浅谈公路路基填筑技术

本文就公路路基填筑技术进行简单介绍,探讨在填筑准备阶段的技术管理。分析了软土地基处理技术以及强夯法处理湿陷性路基技术。     

Analysis of space–time variability in agriculture and the environment with geostatistics

This paper gives an overview of space–time variability in agriculture and the environment. Analysis is based upon geostatistics in the framework of linear regression theory. Common procedures for spatial data are extended towards the space–time domain. Several practical studies are presented. The first study describes the use of REML to estimate semi-variogram models within the presence of trends. The second study describes the use of probability maps in an environmental statistical study. The third study describes the use of geostatistics in modelling the development of a disease in cabbage. Studies are evaluated using quadratic scoring rules.     

水土流失与贫困相关性的计量分析

简要综述了国内水土流失与贫困相关性方面的研究,基于全国各省域的水土流失面积发生率与贫困发生率的合成面板数据,通过建立经济模型,计量分析发现,地区水土流失面积发生率与贫困发生率高度正相关。同时,两者的动态变化存在区域差异,映射着不同区域的经济发展水平。     

新材料路液在工程中的应用

在施工过程中会产生大量废弃的土石方,对环境危害严重。同时,在工程建设中需要炸石采砂,对环境造成严重危害。路液以各类建筑土方、矿渣、工业废弃物、废弃海涂淤泥、河道疏浚淤泥为原材料,将其转化为基础材料,使用这些基础材料替代碎石、沙子等,并减少水泥用量。论文通过实地试验,采用路液与砂砾石进行对比,从经济、环保、稳定性及强度等方面进行分析,得出路液具有造价低、稳定性和强度高、施工速度快、交通零影响及生态环保的优点,拥有良好的环境、经济和社会效益。     

Profitability and opportunity of conservation agriculture in acid savannah grasslands of Laos

In north-eastern Laos, the savannah grasslands of the Plain of Jars cover vast areas of potentially cultivable land. However, soil acidity, low inherent fertility, and the absence of alternatives to tillage represent significant constraints to the development of sustainable smallholder agriculture. Our objective was to evaluate the potential for conservation agriculture (CA) to enhance soil productivity and farming system profitability. A three-year rotation of rice/maize/soybean was tested under three fertilization levels and four agricultural systems: one conventional tillage-based (CT) system and three CA systems based on no-tillage with cover crops. After four cropping seasons, our results show that, compared with CT, CA systems led to similar-to-higher grain production, similar-to-higher profits, higher opportunity of livestock system intensification, and higher labour productivity regardless of fertilization levels. While CA represents a relevant alternative to current practices, our results suggest that its contribution to the emergence of a sustainable smallholder agriculture is conditioned by broader institutional transformations, including the enrolment of local manufacturers and traders for deploying no-till implements and seed market channels for cover crops, long-term public support to maintain active research and technical mentoring to farmers, and possibly the integration of ecosystem services in agricultural policy.     

平海电厂接入系统工程水土保持措施研究

根据水土保持法的有关规定和500kV平海电厂接入系统工程的实际情况,通过现场实际勘察和调查了解,分析了开发建设项目水土流失的特点,并进行了预测,编制了500kV平海电厂接入系统工程输变电水土保持方案。水土保持方案实施后,通过工程和植物措施的综合治理,可得到包括生态效益、社会效益和经济效益的综合效益。     

浅析公路桥梁软土路基处理的技术要点

从已建软土地基上公路运行情况看,工后沉降较大,容易造成"桥头跳车"现象,轻者影响行车速度,损害车辆,严重的导致交通事故,造成人员伤亡。所以,选择合理的软基处理方案及方法快速实施,从而取得预期的经济和社会效益,就具有重大的实际意义。在本文中,笔者对公路桥梁软土路基处理的技术要点提出了自己的几点看法。     

汉宜高速铁路路基石灰改良土填筑施工的质量控制

为满足列车高速运行时路基强度、变形以及路基工后沉降的要求,在缺乏优质填料的情况下,新建武汉至宜昌高速铁路路基回填采用石灰改良土来改善土的结构,提高承载力,以满足工程需要,并降低成本,缩短工期,取得较好的经济效益。本文就土料料源、石灰质量、灰剂量、含水量四方面以及现场施工工艺来分析石灰改良土的施工质量控制要点。     

滇东南岩溶区土壤厚度与植被生长的关系研究

受喀斯特特殊地质环境的影响,滇东南岩溶区的生态环境相对脆弱,这些地区土壤先天总量不足,土被分布不连续,水土流失后常常会出现土地石漠化。本文通过对滇东南岩溶山地地区不同条件(包括地形、海拔高度和植被情况)下土壤厚度和植被覆盖度等植物生长状况的调查,分析了该地区植被类型、覆盖度与土壤厚度的关系。     

高速铁路在特殊地区工后沉降的预测研究

南方地区由于特殊地理环境影响,使得高速铁路建设中的软土地基工后沉降问题显得非常突出。通过对双曲线模型和指数曲线模型进行对比,发现双曲线模型能较好的预测软土地基工后沉降。应用该方法预测了南方某高速铁路工程中软土地基工后沉降,并对其进行了检验。结果表明,双曲线法预测高速铁路软土地基工后沉降数据利用率高、偶然性小、误差低、可靠度高、计算简便,能较准确的预测特殊地理环境下地基工后沉降。