Multi-Objective Optimization of Slope Stability Using Wedge Analysis and Genetic Algorithm

Multi-Objective Optimization of Slope Stability Using Wedge Analysis and Genetic Algorithm

Sarat Kumar Das (Indian Institute of Technology Dhanbad, India)
DOI: 10.4018/978-1-5225-4766-2.ch010
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Slope stability of different waste containment systems is a matter of serious concern due to its impact on air, land, and water pollution, affecting human and aquatic lives. It has been observed that most of the waste containment slope failures are translational failure. In this chapter, the slope stability analysis of the waste containment is discussed with translational failure (wedge analysis) in single and multi-objective optimization framework using genetic algorithm (GA). Non-dominated sorting genetic algorithm II (NSGA-II) is found to efficient in developing the Pareto front in terms of factor of safety (FOS), height of embankment, and volume of the failed slope. The FOS decreased with increase in height of the slope and the volume of the slope also increased. The optimized slope in terms of different slope angle and with seismic coefficients is also discussed. Such a study will help the professional in deciding the height of the slope as per the FOS in a specified seismic zone.
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1. Introduction

This chapter discusses about the analysis of finding out the factor of safety using three-wedge method in conjunction with evolutionary optimization tool, genetic algorithm. Out of various methods (finite element analysis, limit analysis, variational method), limit equilibrium method (LEM) is most widely used for its simplicity form and the results are found to be close to that of rigorous methods. The two-dimensional (2-D) limit equilibrium method is taken as a plane strain problem with no variation in geometry, material and surcharge in direction parallel to the crest of the slope. The problem lies in finding out the critical failure surface and its corresponding factor of safety (FOS). The above concept has led to consider it as an optimization problem (Baker, 1980). Various efforts have been made to apply different LEM suitable for circular and noncircular surface, but literature on wedge analysis is limited (Huang, 1983). However, wedge analysis is used in different slope stability problems like embankment of lined waste containment system, analysis of reinforced earth wall etc. Based on recent observations by Qian and Koerner (2009), Table 1 shows the database of failure of different waste containment system along with the type of failure surface and quantity of waste involved. It can be seen that most of the failures of waste containment system are translational in nature. Hence, in this chapter, three- wedge method is used along with GA for the stability of slopes in a single and multi-objective optimization framework.

Table 1.
Failure of waste containment systems
IdentificationYearLocationType of FailureQuantity of Waste Involved in Failure (m3)
Unlined (or Clay Soil Lined) Sites
U-11984North AmericaSingle rotational110,000
U-21989North AmericaMultiple rotational500,000
U-41997North AmericaTranslational1,100,000
U-51997North AmericaSingle rotational100,000
U-61998North AmericaTranslational13,000
U-72000AsiaSingle rotational16,000
Lined (with Geomembranes) Sites
L-11988North AmericaTranslational490,000
L-31997North AmericaTranslational300,000
L-51997South AmericaTranslational1,200,000
L-72000North AmericaTranslational100,000

Qian & Koerner, 2009.

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