A study on the efficiency of a capped hardening elasto-plastic model for soft clays

It is well known that the deformation and stress-resistant characteristics of fine-grained soils, especially soft clays, are significantly influenced by the soil softness. It is therefore very important to employ a model which can accurately simulate the effects of this phenomenon. A constitutive model must be able to create a balance among stress paths, the number of parameters, the process of parameter determination, and finally, the simplicity of the computational calculations.The current study investigates the performance of a two-yield surface (cone and cap yield surface) model for soft soils. The efficiency of the cap yield surface has been studied as well. The model has been calibrated by employing the data derived from previous researches for Bangkok clay. The incorporated data have been obtained from the results of CD triaxial, CU triaxial, and oedometer tests. The proposed method for the model calibration can accurately predict the triaxial test results and oedometer test stress path simultaneously. This method for predicting the soil behavior is based on the main soil characteristics taken from common soil mechanics tests. It can be widely employed for engineering practices, especially when complicated soil behavior is encountered.     

含高承压水黄土层中注浆堵水的理论与实践

在高承压水黄土层中掘井筒，使用冷冻法似乎又成了工程定例，但其高昂的施工费用常令建设者望而却步。而运用廉价的普通注浆的方法进行堵水能保证井筒安然通过，国内外鲜有成功 例。     

4A分子筛合成研究

本实验主要以化学原料、高岭土和凹凸棒石粘土为原料,通过酸化,碱化,成胶,晶化这一工艺过程,利用传统水热法成功合成了4A分子筛,并通过微波法进行对比。实验过程使用光学显徽镜进行观察;产品通过X射线粉末衍射、NEXUS670型傅里叶红外光谱仪进行了表征。结果表明,传统水热法与微波法均能合成出4A分子筛,并且微波法合成出的样品粒度小且均匀,合成时间大幅减少,降低了能耗。     

镁钙炭砖在LF-VD精炼炉渣线部位的试用

天津钢管公司150tLF－VD精炼炉渣线部位成功地试用了不烧镁钙炭砖,平均寿命达20炉。实现了与炉身铝镁炭砖同步,解决了几年来使用镁炭砖必须拆砌一次渣线砖的问题,大大降低了耐火材料消耗和费用,提高了精炼炉作业率。     

Thermal,mechanical, and corrosion resistance properties of vinyl ester/clay nanocomposites for the matrix of carbon fiber‐reinforced composites exposed to electron beam

Vinyl ester/clay nanocomposites with 1, 3, and 5% nanoclay contents were prepared. X‐ray diffractography patterns and Scanning Electron micrographs showed that nanocomposites with the exfoliated structure were formed. Thermogravimetric analysis, water absorption test, and Tafel polarization method, respectively, revealed the improvements in thermal resistance, water barrier properties, and corrosion resistance properties of the samples with an increase in the amount of the incorporated nanoclay. Tensile tests showed that nanoclay also enhanced the mechanical properties of the polymer, so that the tensile strength of the samples with 5% nanoclay was more than 3 times higher than tensile strength of pure vinyl ester samples. Overall, the best properties were observed for the samples containing 5% nanoclay. Pure vinyl ester and nanocomposite with 5% nanoclay content were exposed to the electron beam radiation and their mechanical properties improved up to 500 kGy irradiation dose. Finally, pure vinyl ester and vinyl ester/nanoclay (5%) matrixes were reinforced with carbon fiber and the effect of electron beam irradiation on their mechanical properties was examined. The tensile strength and the modulus of the samples initially increased after exposure to the radiation doses up to 500 kGy and then a decrease was observed as the irradiation dose rose to 1000 kGy. Moreover, nanoclay moderated the effect of the irradiation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42393.     

Composition and microstructure of a periclase–composite spinel brick used in the burning zone of a cement rotary kiln

The composition and microstructure of a periclase–composite spinel brick used in the burning zone of a cement rotary kiln were investigated and compared to the original brick. The results indicate that cement clinker and alkali salts are two important agents that cause corrosion especially of the bonding phase of refractories in cement rotary kilns. When the molar ratio of alkalis to anions ((Na+K)/(Cl+2S)) is more than one, alkali salts accumulated in the pores, cracks and grain boundaries of the refractory but the severe corrosion of the bonding phase of the refractory did not occur in zones with lower temperatures. The interaction between the cement clinker and the refractory formed a liquid, which, together with alkali salts, improved sintering. The reaction between the cement clinker and the refractory formed a dense reaction layer. Cracks formed in the dense layer and extended through the boundary between the reaction and non-reaction (penetrated) layers by mechanical and thermal stress, which caused the spalling of the reaction and coating layer from the refractory. The recurrence of this process during service leads to degradation of the refractory.     

软粘土中单桩承载力时间效应的研究

采用静力触探资料估算单桩竖向承载力的方法经大量的工程实践证明是行之有效的 ,它可以充分发挥地基土的潜力 ,节省工程投资。但对于某些处于深厚软粘土中的桩 ,按规范规定的休止时间进行试桩时 ,实测的单桩极限承载力有时与理论计算结果相去甚远 ,本文结合具体工程实例详细说明了在工程中遇到此类问题的几种的处理措施 ,提出了此类地层中确定单桩竖向承载力的一些建议。     

胶体级凹凸棒石粘土的生产工艺研究

在总结了胶体级凹凸棒石粘土的生产技术基础上 ,结合实际提出了两种干法加工工艺 ,给出了工艺参数 ,并对添加Mg(OH) 2 或MgO以及挤压提高凹凸棒石粘土造浆性能的机理作出了分析。     

湘南地区高液限红粘土土性指标概率统计分析

基于厦成高速公路湖南郴州段高液限红粘土土工实验数据, 采用数理统计分析理论, 计算了高速公路沿线高液限红粘土抗剪强度、天然含水率、天然密度等指标的变异系数、峰度、偏度、置信区间和标准值等概率特征值, 得出湘南地区高液限红粘土液限、孔隙比、塑性指数的置信区间分别为64.2~67.0、1.09~1.14、32.9～35.3。建立了各物理力学指标之间的相关性经验公式。研究结果可为湘南地区红粘土路基的设计、施工提供有益参考。     

Clay Bodies: Crafting the Future with 3D Printing

People have been using clay to make objects and shelters since time immemorial; but could it also be a key material of the future? San Francisco-based xyqmake-tank’ Emerging Objects has been experimenting with the use of clay in 3D printing, with sophisticated codes producing woven and textured forms and mixing different clays together. The studio's cofounders Ronald Rael and Virginia San Fratello here present these projects, as well as offering a potted history of clay's use and nature. Given its re-resistance and thermal qualities, the benefits of eventually applying such techniques on an architectural scale are clear.