Strip loading test theory and equipment development

One of the important issues for geotechnical engineers is the characterization of soil properties such as cohesion and internal friction angle by means of soil testing. A new experimental method of soil characterization based on the surface displacement of strip loaded soils is proposed. The theory to relate the soil deformation/displacement to soil strength properties is presented and compared with a series of conventional soil characterization techniques with direct shear tests. The proposed/developed strip loading tests provide reasonably accurate results compared with traditional direct shear tests. The new strip loading physical simulation and testing devices are helpful for understanding soil strength concepts and also provide an effective bridge connecting with engineering mechanics and foundation engineering courses instructions wherein derivation of bearing capacity theory equations is based on the same MohrCoulomb soil strength parameters. The advantages, limitations, and use of the strip loading modeling/testing technique in engineering education and further more in depth researches are discussed in the concluding remarks part.

EXACT SOLUTION FOR A TWO-DIMENSIONAL LAMB'S PROBLEM DUE TO A STRIP IMPULSE LOADING

By applying the integral transform method and the inverse transformation technique based upon the two types of integration, the present paper has successfully obtained an exact algebraic solution for a two-dimensional Lamb＇s problem due to a strip impulse loading for the first time. With the algebraic result, the excitation and propagation processes of stress waves, including the longitudinal wave, the transverse wave, and Rayleigh-wave, are discussed in detail. A few new conclusions have been drawn from currently available integral results or computational results.

Prediction of Rolling Load in Hot Strip Mill byInnovations Feedback Neural Networks

Because the structure of the classical mathematical model of rolling load is simple, even with the self-adapting technology, it is difficult to accommodate the increasing dimensional accuracy. Motivated by this fact, an Innovations Feedback Neural Networks （IFNN） was presented based on the idea of Kalman prediction. The neural networks used the Back Propagation （BP） algorithm and applied it to the prediction of rolling load in hot strip mill. The theoretical results and the off-line simulation show that the prediction capability of IFNN is better than that of normal BP networks, namely, for the prediction of the rolling load in hot strip mill, the prediction precision of IFNN is higher than that of normal BP networks. Finally, a relative complete rolling load prediction system was developed on Windows 2003/XP platform using the OOP programming method and the SQL server2000 database. With this sys- tem, the rolling load of a 1700 strip mill was calculated, and the prediction results obtained correspond well with the field data. It shows that IFNN is valid for rolling load prediction.

Studies of Heterogeneous Hydrothermal Stripping from Iron-loaded Naphthenic Acid-Alcohol-Kerosen

The technique of hydrothermal stripping from mixed aqueous-organic systems is a promising method for synthesizing oxide ceramic powders for high-performance applications. Some factors influencing heterogeneous hydrothermal stripping with water from iron-loaded organic phase of naphthenic acidisooctyl alcoholkerosene, such as initial concentrations of iron and naphthenic acid, concentration of Fe2O3 搒eed, temperature and time, were investigated. Based on the experimental results, the rate equation was established. Nano-ferric oxide powders were obtained by the technique of hydrothermal stripping from the iron-loaded organic phase. The results suggest that the heterogeneous hydrothermal stripping proceeds in 3 steps: adsorption of naphthenic acid dimers and naphthenic complex of iron onto the surface of seed? hydrolysis of adsorbed complex of iron, and condensation of hydrolyzed complex. The process activation energy is 115 kJ/mol and the heterogeneous hydrothermal stripping is controlled by a chemical reaction (the hydrolysis of naphthenic complex of iron).

Effect of Load Distribution on Strip Crown in Hot Strip Rolling

In order to establish precision model, a software to calculate the strip crown of four-high hot rolling mill was developedby using affecting function method according to the strip crown calculation theory. The effect of work roll diameter,unit width rolling load, roll bending force, work roll crown, initial strip crown and reduction, etc, on load distributioneffect rate was simulated by using the software. The results show that the load distribution effect rate increaseswith the increase of strip width, work roll diameter, unit width rolling load, roll bending force, work roll crown,initial strip crown and reduction. Based on the simulation results, base value of load distribution effect rate andfitting coefficients of six power polynomial of load distribution effect rate modification coefficient were determinedconsidering all of the above parameters. A simplified mathematical model for calculating load distribution effect ratewas established.

