浅析土体抗剪强度的影响因素

在建筑工程中,土体的抗剪强度是评价建筑地基稳定性与承载力等土的主要力学性质指标。文章以直接剪切试验为例,综合分析影响土体抗剪强度试验的因素,以期通过对土体抗剪强度试验方法的改进,达到提高试验结果准确性的目的。     

水泥颗粒粒度分布分形维与其胶砂抗压强度的关系研究

为研究水泥颗粒粒度分布分形维与其胶砂抗压强度的关系,利用粒度分布分形维的计算模型分析了有关文献报道的10种水泥颗粒粒度分布分形维值,结果表明:定量表征其分形特征的分形维值在2.325～2.435之间,各水泥颗粒粒度分布具有分形特征;分析了水泥颗粒粒度分布分形维值与水泥3d抗压强度、28d抗压强度的关系,分析表明:化学组成和矿物组成基本相同的条件下,水泥颗粒粒度分布分形维与水泥胶砂的3d、28d抗压强度具有较好的正线性相关关系。     

甘肃红层泥岩填料物理力学特性的试验研究

红层泥岩作为一种常见的特殊土路基填料,其物理力学性质在不同地域表现出显著的差异性.本文针对G6京藏高速公路兰海段路基填料红层泥岩土,通过土工试验(击实试验、界限含水率试验、固结试验)、X射线衍射、化学分析和电镜扫描试验、三轴压缩(UU)等试验,研究含水率、压实度等因素对红层泥岩物理力学特性的影响.研究结果表明:所有工况下的应力-应变曲线均为应变硬化型,当围压为50 kPa且小于最优含水率时的应力-应变曲线趋于平稳;压实度不变,随着含水率的增加,黏聚力和内摩擦角逐渐减小,二者均随含水率的增加呈非线性下降关系,且内摩擦角减小的幅度更大;含水率不变,随着压实度的增加,黏聚力急剧增加,与压实度呈二次多项式关系,而内摩擦角变化不大.     

磨细粉煤灰的活性与其粒度分布特征参数的关系

研究了粉煤灰在机械磨细过程中粒度分布的变化规律,分析了磨细灰的粒度分布特征对其活性的影响。结果表明,磨细灰的强度与粉煤灰的特征粒径De、分布宽度Nx之间具有很好的线性关系,其3d、28d抗压强度随着特征粒径变小、分布宽度变大而增大.     

飞灰沉积行为与粒度分布关系的研究

针对Shell煤气化装置合成气冷却器段出现的积灰与堵灰现象,选取Shell煤气化飞灰(SH)与电厂飞灰(DH),利用Shell煤气化冷态模拟装置采集沉积于器壁的飞灰样品,并采用激光粒度分析仪进行粒度分布的研究。结果表明:DH飞灰粒度大于SH飞灰,喷射时间相同时,DH飞灰沉积质量大于SH飞灰,且DH飞灰与SH飞灰分别在沉积30 s与60 s时D 50为最大值,其他喷射时间下D50相差不大,随着喷射时间的延长,DH飞灰颗粒(0～5μm)与SH飞灰颗粒(0～1μm)含量不断增多,DH飞灰颗粒(38～75μm)百分含量与SH飞灰颗粒(38～75μm)百分含量分别在沉积30 s与60 s时为最大值。     

大豆蛋白酶解产物的分子量分布与其发泡性能关系的研究

研究木瓜蛋白酶水解大豆蛋白所得到的酶解产物的分子量分布与其发泡性能的关系。酶解产物经过分离纯化,根据标准曲线的回归方程得到,大豆多肽的分子量分别为大于5000 Da和1148 Da、501 Da三个级分,其中第二个为主要成分。通过泡沫性能测试,结果表明,分子量在2000 Da以下的酶解产物的发泡性能最好,依次为分子量在3000~5000 Da之间的产物、2000~3000 Da之间的、5000~10000 Da之间的,分子量10000 Da以上的产物的发泡性能最差。     

水泥改性加筋土的筋-土界面剪切特性试验研究

为了研究水泥改性加筋土的筋-土界面抗剪强度特性,基于大型直剪试验获取了土工织物与水泥土界面的应力-应变曲线,并分析了水泥掺量对土工织物-水泥土界面强度的影响特点,同时结合SEM照片对加筋土的抗剪强度改性机理进行了初步探讨.结果 表明,水泥改性加筋土的筋-土界面应力-应变曲线都经过了线弹性、弹塑性和应力软化3个不同变形阶段,界面的剪应力与应变为应变软化关系;水泥掺量对加筋土强度有明显影响,筋-土界面的摩擦角、黏聚力均与水泥掺量成线性上升关系,且黏聚力受影响的程度明显更大;根据土工织物的破坏形式与SEM微观形态,发现土工织物内部纤维在剪切过程中受拉应力作用,在土工织物-水泥土界面起到阻止或减少水平位移的效果.     

