关于JG／T193—2006（《钠基膨润土防水毯》有关问题的讨论

对建材行业标准JG／T193—2006《钠基膨润土防水毯》中有关膨润土的诸如标准的制定、标准的命名、膨润土吸蓝量、钠基膨润土、人工钠基膨润土的变质以及膨润土的耐久性等一些有争议的问题进行了讨论,并就有关膨润土防水毯国家标准的编制提出了一些建议。     

钠基膨润土粉在地下混凝土建筑物防水中的应用

本文主要阐述钠基膨润土粉的防水机理、模型试验和工程应用实例。并提出采用钠基膨润土粉作防水层的施工方法．     

钠基膨润土放水毯及地下工程防火技术规范有关膨润土条款中的若干问题探讨

本文以工程防水失败的实例,阐述了行业标准JG／T193-2006、国家标准GB50108-2008中有关膨润土的错误规定和地下防水工程及河湖防渗工程必须用天然钠基膨润土而不允许用人工钠化膨润土的理由,并提供了区分天然钠基膨润土和人工钠化膨润土的方法,同时也找出了我国富有丰富天然钠基膨润土的实证。     

膨润土系列防水材料

以国内钠基膨润土为原料,选择合适的匹配材料和添加剂加工制作的膨润土防水板、膨润土胶泥和膨润土止水条,是防水材料中的新品种.该系列材料具有遇水膨胀、以水止水的特点,而且使用寿命长、有自封功能,施工方便,是适合我国国情的有良好前景的防水新材料。     

钠基膨润土防水毯在国贸三期地下工程中的应用

介绍了钠基膨润土防水毯在北京国贸三期地下防水工程中的施工工艺,并对工程各构造部位的防水设计方案及质量监控要点作了阐述。     

《钠基膨润土防水毯》行标开始实施

按照建设部第508号公告的要求，2007年3月1日起《钠基膨润土防水毯》行业产品标准正式实施，《钠基膨润土防水毯》为建筑工业行业产品标准，编号为JG，T193—2006。     

天然钠基膨润土干法提纯研究

通过中试和1:1工业试验对天然钠基膨润土原矿进行干法提纯.确定了最佳工艺生产条件.试验证明,提纯后产品的性能较原矿有较大的提高,各项指标可达到膨润土防水毯产品原料的标准要求.     

关于膨润土防水毯防渗性能及稳定性的影响因素分析

总结了钠基膨润土防水毯（GCL）的防渗机理,从膨润土质量特性、渗透液水质、干湿循环、冻融循环等方面对GCL防渗性能及服务期稳定性的影响因素进行了论述,希望对改善防水毯性能研究提供参考。     

膨润土防水毯在水利工程中的应用

介绍了钠基膨润土防水毯的优点,通过水利工程中底部防渗处理对钠基膨润土防水毯应用的工程总结,提出了对水利工程中钠基膨润土防水毯施工的几点建议。     

膨润土在污染场地土壤修复和地下水污染防治中的应用

针对土壤污染严重、治污费用高昂等问题,本文提出应首选国内外普遍采用的膨润土和天然钠基膨润土防水毯隔绝污染源,防止水土污染进一步扩大,并就该技术的机理做了简要介绍.     

Empfehlungen des Arbeitskreises 6.1 “Geotechnik der Deponiebauwerke” der Deutschen Gesellschaft für Geotechnik e., V. (DGGT)

Recommendations of the DGGT Committee “Geotechnics of Landfill Structures”. The Committee “Geotechnics of Landfill Structures” published up to now 76 recommendations. The series is continued by the fundamentally revised recommendation E2‐36 “Capping Systems with Geosynthetic Clay Liners”, published in 2001 as first edition. Recent results of research as well as experiences of practicing engineers with planning, construction and monitoring of such liners are considered in this new edition.     

Experimental investigation of the effect of airgaps in preventing desiccation of bentonite in geosynthetic clay liners exposed to high temperatures

This paper investigates whether the introduction of an airgap above a composite liner made of a geomembrane (GMB) and a Geosynthetic Clay Liner (GCL) can decrease thermal loads on the GCL, reduce the risk of bentonite desiccation and/or help maintain its low hydraulic conductivity. A composite liner, subject to 20?kPa overburden load, over a well graded sand was subjected to a thermal gradient. In addition, to the reference base case in which no airgap was present, two designs included air gaps through the placement of a 10?mm and 20?mm-thick geocomposites (GC) on top of the GCL-GMB, respectively.Temperatures on top of the GCLs were found to be significantly reduced by the presence of air gaps, relative to the reference base case. All three designs resulted in GCL desiccation cracks at the end of the tests, due to the relatively high temperature gradients and low water retention of the subsoil, even in the presence of air gaps. However, X-Ray imaging revealed that crack patterns in bentonite samples from designs with air gaps were finer and narrower. Subsequent rehydration (and permeation tests) with distilled water indicated that significant self-healing of bentonite was in evidence in all three cases. However, while in the absence of an air gap the saturated hydraulic conductivity was found to be 2.8 times its pre-heating value, no significant increase was recorded for other two cases. X-Ray imaging of rehydrated samples confirmed that more effective healing had occurred in samples with an air gap.     

