共查询到20条相似文献,搜索用时 125 毫秒
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针对复杂超高应力条件下粗粒筑坝材料的动力变形特性较复杂问题,采用反映粗粒筑坝材料振动硬化特性的动力模型及考虑初始固结围压影响的粗粒料动力残余变形模型,利用试验动孔压比与动剪应力比关系曲线计算动孔压的方法研究了高土石坝的动力反应特性.计算结果表明,大坝遭遇场地谱人工波的最大水平向加速度反应为3.97 m/s2,位于坝项部位;暨直向地震永久变形占坝高的0.17%;受水库蓄水的影响,坝体上游坡的永久变形较下游坡更明显;地震过程中坝体心墙料、反滤料和坝基砂层的动孔压比均小于0.3,不会发生液化;建造于基岩上的高土石坝具有良好的抗震性能. 相似文献
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在土石坝分布式光纤变形监测技术中,监测管是光纤与坝体间力-光转换的媒介,它需要适应土石坝围压大、变形量大等特点。据此,采用分段刻槽的ABS管作为光纤应变传递载体的监测管方案,建立坝料-监测管复合体的三维非线性有限元模型,并通过坝料-监测管的大型土工三轴试验验证了该数值模型的有效性。基于该数值模型,研究了监测管在最不利受力情况下的应力分布,以检验其在高围压下的适应性。结果表明,ABS管具有较高强度,可适应300m级高土石坝的高应力状态。研究成果可为土石坝的变形监测提供参考。 相似文献
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采用邓肯张E-B非线性模型对某深覆盖层坝基上沥青混凝土心墙土石坝进行了三维有限元应力应变分析,采用无质量地基模拟坝基和山体对坝体沉降变形和应力的影响,给出了深覆盖层上坝体的应力和变形特点,特别是沥青混凝土心墙上的应力、位移分布特点,为大坝的安全设计提供理论依据。 相似文献
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通过对大梁水库大坝砂砾料重塑土进行动三轴试验,分析了该重塑土在动荷载作用下的力学特性,发现在不同围压、不同固结应力比条件下砂砾料的动强度与振动周数之间均可用乘幂函数进行拟合。在等压固结时轴向应变在动荷载作用下存在一个"临界应变点",该点处的动孔压比约为0.8;而在偏压固结时,轴向应变的增长较平稳,无明显临界应变点。不同固结比条件下动剪应力比与动孔压比变化规律为等压固结时,动孔压比增长较快,且动孔压比能够达到1.0,而偏压固结时最大动孔压比仅能达到0.7左右。 相似文献
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为确定新型土工合成材料轻量土在不同发泡颗粒(EPS)粒径下的变形机理,通过三轴固结不排水试验系统研究其变形强度特性的影响规律。试验结果表明,轻量土应力-应变关系具有非线性、多阶段性、应变软化和应变硬化特性;抗剪强度破坏包络线有折线型与直线型两种,取决于自身结构强度与围压;粘聚力与内摩擦角均随EPS粒径的增大而递减。 相似文献
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《International Journal of Hydrogen Energy》2022,47(63):26789-26797
The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO2 and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized. 相似文献
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Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined. 相似文献
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使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。 相似文献
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M.R. Salimpour M. SharifhasanE. Shirani 《International Communications in Heat and Mass Transfer》2011,38(1):93-99
This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed. 相似文献
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基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁(MgO),研究了该型MgO膨胀剂(MEA)细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析(TG DSC)分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。 相似文献
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本文对漫灰均温物体在常物性条件下对外辐射传热的Yong值计算建立了数学模型。通过与物体内能Yong公式的数值计算比较,得出了辐射能量的Yong值不大于内能Yong值的结论。从初步的热射Yong值计算公式发现。Yong与物体表面辐射率有关。 相似文献
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《International Journal of Hydrogen Energy》2022,47(83):35515-35526
The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%. 相似文献
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介绍了汽轮机零件的封存特点、防锈要求及防锈油性能对比试验的方法,通过对试验结果的对比分析,客观验证了各种防锈油的性能。试验表明,只有选择了合适的防锈油,才能保证汽轮机零件长期封存的质量。 相似文献