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影响斜坡地基上填方路堤极限承载力的因素主要有:斜坡坡度、路堤填土高度、路堤顶面宽度、路堤边坡坡度等。运用极限分析上限法对斜坡地基上不同斜坡坡度、不同填土高度、不同路堤宽度以及不同路堤边坡坡度的填方路堤极限承载力进行计算,得出了各个因素对其极限承载力的影响。研究结果表明路堤填筑高度和顶面宽度对其极限承载力的影响最大,其次为斜坡坡度的影响,而路堤边坡坡度对其影响并不显著。建议综合考虑斜坡坡度、填土高度、路堤宽度、路堤边坡坡度、极限承载力等各种因素来指导斜坡地基上填方路堤的设计与施工,以确保山区高速公路安全畅通。 相似文献
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针对半填半挖路基,建立非饱和土流固耦合有限元模型,进行雨水入渗条件下红粘土路基边坡渗流与沉降变形耦合的数值模拟,计算出降雨条件下路基含水率及孔隙水压力发展变化情况,并分析填挖方不同渗透性对路基差异沉降的影响,对比边坡防护前后降雨入渗对差异沉降变形的影响。分析得出:半填半挖路基降雨入渗时,填方土体入渗快于挖方土体,随着时间的增加,饱和区逐步扩大,红粘土路基发生湿软变形,填挖交界处产生差异沉降,通过采取路基顶面及坡面的防水处理,能显著降低雨水入渗对路基内部渗流场和应变场的影响及由此造成的湿化差异沉降变形,路基边坡竖向以及侧向变形均有大幅度减小。 相似文献
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山岭地区路基结构多采用填挖方式构建,填方体稳定性受到填土材料、压实工艺以及环境等综合因素影响,其工后沉降变形是影响填方体稳定性的重要因素。为此,借助数值分析工具Origin,通过构建指数预测模型对填方体沉降变形情况进行分析,结果显示建模预测精度均控制在毫米级别,满足工程建设中对填方体整体稳定性的把控要求。 相似文献
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《公路工程》2019,(3)
随着公路建设的发展,半填半挖路基工程越来越多,其稳定性研究越来越受到科研人员的关注。为了保障某一级公路半填半挖段路基施工安全,从路基稳定性影响因素入手,对路基稳定性的评价方法进行了介绍,并采用Plaxis有限元软件,就路基填筑高度对该边坡稳定性的影响进行了数值模拟研究。得到以下主要结论:随着填筑高度增加,增量位移从填土路基外逐渐向填土路基内转移,最终逐渐发展为一条光滑的圆弧,该圆弧即为路堤边坡失稳时的破裂面;当填筑高度小于12 m时,破裂面位于填挖交界面附近,之后随着填筑高度增加,破裂面上移至填土路堤内部;当填筑高度达20 m时,破裂面发展成为一条坡顶至坡底的狭长圆弧面。 相似文献
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半填半挖路基挡土墙后填土属于有限填土,当挡土墙为重力式且修建在坚硬的基岩上,挡土墙刚度大变形小,墙后填土处于弹性平衡状态,土压力按照有限填土的静止土压力计算更加合理.基于已激发内摩擦角的概念,通过对墙后填土应力莫尔圆的分析,建立了半填半挖路基挡土墙后有限填土静止土压力的计算方法.针对挡土墙墙背和基岩倾斜面与水平面夹角不同,以及与填土之间摩擦角不同的各种情况,分别给出了静止土压力系数的计算公式.工程设计中应根据实际情况合理选择相应的公式进行土压力的计算. 相似文献
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西南山区公路半填半挖路基排水系统设计研究 总被引:3,自引:3,他引:0
通过对一段半填半挖路基的破坏机理分析,认为降雨渗流是诱发该段路基病害的重要因素。利用三维数值模拟方法对该段路基、边坡和排水系统组成的地质单元地下水渗流场进行了模拟分析,结果证实设置排水系统能够显著降低路基和边坡内的地下水位,提高边坡的稳定性,减少路基灾害的发生。 相似文献
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半填半挖路基加固技术探讨 总被引:2,自引:0,他引:2
结合少(林寺)—洛(阳)高速公路的施工实践。从路基排水、挖台阶、铺土工格-网、填方段施工控制四个方面介绍了半填半挖路基的加固技术,这些方法的采用有效地防止了半填半挖路基不均匀沉降的产生。 相似文献
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随着科技的进步,人们消费观念的改变,消费水平的提高,玻璃升降系统已经变成汽车的一项标准配置。玻璃升降器经历了由手动到电动的转变。随着电动玻璃升降器大量普及,侧门由纯机械部件变成机电一体化的部件。升降系统作为一个系统部件,涉及呢槽、侧门钣金、玻璃、升降器、导轨等结构的设计及布置。本文重点阐述升降器原理及结构,常见问题处理方法,以期实现理论对工程实践的指导。 相似文献
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中国《经济》杂志在2006年政府采购高峰论坛上,公布了2006年部分政府采购(汽车)计划清单:
2005年中国政府采购总额2300亿人民币,其中汽车500多亿。随着我国政府采购规模不断扩大,汽车采购在政府采购中所占份额也将逐年递增。2006年汽车采购将达到700亿。为推进协议供货制度,提高政府采购效率,促进协议供货制度... 相似文献
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Design of conformal cooling channels for an automotive part 总被引:2,自引:0,他引:2
The cooling system plays a crucial role in determining the productivity and quality of an injection molding process. With
the current growth of Solid Freeform Fabrication (SFF) techniques, mold designers have been striving for not only improvement
in cooling system performance but also for a method to do so automatically. In this paper, a method is proposed for developing
a conformal cooling system that facilitates uniform cooling over the entire mold surface with minimum cycle time. Based on
the temperature distribution after the filling stage, the mold surface is split into zones which will be cooled by optimized
subconformal channels obtained from the optimization process. The optimization process in which the objective function is
stated as minimization of the cooling time with boundaries ensuring a realistic design will optimize the cooling system layout
