盾构隧道纵向地震响应简化动力有限元法分析(英文)

本文重点关注对盾构隧道的纵向地震响应分析方法的研究,提出了一种简化的动力有限元分析方法。这种方法采纳了响应位移法的一些基本思想,采用和响应位移法一样的环梁和土弹簧模型,但采用动力有限元法来评估地基地震动,而摒弃了响应位移法中采用的地基振动为谐波形式的假定。与响应位移法相比,简化动力有限元法能够提高地基震动的计算精度,从而提高结构响应的计算精度;而与三维连续模型相比,新方法的计算规模小得多,从而能够大幅提高计算效率。然后,本文分别采用相应位移法和新提出的简化动力有限元法,对武汉长江隧道盾构段隧道进行了纵向地震响应分析,并对这2种方法计算结果的差异进行了分析。     

西安咸阳国际机场污水排放口潜在滑坡稳定性分析

对西安咸阳国际机场污水排放口潜在滑坡的工程地质勘察结果表明,该滑坡处于极限平衡状态。采用B ish-op法参数反演和直快剪试验结果,分别用二维、三维极限平衡法和二维、三维有限元法,对该滑坡进行稳定性计算。结果表明:有限元法(二维、三维)的计算结果偏大,二维极限平衡法的计算结果最小;极限平衡法(二维、三维)与二维有限元法宜选取试验结果的大值平均值,三维有限元法则取试验结果的小值平均值较为合理。最后,根据三维有限元法的计算结果,提出了削坡压脚的防护措施。     

Nutritionally relevant elements in staple foods: influence of arable site versus choice of variety

Eighteen representative sites for the Austrian grain-growing and eight for the potato-growing zones (soils and crops) were investigated. On each site, total element contents (B, Ba, Ca, Cd, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, P, Sr and Zn) were determined in 4–12 varieties of winter wheat (n = 136), 6 varieties of spring durum wheat (n = 30), 5 varieties of winter durum wheat (n = 15), 7 varieties of rye (n = 49), 5 varieties of spring barley (n = 30) and 5 varieties of potatoes (n = 40). Element accumulations in grain species and potato tubers varied significantly with site conditions, with the main exceptions for B in potatoes and wheat as well as for Zn, Cu and Co in durum wheat. On average, across all investigated sites, differences in varieties occurred concerning the elements Ca, Cd, Ba, Sr and Zn (except Zn in potatoes and winter durum). A rough estimation revealed that an average Austrian consumer of wheat, rye and potatoes meets more than 50% of the needs of daily element intake for K, P and Mg, between 36 and 72% for Fe, Zn and Cu, and more than 100% for Co, Mo and Mn. In particular, the elements Ca and Na have to be added from other sources.     

基于元素毒性赋值的模糊数学环境质量评价

利用模糊数学方法，根据元素毒性的大小进行权重赋值，对成都经济区近地表大气尘进行地球化学环境质量评价。结果显示：不同城市中，成都、乐山、眉山的大气环境质量较好，处于一级清洁级别；眉山、雅安的大气环境质量处于二级安全级别；德阳的大气环境质量已经处于三级警戒级。不同地区中，绵阳和眉山的大气环境质量较好，处于一级清洁级别；德阳和雅安处于二级安全级别，成都和乐山处于三级警戒级.     

首钢孟家冲尾矿坝渗流稳定分析

针对孟家冲尾矿库坝面出现的渗水现象,对坝体的渗流以及稳定进行计算分析。计算结果表明,由于堆积坝的不断升高,导致坝体浸润线抬高,安全稳定系数降低,从而将造成坝体失稳,出现溃坝事故。为消除隐患,提出采用辐射井排渗的设计方案,并对该方案的可行性进行计算分析。     

单块集尘板振打加速度的有限元分析

采用有限元分析软件ABAQUS，对单块集尘板振打加速度进行了分析计算。并将计算结果与解析法和实测法结果进行对比。对比结果表明，有限元计算值更接近于实测值。用有限元法对某厂实际运行的电除尘器加速度进行求解，计算结果与实际基本吻合。由于有限元法能非常方便地处理各种复杂板型、不同的悬挂方式、振打锤的大小以及振打方式，因此，有限元法对于现有极板的分析与新型极板的研究均具有重要的实际意义。     

