中国西部干旱半干旱地区高速公路建设中的若干生态学问题探讨

文章从中国西部干旱、半干旱生态脆弱地区的环境特征出发,系统分析了该区高速公路建设引发的主要生态问题,提出了干旱、半干旱地区高速公路建设环境保护的合理化建议,以期保护高速公路带的生态环境,实现可持续发展。     

重复机车荷载作用下青藏铁路冻土路基累积塑性变形分析

在青藏铁路北麓河试验段选取素填土路基断面,于暖季7月份开展列车通过实时振动测试,获得铁路货运机车振动荷载作用下路肩处的加速度时程曲线。将现场测得的加速度时程曲线作为有限元计算的荷载边界条件,通过非线性动力计算获得路基坡脚和天然地表处的加速度时程曲线,分析机车振动沿路基的传递衰减特性。阐明路基土体内部动应力分布特征和沿深度的衰减规律。应用累积塑性应变模型,对多年冻土路基在重复机车荷载作用下的永久变形进行初步分析和预测。研究结果表明:机车荷载作用所导致的路基变形随着荷载作用次数的增加逐渐趋于稳定。在机车作用1年之后,路基累计变形为27.74 mm,机车作用10年之后,该变形值发展为40.12 mm。     

Analysis on intensity zonation in thick loess region

The earthquakes, which occurred in Haiyuan, Tangshan and Wenchuan, have caused serious damages in the loess area and the abnormal intensity sites are commonly found during the earthquakes. The investigation of the actual earthquake damages and character analysis on sites shows that the topography, loess overburden and underground water level and many other factors affect the intensity. In this paper, the thickness of loess overburden of Tianshui City is achieved by inversion algorithm based on site exploration and microtremor test; the amplification effect of peak ground motion acceleration is calculated using numerical method; a complete formula is obtained through summarizing previous achievements and is used to calculate the abnormal intensity under the multifactorial influence. Finally, a seismic intensity anomaly distribution map is plotted applying the graphic information system （GIS） software in Maiji District, Tianshui City. Through the practical investigation of earthquake disaster, it is found that the figure fits the distribution of actual intensity anomaly very well.     

LNG船C型独立液货舱支座层压木的设计

层压木是C型独立液货舱围护系统的重要组成部分,其不仅承受较复杂载荷作用,当装载-163℃的LNG时,还为主船体钢结构提供绝热保护。因此,层压木的设计直接关系到整个液货舱围护系统及船体的安全性和可靠性。结合IGC规则要求,探讨了LNG船C型独立液货舱支座层压木的布置设计和尺寸设计,并通过有限元方法进行了验证及研究。     

分幅距离对青藏高速公路分离式路基动力响应的影响

为研究地震波作用下分离式路基的动力响应特性,结合现场钻孔资料,以标准断面的分离式路基为研究对象,采用二维非线性动力有限元非关联流动法,建立2幅坡脚距离分别为5,10,15和20 m的路基模型。通过施加50 a超越概率2%,10%和63%的地震波,得到分幅距离变化对路基地震动力响应的影响效应。研究结果表明:路基表面的Mises应力值大小受坡脚距离变化影响较大,对天然地表与坡脚影响微小,而对剪应力S12值大小的影响规律与此相反;随着坡脚距离的增加,路基表面与天然地表的水平峰值位移呈现先升高后降低的变化规律,在10 m坡脚距离的参考点水平峰值位移出现极大值。研究结果为青藏工程走廊内的路基选型布线与抗震设计提供一定参考。     

LNG船C型独立液货舱支座层压木的设计

LNG船C型独立液货舱支座处的层压木不仅承受来自液货舱的复杂载荷作用,还为主船体钢结构提供绝热保护。为了研究层压木设计的一般方法,结合IGC规则要求,探讨了层压木的布置设计和初步尺寸设计,并通过有限元方法进行了分析,得到了较真实的层压木压力分布和热传导规律。同时也研究了层压木主要设计参数对其性能的影响。     

Explore the possibility of forming fcc high entropy alloys in equal-atomic systems CoFeMnNiM and CoFeMnNiSmM

The multi-principal high-entropy alloys (HEAs) are promising new alloys. However, it is a challenge to screen out the suitable composition from the diverse combinations. Referring to the prototype AuCu₃ with AB₃-L1₂ structure, where it becomes a face-centered cubic (fcc) structure if element A and B are the same element, the site occupying tendencies of the elements and thermodynamic functions are predicted by using the sublattice model supported with first-principles total energy calculations. By considering the Gibbs energy of formation and the configurational entropy, the fcc HEAs in available literatures are examined, and the results of the quinary system with equal-atomic composition CoFeMnNiM and the hexbasic system with equal-atomic composition CoFeMnNiSmM are reported, respectively, where the element M is selected from the rest of the periodical table. When M=Cr, Zn, Ru, Rh, Pd, Re, Os, Ir, or Pt in the quinary systems CoFeMnNiM and when M=Ru, Pd, or Pt in the hexbasic systems CoFeMnNiSmM, respectively, the alloys are recommended to be potential fcc HEAs. The new approach opens a new way to mine the rich ores of HEAs.     

YJ92型牵引电机三相电连接器插针偏斜原因分析及处理

针对在动车组转向架高级检修过程中出现的大量YJ92型牵引电机三相电连接器插针偏斜故障,深入分析故障产生的原因,提出故障消除的办法,从而提高牵引电机的检修质量,确保动车组安全稳定运行.