基于掌子面岩体结构扫描的隧道岩体力学参数确定方法研究

由于岩体赋存环境的特殊性和复杂性,使得岩体具有明显的非均质、不连续及各向异性等特点,快速准确获取岩体力学参数对于岩土工程设计和施工意义重大。针对GSI围岩分级系统量化问题,以某隧道工程为背景,引入基于数码成像的掌子面地质特征信息系统,通过采集掌子面结构面信息数据,采用图像信息处理技术及掌子面图像网格划分法确定RQD值,并设计了相应的岩体力学参数计算流程,以快速确定不同围岩段的岩体力学参数;将新方法与BQ法、RMR法、费森科法、M.Georgi法进行对比分析,结果显示,新方法计算得到的岩体力学参数与BQ法相符、与RMR法等效、与费森科法和M.Georgi法较为接近。综合分析认为,采用新方法确定的岩体力学参数具有较高的准确性和合理性,可为快速获取岩体力学参数提供参考。     

HDPE树脂流变参数与分子量分布的关系研究

测定了4种高密度聚乙烯(HDPE)树脂的分子量及其分布,研究了其毛细管流变行为和动态流变行为,并分析了得到的流变参数和分子量分布的关系。结果表明:仅在较低挤出速度或较高温度条件下,用毛细管流变测得的非牛顿指数才能用作分子量分布的量度;用动态流变测得的剪切变稀指数、流变多分散指数、幂率指数均可在一定程度上反映了HDPE树脂分子量分布的大小,其中幂率指数与分子量分布的相关性最好(相关系数r2=0.994)。     

Study on relationship between mechanical properties and particle size distribution for polyhexamethylene carbonate diol toughened epoxy resin

The relationship between the mechanical properties and morphology of polyhexamethylene carbonate diol (PHMCD) toughened epoxy resin was investigated. The parameters describing the morphology (e.g., average diameter of particles and volume fraction of dispersed phase, etc.) were determined through SEM observation. It was observed that the particle size distribution changes from a unimodal distribution to a bimodal one and then tounimodal again with an increase in curing temperature. When it was cured at 120°C, an epoxy resin with a bimodal distribution of rubber particle size was obtained. The mechanical properties, especially the impacting strength, of the resin are the best because of the synergistic effect of the PHMCD particles. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 569–575, 1998     

掺煤矸石的水泥性能与颗粒群分布的关系研究

将不同细度的煤矸石、纯硅酸盐水泥分别按30％和70％的比例混合，测其胶砂流动度、净浆标准稠度用水量和3d、28d胶砂抗压强度。以宏观性能指标为z轴，水泥与煤矸石的中位径D50之差为x轴，水泥与煤矸石混合样的中位径D50为y轴，进行三维区域图分析。给出各项性能指标发展趋势与水泥、煤矸石的相对位置以及混合体系总体细度的相互关系。     

Clarifying the effects of comonomer distribution between short and long chains on physical and mechanical properties of ethylenic copolymers

In this paper, two Zigler-Natta catalysts (ZNCs) were used to synthesize a commercially available linear low-density polyethylene (LLDPE), widely used in the packaging industry, on an industrial scale. The catalysts differ only in their ability to distribute comonomers between short and long chains. Both catalysts were fully characterized in the first section, and two similar ethylene/1-butene copolymers were made using them. Afterward, the produced copolymers were fully characterized using different techniques; namely, differential scanning calorimetry (DSC), successive self-nucleation and annealing (SSA), oxygen induction time (OIT), melt flow index (MFI), rheometric mechanical spectroscopy (RMS), and a wide range of mechanical experiments. It was revealed that while the presence of comonomers in short chains can reduce their resistance against oxidation (by more than 30%) and can cause a dramatic change in friction coefficients (by more than 20%), some of the other main mechanical properties of the made copolymers were independent of comonomer distribution between long and short chains. In addition, it was shown that ethylenic copolymers' strain hardening modulus (SHM) takes advantage of the homogenous distribution.     