in terms of cooling channel size and location. Finally, all subcooling channels are combined to generate the entire conformal
cooling system for the injection mold. 相似文献
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Variable valve timing (VVT) and cylinder deactivation (CDA) are promising methods in reducing fuel consumption and emission at part load in SI engines. An SI engine which uses electromagnetic valvetrain (EMV) will eliminate flow restriction from the throttle valve and produce higher indicated mean efficiency pressure (IMEP) due to the disabling of some of the working cylinders at part load. Therefore, pumping loss can be significantly reduced at part-load conditions. In addition, duration and timing of valve events are variably controlled at different operating conditions. This contributes to the improvement of engine efficiency. In this study, a dynamic model of an unthrottled SI engine has been developed to simulate the engine cycle. The model uses an EMV system that allows valvetrain control and cylinder deactivation techniques to be carried out in simulation flexibly. The simulated results find the optimal valve timing for different engine speeds. The optimal timing of intake valve closing depends on engine speed linearly, while the intake valve opening insignificantly influences engine performance. Additionally, this study also shows that cylinder deactivation modes can be successfully applied in improving engine efficiency at different engine loads. Different cylinder deactivation strategies have been applied for the full range of engine loads. It is concluded that the two-cylinder deactivation mode (50% CDA) considerably improves fuel consumption at low engine load. Meanwhile, one-cylinder deactivation (25% CDA) is an optimal fuel economy mode at medium engine load. With proper uses of VVT and CDA strategies, the efficiency of an SI engine can be increased more than 30% at low engine load and 11.7 % at medium engine load. 相似文献
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本文主要就售后退回的主动锥齿轮尾部掉头导致整桥失效的现象进行原因分析,通过对各相关件材质及尺寸方面的检测及分析,最终发现主动轮上安装30312轴承轴颈尺寸不符合技术要求,使用发生滑转,导致与主动轮花键配合的未经调质处理的凸缘产生严重磨损,最终导致主动轮发生掉头现象。 相似文献
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曾是六朝古都的南京在江浙地区的物流市场中并不算是数一数二的集中地区,但其辐射作用不可小视。该地区是国内各卡车生产厂家的必争之地,除了解放、东风,陕汽、重汽、福田欧曼在此地区的影响力也很明显。为深入了解南京地区市场,《商用汽车》杂志记者随"北奔重卡——商用汽车2007用户、读者走访活动"组行至南京,走访了南京丰贺汽车销售有限公司总经理钱辉。 相似文献
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H. Yang B. Kim Y. Park W. Lim S. Cha 《International Journal of Automotive Technology》2009,10(3):381-390
In recent studies, various types of multi-mode electric variable transmissions for hybrid electric vehicles have been proposed.
A multi-mode electric variable transmission consists of two or more different types of a planetary gear hybrid powertrain
system (PGHP), which can change power flow type using clutches to improve transmission efficiency. Input split systems are
generally used for the single-mode powertrain because of their overall superiority, but other power split systems such as
output split and compound split systems can be used in the dual-mode powertrain. In this study, we analyze the power transmission
characteristics of output split systems, and evaluate their fuel economies in the FTP72 cycle, acceleration performance, and
constant vehicle speeds. These results enable the selection of appropriate systems for a dual-mode powertrain. 相似文献