测绘工程外文翻译Word格式文档下载.docx

1、the situation with large ratio of depth to thickness. Otherwise, they would be discontinuous and irregular. Movement basin and diverse displacement or deformation curves of horizontal coal strata show fine regularity. As for inclined coal layer（i.e., N-Mine）, the largest displacement point will move

2、 towards the downhill but not in the middle of movement basin. Subsidence curve and horizontal movement are unsymmetrical. Usually, long wall mining of the strike working method is widely adopted, the ground subsidence and rock layer movement gradually developing along the long profile of coal strat

3、a, at last will be kept stable. Meanwhile the rule of ground movement is obvious. There is no obvious rule for the ground movement along transverse profile, it dependson the geological condition of a specific mine. The research results based on the transverse profile of coal strata are described in

4、following paragraphs.3Simulation material model experiment3.1Modeling ratioThe constants including the modeling ratio of geometry, density, intensity and time need to be defined for modeling.3.1.1Structural similitude ratio. The stratums thickness, mining depth and space conformed to exact proportio

5、n between model and prototype are necessary for modeling experiment. In simulation of the subsidence, the structural similitude ratio is an essential parameter. Usually, the larger the structural similitude ratio, the more precise the results. The structural similitude ratio should be theoretically

6、large enough, but it is difficult to operate in fact. It requires not only much expense, but also strict conditions. However, the experiment accuracy would not be affected by use of an adequate structural similitude ratio and adoption of the suitable measure and means. Considering the practical cond

7、itions in N-coal mine as shown in Table 1, model experiment would mimic the area with 500m deep. If structural simili tude ratio were little, the model would be too big to operate, so the structural similitude ratio chosen is 1400 （Cl）.Table 1Rocks mechanical parameters inN-mineStratumYoungs Modulus

8、（/Mpa）Poissons RatioCohesion（/Mpa）Internal friction angle/（）Uniaxial tension strength/MpaDensity / （tm-3）TJ11064950.342314.5133.42.3297-2.60TF1996390.306016.8122.92.0685-2.45TF21046930.33331.9554-2.55PL814774.50.295020.5034.20.7047-2.25PM1120557.50.27273.218 3.1.2Dynamic similitude ratio.Dynamic sim

9、ilarity rule requires that forces conform to the exact proportion between model and prototype. In experiment, characteristic parameter reflects forces including density, boundary stress and intensity. Modeling material contains sand, gypsum and lime. The adopted density ratio is as follows. Cr= H/ =

10、 =1.667, in which,Cris density ratio;r1H,No.1 layers density in prototype andr1m, No.1 layers density in model.3.1.3Excavation time ratio. For the limit of experiment condition, the time proportion between model and prototype is adopted by kinematics similarity rule under gravity, = 20.3.2Modeling m

11、aterialPresently, the modeling material commonly used includes gypsum mixture, lime mixture and synthetic gum mixture,etc.Mixture contains supporting and clotting material. Normally, sand, mica powder and talcum powder are used as supporting material while gypsum and gypsum-lime used as clotting mat

12、erial. Considering material selecting, transporting, expenditure and availability, sand is applied as supporting material and gypsum-lime as clotting material. Furthermore, talcum powder layers are laid to mimicthe effect between layers.Intensity, /（ *） = /666.7; model frame, lengthwidthheight=1.5m0

13、.3m1.2m; modeling range, 500m depth （from ground surface to coal layer）, 120m width （along coal layer）, 600m length （across coal layer）. Because coal layer is too thin, it is enlarged to 5 multiple thickness. For the measurement of displacement and deformation, 14 micrometers are fixed to the top of

14、 model. 7 of them （No.1No.7） are to measure vertical displacement, and others （No. 8 No. 14） are to measure horizontal displacement （Fig.1）.Fig.1Strata movement after modeling excavationFig.2Restraint condition and ground movement in numeric model3.3ExcavationThe top of model is a free surface where

15、 is no any load. During excavation mimicking, 4 groups of excavation would be executed, and 4 excavation steps are put into practice in each group. The excavating step is 2 centimeters long, and the interval between 2 steps is 2 hours. It takes 2 days for 2 groups, thus obvious deformation could be

16、measured. After finished excavation of upper coal layer, lower coal stratum would be excavated continually. Some curves are drawn as indicated in Fig.3 according to the simulation material model.（a）-Inclined deformation curve; （b）-Subsidence curve; （c）-Horizontal deformation curve; （d）-Displacement

17、curveFig.3Simulation curves of material model4Numeric analysisRock has both elastic and plastic properties. There are two kinds of force according to elastic mechanics. One is plane stress, and the other is plane strain. In fact, the same result for stress can be obtained whether considering strain

18、or not. The numeric analysis in this paper is made for stress analysis. Furthermore, stress analysis is done along the same transverse profile in the simulation material model, thus 2D finite element method（FEM） program is sufficient. 2D- is a numeric analyzing system which supports the rock and soi

19、l designing, by which the mechanics status and characters of objects can be illuminated. For plotting cells, quadrangle cell is used morelargely than triangle cell. Cells in coal strata and rock strata near coal one are densely plotted. The cells of rock strata far from coal strata are sparse. Strat

20、a with thin thickness are divided into cells densely. In FEM modeling, Mohr-Coulomb mechanics model is established to analyze stress situation along the transverse profile. The deformation situation of proof and floor rock layers in the subsidence basin of numeric model is shown in Fig.2. It is seen

21、 in Fig.4 and Fig.5 that the effect of beginning excavation on subsidence and ground movement is slightly. The destruction degree figure indicated in Fig.7 is drawn with the 2D- program. After all excavation steps finished, the effect of shearing strength on ground movement is serious as indicated i

22、n Fig.8. Stress concentrates on uphill and downhill coal wall. Various stresses not listed here for limited space can be calculated with FEM program, such as maximal and minimal stress,etc.Fig.4X-stress after first excavation stepFig.5Y-stress after first excavation stepFig.6Destruction degree after

23、 all excavationFig.7Shearing strength after first excavationFig.8Destruction degree after first excavation stepFig.9Shearing strength after all excavation step5ConclusionThe results of modeling experiment and numeric analyzing show that the subsidence curve and horizontal movement curve are not continuous and smooth, but are unsymmetrical with some variation caused by geological conditions. The