水泥粒度分布的分维评价研究

对比分析了7种水泥样品的粒度分布实测值与Fuller曲线计算值，结果表明：所研究的水泥样品中较细颗粒的含量与较粗颗粒的含量均偏少，而中间段颗粒的含量偏多；测算了水泥样品实测粒度分布分维与Fuller曲线计算粒度分布分维，将两者分维的差值作为表征水泥粒度分布偏离最佳粒度分布程度的参数。研究发现：7种水泥样品的粒度分布均偏离了最佳粒度分布，随着分维差值的减小，样品空隙率降低。     

Effect of a coupling agent on the electromagnetic and mechanical properties of carbon black/acrylonitrile–butadiene–styrene composites

Titanate coupling agent (TCA) is widely used as a plasticizer in filled polymer processes. In this study, the effect of TCA with different contents (2 and 10 wt %) on the electrical conductivity, wave absorption, and mechanical properties of carbon black (CB)/acrylonitrile–butadiene–styrene (ABS) composites were investigated. The results indicate that with the addition of 2 wt % TCA to the filled CB, the electrical conductivity of CB/ABS composites improved greatly, but its wave absorption performance was weakened. In contrast, the addition of 10 wt % TCA to the filled CB improved the microwave absorption performance of the CB/ABS composites but led to poor electrical conductivity. However, TCA, regardless of the contents of 2 or 10 wt %, greatly improved the mechanical properties of the composites. The probable reasons for this are discussed on the basis of the fracture morphology of the sample, a chemical band between the filling and resin, and the physical coating between the filling and TCA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1839–1843, 2006     

绿色阻垢剂聚环氧琥珀酸的合成与阻垢机理初探

以顺丁烯二酸酐为原料一步法合成了聚环氧琥珀酸（PESA）,并对产物进行了IR和¹³C NMR表征.分别采用粒径分布仪和电子显微镜考察了PESA对CaCO₃垢粒径及其垢形的影响,研究了CaCO₃成垢过程的动力学,探讨了PESA的阻垢机理.结果表明：PESA具有优良的阻垢性能,对CaCO₃垢既具有较强的分散作用又具有明显的晶格畸变能力.     

The effects of cast industry waste of scale instead of cement on the mechanical and microstructural properties

The scale is a waste coming from the metal casting industry. It is an iron oxide layer formed as a result of oxidation after annealing on steel surfaces. Casting wastes, which have been left uncontrolled for many years, have caused considerable environmental damage. In the present paper, the mechanical properties and microstructural characterization of cement mortars, prepared by using scale coming from Turkey steel manufacturer were experimentally investigated. The steel scale was used as a partial replacement of cement. Recycling of solid waste scale is considered as an environmental-friendly alternative to solve the problem of disposing of wastes. Cement mortar admixtures were prepared by variable percentages of scale from 2% to 10%. The effect of scale on the strength of cement mortar was analyzed. The compressive strength values of all the specimens were recorded for 3, 7, and 28 days and the results showed that when the amount of scale replacement was increased, the strength increased slightly. However, cement mortar containing 4% wt. additive has shown the highest strength value at 3 and 28 days. As a result an optimum additive amount of scale in the cement mortar is found as 4% wt. Microstructural observation of the samples using SEM showed that scale particles were well embedded in the c matrix.     

PTA粒度分布对其浆料性能的影响

浆料的稳定性和浆料性是影响聚酯产品质量的重要因素 ,PTA作为浆料的主要成份 ,又直接影响到浆料的性能。本文论述了平均粒径和粒度分布情况对浆料性能的影响     

煤矸石颗粒群分布与其水泥性能的关系

把对经过热激活处理的煤矸石试样按不同粉磨工艺处理成具有不同颗粒群分布的试样,用激光粒度仪对煤矸石粉体试样进行了颗粒群分布测试,并以Rosin-Rammler线性回归进行拟合。在均匀性系数n,特征粒径De与勃氏比表面积S三个颗粒群特征参量中,分别确定其一,变化其它参量进行煤矸石水泥胶砂宏观性能测试,以期考察煤矸石粉体颗粒群分布与其水泥性能的关系。     

聚氯乙烯糊树脂颗粒形态与增塑糊性能关系的研究

用激光散射法对聚氯乙烯糊树脂 (PPVC)浆料粒径及其分布和粉料颗粒粒径及其强度进行了测定和研究。结果表明 :初级粒子的粒径大小和分布是决定 PPVC树脂糊性能的关键因素 ;在一定范围内 (3 0～ 60μm) ,二次粒子颗粒强度即二次粒子的解碎程度是影响 PPVC树脂成糊性能的重要因素之一