Bentonite transformations in strongly alkaline solutions

Strongly alkaline solution pH causes changes to the mineralogy of bentonites which might impact on their performance as environmental barriers. The long term effect of solution pH on the performance of bentonite barriers such as in Geosynthetic Clay Liners needs to be studied from the viewpoint of solubility and stability of the mineral phases present at extreme pH values. Changes to bentonite mineralogy brought about by extended reaction with 1 M sodium hydroxide solutions at 20–25 °C reveal that certain components of bentonites, namely smectite, opaline silica and quartz, are subject to dissolution in alkaline solution. Associated with dissolution is the formation of hydrous hydroxy-aluminosilicate as well as hydrous carbonate mineral phases. It is postulated that these precipitates, formed from reaction of bentonite with alkaline leachates can result in pore filling, which is responsible for recently measured lower hydraulic conductivity of some bentonites to high pH leachates.     

A comparative assessment of volatile organic compound (VOC) sorption to various types of potential GCL bentonites

The potential improvement in the sorption of volatile organic compounds (VOCs) to bentonite used in Geosynthetic Clay Liners (GCLs) is examined for mixtures of bentonite and several organoclays or activated carbon. Results of batch tests performed with dichloromethane (DCM), 1,2-dichloroethane (1,2-DCA), trichloroethylene (TCE), benzene and toluene are reported. It is shown that all organoclays could potentially increase VOC sorption to GCLs by several orders of magnitude but activated carbon generally appears to provide the most improvement for the samples tested. The engineering relevance of this potential improvement is assessed with respect to design of municipal solid waste landfill liner systems by performing contaminant transport modeling. It is shown that only slight changes in contaminant migration will occur, despite the large potential increases in GCL sorption. This suggests that increased costs associated with modifying GCLs may outweigh the benefit of such additives to GCLs for municipal solid waste landfill applications for the conditions examined herein.     

Feedback and guidelines for geomembrane lining systems of mountain reservoirs in France

Mountain reservoirs are hydraulic structures in mountains, used in ski resorts to store water, generally for producing artificial snow; there are about 120 of them in France. Despite their modest volumes (5000-400,000 m³) and dam heights of between 5 and 20 m, these structures do induce potentially high risks, due to their location in mountain at altitudes of between 1200 and 3000 m. These reservoirs are very often made watertight artificially by geomembrane. A survey conducted on about 70 of these reservoirs provided considerable information on their pathologies, incidents and even accidents and served as a basis for writing a set of guidelines for studying, designing, constructing, monitoring and rehabilitating. The paper is divided into two parts; the first based on an analysis of the 32 best documented structures is a feedback of water-tightness quality of Geosynthetic Liner Systems (GLS) at high altitudes; the second based on the guidelines above-mentioned, concerns the construction choices and behaviour of GLS at high altitudes. In particular, the guide advises using a cover layer in most cases to protect the geomembrane, and paying particular attention to the support layers and to drainage under the geomembrane.     

Modified stress and temperature-controlled direct shear apparatus on soil-geosynthetics interfaces

In this paper, a bespoke stress and temperature controlled direct shear apparatus to test soil-geosynthetics interfaces is introduced. By adopting the apparatus, a series of ‘rapid loading’ shear tests and creep tests were conducted on the Clay – Geosynthetic Drainage layer (GDL) interfaces to assess the functionality of the apparatus. The experimental results indicate that, the modified apparatus can allow the shear deformation behaviour of soil-geosynthetics interfaces under environmental stress during thermal and drying-wetting cycles to be investigated, with a reliable performance. The resistance of Clay-GDL interfaces to shear deformation under the rapid loading of shear stress decreases after drying-wetting cycle and at elevated temperature. In the creep tests, the interfaces subjected to drying-wetting cycles and thermal cycles fail under a lower shear stress level than that of the interfaces without experiencing drying-wetting cycles and thermal cycles, respectively. The impacts of drying cycles on the horizontal displacement is significantly larger than that of wetting cycles. The first drying cycle has the largest impacts on the horizontal displacement than those of the following drying cycles. The impacts of drying alone on the horizontal displacement of Clay-GDL interfaces during drying cycles are small, and the main influence factor is the elevated temperature.     

高速列车荷载下桩承加筋路堤荷载传递机制数值分析

桩承加筋路堤是近来发展起来的软土地基处理技术,具有用桩数量少、节约工程成本、加快工程进度的优点。采用有限元方法研究高速列车荷载下桩承加筋路堤的应力变化规律,分析路堤各部分应力随软土的变形模量、桩弹性模量、格栅弹性模量和桩间距的变化规律。结果表明:上述4个因素对桩中应力、土中应力、桩土应力比、格栅拉应力都有一定的影响。     

The role of geosynthetics in erosion and sediment control: An overview

The use of geosynthetic erosion and sediment materials continues to expand at a rapid pace. From their early beginnings in the late 1950s, geosynthetic materials today are the backbone of the erosion and sediment control industry. Geosynthetic components are an integral part of erosion and sediment materials ranging from temporary products such as hydraulic mulch geofibers, plastic erosion control meshes and nettings, erosion control blankets and silt fences to high performance turf reinforcement mats, geocellular confinement systems, erosion control geotextiles and fabric formed revetments. This paper provides a brief overview of these materials and concepts.