CMK复合微粉对盐渍土物理力学性能的影响

以山西运城南部地区盐渍土为研究对象,采用煤系偏高岭土(coal metakaolin,CMK)、矿粉(mineral powder,MP)及水泥(ordinary portland cement,OPC)作为多元复合改良微粉,针对不同养护龄期下改良盐渍土的无侧限抗压强度试验、渗透试验、固结结构物含量试验及扫描电镜(scanning electron microscope,SEM),探讨不同CMK复合微粉掺量对盐渍土物理力学性能的影响规律及作用机理。研究结果表明:低掺量(质量分数)煤系偏高岭土-矿粉-水泥复合胶凝材料可以显著提高盐渍土的无侧限抗压强度,且随龄期延长呈不断提高趋势,其中掺加2%CMK,6%MP,2%OPC时效果最优。固结结构物含量可以作为一项综合指标,反映盐渍土性能,其与无侧限抗压强度和渗透系数可建立良好的线性相关关系。SEM试验表明,盐渍土改良后,其微观结构得到改善,缺陷率降低,更为致密。

疏松砂岩储层物性参数敏感性物理模拟实验

利用物理模拟技术制作了一组微弱胶结、非固结高孔隙度人造样本。疏松砂岩储层物性参数的敏感性实验结果表明,与致密砂岩相比,疏松砂岩的弹性波速度对孔隙度的依赖性较弱,胶结物的性质对疏松砂岩岩石物理特性有重要影响。在纯砂岩中加入粘土或少量的粒间胶结物,会使弹性波速发生明显的变化;胶结温度影响岩样抗压强度。温度过低,会使胶结程度不够,固结强度较低;温度过高,岩样将变得松散。

高速铁路盐渍土路基填料复掺改良试验研究

利用复掺水泥+S95级矿粉+煤系偏高岭土(CMK)方式对取自包银铁路的盐渍土进行改良试验,结果表明:掺入CMK能明显改善土体结构,增强密实度和稳定性,提高强度和抗渗性能,固结物含量、强度随CMK掺量增加呈先增大后减小变化特征,渗透系数随CMK掺量增加呈先减小后增大变化特征;随着CMK掺量提升,最优含水率逐渐增大,土体内部的孔隙水含量增加,土体的导电性随之增大,电阻率随着CMK掺量增加而减小;盐渍土∶水泥∶S95级矿粉∶CMK=90∶2∶6∶2为最佳的路基改良处治方案,其固结物含量最高,强度可提高数倍,抗渗性提升一个数量级以上,电阻率提升2.8~3.3倍。

Study on Soil Microbiotic Crust and Its Influences on Sand-fixing Vegetation in Arid Desert Region

Based on secular fixed_site data in the artificial sand_fixing vegetation district at the southeast fringe of the Tengger Desert, the formative characteristics of soil microbiotic crusts and its influences on vegetation dynamics were analyzed. Once sand barrier and artificial vegetation have stabilized the surface of the sifting sand, could form aeolian deposition crust and then evolve into algae_dominated crust. Such processes result from the interactions of physical effects of atmospheric dust and silt deposition on sand surface, sinking and raindrop impact, and soil microorganism activities. Under the condition of less than 200 mm precipitation, the presence of microbiotic crust changes the soil hydraulic conductivity, alters the temporal and spatial distribution of the limited precipitation in sand layer and leads to the decline of deep_rooted shrubs. The development of microbiotic crust and subsurface soil affects the plant growth and seed rain distribution, as a result, the diversity of plant species gradually tend to become saturated and finally affects the vegetation stability.

