2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
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1、2900 英文單詞, 英文單詞,1.9 萬英文字符,中文 萬英文字符,中文 4400 字文獻(xiàn)出處: 文獻(xiàn)出處:Procedia Engineering 181 (2017) 52 - 59Slope Stability of Railway EmbankmentsMadalina Ciotlaus, Gavril Kollo, Dorin Moldovan, Lavinia MunteanAbstractThe paper presen

2、ts a research regarding the stresses in the railway embankments taking into account the static and dynamic action of the rolling material. The railway is subjected to heavy and complex stresses, and the axle loads increa

3、se with the traffic speed. Therefore, it is necessary to know as accurately as possible the service conditions for the embankments to help the railway infrastructure to provide a sure and continuous support for the super

4、structure.To search an earth bulk, it is necessary to know the distribution of the tensions inside it. The design model admits the idea of a homogeneous, isotropic, continuous and linear space that can be deformed. The s

5、tudy presents the manner in which railway vehicle loads are transmitted from the rail to the sleeper and then to the embankment through the ballast bed. The simulation was made with the Slope software, and maximum deform

6、ations for various heights of the embankments loaded with railway convoys were produced.Keywords: railway embankment stability; rail sleeper load; transmission of stresses in the railway; failure mode; bearing capacity;

7、fill embankment. 1. IntroductionThe railway is subjected to dynamic loads originating in the weight of the moving rolling material, in the shocks in the joint area, irregularities and other causes related to deviations f

8、rom admitted tolerances. These stresses are transmitted through the rail-sleeper system to the ballast bed towards the embankment, where stresses and strains due to these forces and the own earth height occur.2. Railway

9、embankments and surcharge loads2.1. Generalities. Static and dynamic loads.Railway embankments are subjected to stresses coming from convoy traffic, own weight and other accidental stresses affected by the vibrations cau

10、sed by railway traffic and earthquakes. The classical railway superstructure is made up of a set of elements with variable elasticity values that convey to the deformable in itself railway platform, stresses originating

11、in the dynamic and static action of the rolling material.weight are analysed through the distributions inside it, in the particle contact points. Soils are discontinuous grain environments made up of solid particles of v

12、arious shapes and sizes, with lack of homogeneity, and consequently, with a very complex tension distribution. In order to make a similitude between the actual continuous distribution and an equivalent continuous distrib

13、ution, a piece of earth bulk will be symbolized as a discrete environment in which all particles are spherical in shape and identical in size, hypothesis accepted for continuous granulometry types of earths.3.2. Distribu

14、tion of tensions in the crushed stone prismAdmitting that spherical particles under the rail are loaded with an unitary load (Fig. 3 a.), each particle receives loads from two other particles from the line immediately ab

15、ove it. One can notice that of all admissible spheres in the thickness layer there will be loaded only those in the trapezoid surface defined by the width of the sleeper base and the unparallel sides, inclined by 8=30

16、76; to the vertical line. C angle is formed by the contact forces among the spheres with the vertical line. The loading degree of a sphere depends upon its placement in the line and the position of the line in relation t

17、o the sleeper base. The more a sphere is placed towards the sleeper axis and in a higher line, the more loaded it is and vice-versa. The sum of the pressures exerted upon the spheres in a line has a constant value, irres

18、pective of their position relative to the sleeper base. Replacing the diagrams of pressure distributions in the spheres in each line, it can be noted that they can have an almost trapezoidal form except for the first lin

19、e, which is linear, and the fourth line where it is triangular. The smaller the spheres, the more the pressure line in a level nears the shape of a trapezoid. It yields that, at a certain depth relative to the sleeper ba

20、se, the diagram of pressure distribution (trapezoid or triangular) is determined by the distribution linesΔ1, Δ2, Δ3 and Δ4. The surfaces of pressure distribution diagrams are constant and equal to the pressure transmitt

21、ed by the sleeper, irrespective of the depth. The larger the depth is the smaller the pressure maximum value is. This pressure distribution manner is achieved both cross through and along the sleeper.For the real case of

22、 a sleeper placed upon a ballast bed, the pressure distribution in its mass does not occur as in the ideal case presented above, because the ballast particles are not spherical and hence, the distribution angle is not eq

23、ual to 30°, but to the internal friction angle, then the distribution lines are not straight lines, the pressures exerted upon the sleeper base are not uniformly distributed and the crushed stone prism add their own

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