Slope stability analyses are commonly performed using computer programs hich perform safety factor calculations using limit equilibrium solutions and search for the critical, or most probable failure surface. These searches are always performed using "direct search" techniques, which are the simplest but least efficient optimization methods. In the future, more advanced optimization algorithms will be incorporated into existing slope stability programs, which will greatly increase the speed with which the search converges to the critical slip surface. The relative efficiency and reliability of these new search strategies must be established by comparative testing on a variety of slope problems. This paper presents a set of problems that will serve as a basis for future comparative testing of different optimization procedures. These problems span the range of slope problems encountered by geotechnical engineers. Baseline measures of efficiency are obtained using an existing slope stability program with grid and pattern search capabilities.

Slope stability problems often arise in construction engineering projects. They are major problems in dams construction and mines excavation. For the purpose of improving the efficiency of slope stability analysis, the optimization method suggested by Powell (1964) is used to locate the critical failure surface. The reader should bear in mind the possibility of applying optimization to a wide variety of different civil engineering problems.

Plant roots provide important soil reinforcement and improve the stability of slopes. From an engineering view, roots mechanically increase soil shear strength by transforming shear stress from soil into tensile forces of roots themselves via interface friction thus acting like soil nails. However, due to the complex spatial geometries and mechanical heterogeneities of natural root systems, more specific considerations are needed when analyzing the root reinforcement issues. According to a literature review, most studies on slope stability consider root reinforcement as an apparent cohesion by upscaling the behaviour of static individual roots. However, recent studies have shown that better predictions can be made if the progressive failure of roots is considered, thus highlighting the importance of load-displacement relations of soil-root interaction. Therefore, numerical pull-out tests considering the progressive friction interface relationship were carried out in this study to investigate the mechanism and the influences of various factors on plant root pull-out behaviour, which is of great importance to evaluating the stabilization effect of roots. In this study, the classic Coulomb friction model was adopted to simulate the interaction along the root-soil interface with the surface to surface modelling technique available in ABAQUS. The numerical investigations could be mainly divided into three parts: study of single straight root pull-out behaviour, study of the branched root segments with only first-order lateral branches (herringbone system), and study of the root segments with second-order branches (dichotomous system). Conclusions regarding the mechanism of the root pull-out process, the influence of geometry-related factors and the influence of the intrinsic factors related to mechanical properties and root-soil interaction were drawn based on the observations of the numerical pull-out tests. Progressive stick-to-slip behaviours along the root-soil interface were observed in the numerical models. Generally, the pullout resistance of roots increased with the branch depth and branch length. It was also observed that the pullout resistance had strong regression with the weight of the soil potentially lifted by the root system. The most efficient branch angle for providing pull-out resistance for the herringbone system was between 60 and 90 degrees and the most efficient branch angle for the dichotomous root system was shown to be around 45. The central symmetrical branch arrangement pattern was observed to be the most efficient in providing pull-out resistance compared with the plate symmetrical and asymmetrical patterns. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

No description available.

In this study the shear strength parameters for a consolidated, well-cemented boulder conglomerate at the Cyprus Miami Copper Mine are determined by a newly developed field test. The values obtained are used to investigate the probability of failure of pit slopes cut into the conglomerate. Any boulder conglomerate is impossible to test accurately with conventional laboratory techniques due to its large particle sizes and the destruction of cementation by conventional sampling methods. For these reasons a simple in situ test was developed which could be used in conjunction with laboratory techniques and analytical procedures to estimate the in situ strength properties of the Gila Conglomerate. The variability in the testing of the shear strength parameters of Gila Conglomerate make a probabilistic approach to design appropriate.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Li, Lu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 169-179). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