一种聚醚多元醇及其制备的聚氨酯防水灌浆料研究

以环氧乙烷、环氧丙烷为原料,在催化剂(KOH、NaOH、Na或NaH中的一种)与定量的起始剂(二乙二醇、丙三醇、季戊四醇、山梨醇等中的一种或几种)作用下,合成了一种聚醚多元醇以及由其制备的聚氨酯防水灌浆材料。实验结果表明:所合成的聚醚多元醇具有高活性和较高的储存稳定性,用其制备的聚氨酯防水灌浆材料异氰酸酯指数优选0.5~3.0;以三乙醇胺作交联剂,选用羟值为325~425mg/g的聚醚多元醇,所得灌浆材料遇水反应快,形成的固结物强度高,与基材的黏结力强,适应各种不同条件下的防水堵漏要求。

Relationship Between 2:1 Mineral Structure and the Fixation and Release of Cations

The effects of different structures of 2:1 layer minerals, layer charge location, and changes of structure and charge during the weathering process on the fixation and release of interlayer cations are reviewed. It could be concluded that the fixation capacity is determined by the total amount of interlayer charge originating from both octahedral and tetrahedral sheets. The relationship between interlayer cation fixation and octahedral structure of the secondary minerals may be different from that of the primary minerals. The oxidation and reduction of cations with variable valence can greatly influence the cation-fixation capacity.

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of Such crystals as SiO2, CaSO4 and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.

Sediment consolidation settlement of Chengbei Sea area in the northern Huanghe River subaqueous delta,China

One of the most important factors controlling the morphology of the modem Huanghe （Yellow） River delta is consolidation settlement, which is impacted by fast deposition, high water content, and low density of seafloor sediment. Consolidation settlement of the Huanghe River subaqueous delta was studied based on field data, laboratory experiments on 12 drill holes, and the one-dimensional consolidation theory. Results show that vertical sediment characteristics varied greatly in the rapidly forming sedimentary bodies of the modem Huanghe River subaqueous delta. Sediments in the upper parts of drill holes were coarser than those in the deeper parts, and other physical and mechanical properties changed accordingly. On the basis of the one-dimensional consolidation theory and drilling depth, the final consolidation settlement of drill holes was between 0.6 m and 2.8 m, and the mean settlement of unit depth was at 1.5-3.5 cm/m. It takes about 15-20 years for the consolidation degree to reach 90% and the average sedimentation rate within the overlying 50 m strata was at 5 cm/a to 12 cm/a. This study helps to forecast the final consolidation settlement and settlement rate of the modem Huanghe River subaqueous delta, which provides key geotechnical information for marine engineers.

Gastrointestinal migrating motor complex during early stage of cholesterol gallstone formation in guinea pigs

Objective： To determine the changes of gastrointestinal migrating motor complex （MMC） during the early stage of cholesterol gallstone formation. Methods：Totally 45 healthy adult guinea pigs were randomly and equally divided into 3 groups, that is, normal control, group B （1% cholesterol diet for 2 weeks） and group C （1% cholesterol diet for 4 weeks）. Three pairs of silver electrodes were inserted into the gastric antrum, duodenum and jejunum of every animal respectively. Record of gastrointestinal MMC of these guinea pigs were recorded and analyzed. Gallbladder bile was taken to detect the formation of cholesterol gallstone. Results： There were only 29 guinea pigs living. The MMC cycle time and the duration of phase Ⅱ were prolonged significantly and gradually compared with the control group （P〈0.01）, but the duration of phase Ⅲ became significantly and gradually shorter. Conclusion： During the early stage of cholesterol gallstone formation, the MMC cycle time and the duration of phase Ⅱ are prolonged and the duration of phase Ⅲ is shortened.

Design and fabrication of a large-scale oedometer

The most common apparatus used to investigate the load-deformation parameters of homogeneous fine-grained soils is a Casagrande-type oedometer. A typical Casagrande oedometer cell has an internal diameter of 76 mm and a height of 19 mm.However, the dimensions of this kind of apparatus do not meet the requirements of some civil engineering applications like studying load-deformation characteristics of specimens with large-diameter particles such as granular materials or municipal solid waste materials. Therefore, it is decided to design and develop a large-scale oedometer with an internal diameter of 490 mm. The new apparatus provides the possibility to evaluate the load-deformation characteristics of soil specimens with different diameter to height ratios. The designed apparatus is able to measure the coefficient of lateral earth pressure at rest. The details and capabilities of the developed oedometer are provided and discussed. To study the performance and efficiency, a number of consolidation tests were performed on Firoozkoh No. 161 sand using the newly developed large scale oedometer made and also the 50 mm diameter Casagrande oedometer. Benchmark test results show that measured consolidation parameters by large scale oedometer are comparable to values measured by Casagrande type oedometer.

