外文翻譯--數(shù)值模擬中原位巖體與實驗巖體的力學(xué)特性關(guān)系

1、1800 單詞， 單詞，9000 英文字符， 英文字符，3000 漢字 漢字出處： 出處：Mohammad N, Reddish D J, Stace L R. The relation between in situ, and laboratory rock properties used in numerical modelling[J]. International Journal of Rock Mechanics &

2、Mining Sciences, 1997, 34(2):289–297.翻譯部分 外文原文：The Relation Between In situ and Laboratory Rock Properties Used in Numerical Modelling（N. MOHAMMAD，D. J. REDDISH，L. R. STACE）INTRODUCTIONNumerical models are being used i

3、ncreasingly for rock mechanics design as cheaper and more efficient software and hardware become available. However, a crucial step in modelling is the determination of rock mass mechanical properties, more precisely roc

4、k stiffness and strength properties.This paper presents the results of a review of numerical modelling stiffness and strength properties used to simulate rock masses. Papers where laboratory and modelling properties are

5、given have been selected from the mass of more general modelling literature. More specifically papers that have reduced stiffness and/or strength parameters from laboratory to field values have been targeted. The result

6、of the search has been surprising: of the thousands of papers on numerical modelling, a few hundred mention laboratory and rock mass properties, and of those, only some 40 appear to apply some kind of reduction. The pape

7、rs that apply a reduction have been used to produce the graphs that constitute the main content of this paper. Rock stiffness properties have been separated from those of strength in the analysis and this has illustrated

8、 interesting differences in their respective average reduction factors.METHODOLOGYThe review conducted has studied case histories and back analysis examples of numerical modelling for a wide range of rock structures. Eac

9、h reviewed paper has been databased in terms of laboratory measured rock properties and numerical modelling rock mass input properties plus other relevant quantitative data [1-37].The vast majority of papers have provide

10、d incomplete data either omitting key parameters or synthesizing parameters. Some papers have given laboratory and mass properties, and a few papers have explained the process by which laboratory properties have been adj

11、usted to the rock mass by use of rock mass ratings. One can only conclude that this is related to the origin of the models or modellers, being from environments where materials like steel have no scale effects. There wou

12、ld be few rock mechanics specialists who would not acknowledge that even the strongest rock types need some adjustment of their rock mass properties. The graphs and data provided in this paper have therefore concentrated

13、 on papers where reductions have been applied. A list of the most valid and relevant numerical papers is included at the end of the paper.（4） int0.5 1 cos( ) 100rm E RMR RF E ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?Equations

14、(3) and (4) have been plotted (Fig. 9) in a similar way to the above data. Equation (3) can be seen to apply large reductions to the stiffness once the RMR is below 30. Equation (4) is a much better fit to the data and h

15、as perhaps more realistic reductions in the low RMR and stiffness range. Although comparisons between the equation lines and the data are composed by the simple linear relation being used between the RMR and laboratory s

16、tiffness, it is still clear that both formulae reduce stiffness too much in the low RMR range.Matsui [9] presented a direct approach based on the minimisation of an error function, equation (5). This function represents

17、a least squares reduction of discrepancy between the n displacements ，actually measured around a roadway and the n displacements , obtained i u * i uby a finite element analysis. Since the numerical model output depend

18、s on the values of * i uelastic parameter E assumed in the finite element calculations, the error is in turn a function of ?these parameters (i.e. ). Thus, the elements of vector E minimising represent the ? ? f E ? ?

19、 ?values of the elastic constants which lead to the best description of the behaviour of the real rock mass by means of the finite element model. To use this approach it is necessary to integrate it into the finite eleme

20、nt package. It is therefore difficult to compare, in simple terms, with other approaches. It is, in effect, a systematic back analysis approach where the unknown is the rock mass property.（5）2 *1ni iiu u ??? ? ? ? ? ? ?D

21、aniel [8], using a volumetric approach, reduced the laboratory-determined mechanical properties, rock stiffness and strength by a scale factor of 1/6 for input into the model. This was to account for discontinuities and

22、pore water pressure which depend on the size of the element representing the rock. The reduction factor was estimated according to formula (6).（6）0.1670( ) V RF V ?Where V0 is the volume of the rock used in the laborator

23、y testing and V is the volume of the rock used in the finite element model.Trueman [12], after reviewing different reduction factors proposed by others, derived the RMR based expressions for reduced strength parameters.

24、Uniaxial compressive strength of rock mass:（7） 0.06 0.5 ( ) RMRrm e MPa ? ?Cohesion of rock mass：（8） 0.05 0.25 ( ) RMRrm C e MPa ?Friction angle of rock mass：（9） 0.5 5(deg ) rm RMR rees ? ? ?Trueman's technique has b