to bending, and (iii) the shear failure can take place between the reinforcement and soil mass. It is expected that the different approximations on which the analysis has been based would generally remain applicable for reinforcements in the form of geogrid sheets. A method has been proposed to incorporate the effect of the reinforcement in the analysis. The efficiency factors, η_c and η_γ, to be multiplied with N_c and N_γ , for finding the bearing capacity of reinforced foundations, have been established. The results have been obtained (i) for different values of ? in case of fully granular and cohesive‐frictional soils, and (ii) for different rates at which the cohesion increases with depth for a fully cohesive soil. The optimum positions of the reinforcements' layers have also been determined. The effect of the reinforcements' length on the results has also been analyzed. As compared to cohesive soils, the granular soils, especially with higher values of ?, cause a much greater increase in the bearing capacity. The results compare reasonably well with the available theoretical and experimental data from literature. Copyright © 2013 John Wiley & Sons, Ltd.     

One‐dimensional consolidation with a threshold gradient: a Stefan problem with rate‐dependent latent heat

During the process of one‐dimensional consolidation with a threshold gradient, the seepage front moves downward gradually, and the problem is indicated as a Stefan problem. The novel feature in this Stefan problem is a latent heat that varies inversely with the rate of the moving boundary. An exact solution for the external load that increases in proportion to the square root of time is constructed using the similarity transformation technique. Computational examples concerning the effect of different parameters on the motion of the seepage front are presented. The exact solution provides a worthwhile benchmark for verifying the accuracy of numerical and approximate methods. Copyright © 2013 John Wiley & Sons, Ltd.     

Analytical solutions for Euler–Bernoulli beam on visco‐elastic foundation subjected to moving load

Analytical solutions for the steady‐state response of an infinite beam resting on a visco‐elastic foundation and subjected to a concentrated load moving with a constant velocity are developed in this paper. The beam responses investigated are deflection, bending moment, shear force and contact pressure. The mechanical resistance of the foundation is modeled using two parameters k_s and t_s — k_s accounts for soil resistance due to compressive strains in the soil and t_s accounts for the resistance due to shear strains. Since this model represents the ground behavior more accurately than the Winkler spring model, the developed solutions produce beam responses that are closer to reality than those obtained using the existing solutions for Winkler model. The dynamic beam responses depend on the damping present in the system and on the velocity of the moving load. Based on the study, dynamic amplification curves are developed for beam deflection. Such amplification curves for deflection, bending moment, shear force and contact pressure can be developed for any beam‐foundation system and can be used in design. Copyright © 2012 John Wiley & Sons, Ltd.     

大气降水热液成矿——西秦岭某硅、灰、泥岩型铀矿床成矿模式探讨

西秦岭某硅、灰、泥岩型层控铀矿床是在矿源层(中志留统)的基础上,由地下水热液渗滤改造而成。铀的工业富集发生在矿源层褶皱成陆之后,成矿高峰则发生在中、新生代交替时期。成矿溶液是受大气降水补给的地下水热液;成矿物质主要来自矿源层本身。矿源层长期遭受地下水热液作用,溶液中大量的铀酰离子形成稳定的碳酸铀酰络合物,并被运移至岩性和构造的圈闭部位,通过吸附和共沉淀等作用富集,或通过还原、水解和过饱和沉淀等作用形成沥青铀矿或再生铀黑。该层控铀矿床的整个成矿过程具有典型的逐级增量特点,属于塔式累积成矿的基本模式,后生富集是成矿的关键。     

城门山铜、钼矿床的稳定同位素地质

城门山铜、钼矿床由斑岩型铜、钼矿床,矽卡岩型铜矿床和块状硫化物型铜矿床组成。本文从锶、铅、硫、氢、氧、碳等多种稳定同位素的组成特征,讨论矿床中成矿物质和热液的来源。     

大气中一类非线性方程的非线性波解及周期的近似计算法

大气中许多模式可化为Ｆ＇＇＝ＡＦ／Ｆ＋Ｂ（ＡＢ≠０）一类非线性常微分方程。利用常微分方程定性理论说明了该方程存在非线性波解，讨论了其周期的计算问题，并求得了波解及其周期的近似表达式。     

1991年江淮梅雨暴雨与亚洲季风的关系

利用实际大气参数取值进行尺度分析，求得斜压半地转模式中非线性斜压Ｒｏｓｓｂｙ波的非频散周期解的存在条件与解。给出了能够描述非线性特性波动的无量纲拟能效ε，由此推导了非线性特征波动的波速公式及波参数间的一些诊断关系。