Characterization of semi-coke generated by coal-based direct reduction process of siderite

Solid wastes derived from metallurgical industries pose a significant threat to environment. The utilization and disposal of these solid wastes are the major concern in the world. Semi-coke generated in coal-based direct reduction process of iron ore is a by-product and its suitable utilization is not available so far. In order to handle it properly, the characteristics of this by-product were comprehensively investigated. A series of analysis methods were used to demonstrate its mineral compositions, petrography and physico-chemical properties. The results reveal that the semi-coke has poor washability. The fixed carbon content of semi-coke reaches 76.11% and the gross calorific value is 28.10 MJ/kg, both of which are similar to those of traditional sinter coke breeze. Also, semi-coke ash possesses lower content of SiO2, Al2O3, S and higher content of CaO and MgO, which could improve the strength of sinter ore when partially substituting for coke breeze in sintering. Semi-coke features well-development porous structure and higher reaction activity, which predicts that the sintering speed could be elevated to some extent when employing it as a partial replacement of coke breeze, so the studies further suggest that the potential adverse effect of the high reactivity on sintering process could be weakened by adequately coarsening the semi-coke's particle size.

Analysis of 13Cr bloom solidification structure using CA-FE model

Solidification structure is critical in the control of the mechanical properties and quality during the continuous casting process. The thermo-physical properties of 13 Cr steel added some rare metals, such as Mo, V, Nb, are measured to better understand the solidification structure of 13 Cr bloom. A computational model using CA-FE(cellular automation-finite element) method coupled with heat transfer model is developed to describe the solidification structure in continuous casting process. It is found that the calculated solidification structure is in good agreement with the observed data. The influence of casting speed and superheat on the solidification structure of the bloom is studied in detail. In order to obtain more equiaxed crystal ratio and low degree of the segregation in the bloom, the optimized casting speed 0.6 m/min and superheat less than 25 °C are determined for the caster. Using the optimized manufacturing parameters, these samples are 60% with the equiaxed zone ratio of 8%–10% and below the degree of segregation 1.05.

Studying on the increasing temperature in IT-SOFC:Effect of heat sources

The dimensions and the materials type limit the performance of fuel cell. The increase of the temperature in electrodes and electrolyte of the cell,is due to the over potential of activation (transfer of load),the over potential Ohmic (resistance of polarization),the over potential of reaction (heat released by the chemical reaction) and the over potential of diffusion. In this paper,we studied the thermo-electrical performance of an intermediate temperature solid oxide fuel cell (IT-SOFC) with electrode supported. The aim of this work is to study this increasing temperature of a single cell of an IT-SOFC under the influence of the following parameters: heat sources,functioning temperature and voltages of the cell,geometric configuration and materials type. The equation of energy in one dimension is numerically resolved by using the method of finite volumes. A computing program (FORTRAN) is developed locally for this purpose in order to obtain fields of temperature in every element of the cell.

Band Structure： A Solid-State Physics Model with Cosmological Implications

This work is aimed at showing that the ＂band structure＂ of the energy distribution in solids which is a well-known model for electronic engineers and solid-state physics scientists is an efficacious description also for phenomena not tied to energy neither related to microcosm. In particular, it is displayed that how the elements of the consolidated physical theories, arranged together using the ＂band structure＂, lead to a model for the distribution of speed in the universe that is essentially analogous to the distribution of energy in solids. The description is accompanied by references to the experimental data that sustain it, together with an overview of the possible development opportunities.

Impact of ultrasonic power on liquid fraction,microstructure and physical characteristics of A356 alloy molded through cooling slope

This study involves A356 alloy molded through ultrasonically vibrated cooling slope.The slope alongside ultrasonic power enables indispensable shear for engendering slurry from which the semisolid cast/heat treated billets got produced.An examination demonstrates ultrasonically vibrated cooling slope influencing the liquid fraction/microstructure/physical characteristics of stated billets.The investigation encompasses five diverse ultrasonic powers(0,75,150,200,250 W).The ultrasonic power of 150 W delivers finest/rounded microstructure with enhanced physical characteristics.Microstructural modifications reason physical transformations because of grain refinement and grain boundary/Hall-Petch strengthening.A smaller grain size reasons a higher strength/shape factor and an increased homogeneity reasons a higher ductility.Microstructural characteristics get improved by reheating.It is owing to coalescence throughout temperature homogenization.The physical characteristics is improved by reheating because of a reduced porosity and enhanced dissolution besides augmented homogeneity.A direct comparison remains impossible owing to unavailability of researches on ultrasonically vibrated cooling slope.

