滑坡防治工程安全性评价研究

滑坡灾害防治是一门综合性工程,防治工程的安全性取决于滑坡勘察、设计以及施工质量,本文就滑坡治理过程中各阶段易出现的问题予以实例说明,探讨滑坡防治工程中应注意的几个问题,对这些经验教训进行总结,同时强调监测在防治工程中的作用,其对于滑坡防治工程具有一定借鉴意义。     

甘肃引洮供水工程饱和黄土隧洞施工方法选择的工程地质研究

甘肃引洮供水一期工程总干渠13#、14#、15#隧洞围岩为al-lQ2饱和黄土,地下水位高于洞顶4³7m,饱和度一般在98%¹00%,水稳性很差。因此,该段隧洞施工方法的选择十分重要,从工程地质角度研究其工程特性,采用D rucker-Prager弹塑性模型、关联流动法则,模拟了传统钻爆法开挖时隧洞稳定性,计算表明,若采用钻爆法,由于围岩的岩性软弱,隧洞开挖后,在隧洞周围较大范围内存在应力降低区,隧洞位移十分迅速而且位移量非常大,洞顶下降发生塌方并引起地面沉降。从盾构法施工对地质条件的适应性分析,其施工风险相对较小,施工过程中可利用护盾很快封闭围岩,因此该段隧洞宜采用盾构法施工。     

Numerical analysis of free vibrations of a beam with oscillators

The problem of free vibrations of a beam with free ends of variable cross section and mass, from which point masses (oscillators) are suspended by bars, is considered. It is shown that parametric resonances can occur in this oscillating system. Numerical examples showing the efficiency of the calculation method proposed are given. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 135–144, July–August, 2006.     

低密度开孔泡沫材料力学模型的理论研究进展

开孔泡沫材料主要用于隔音、减振和填充方面，对其力学行为进行理论描述，探讨力学性能与密度及复杂微结构的关系具有十分重要的学术价值和工程意义．为了促进国内泡沫材料力学的发展和交流，文中对低密度开孔泡沫材料力学模型的研究历史进行了简要回顾，重点介绍了能较好地反映开孔泡沫材料真实胞体结构特点的十四面体胞体模型和随机胞体模型，并报道了近年来基于十四面体胞体模型和随机胞体模型研究低密度开孔泡沫材料力学行为的一些理论工作、同时，也对国内的一些相关研究情况进行了简要评述，指出了该领域今后的一些研究方向．     

用等离子体增强化学气相沉积技术制备类金刚石碳薄膜的摩擦磨损性能研究

利用射频-直流等离子体增强化学气相沉积技术在单晶硅衬底上沉积类金刚石碳薄膜,采用激光拉曼光谱仪和原子力显微镜对薄膜的结构和表面形貌进行表征,采用纳米压痕仪测定薄膜的硬度,并用UMT型微摩擦磨损试验机考察了薄膜在不同试验条件下的摩擦磨损性能.结果表明:所制备的类金刚石碳薄膜表面光滑致密且硬度较高;在干摩擦条件下与GCr15钢球或Al2O3球配副时显示出良好的减摩抗磨性能,摩擦系数较低,耐磨寿命较长,而在水润滑条件下同Al2O3球配副时发生灾难性磨损.     

Model equations for the Eiffel Tower profile: historical perspective and new results

Model equations for the shape of the Eiffel Tower are investigated. One model purported to be based on Eiffel's writing does not give a tower with the correct curvature. A second popular model not connected with Eiffel's writings provides a fair approximation to the tower's skyline profile of 29 contiguous panels. Reported here is a third model derived from Eiffel's concern about wind loads on the tower, as documented in his communication to the French Civil Engineering Society on 30 March 1885. The result is a nonlinear, integro-differential equation which is solved to yield an exponential tower profile. It is further verified that, as Eiffel wrote, “in reality the curve exterior of the tower reproduces, at a determined scale, the same curve of the moments produced by the wind”. An analysis of the actual tower profile shows that it is composed of two piecewise continuous exponentials with different growth rates. This is explained by specific safety factors for wind loading that Eiffel & Company incorporated in the design of the free-standing tower. To cite this article: P. Weidman, I. Pinelis, C. R. Mecanique 332 (2004).     

