抗旱保水剂膨润土-聚丙烯酸盐吸水树脂研究

利用丙烯酸盐在蒙脱石层间进行原位聚合，研究开发一种适用于农林业的抗旱保水剂。实验结果表明：聚合产物的综合性能较为理想，吸水树脂的保水作用主要体现在能够吸收大量的水，并且在压力下不脱水。     

Monitoring Large-Scale Tests for Nuclear Waste Disposal

Two large-scale “in situ” demonstration experiments and their instrumentation are described. The first test (FEBEX Experiment) involves the hydration of a compacted bentonite barrier under the combined effect of an inner source of heat and an outer water flow from the confining saturated granite rock. In the second case, the progressive de-saturation of Opalinus clay induced by maintained ventilation of an unlined tunnel is analyzed. The paper shows the performance of different sensors (capacitive cells, psychrometers, TDR’s) and a comparison of fill behaviour with modelling results. The long term performance of some instruments could also be evaluated specially in the case of FEBEX test. Capacitive sensors provide relative humidity data during long transient periods characterised by very large variations of suction within the bentonite.     

Mineralogy and chemistry of bentonite (?) deposits at Minjingu, Lake Manyara, North Tanzania

Olive green clays likely to be bentonitic in composition have been mineralogically and chemically studied. They occur in association with other lacustrine sediments at Lake Manyara. Radiocarbon dates from four diatom horizons indicate ages ranging from 12 Ka to 135 Ka suggesting a Mid-Holocene age. Middle Pleistocene age have been assigned to the ridged oncolites of Lake Manyara. The olive green coloured clays in the Manyara basin are known to occur in association with other lake beds including phosphorite deposits, stromatolites, bioturbated silty clays, partly silicified marls, conglomerates and olive green coloured opal beds. The results presented herein are from the olive green coloured clays. The olive green clays (bentonite?) are a result of devitrification or alteration of volcanic ashes and/or pyroclasts. The green clays occur in different forms as they are separated from each other by other lacustrine sediments. The alteration might have taken place in slightly different environments in terms of salinity and alkalinity. One of the top layer is friable and shows conchoidal fractures when dry. The other beds below in the lacustrine sequence are cemented with calcite and some dolomite as well as zeolites. The lowermost layer in the sequence is friable and shows cracks filled with coarse crystalline calcite. Mineralogically the bentonite is composed of the clay minerals illite, illite-smectite mixed layer clays, and chlorite. Other authigenic minerals include various zeolites (analcime, clinoptilolite, erionite and some traces of mordenite), opal, and fluorapatite. The clays have magnesium contents varying from 3.01% to 7.43%. The calcium contents vary widely due to presence or absence of one of the two minerals calcite or apatite. Trace elements like Ba, Ce, Sr, Zr are equally attributed to the presence of calcite and apatite. The formation of the illite-smectite mixed layer clays in an alternating manner with other lake sediments depicts different episodes of volcanic eruptions in the area. The mineralogical composition of smectites, zeolites, and opal in the green clays suggests a deposition of pyroclasts and volcanic ashes in a closed lake system with fluctuating levels. Due to evaporation alkalinity and salinity levels were fluctuating. The clays might have been bentonite which have undergone illitisation, a phenomena noted in other neighbouring rift basins.     

膨胀土与地形变

本文根据南京地震台短水准场地膨胀土研究的实际资料,指出了在膨胀土发育区进行地形变观测、地震地质和震害调查、烈度小区划等项工作时,必须考虑到膨胀土特性这个因素,以避免失误。     

Subterranean microorganisms and radioactive waste disposal in Sweden

In 1987, microbiology became a part of the Swedish scientific program for the safe disposal of high level nuclear waste (HLW). The goal of the microbiology program is to understand how subterranean microorganisms will interact with the performance of a future HLW repository. The Swedish research program on subterranean microbiology has mainly been performed at two sites in granitic rock aquifers at depths ranging from 70 m down to 1240 m, the Stripa research mine in the middle of Sweden and the Äspö Hard Rock Laboratory (HRL) situated on the south eastern coast of Sweden. Some work has also been performed in cooperation with other national or international research groups in Sweden, Canada and at the natural analogue sites Oklo in Gabon and Maqarin in Jordan. The following conclusions are drawn. There is a very high probability of the existence of a deep subterranean biosphere in granitic rock. The documented presence of a deep biosphere implies that relevant microbial reactions should be included in the performance assessment for a HLW repository. A HLW repository will be situated in a subterranean biosphere that is independent of solar energy and photosynthetically produced organic carbon. The ultimate limitation for an active microbial life will be the availability of hydrogen as energy source over time, and hydrogen has indeed been found in most deep groundwaters. Sulphide producing microorganisms are active in environments typical for a Swedish HLW repository, and the potential for microbial corrosion of the copper canisters must be considered. The bentonite buffer around the copper canisters will be a hostile environment for most microbes due to the combination of radiation, heat and low water availability. Discrete microbial species can cope with each of these constraints, and it is theoretically possible that sulphide producing microbes may be active inside a buffer, although the experiments conducted thus far have shown the opposite. Microorganisms have the capability to enzymatically recombine radiolysis oxidants formed by radiation of water. It has earlier been concluded that the migration of radionuclides due to sorption on microorganisms can be neglected. The influence of microbially produced complexing agents remains to be studied at realistic conditions in deep groundwater. Microorganisms have been found in natural alkaline groundwaters, but it could not be conclusively demonstrated that they were in situ viable and growing, rather than just transported there from neutral groundwater. A possible hypothesis based on the obtained results from investigations of natural alkaline groundwaters is that fresh concrete may be a bit too extreme for active life even for the most adaptable microbe – but this remains to be demonstrated.     

