采动与承压水耦合作用下煤层底板的 力学效应及破坏机理分析

应用三维弹性中厚板理论,分析了采动与承压水耦合作用下煤层底板的力学效应及破坏机理。基于Hamilton原理推导了采空区底板在采动和水压耦合作用下的变形和应力表达式,分析了其变形和应力的分布特征。最后,推导了在采动与承压水耦合作用下煤层底板破坏极限载荷PS,讨论了影响煤层底板破坏极限载荷PS的因素。研究成果对揭示回采工作面开采时煤层底板隔水层变形破坏,预防煤层底板突水提供了理论依据。     

不同推进速度下煤岩体采动力学行为响应特征与控制

为获得不同推进速度下煤岩体的采动力学行为特征,通过轴压和围压分别模拟不同推进速度下垂直应力、水平应力,采用增轴压降围压的方式模拟煤岩体的采动力学行为,同时采用数值模拟和工程实践相结合的方法对不同推进速度下煤岩体的采动力学行为进行研究。结果表明:在围压卸载速率相同的条件下,随着轴压加载速率（推进速度）的增加,煤体的峰值强度、轴向应变和横向应变呈增大趋势,在峰值阶段产生了较大的轴向应变和横向应变,呈现出一定的延性,破坏形式具有塑性特征;在轴向加载和围压卸载的综合作用下,煤体体积一直处于膨胀变形状态,围压的卸载加速了煤体损伤破坏的进程,煤体破坏时的峰值应力和体积扩容受控于围压卸载的程度,控制轴压加载速率和围压卸载程度可控制煤体破坏时的峰值应力和体积变形。生产实践中,应结合煤岩体的采动力学行为特征,确定合理的推进速度并加以控制,以保证回采巷道与采场围岩的稳定性。     

Lignin-based Carbon Fibers: Effect of Synthetic Polymer Blending on Fiber Properties

Carbon fibers have been produced from hardwood lignin/synthetic polymer blend fibers. Hardwood kraft lignin was thermally blended with two recyclable polymers, poly(ethylene terephthalate) (PET) and polypropylene (PP). Both systems were easily spun into fibers. A thermostabilization step was utilized prior to carbonization to prevent fusion of individual fibers. For the lignin-based carbon fibers, careful control of heating rate was required. However, PET–lignin blend fibers can be thermostabilized under higher heating rates than the corresponding homofibers. Carbon fiber yield decreased with increasing incorporation of synthetic plastic. However, carbon fiber yield obtained for a 25% plastic blend fiber was still higher than that generally reported for petroleum pitch. Blend composition also affected surface morphology of the carbon fibers. Immiscible lignin–PP fibers resulted in a hollow and/or porous carbon fiber; whereas carbon fiber produced from miscible lignin–PET fibers have a smooth surface. Synthetic polymer blending also affected the mechanical properties of the fibers, especially MOE; lignin-based carbon fiber properties improved upon blending with PET.     

Biobased Epoxy/Layered Silicate Nanocomposites: Thermophysical Properties and Fracture Behavior Evaluation

The biobased epoxy containing epoxidized linseed oil (ELO) and its clay nanocomposites were processed with an anhydride curing agent. The certain amount of diglycidyl ether of bisphenol F (DGEBF) was replaced by ELO. The selection of the DGEBF, ELO, an anhydride curing agent, and organo-montmorillonite clay resulted in an excellent combination, to provide new biobased epoxy/clay nanocomposites showing high elastic modulus, high glass transition temperature, and high fracture toughness with larger amount of ELO. Izod impact strength was almost constant while changing the amount of ELO. This is a promising result for future applications in different engineering industries.     

Properties of Starch/PVA Blend Films Containing Citric Acid as Additive

Starch/polyvinyl alcohol (PVA) blend films were prepared successfully by using starch, polyvinyl alcohol (PVA), glycerol (GL) sorbitol (SO) and citric acid (CA) for the mixing process. The influence of mixing time, additional materials and drying temperature of films on the properties of the films was investigated. With increase in mixing time, the tensile strength (TS), elongation (%E), degree of swelling (DS) and solubility (S) of the film were equilibrated. The equilibrium for TS, %E, DS and S value was 20.12 MPa, 36.98%, 2.4 and 0.19, respectively. The mixing time of equilibrium was 50 min. TS, %E, DS and S of starch/PVA blend film were examined adding glycerol (GL), sorbitol (SO) and citric acid (CA) as additives. At all measurement results, except for DS, the film adding CA was better than GL or SO because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA and additives. Citric acid improves the properties of starch/PVA blend film compared to glycerol and sobitol. When the film was dried at low temperature, the properties of the films were clearly improved because the hydrogen bonding was activated at low temperature.     