与冲蚀有关的粘着与犁沟摩擦系数

提出一种与冲击磨损有关的有效摩擦系数，它被定义为冲击过程中，每一瞬间的切向有效摩擦力与法向载荷之比．有效摩擦力被表示为剪切项与犁沟项之组合．剪切项依赖于剪切金屑接合点的状态——滑移或滚动．犁沟项依赖于冲击物在冲击途中使靶材料发生移动的状态．此有效摩擦系数被应用于研究刚性球自由斜冲击延性靶问题．在忽略剪切项仅计及犁沟项的情况下，研究表明，Hutchings实验中的有效冲击摩擦系数是冲击过程与初始冲击角的函数，就时间平均而言，大于Hutchins为拟合计算与实验结果所取的摩擦系数常值0.05．有迹象表明，对于与固粒延性冲蚀有关的刚性球自由斜冲击延性靶问题，在一定条件下，有效摩擦系数主要由犁沟效应确定．     

脉冲直流等离子体增强化学气相沉积Ti—Si—N纳米薄膜的摩擦磨损特性

采用工业型脉冲等离子体增强化学气相沉积设备，通过调节氯化物混合比例控制薄膜成分，在高速钢基材表面于550℃下沉积由纳米晶TiN和纳米非晶Si3N4组成的Ti—Si—N复合薄膜；采用扫描电子显微镜、透射电子显微镜、X射线衍射仪及X射线光电子能谱仪分析了薄膜的结构、组成和化学状态；采用球-盘高温摩擦磨损试验机考察了薄膜同GCrl5钢对摩时的摩擦磨损性能．结果表明：薄膜的Si含量在0％～35％范围内变化，随着Si含量增大，薄膜沉积速率增大，但薄膜由致密形态向大颗粒疏松态过渡；薄膜的晶粒尺寸为7～50nm；Ti—Si—N薄膜的显微硬度高于TiN的硬度，最高可达60GPa；引入少量Si可以显著改善TiN薄膜的抗磨性能，但薄膜的摩擦系数较高(室温下约0．8、400℃下约0．7)；随着Si含量的增加，Ti—Si—N薄膜的耐磨性能有所降低，其原因在于引入导电性较差的Si元素使得薄膜的组织变得疏松．     

VIBRATION AND ACOUSTIC RADIATION FROM SUBMERGED STIFFENED SPHERICAL SHELL WITH DECK-TYPE INTERNAL PLATE

Based on the motion differential equations of vibration and acoustic coupling system for thin elastic spherical shell with an elastic plate attached to its internal surface, in which Dirac-δ functions are employed to introduce the moments and forces applied by the attachment on the surface of shell, by means of expanding field quantities as Legendre series, a semi-analytic solution is derived for the vibration and acoustic radiation from a submerged stiffened spherical shell with a deck-type internal plate, which has a satisfactory computational effectiveness and precision for an arbitrary frequency range. It is easy to analyze the effect of the internal plate on the acoustic radiation field by using the formulas obtained by the method proposed. It is concluded that the internal plate can significantly change the mechanical and acoustic characteristics of shell, and give the coupling system a very rich resonance frequency spectrum. Moreover, the method can be used to study the acoustic radiation mechanism in similar structures as the one studied here.     

Inhomogeneity effects on the crack driving force in elastic and elastic-plastic materials

This article evaluates the effect of material inhomogeneities on the crack-tip driving force in general inhomogeneous bodies and reports results for bimaterial composites. The theoretical model, based on Eshelby material forces, makes no assumptions about the distribution of the inhomogeneities or the constitutive properties of the materials. Inhomogeneities are modeled by making the stored energy have an explicit dependence on the reference coordinates. Then the material inhomogeneity effect on the crack-tip driving force is quantified by the term C_inh, which is the integral of the gradient of the stored energy in the direction of crack growth. The model is demonstrated by two model problems: (i) bimaterial elastic composite using asymptotic solutions and (ii) graded elastic and elastic-plastic compact tension specimen using numerical methods for stress analysis.