水泥土桩复合地基桩土应力参数研究

本文首先通过理论分析,认为桩土应力比、桩土荷载分担比等是反映水泥土桩复合地基工作性状的重要参数。然后通过现场试验,研究桩土应力比、桩土荷载分担比随荷载变化的规律。结果认为:随着荷载增加,桩土应力比逐渐减小,当比值达到某一特征值后,不再发生明显变化;桩土应力比、桩土荷载分担比不为常数,其变化是桩土变形协调的结果。最后得出有一定参考价值的结论。     

花岗岩-流体相互作用的实验研究进展

花岗岩-流体相互作用的实验研究，对于解决放射性核废料的处理，地热能的有效开发利用和成岩成矿作用的理论研究等问题，具有重要的意义和应用价值。因此，本文引用近期的资料，从矿物表面的解吸作用、次生矿物的沉淀、矿物及花岗岩的溶解速率和花岗岩-流体反应的效应四个方面，对花岗岩-流体相互作用的实验研究进行论述，以期达到抛砖引玉的效果。     

Leaching of nitrogen in Swedish agriculture — a historical perspective

There is a need to examine long-term changes in nitrogen leaching from arable soils. The purpose of this study was to analyse variations in specific leaching rates (kg ha⁻¹ per year) and gross load (Mg per year) of N from arable land to watercourses in Sweden from a historical perspective. The start of the study was set to 1865 because information on crop distribution, yield and livestock has been compiled yearly since then. The SOIL/SOILN model was used to calculate nitrogen leaching. Calculations were done for cereals, grass and bare fallow for three different soil types in nine agricultural regions covering a range of climatic conditions. Results indicate that both specific leaching rates and gross load of nitrogen in the middle of 19th century were approximately the same as they are today for the whole of south and central Sweden. Three main explanations for this were (1) large areas of bare fallow typical for the farming practice at the time; (2) enhanced mineralisation from newly cultivated land; and (3) low yield . From 1865, i.e. the start of the calculations, N leaching rates decreased and were at their lowest around 1930. During the same period, gross load was also at its lowest despite the fact that the acreage of arable land was at its most extensive. After 1930, average leaching increased by 60% and gross load by 30%, both reaching a peak in the mid-1970s to be followed by a declining trend. The greatest increase in leaching was in regions where the increase in animal density was largest and these regions were also those where the natural conditions for leaching such as mild winters and coarse-textured soils were found. Extensive draining projects occurred during the period of investigation, in particular an intensive exploitation of lakes and wetlands. This caused a substantial drop in nitrogen retention and the probable increase in net load to the sea might thus have been more affected by this decrease in retention than the actual increase in gross load.     

用滑移线理论确定工件塑性区的一种方法

在分析了变形体和模具的接触特点和接触面金属的流动应力与应变特点的基础上,在考虑接触摩擦为最大剪应力K的情况下,绘制出接触面的滑移线场,应用滑移线理论求解出接触金属进入塑性区的极限载荷,并以此为标准来判断接触金属是否进入塑性区。     

苏南太湖水系农业面源污染及其控制对策研究

提出并应用了差额污染负荷量的概念，建立了平原水网地区大面积集水区网络试验法，并设计了可以覆盖苏南太湖地区的７种类型水、旱田网络试验区、通过点面结合，室内外试验配合，采用１５＾Ｎ同位素示踪技术进行农田氮素流失模拟试验等研究，结果表明，农业面源氮素污染负荷量随年降水量和灌溉量的增加而增大；浅层地下水硝态氮的污染负荷量与氮肥的施用量呈正相关；稻田氮素污染负荷量显地高于旱田；农业面源磷素污染差额总负荷量     

填埋场渗滤液水质变化预测模型实验研究

利用垃圾污染负荷浸出实验装置对下坪垃圾填埋场渗滤液水质变化规律进行了模拟研究。并利用实验数据通过指数回归法确定了渗滤液水质预测模型的有关参数。实验结果和现场监测数据表明,单批填埋垃圾渗滤液的浓度在垃圾填埋75d后达到最大值,COD最大可达31581mg/L。利用渗滤液水质预测模型计算表明,垃圾填埋90．9d后垃圾渗滤液COD达到最大值,模拟计算结果和现场监测数据符合较好,说明该模型以及通过污染负荷浸出实验得出的模型参数可以较准确地对填埋场渗滤液水质变化进行预测。     

水污染控制指标交易市场的工作原理

为提高区域总量控制管理系统的效率,提供我国实施排污许可证有偿转让政策的理论依据,设计给出了两种水污染控制指标转让的交易市场模型并讨论其工作原理。     

以马蹄莲为主体植物的人工湿地处理低浓度污水中试研究

人工湿地中集污染物吸收效果好、生境改善、观赏性好和经济性好于一体的植物筛选将支持湿地的长效低耗运行。报道了以观赏性和经济性植物马蹄莲(Zantedeschia aethiopica)为主要植物的人工湿地中试床(5 m×1 m×1.1 m)处理低浓度农村污水的研究。结果表明,在水力负荷为6,10和20 cm.d-1的条件下,该系统对CODCr(化学需氧量)、TN(总氮)、硝氮、氨氮和TP(总磷)的去除率分别大于56.4%、71.4%、71.4%、49.6%和56.6%。同处旺盛生长期(8月)而温度相近时,低水力负荷(6 cm.d-1)组的硝氮、氨氮和TP的去除率高;高水力负荷(20 cm.d-1)组的TN去除率高,进水TN中的有机氮占的比例比低水力负荷(6 cm.d-1)的高10%。马蹄莲人工湿地系统在休眠期(6月和7月)和在旺盛生长期相比,由于温度高而具有高的CODCr和N去除率,由于枯枝落叶的腐烂溶出以及进水负荷高而具有低的TP去除率。研究结果可为人工湿地等生态系统中选择植物时参考。     

基于单元分析的青铜峡灌区农业非点源污染估算

针对灌区农业非点源污染难以监测控制的具体特点,基于单元分析的观点,提出了负荷贡献率的概念,并在此基础上,建立了灌区农业非点源污染负荷估算方法;以青铜峡灌区为例,利用2005-2006年灌溉周期灌排水质监测试验资料对灌区年农业非点源污染矿化度、铵氮、总氮和总磷负荷进行了估算,并与平均浓度法进行比较.计算结果表明:青铜峡灌区农业非点源污染年输出盐分283万t,铵氮0.55万t,总氮4.11万t,总磷123 t;结合黄河干流控制断面水质资料比较分析,青铜峡灌区农业非点源污染负荷中盐分输出占干流区间增量的70%,铵氮和总氮分别是区间点源污染负荷的0.28倍和1.52倍,对黄河干流水质影响很大;而总磷由于输出量较小,对干流水质影响不大.     

土壤施加垃圾堆肥的允许负荷量

利用城市生活垃圾堆肥进行生菜、青菜、小麦三种作物的盆栽试验，并根据作物中金属元素Ｃｄ、Ｃｕ、Ｃｒ、Ｐｂ、Ａｓ的含量，探讨了三种土壤施加垃圾堆肥的效果及允许负荷量，结果表明：土壤消纳垃圾肥的潜力很大，但不同土壤类型对垃圾肥的负荷量有明显差异。