尾矿坝的液化判别研究

概述尾矿坝液化试验判别的一般步骤,即根据《建筑抗震设计规范》中的初判条件对尾矿坝土层进行初判,在尾矿坝土层不满足初判的条件下,利用标准贯入试验对尾矿坝是否存在液化危害进行复判。影响尾矿料液化的因素很多,现有的液化判别方法过于繁琐,在综合考虑希德简化法和《构筑物抗震设计规范》提出的简化法的基础上,提出了一种主要考虑地震震级以及尾矿料的中值粒径、相对密度、静应力和尾矿料物理力学指标影响因素,并将其他影响因素综合为一个影响因素的简化判别法。以某个进行了标准贯入试验的尾矿坝为工程实例,采用简化判别法对该尾矿坝进行理论分析计算,并对试验和计算结果进行比较,得出理论分析结果与试验结果一致,表明该方法切实可行,可供类似工程参考。     

建筑物最佳机械排烟量的研究

基于工程性能的防排烟设计,最佳机械排烟量的确定是个关键性的问题。在分析火灾中烟流性状的基础上,给出了火灾安全疏散判别依据,从烟控系统性能化设计的角度提出了最佳机械排烟量的基本思想,并利用实例进行了验证。计算结果表明:综合了安全性和经济性的最佳排烟量定义是正确的,该建筑物的最佳机械排烟量为72m3/(h.m2)。研究成果对建筑物防排烟系统的性能化设计具有重要参考价值。     

中国废旧家电处理技术的现状与对策研究

家用电器的更新换代使得废旧家电的资源化利用问题日益突出,不合理处置和回收会给环境造成极大污染。因此,广泛开展废旧电器回收利用方面的研究,使这些宝贵的二次资源得到科学合理的资源化和无害化处置,对保证人类所需生产和生活资源的永续利用,促进人类的可持续发展具有十分重要的意义。介绍了中国废旧家电年废弃量及回收利用价值,总结了处理废旧家电的基本技术特点及中国处置技术方面存在的问题。在此基础上,对中国废旧家电回收处理工艺提出建议和对策。     

防护性有机涂层失效研究的发展趋势

结合目前国内外防护性有机涂层失效研究现状,总结了该领域在环境因素的协同作用,力学因素对涂层耐久性的影响,综合评价涂层防护性能的表征方法和预测涂层失效的数学模型等方面的若干新进展。扼要叙述了该领域当前的主要研究需求,提出了针对未来研究工作的若干建议,包括应更重视环境因素之间的相互作用,通过叠加不同环境因素的加速模拟试验研究环境因素在涂层失效中的协同效应。研究不同形式、不同大小的载荷对涂层失效机理的影响,研究力学因素、老化因素和腐蚀过程在涂层失效中的交互作用。利用涂层防护性能物理、化学参数的测量结果建立预测涂层防护性能下降的数学模型,以实现涂层性能评价和涂层寿命预测。     

垃圾焚烧发电厂机械通风冷却塔噪声治理技术研究

针对城市典型垃圾焚烧发电厂机械通风冷却塔的噪声污染问题,采用现场实际测量方法分析了冷却塔的主要噪声源和频谱特性,研究了冷却塔的淋水噪声、风机、电机噪声的治理技术方案。淋水噪声的治理包括塔内降噪与塔外声波阻隔两条途径,塔内治理采用落水消能降噪导流装置,塔外治理采用交错式吸声隔声屏衰减技术。风机和电机噪声的治理分别采取双层微穿孔板消声器和复合式百叶隔声屏法。结果表明,该方案的淋水噪声塔内降噪、塔外声波阻隔、风机及电机噪声的噪声削减量分别为6.1、16.2、15~18、14.6dB,冷却塔整体噪声削减量为15.1~16.1dB,治理效果良好。