SELF-ALIGNING EVEN LOAD MECHANISM OF MULTI-ROW BEARINGS OF LARGE STRIP ROLLING MILL

The load distribution of multi-row bearings of large strip rolling mill is fully analyzed by 3D contact boundary element method （BEM）. It is found out that bearings are frequently worn out due to serious uneven load on the multi-row rollers. The constraint mechanism of the previous rolling system is found to be unreasonable by theoretical analysis on heavy machinery structure. A mechanism of self-aligning even load for workroll bearing of 2 050 mm hot rolling mill of Baoshan I＆S Co. is developed. This device is manufactured with particular regard to the structure of 2 050 mm hot rolling mill mentioned above. Hence, uneven load on multi-row bearings is greatly relieved and their lives are remarkably prolonged. Meanwhile, theoretical analysis and on-spot tests prove the rationality and validity of the device.

On-line control of surface quality for an axially moving steel strip partially immersed in fluid under tension

An on-line control method of surface quality for continuous hot-dip galvanized steel strip after cooling is presented, which combines analytical dynamics theory of a thin plate with the finite element method. The inherent characteristics of the non-immersed and partially immersed strip in liquid zinc were calculated on the basis of theoretical analysis and numerical simulation, respectively. Multi-parameter fitting of the deviation between results using different methods was performed. To optimize the strip excitation frequency away from the resonance region, on-line vibration control of the strip near the air knife under full product conditions was achieved by changing the field production parameters based on the field test results. The results indicate that although the axial velocity has little effect on the inherent characteristics of the strip compared with other manufacturing parameters such as the steel specifications and tension, it induces external excitations,including moving the aerodynamic load and bearing vibration. To some degree, the vibration near the air knife can be reduced by strengthening the support stiffness of the contact rolls. A total on-line control program of surface quality for continuous hot-dip galvanized pure Zn and galvannealed steel sheet in the cooling section is proposed.

冲击力下薄壁内衬复合管界面黏结强度效应分析

【目的】研究薄壁内衬复合管在受冲击力作用下的界面黏结强度对层间剥离屈曲的影响。【方法】建立薄壁内衬复合管在弹性阶段的非线性分析模型,对薄壁内衬复合管材模态试验与分析模型的分析结果进行对比,验证有限元分析模型可靠性。通过改变衬层与原基层管壁间的界面黏结强度,研究复合管在冲击力下的动态特征。【结果】研究结果表明,当冲击荷载较小、管道变形处于弹性阶段时,薄壁内衬复合管的损伤大都集中在层间界面处。界面黏结强度对层间剥离屈曲有较大的影响,随着层间界面黏结强度的增加,外基层管与内衬层的最大等效应力差值减少。此外,外基层管和内衬层的变形协调性能力随着黏结强度增加而增大,径向层间位移减小,增加了复合管的整体性和连续性。【结论】研究结果可为薄壁内衬修复管道设计方法及层间界面效应分析提供参考。

地震与墙顶荷载作用下加筋桥台稳定性极限分析

与传统桥台相比,加筋桥台结构轻便、造价经济、抗震性能优越,然而国内规范缺少针对地震与墙顶荷载共同作用下加筋桥台稳定性的计算方法。基于极限分析上限定理,本文对地震与墙顶荷载同时作用下整体式面板加筋桥台的安全系数进行计算分析,研究地震加速度系数、筋材强度与间距、墙顶荷载等因素对加筋桥台稳定性的影响。结果表明:墙顶荷载作用下,水平地震加速度系数由0增大到0.4时,安全系数降低约10%。竖向地震惯性力向下时安全系数小于向上时的安全系数;安全系数随筋材竖向间距的增大而减小,当筋材竖向间距小于墙高的5%时减小趋势明显;当筋材长度超过墙高的70%后,长度对安全系数的影响减弱,仅当筋材设计强度超过20 kN/m、筋材竖向间距小于0.2 m时安全系数出现增大趋势;安全系数随墙顶荷载的增大呈倒V形分布,当墙顶荷载为2倍墙体自重时安全系数取得最大值。