基于可拓学石化装置失效后果严重度评估方法研究

石化企业中，石化装置的安全运行对保证企业的安全生产起到关键作用，其一旦失效发生事故，将导致巨大的人员伤亡及财产损失。因此，开展石化装置失效后果严重性的评价研究，对保证石化企业的安全生产具有重要意义。本文根据物元可拓性理论，结合石化装置失效后果的严重性情况，运用可拓评判方法建立石化装置失效后果严重度的综合评判模型，给出了评价步骤，最终确定设备失效后果的严重程度。研究结果表明，该方法可应用于多层次的工程风险评价问题，从而为石化工程项目风险管理提供了一种有效的分析方法。     

A hybrid method for quasi-three-dimensional slope stability analysis in a municipal solid waste landfill

Limited space for accommodating the ever increasing mounds of municipal solid waste (MSW) demands the capacity of MSW landfill be maximized by building landfills to greater heights with steeper slopes. This situation has raised concerns regarding the stability of high MSW landfills. A hybrid method for quasi-three-dimensional slope stability analysis based on the finite element stress analysis was applied in a case study at a MSW landfill in north-east Spain. Potential slides can be assumed to be located within the waste mass due to the lack of weak foundation soils and geosynthetic membranes at the landfill base. The only triggering factor of deep-seated slope failure is the higher leachate level and the relatively high and steep slope in the front. The valley-shaped geometry and layered construction procedure at the site make three-dimensional slope stability analyses necessary for this landfill. In the finite element stress analysis, variations of leachate level during construction and continuous settlement of the landfill were taken into account. The "equivalent" three-dimensional factor of safety (FoS) was computed from the individual result of the two-dimensional analysis for a series of evenly spaced cross sections within the potential sliding body. Results indicate that the hybrid method for quasi-three-dimensional slope stability analysis adopted in this paper is capable of locating roughly the spatial position of the potential sliding mass. This easy to manipulate method can serve as an engineering tool in the preliminary estimate of the FoS as well as the approximate position and extent of the potential sliding mass. The result that FoS obtained from three-dimensional analysis increases as much as 50% compared to that from two-dimensional analysis implies the significance of the three-dimensional effect for this study-case. Influences of shear parameters, time elapse after landfill closure, leachate level as well as unit weight of waste on FoS were also investigated in this paper. These sensitivity analyses serve as the guidelines of construction practices and operating procedures for the MSW landfill under study.     

MODEL FOR PREDICTING TRANSPORT OF PESTICIDES AND THEIR METABOLITES IN THE UNSATURATED ZONE1

ABSTRACT: A finite element model based on Galerkin's upstream weighted residual technique was developed to predict the simultaneous convective-dispersion transport and transformations of pesticides and their metabolites in the unsaturated zone. Transformations of the parent compound and its metabolites were assumed to be first-order reactions for oxidation and hydrolysis, while adsorption of the pesticide species (parent compound and metabolites) to the soil components was assumed to be represented by a linear equilibrium (Freundlich type) isotherm. Volatilization and plant root uptake of pesticides in the solution phase were neglected in the analysis. The proposed model was used to simulate the transport and transformation of aldicarb and its metabolites, aldicarb sulfoxide and aldicarb sulfone, in the soil profile. Several examples are used to demonstrate the accuracy, validity, and applicability of the proposed model. Simulated results indicate that the proposed model can potentially be used to estimate the mass flux of water, and pesticide and pesticide metabolite concentrations in the subsurface environment. However, further verification of the model against actual field data is needed to fully demonstrate the model's potential.     

黄土滑坡稳定性评价的反演分析

本文根据黄土滑坡的变形监测结果，同时考虑了边坡的初期应变分布状况，通过有限元反分析法，反推出边坡地基的力学参数，为黄土滑坡的稳定性评价和预报提供了可靠的依据。