Applications of Glass and Glass Fiber Retrofit Polymer in Modern Footbridges

The architecture of footbridge design takes the form of a number of submissions from leading architects and engineers, each setting out their views on bridge design--present and future. It looks at the functions of a bridge, defining purpose of place and context, the spirit of creativity and the reasoned progression of an idea. It also explores the exploitation of materials technology and construction innovation and the tension between lightness and mass and between sculpture and scale. Present parameters of tempered and laminated glass create possibility of modern architecture of footbridges which are being full of transparency and light reflex effects. Four projects, using glass panels designed by Santiago Calatrava, have been presented in this paper. GFRP （glass fiber retrofit polymer） makes new horizon in material technology, helps to enrich new conception of structure with longer durability, low weight of deck and new creation of architecture line. The paper has described a few results of FEM （finite element method） analysis of footbridge with modular bridge GFRP deck system. The footbridge was excited by impact and human-induced vibrations. Composite material consists of glass fibers and polymer matrix is a promising alternative against traditional materials. New architecture and modern material engineering are looking for fresh possibilities of form and shape of structure, long durability and extraordinary technical parameters of building elements.

Discussion on the Effects of Temperature, Carbon Fiber and Silica

Concrete, as an essential construction material in the construction industry, is the main component of solid waste. To improve the strength and durability of concrete, some additives can be added into concrete to replace parts of cement. Carbon fiber and silica powder are the most common additives. Under a series of experiments, the effects of temperature, carbon fiber and silica powder on the mechanical properties of concrete were studied under normal circumstances. In this paper, a conclusion on the effects was drawn up mainly through some experimental analyses, so as to discuss the effect laws and provide a reference to manufacture the concrete of high strength and properties.

Ornaments as Means of Efficient Reinforcement in Heritage Buildings

Heritage consists of those items people have inherited and want to keep, as they give them the sense of the past of their cultural identity, but these items, especially the buildings, could not face deteriorations during their period of life, such as the change of loads, the act of the environmental conditions, the effect of the duration time of the materials and the misuse of the occupants. They need special treatments and reinforcements to keep the structural state or to gain extra forces to receive the new loads. But the traditional ways of reinforcement do not prove endless solutions as the most means of the deteriorations from the nature. So, the liability issue is how to find the least reinforcement within the means of technology with the least deterioration and in a less time or by other ways efficiently. The hypothesis considers that the ornaments in some heritage buildings are found in critical levels of the construction which can share in an efficient way in the reinforcement processes of such buildings.

Process structuring of polymers by solid phase orientation processing

Solid phase orientation of polymers is one of the most successful routes to enhancement of polymer properties.It unlocks the potential of molecular orientation for the achievement of a range of enhanced physical properties.We provide here an overview of techniques developed in our laboratories for structuring polymers by solid phase orientation processing routes,with a particular focus on die drawing,which have allowed control of significant enhancements of a single property or combinations of properties,including Young's modulus,strength,and density.These have led to notable commercial exploitations,and examples of load bearing low density materials and shape memory materials are discussed.

Majorana zero mode in the vortex of an artificial topological superconductor

Majorana fermion （MF）, an exotic particle that is identical to its own antiparticle, was recently found in solid matter as a quasiparticle excitation, the Majorana zero mode （MZM）, in the vortex of an artificial topological superconductor （TSC）. This artificial TSC, first proposed by Fu and Kane in 2008, is a heterostructure made of a topological insulator BiETe3 and an s-wave superconductor NbSe2. This paper will briefly review the experimental progresses based on the Bi2Te3/NbSe2 heterostructure. All evidences are self-consistent and reveal that the MZM exists in the center of vortex. Those experimental results are also supported by theory. This finding is a milestone in the research ofMajorana fermions in solid state physics and a starting point of MZM＇s application in topological quantum computation.