竹条铺设间距不同的敷面墙板竖向承载力试验

以方木为骨架、正交斜放竹条敷面制成的竹木墙板,其竖向承载力与敷面竹条铺设间距密切相关,在确保竹条敷面墙板满足承载要求的同时,兼顾经济性的竹条铺设间距问题值得探究。本工作设计制作了四组敷面竹条间距不同的竹木墙板试件,通过开展墙板竖向承载力试验,对比分析各墙板的破坏特征与极限承载能力等关键指标,并结合试验荷载-位移曲线和荷载-应变曲线,得出最佳竹条铺设间距。试验结果表明:竹条间距为10 mm与20 mm的墙板均具有较高承载力且二者极限承载能力相当(最大值偏差仅为2.2%),同时,两组墙板中敷面竹条性能发挥也体现出较小差别。因此,在考虑极限承载能力相同的情况下,选择竹条间距为20 mm的墙板在实际应用中可更好地兼顾实用性与经济效益。

长条形件杂货集装箱化的智慧分拣系统设计与管理研究

以具备标准化运输的长条形件杂货为研究对象,参考标准40英尺集装箱以及现有件杂货装卸设备的尺寸结构,设计从存储到装卸分拣的智能设备和一体化系统。通过数值计算、应用CAD构图和三维模型对智慧分拣系统进行结构分析,并配合作业流程标准化设计,提出可适用于长条形件杂货集装箱化的智慧分拣系统实现方案。仿真模拟的结果表明,长条形件杂货集装箱化后箱体立体化堆叠效果可将土地利用率提高1.6~2.4倍,构建的智慧分拣系统能够减少5倍的人力需求并提高近2.4倍的装卸效率。智慧分拣系统的设计打破人工作业能力限制,满足高峰生产作业时段对效率的需求,也为件杂货智慧港口的发展提供了参考方向。

某MPV前门区域风噪啸叫与密封优化分析

为解决某MPV前门区域发生“呜呜”风噪啸叫问题,路试验证密封条、车门、A柱区域密封系统,采用格子波尔兹曼方法模拟风洞仿真分析A柱、侧窗区域流场。结果表明,车门侧密封条和A柱钣金空腔的气流从密封条唇边泄露,与A柱区域的涡流形成耦合振动,产生啸叫。啸叫问题与车门侧密封条、车门以及A柱造型有关。更改车门侧密封条外唇边根部材料,提高压缩负荷,并在与A柱接角处增加两个凸筋,进一步试验验证,啸叫消失,问题得到解决。

不同结构气化炉激冷室气液两相流的数值模拟

针对目前工业用激冷室存在的粗合成气洗涤效果不佳、破泡器堵渣等问题,提出了改变液池直径与下降管直径之比、在床层内减少破泡条、调整单层破泡条节距等调整方案,基于双流体模型和群平衡模型对含破泡条的激冷室进行了三维CFD模拟,比较了70%、100%、110%负荷下的液相含率、速度分布、湍动能分布、涡分布、气泡直径分布等,结果表明:调整后激冷室中的气泡直径更小,洗涤效果更好,气液两相传质传热更加充分,且能适应不同负荷工况。

气肋式充气膜结构风荷载作用下结构特性分析及模型试验

气肋式充气膜结构具有轻质、可移动、施工方便等优点,在临时会馆、机库等方面得到了广泛的应用。首先对气肋式充气膜结构的结构形式进行综述分析;随后以索笼绑带型气肋式充气膜结构为研究对象,建立共节点模型分析气肋直径、箍带数、内压对结构风荷载效应的影响,同时,通过在模型中删除索段的方法明确了各类索段的作用;最后进行了气肋加载试验,将试验结果和有限元计算结果进行了对比分析。

潮汐效应对沿海多条带时序InSAR地表形变监测的影响

潮汐效应对沿海大范围、高精度的合成孔径雷达干涉测量(Interferometric Synthetic Aperture Radar,InSAR)技术地表形变监测的影响不可忽略.潮汐效应中的固体潮(Solid Earth Tide,SET)位移和海洋潮汐负荷(Ocean Tide Loading,OTL)位移会在时间和空间域上对沿海大范围InSAR地表形变监测产生分米级的误差,而且不同条带中地表潮汐形变时空差异性会对多条带InSAR影像拼接产生较大误差.本文针对沿海地区多条带InSAR形变时序,重点分析了潮汐效应在不同条带InSAR地表沉降监测中的影响,并采用多种潮汐位移估计方法对多条带地表潮汐形变进行改正.结果表明,研究区域不同条带时序InSAR中地表潮汐形变具有较大的时空差异性,其造成沿海地区相邻条带时序InSAR地表沉降速率差异能达到1~2 cm·a^(-1);通过固体潮模型、海潮负荷模型或GPS参考站网海潮位移改正,能够消除不同条带中地表潮汐形变时空差异性对时序InSAR形变结果拼接产生的空间高阶非线性误差,弥补了传统拼接方法在拟合潮汐位移偏差的不足.在大气延迟误差改正的基础上,时序InSAR形变残差的标准差(Standard Deviation,STD)由潮汐改正前的2.3 cm减少至0.75 cm;本文研究揭示了沿海地表潮汐形变改正对多条带时序InSAR形变结果拼接的重要性,可大幅提高沿海地区广域时序InSAR地表形变监测的精度.