Utilizing Natural Liner Materials for Heavy Metal Removal in Simulated Landfill Conditions

Inorganic industrial waste landfills have the potential to contaminate subsurface groundwater supplies through migration of leachates down to the water table and into groundwater aquifers, despite the use of compacted low permeability clay or polyethene liners. This paper aims the removal of Cu²⁺ and Zn²⁺ in the leachate from an industrial waste landfill using natural materials (natural zeolite, expanded vermiculite, pumice, illite, kaolinite, and bentonite) as a liner material. Cu²⁺ and Zn²⁺ concentrations for all treatments decreased during the process. Of all the different natural materials, natural zeolite, expanded vermiculite and pumice, with bentonite, were effective in removing Cu²⁺ and Zn²⁺ present in the leachate. However, the use of illite and kaolinite with bentonite as liner materials could be of disadvantage in Cu²⁺ and Zn²⁺ removal from leachate. The adsorption kinetic models were also tested for the validity. The second order kinetics with the high correlation coefficients best described adsorption kinetic data.     

Simplified evaluation for swelling characteristics of bentonites

Bentonite is currently planned to be used as buffer and backfill materials for repositories of high-level nuclear waste because these materials must have the swelling characteristics to seal the waste. In the design for buffer and backfill materials, we must choose the adequate bentonite among many kinds of bentonite in the world. The database of the swelling characteristics of various bentonites and its evaluation will be available when we will select the adequate bentonite. For this purpose, this study performed the laboratory tests on the swelling pressure and swelling deformation of four kinds of bentonite produced in Japan and the United States. These bentonites have different physicochemical properties. This study investigated the characteristics of swelling pressure and swelling deformation from the viewpoint of the physicochemical properties of each bentonite. Furthermore, this study also proposed the simplified evaluation of swelling characteristics of various bentonites on the basis of microscopic analysis.     

Seepage and consolidation of bentonite saturated with pure- or salt-water by the method of unified molecular dynamics and homogenization analysis

Bentonite clay is a micro-inhomogeneous material, which consists of clay minerals (mainly montmorillonite), macro-grains (mainly quartz), water, air and others. Properties of the saturated bentonite clay are essentially characterized by the montmorillonite and water (i.e. montmorillonite hydrate). We analyze the molecular behavior of sodium montmorillonite hydrate Na_1/3Al₂[Si_11/3Al_1/3]O₁₀(OH)₂·nH₂O by applying a molecular dynamics (MD) simulation method. And by using the MD results we calculate the swelling property of the montmorillonite hydrate, and compare with an experimental result. Next, by using the same MD procedure we treat a montmorillonite mineral with a large number of external water molecules to check the properties of the water. Here we treat pure- and salt-water. Then we calculate the diffusivity and viscosity of water molecules and Na⁺ and Cl⁻ ions.

For extending the microscopic characteristics of constituent materials to a macroscopic seepage behavior of the micro-inhomogeneous material we apply a homogenization analysis (HA). That is, starting with the Navier–Stokes equation with distributed viscosity that is calculated by the former MD procedure we determine macroscopic permeability characteristics of bentonite for both cases of pure- and salt-water. Then, by using the permeability property we calculate long-term consolidation behavior of buffering clay, which is planed to be used for high-level radioactive waste (HLRW) management. Here the deformation is treated under the well-defined Cam clay model.     

句容甲山膨润土矿的地质特征和成因探讨

研究了句容甲山膨润土矿的矿床地质特征,发现地层上覆下白垩统碱性流纹岩,矿石呈黄绿色、粉红色、灰白色和肉红色等多种颜色,局部保留有原岩的角砾结构,并观察到含有风化残余的粗面岩团块和因断层滑移形成的断层角砾。X射线衍射（XRD）分析发现不同颜色矿石的矿物组成差异很大,通过扫描电子显微镜观察到岩石风化现象和伴生的次生矿物类型。研究表明,该矿属于火山熔岩风化残积型膨润土矿床,在开发过程中应进行分类开发或进行深加工处理,可提高开发效益。     

Design of bentonite/crushed rock seals

Summary The use of bentonite/crushed rock mixtures to form hydraulic barriers has greatly increased in recent years. To obtain an appropriate composition for such mixture sealants generally requires extensive laboratory work. Bentonite content and gradation of the crushed rock component are two key parameters in the seal design. This study investigates the effect of crushed rock gradation on the bulk porosity and permeability of systems of crushed tuff particles. Five different gradations are selected from the literature. The bulk porosity of systems of crushed tuff in the presence of bentonite is examined. The Fuller-Thompson gradations yield denser particle arrangements. For mixture samples containing 15% bentonite by weight, the amount of clay accounts for only 45 to 56% of the weight required to fill the interparticle pore space. The bentonite occupancy percentage amounts to 65 to 80% and 75 to 86.5% for samples having 25 and 35% bentonite by weight, respectively. The water content of bentonite at saturation is reduced and the resistance to piping and flow of bentonite is enhanced by the addition of clay. To reduce the bulk porosities of the mixtures containing 25% or more bentonite, a compaction energy higher than the standard Proctor compaction is necessary.