測(cè)繪工程外文翻譯(編輯修改稿)
2024-09-04 15:52 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 nd lime. The adopted density ratio is as follows. Cr= H/ = H/ =, in which,Cris density ratio。r1H, layer’s density in prototype andr1m, layer’s density in model. Excavation time ratio. For the limit of experiment condition, the time proportion between model and prototype is adopted by kinematics similarity rule under gravity, = = = 20. Modeling materialPresently, the modeling material monly used includes gypsum mixture, lime mixture and synthetic gum mixture, contains supporting and clotting material. Normally, sand, mica powder and talcum powder are used as supporting material while gypsum and gypsumlime used as clotting material. Considering material selecting, transporting, expenditure and availability, sand is applied as supporting material and gypsumlime as clotting material. Furthermore, talcum powder layers are laid to mimicthe effect between , = /( *) = /。 model frame, lengthwidthheight=。 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 model. 7 of them (~) are to measure vertical displacement, and others (No. 8 ~No. 14) are to measure horizontal displacement (). Strata movement after modeling excavation Restraint condition and ground movement in numeric model ExcavationThe top of model is a free surface where 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 measured. After finished excavation of upper coal layer, lower coal stratum would be excavated continually. Some curves are drawn as indicated in according to the simulation material model.(a)Inclined deformation curve。 (b)Subsidence curve。 (c)Horizontal deformation curve。 (d)Displacement curve Simulation curves of material model4 Numeric 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 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. 2Dσ is a numeric analyzing system which supports
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