巖土工程外文翻譯--先進值方法在斜坡穩(wěn)定性分析中的應用和限制（英文）

1、 ADVANCED NUMERICAL TECHNIQUES IN ROCK SLOPE STABILITY ANALYSIS – APPLICATIONS AND LIMITATIONS Doug Stead, Earth Sciences, Simon Fraser University, Vancouver, Canada Erik Eberhardt, Engineering Geology, ETH Zurich, Swi

2、tzerland John Coggan, Camborne School of Mines, University of Exeter, UK. Boris Benko, Golder Associates, Abbottsford, Canada ABSTRACT Stability analyses are routinely performed in order to assess the safe and function

3、al design of an excavated slope (e.g. open pit mining, road cuts, etc.), and/or the equilibrium conditions of a natural slope. The analysis technique chosen depends on both site conditions a nd the potential mode of f

4、ailure, with careful consideration being given to the varying strengths, weaknesses and limitations inherent in each methodology. This paper presents a review of numerical techniques used in rock slope stability analy

5、sis emphasising recent developments in numerical modelling, including advances in computer visualisation and the use of continuum and discontinuum numerical modelling codes. INTRODUCTION The engineer today is presente

6、d with a vast range of methods for the stability analysis of rock and mixed rock-soil slopes; these range from simple infinite slope and planar failure limit equilibrium techniques to sophisticated coupled finite-/dist

7、inct- element codes. It is less than 25 years since most rock slope stability calculations were performed either graphically or using a hand-held calculator, the exception being advanced analyses involving critical sur

8、face searching routines performed on a mainframe computer and Fortran cards. The great majority of early stability analysis programs were in-house with very little software being available commercially. Today, every e

9、ngineer has access to a personal computer that can undertake with relative ease complex numerical analyses of rock slopes. Given the wide scope of numerical applications available today, it has become essential for th

10、e engineer to fully understand the varying strengths and limitations inherent in each of the different methodologies. For example, limit equilibrium methods still remain the most commonly adopted solution method in roc

11、k slope engineering, even though most failures involve complex internal deformation and fracturing which bears little resemblance to the 2-D rigid block assumptions required by most limit equilibrium back-analyses. In

12、itiation or trigger mechanisms may involve sliding movements which can be analysed as a limit equilibrium problem, but this is followed by or preceded by creep, progressive deformation, and extensive internal LANDSLIDE

13、S – Causes, Impacts and Countermeasures 17-21 June 2001 Davos, Switzerland pp. 615-624 Table 1. Conventional methods of analysis (after (5)). Analysis method Critical input parameters Advantages Limitations Stere

14、ographic and Kinematic Critical slope and discontinuity geometry; representative shear strength characteristics. Relatively simple to use and give an initial indication of failure potential. Some methods allow i

15、dentification and analysis of critical keyblocks. Links are possible with other analysis methods. Can be combined with statistical techniques to indicate probability of failure and associated volumes. Only really

16、 suitable for preliminary design or design of non-critical slopes. Need to determine critical discontinuities that requires engineering judgement. Must be used with representative discontinuity/joint shear streng

17、th data. Primarily evaluates critical orientations, neglecting other important joint properties. Limit Equilibrium Representative geometry and material characteristics; soil or rock mass shear strength parameter

18、s (cohesion and friction); discontinuity shear strength characteristics; groundwater conditions; reinforcement characteristics and external support data. Wide variety of software available for different failure m

19、odes (planar, wedge, toppling, etc.). Mostly deterministic but increased use of probabilistic analysis. Can analyse factor of safety sensitivity to changes in slope geometry and material behaviour. Capable of m

20、odelling 2-D and 3-D slopes with multiple materials, reinforcement and groundwater profiles. Factor of safety calculations give no indication of instability mechanisms. Numerous techniques available all with vary

21、ing assumptions. Strains and intact failure not allowed for. Do not consider in situ stress state. Probabilistic analysis requires well-defined input data to allow meaningful evaluation. Simple probabilistic ana

22、lyses may not allow for sample/data covariance. Rockfall Simulation Representative slope geometry; rock block sizes and shapes; coefficient of restitution. Practical tool for siting structures. Can utilise probab

23、ilistic analysis. 2-D and 3-D codes available Limited experience in use relative to empirical design charts. Considerable advances in commercially available limit equilibrium computer codes have taken place in recent

24、years. These include: ? Integration of 2-D limit equilibrium codes with finite-element groundwater flow and stress analyses (e.g. GEO-SLOPE’s SIGMA/W, SEEP/W and SLOPE/W (6)). ? Development of 3-D limit equilibrium m

25、ethods (e.g. CLARA (7); 3D-SLOPE (8)). ? Development of probabilistic limit equilibrium techniques. ? Ability to allow for varied support and reinforcement. ? Incorporation of unsaturated soil shear strength crite

26、ria. ? Greatly improved visualisation, and pre- and post-processing graphics. These codes are extremely relevant in the analysis of soil slopes and highly altered rock slopes, where sliding takes place on discrete wel

27、l-defined surfaces. Figure 2 illustrates the use of the 2-D limit equilibrium program SLOPE/W in the back-analysis of a failure in a kaolinised granite slope. Where it is necessary to include the stress state within t