土壤和沉积物中磷素释放过程的影响因子分析

磷素是水体富营养化的限制性因子,土壤和底泥沉积物中磷素的释放和水体中磷素的迁移转化,都会对水体富营养化产生影响。磷素的最终释放量是物理、化学及生物因素共同作用的结果。文章从影响磷素释放的影响因子入手,系统分析影响磷素释放的关键因子,研究其在磷素释放过程中所起的作用,为研究磷素在水-土介质及水-沉积物界面中的迁移转化提供依据。     

铅污染土壤的修复技术

土壤铅污染是目前较为突出的环境问题,而且国内近几年有加重的趋势。为此,国内外对土壤铅污染的修复技术进行了大量的研究。文章主要综述了铅对土壤的污染及其修复技术,主要包括物理化学修复、生物修复、农艺修复、工程修复等技术。同时对铅污染修复的发展方向进行了展望,为土壤铅污染的修复技术研究提供了借鉴和参考。     

GC/MS在分析中的应用与研究

文章主要综述了GC/MS在检测土壤、水中半挥发性有机物(SVOCs)和挥发性有机物(VOCs)的应用以及食品中有害成份的检测,并简单介绍了GC/MS在石油化工、医药等领域的应用,简单分析其在分析样品时的优势和不足。     

垃圾渗滤液污染土壤的生物修复技术的研究

垃圾卫生填埋因操作简单、处理量大而成为我国处理城市生活垃圾的主要方法,其所产生的垃圾渗滤液因含有高浓度的有机污染物对地表水、地下水及土壤环境产生严重的污染。文章概述了垃圾渗滤液的产生及其对环境的影响;介绍了垃圾渗滤液的修复技术;重点阐述了垃圾渗滤液在土壤环境中的吸附行为与生物降解及其在土壤中的迁移行为,以及生物修复技术处理垃圾渗滤液污染土壤的机理和处理效果。     

土壤调理剂及复合微生物菌剂防治烟草青枯病盆栽试验

通过盆栽试验研究了土壤调理剂及复合微生物菌剂对防治烟草青枯病的效果,并与PPF促生真菌试验效果进行了对比。试验结果表明,复合微生物菌剂和土壤调理剂对烟草青枯病均有较好的防治效果,其中复合微生物菌剂在促进烟株生长和防治烟草青枯病方面表现更好。     

土壤重金属污染修复技术研究及进展

总结了目前较常用的土壤重金属污染修复技术有物理修复、化学修复和生物修复,了解到不同修复技术的适用性和局限性;详细阐述了零价铁修复技术的发展概况,以及零价铁用于修复土壤重金属污染的可行性和存在的问题,为今后土壤重金属污染修复指明了一个新的方向。     

物元分析法对土壤重金属质量评价的研究及改进

本文主要针对物元分析法在土壤重金属质量评价中的应用进行研究,并以东莞市12个监测点的土壤重金属监测数据为例对土壤重金属污染现状进行评价。同时,深入剖析物元分析评价法,对其方法的不足进行改进,研究结果证明,采用权重和毒性相结合的"基于加权毒性的物元分析法"是一种合理的计算方法,评价结果可靠、准确,是一种适用于土壤重金属评价的新方法。     

Ein Modell zur Berechnung des Verformungsverhaltens von horizontal hochzyklisch beanspruchten Pfählen

A model for the behavior of horizontally high‐cycle loaded piles For the prediction of the deformation for long or intermediate long piles under lateral high cycle load, embedded in non‐cohesive soil, a simplified engineering model for drained conditions is developed based on the high cycle accumulation (HCA) model of Niemunis , Wichtmann and Triantafyllidis [1]. The monotonic soil deformation under static load is approximated by elastic springs, placed around the pile, whereas the accumulation of soil deformations under cyclic loading is modelled by viscous dashpots (cyclic creep) according to the HCA model. In most instances this contemplation is physically validated by element tests. In conjunction with the pile the spring‐dashpot elements represent an elastically embedded beam system. Two versions of the model with a two‐sided arrangement of springs and dashpots on the Lee‐ and Luv‐side and a one‐sided arrangement only on the Lee‐side will be presented. The pile displacement prediction of the model is compared with the results obtained by existing engineering models already known in the literature and the solution of a 3‐D‐finite element simulation with the HCA model.     

Characterizing the effects of fines on the liquefaction resistance of silty sands

Recent earthquakes in New Zealand and Japan indicate that evaluating the liquefaction potential of silty sands remains an area of difficulty and uncertainty in geotechnical engineering. This paper presents a comprehensive experimental study along with analysis and interpretation in the framework of critical state soil mechanics, with the aim to address the complicated effects of fines. Two series of sand-silt mixtures, formed by mixing two different base sands with the same type of non-plastic silt, were tested under a range of packing density, confining pressure and silt content, and a unified correlation was established between the cyclic resistance and the state parameter that collectively accounts for the effect of packing density and confining pressure. The proposed correlation is independent of packing density, confining pressure, fines content and base sand, and allows prediction of the cyclic resistance of silty sands under different states. Furthermore, the mechanism of the fines-content induced reduction of cyclic resistance and the mechanism of the base-sand effect observed from the tests are elaborated in the sound theoretical context. The present study suggests that the critical state soil mechanics is a rational and appealing framework for liquefaction analysis of both clean and silty sands.     

The ultimate bearing capacity of shallow strip footings using slip-line method

Based on the limit equilibrium theory, an accurate approach is proposed to solve the ultimate bearing capacity of shallow strip footings under general conditions. The foundation soil is considered to be an ideal elastic-plastic material, which obeys the Mohr-Coulomb yield criterion, and is assumed to be an ideal continuous medium which is isotropic, homogeneous and incompressible or non-expansive. Through analyzing the relative motion and interaction between the footing and soil, the problem of the ultimate bearing capacity of shallow strip footings is divided into two categories. A minimum model with the total vertical ultimate bearing capacity as its objective function is established to solve the ultimate bearing capacity using the slip-line method with no need to make any assumptions on the plastic zone and non-plastic wedge in advance. A convenient and practical simplified method is also proposed for practical engineering purposes. Furthermore, the first category of the problem in the case of the same uniform surcharges on both sides of footings is the focus of the study: the applicable conditions of Terzaghi’s ultimate bearing capacity equation as well as the theoretical exact solutions to its three bearing capacity factors are derived, and a new bearing capacity equation is put forward as a replacement for Terzaghi’s equation. The geometric and mechanical similarity principle is proposed by a dimensionless analysis. The results show that for perfectly smooth footings, the total vertical ultimate bearing capacity obtained by the present method is in good agreement with those by existing methods, whereas the existing methods underestimate the ultimate bearing capacity in the case of perfectly rough footings. The classic Prandtl mechanism is not the plastic failure mechanism of the ultimate bearing capacity problem of perfectly smooth footings on weightless soil.