饱和块状混合回填土地基的一维固结分析

用块状渣土置换软弱地基和回填低洼谷地等是处置工程渣土的有效途径。为了分析饱和块状混合回填土地基的固结性状，运用混合物理论建立了其一维固结模型。首先，假定块状土固相和充填土固相之间满足等应变条件，获得了饱和块状混合回填土中各相应变与块状土孔隙变形和充填土孔隙变形的关系式。其次，在小应变条件下，根据自由能势函数方程建立了饱和块状混合回填土的一维线弹性本构方程，再结合达西定律和应力平衡方程获得了一维固结控制方程。再次，利用分离变量法得到一维固结解析解，通过退化本文模型与已有模型进行对比，验证了本文模型的正确性。最后，基于所得解析解，分析了充填土孔隙渗透系数、块状土孔隙渗透系数以及流体交换参数等因素对饱和块状混合回填土地基固结性状的影响。分析结果表明：充填土孔隙渗透系数对饱和块状混合回填土地基整体固结性状起主导作用；在固结初期，块状土超孔压会有一定程度的上升，且3个参数具有相似的作用机理。     

Effect of the particle size ratio on macro- and mesoscopic shear characteristics of the geogrid-reinforced rubber and sand mixture interface

As a new type of material for civil engineering projects, the rubber and sand mixture is widely used in roadbed fillers, offering environmental benefits over traditional tyre disposal methods. This study uses a large-scale direct shear apparatus to examine the interface shear properties of the geogrid-reinforced rubber and sand mixture, considering different particle size ratios (r), rubber contents, and normal stresses. Based on indoor tests, direct shear models of the mixture with different values of r are established in PFC^3D, revealing the meso-mechanical mechanism of the mixture in the direct shear process. The results show that when r is greater than 1, incorporating a certain amount of rubber particles can increase the shear strength of the mixture. The r values of 15.78, 7.63, and 3.98 correspond to an optimal rubber content of 30%, 10%, and 20%, respectively. When r is less than 1, mixing rubber particles can only reduce the shear strength of the mixture. When the rubber content is low, the smaller the value of r, the greater is the thickness of the shear band. Furthermore, the normal and tangential contact forces are greater. The fabric anisotropy evolution law of the mixture is consistent with the change in the contact force distribution.     

飞灰固结体在沥青混合料中应用研究

通过对新型固结剂固化飞灰生成的固结体研磨成微粉全部或部分替代矿粉作为沥青混合料进行试验探究。试验结果表明,当微粉替代矿粉时,混合料的物理性能、水稳定性及高温稳定性得到了提高,确定了微粉替代矿粉最佳替代率。微粉在沥青混合料中重金属的存在状态采用多级提取的方法进行分析,试验结果进一步证明了微粉中重金属在沥青混合料中的长期稳定性。为焚烧垃圾飞灰固化稳定化和资源化利用提供了一定的理论指导。     

Case history on failure of a 67 M tall reinforced soil slope

Construction of this 67 m high RSS was completed in December 2006. After seven years in-service, a tension crack was observed at the top of the slope. In March 2015 this RSS structure catastrophically collapsed. This RSS structure collapsed in a compound failure mode; as the failure plane passed beneath, partially behind, and partially through the reinforced soil mass. The failure plane beneath the RSS was along a shale-claystone interface. The failure surface partially behind the RSS was along sandstone bedrock with water-seeping bedding planes dipping out of the rock mass. The failure surface through the upper portion of the RSS is where the geogrid reinforcement was overwhelmed by stresses originating from underlying deformation. The RSS collapse occurred after 8.3 years in-service as the shear strength along the shale-claystone interface decreased and approached the fully softened strength. The primary causative factors of this failure are: (i) an insufficient subsurface investigation program and interpretation of data for design and detailing; (ii) insufficient specifications and construction plan details for both foundation preparation and rock backcut benching; (iii) insufficient foundation preparation and rock backcut benching during construction; and (iv) adaptations to the design made during construction.     