基于改进斑点鬣狗算法的热轧带钢负荷分配智能优化

针对热连轧过程中由于负荷分配不均匀导致板形控制效果不佳的问题,以传统的轧制机理为基础建立负荷分配均匀、板形良好的目标函数,分别采用斑点鬣狗算法和改进斑点鬣狗算法进行单目标和双目标的负荷分配的优化求解。结果表明,改进斑点鬣狗算法将末机架的相对凸度差从0.000 834 5降低到0.000 014 83和-0.000 026 34,且在允许的范围内,上游机架负荷分配合理,充分发挥了轧机的轧制能力。

复杂条件下重载钢便桥设计与施工技术分析

施工便桥是一种为工程施工和运输需要而修建的临时性桥梁。结合嘉松公路越江新建工程施工进场道路受阻的实际情况,经方案比选采用型钢便桥,以保证施工所需材料构件及设备顺利进场。阐述了复杂施工条件下施工便桥方案的选取原则,介绍了便桥的设计思路及施工要点。

K_(0)≠1时条形基础地基临塑荷载公式

目前土力学教材中给出的条形基础临塑荷载公式都是假定侧压力系数K_(0)=1,其计算结果偏大。已有文献在推导K_(0)≠1的临塑荷载公式时,由于近似计算或假定不合理,导致给出的公式不准确。本文首先沿基底附加应力产生的地基中主应力方向建立局部直角坐标系,得到K_(0)≠1时地基中一点的应力表达式;再通过误差分析,确定出主应力开平方近似计算式中系数的合理取值;然后根据塑性区开展深度为0,得到局部坐标系与竖向的夹角;最后将应力表达式代入Coulomb准则,利用开平方近似计算式、三角函数级数展开式,通过求导得到临塑荷载公式。算例表明:对于通常情况下的条形基础,K_(0)≠1时地基土自重应力引起的主应力轴偏转角度较小,采用土力学教材中公式计算临塑荷载误差在10%以内,采用本文提出的公式计算临塑荷载,可以保证误差小于1.0%。

轮胎裂解油加氢装置主汽提塔的操作优化分析

设定初始操作条件,对轮胎裂解油加氢装置主汽提塔进行物料衡算,并讨论混合低分油温度、进料位置、汽提蒸汽用量和塔顶操作压力对主汽提塔脱硫效果和冷却器热负荷的影响。结果表明,混合低分油温度、进料位置、汽提蒸汽用量和塔顶操作压力分别设定为230℃、第8块板、60 kg/h和0.8 MPa较为合理,在该条件下,塔底流出物中硫化氢质量分数和冷却器热负荷分别为6.2μg/g和1479.1 kW。

装饰条干扰下超高层建筑表面风压系数及风荷载体型系数研究

为解决因幕墙装饰条对超高层建筑外表面风压分布造成干扰使其分布不均衡导致的装饰条掉落问题,基于Davenport脉动风速功率谱及拟合函数、LES湍流模型和《建筑结构荷载规范》(GB 50009—2012)的推荐计算公式,利用计算流体动力学方法对装配不同型号装饰条的超高层建筑进行三维风场流体模拟。研究了超高层建筑及装饰条自身表面的风压分布特征和装饰条风荷载体型系数随其横截面体型特征及布置间距变化的规律。结果表明:超高层建筑外表面平直区域风压极值增高,拐角过渡区域风压极值降低,配置装饰条能够改善建筑表面拐角区域风压突变现象;当装饰条横截面为矩形时,其正侧表面的风荷载体型系数随截面高度增大而增大,横截面为梯形时,其侧表面的风荷载体型系数随下底的减小而减小,风荷载体型系数随装饰条间距变化的趋势不明显。