一种外LET柔顺半铰的动力学建模与分析

对一种外LET柔顺半铰进行建模与动力学特性分析。采用斜率不连续的绝对节点坐标法（ANCF）建立了该柔顺半铰系统动力学方程；对外力作用下半铰中心线和外轮廓的运动变形进行仿真，与实验结果对比，证明了绝对节点坐标法对柔顺半铰动力学建模的有效性；进一步分析了半铰外形尺寸变化对其变形规律的影响。     

Comprehensive analysis on anomalous phenomenon of ethanol-soluble poly(vinyl butyral) membrane for ethanol recovery via pervaporation

Poly(vinyl butyral) (PVB) is selected as a promising ethanol-permselective membrane based on the solubility parameter theory; however, it exhibits anomalous water perm-selectivity in practical pervaporation (PV) process. Comprehensive analysis based on experimental and theoretical methods were carried out to explore the inherent mechanism of the anomalous performance. Firstly, sum frequency generation vibrational spectra and contact angle were developed to quantify the surface reconstruction of membrane in air and ethanol, which indicated that hydrophilic hydroxyl tended to expose on membrane surface with ethanol thus improving the membrane affinity to water. Meanwhile, swelling behaviors proved more water would accumulate in the ethanol swollen membrane. Furthermore, theoretical analysis in terms of sorption and diffusion process, based on the UNIFAC-FV model and Fujita free-volume theory, confirmed the mechanism of anomalous phenomenon of PVB membrane. The comprehensive investigation was expected to provide insights into the basic separation mechanism of PV process.     

Bench-scale bubbling fluidized bed systems around the world - Bed agglomeration and collapse: A comprehensive review

Thermochemical conversion by gasification process is one of the most relevant technologies for energy recovery from solid fuel, with an energy conversion efficiency better than other alternatives like combustion and pyrolysis. Nevertheless, the most common technology used in the last decades for thermochemical conversion of solid fuel through gasification process, such as coal, agriculture residues or biomass residues are the fluidized bed or bubbling fluidized bed system. For these gasification technologies, an inert bed material is fed into reactor to improve the homogenization of the particles mixture and increase the heat transfer between solid fuel particles and the bed material. The fluidized bed reactors usually operate at isothermal bed temperatures in the range of 700–1000 °C, providing a suitable contact between solid and gas phases. In this way, chemical reactions with high conversion yield, as well as an intense circulation and mixing of the solid particles are encouraged. Moreover, a high gasification temperature favours carbon conversion efficiency, increasing the syngas production and energy performance of the gasifier. However, the risk of eutectic mixtures formation and its subsequent melting process are increased, and hence the probability of bed agglomeration and the system collapse could be increased, mainly when alkali and alkaline earth metals-rich biomasses are considered. Generally, bed agglomeration occurs when biomass-derived ash reacts with bed material, and the lower melting temperature of ash components promotes the formation of highly viscous layers, which encourages the progressive agglomerates creation, and consequently, the bed collapse and system de-fluidization. Taking into account the relevance of this topic to ensure the normal gasification process operating, this paper provides several aspects about bed agglomeration, mostly for biomass gasification systems. In this way, chemistry and mechanism of bed agglomeration, as well as, some methods for in-situ detection and prediction of the bed agglomeration phenomenon are reviewed and discussed.     

基于声发射和高斯混合模型的灰岩破裂特征识别研究

通过单轴压缩条件下灰岩破裂过程的声发射试验研究,利用高斯混合模型(GMM)对加载过程声发射信号波形特征进行深入分析,探索性识别灰岩破裂失稳过程的裂纹模式及其前兆特征。分析结果表明,灰岩在单轴加载过程中先后主要存在张拉和剪切两种破裂模式。其中,张拉破裂的声发射信号波形特征在AF-RA坐标空间呈现低A_F值、高R_A值分布;剪切破裂的声发射信号波形特征在AF-RA坐标空间呈现低R_A值、高A_F值,且随着应力的增加分布中心向A_F轴靠拢。GMM分析结果揭示了灰岩在整个应力加载过程中以张拉裂纹为主,在加载前中期几乎全为张拉裂纹,临近破坏阶段过渡到剪切破坏为主。剪切裂纹所占比例的最大值出现在(0.8～0.9)σ_c阶段,也是AF-RA坐标轴分布呈现最大A_F值时。研究结果可为预测早期灰岩破裂失稳提供参考,同时为深入研究识别岩石破裂失稳前兆信号特征提供了一种分析方法。     

高低孔爆破处理高陡边坡的技术分析

针对前期规划不当,大宝山露天矿877 m平台高陡边坡局部存在难以采用预裂爆破技术进行处理的情况,决定采用高低孔爆破处理技术。为了解决这一难题,首先分析了高低孔的相对内涵,并对高低孔孔深计算公式进行了简单推导,然后通过公式计算得到了高低孔的孔深。在施工阶段,为了确保低孔的实施效果,两排低孔分区域使用同段别毫秒延时雷管,晚于高孔起爆。实践表明,处理后的平台平整度良好,坡面较为稳定,对高陡边坡采用高低孔爆破处理具有可行性,效果较好,可为类似边坡处理提供新思路。