Chiu Pik Ki Becky. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 112-124). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgements --- p.v / Table of Contents --- p.vi / List of Tables --- p.x / List of Figures --- p.xi / List of Plates --- p.xii / Chapter Chapter One --- introduction / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Trends in slope design --- p.2 / Chapter 1.3 --- Bioengineering practices --- p.3 / Chapter 1.4 --- Factors affecting slope vegetation growth --- p.4 / Chapter 1.5 --- Conceptual framework of the study --- p.5 / Chapter 1.6 --- Objectives of the study --- p.8 / Chapter 1.7 --- Significance of the study --- p.9 / Chapter 1.8 --- Organization of the thesis --- p.9 / Chapter Chapter two --- Literature Review / Chapter 2.1 --- Introduction --- p.11 / Chapter 2.2 --- Slope bioengineering practices --- p.12 / Chapter 2.3 --- Local techniques --- p.14 / Chapter 2.4 --- Factors affecting performance of slope --- p.19 / Chapter 2.4.1 --- Species selection --- p.19 / Chapter 2.4.2 --- Site characteristics --- p.21 / Chapter 2.4.3 --- Physical properties of growth medium --- p.21 / Chapter 2.4.4 --- Nutrients and fertilization --- p.23 / Chapter 2.4.5 --- Water and irrigation --- p.25 / Chapter 2.4.6 --- Management --- p.28 / Chapter 2.5 --- Summary --- p.28 / Chapter chapter Three --- Common Slope Bioengineering Techniques in Hong Kong / Chapter 3.1 --- Introduction --- p.29 / Chapter 3.2 --- Study sites --- p.31 / Chapter 3.3 --- Methodology --- p.34 / Chapter 3.3.1 --- In situ substrate measurements --- p.34 / Chapter 3.3.2 --- Substrate sampling --- p.35 / Chapter 3.3.3 --- Laboratory analysis --- p.35 / Chapter 3.3.4 --- Vegetation performance --- p.39 / Chapter 3.3.5 --- Statistical analysis --- p.39 / Chapter 3.4 --- Results and discussion --- p.40 / Chapter 3.4.1 --- Physical properties of substrates --- p.40 / Chapter 3.4.2 --- Chemical properties of substrates --- p.42 / Chapter 3.4.3 --- Vegetation performance --- p.48 / Chapter 3.5 --- Summary --- p.55 / Chapter chapter Four --- Substrate Properties and Nutrient Dynamics / Chapter 4.1 --- Introduction --- p.57 / Chapter 4.2 --- Experimental design of trial plots --- p.58 / Chapter 4.3 --- Methodology --- p.62 / Chapter 4.3.1 --- Substrate sampling and measurement --- p.62 / Chapter 4.3.2 --- Laboratory analysis --- p.63 / Chapter 4.3.3 --- Vegetation coverage --- p.63 / Chapter 4.3.4 --- Statistical analysis --- p.64 / Chapter 4.4 --- Results and discussion --- p.64 / Chapter 4.4.1 --- General substrate properties --- p.64 / Chapter 4.4.2 --- Seasonal variation in substrate properties --- p.68 / Chapter 4.4.3 --- Comparison between hydro-mulching and fibered-soil --- p.71 / Chapter 4.4.4 --- Nutrients and vegetation performance --- p.72 / Chapter 4.5 --- Summary --- p.72 / Chapter chapter Five --- Effect of Water and Management Practices on Slope Vegetation / Chapter 5.1 --- Introduction --- p.74 / Chapter 5.2 --- Rationale of the experiment --- p.77 / Chapter 5.2.1 --- Substrate thickness --- p.77 / Chapter 5.2.2 --- Irrigation --- p.78 / Chapter 5.2.3 --- Trimming --- p.78 / Chapter 5.2.4 --- Potential revegetation species besides grasses --- p.78 / Chapter 5.3 --- Methodology --- p.80 / Chapter 5.3.1 --- In situ moisture measurement --- p.81 / Chapter 5.3.2 --- Vegetation coverage --- p.81 / Chapter 5.3.3 --- Statistical analysis --- p.81 / Chapter 5.4 --- Results and discussion --- p.82 / Chapter 5.4.1 --- Dynamics of water on slopes --- p.82 / Chapter 5.4.2 --- Water content and vegetation coverage --- p.85 / Chapter 5.4.3 --- Vegetation and rooting depth --- p.89 / Chapter 5.4.4 --- Vegetal response to management practices --- p.90 / Chapter 5.4.5 --- Species trial --- p.90 / Chapter 5.4.6 --- Invasion of species --- p.92 / Chapter 5.5 --- Summary --- p.92 / Chapter Chapter Six --- Limitations of Present Bioengineering Techniques / Chapter 6.1 --- Introduction --- p.94 / Chapter 6.2 --- Physical setting --- p.94 / Chapter 6.2.1 --- Steep gradient --- p.94 / Chapter 6.2.2 --- Shotcreted slope surface --- p.94 / Chapter 6.3 --- Substrate properties --- p.95 / Chapter 6.3.1 --- Substrate thickness --- p.95 / Chapter 6.3.2 --- Compaction --- p.96 / Chapter 6.3.3 --- Presence of wire mesh --- p.96 / Chapter 6.3.4 --- Heterogeneous properties --- p.97 / Chapter 6.3.5 --- Highly organic peat moss composition and C:N ratios --- p.97 / Chapter 6.4 --- Water stress --- p.98 / Chapter 6.5 --- Vegetation on slopes --- p.99 / Chapter 6.5.1 --- Species selection --- p.99 / Chapter 6.5.2 --- Isolation from natural vegetation --- p.100 / Chapter 6.6 --- Management and maintenance --- p.100 / Chapter 6.6.1 --- Timing of hydroseeding and transplanting --- p.100 / Chapter 6.6.2 --- Maintenance requirements --- p.101 / Chapter 6.6.3 --- Poor workmanship --- p.101 / Chapter 6.7 --- Ultimate goal of slope bioengineering --- p.102 / Chapter 6.8 --- Summary --- p.102 / Chapter Chapter Seven --- Conclusion / Chapter 7.1 --- Summary of major findings --- p.104 / Chapter 7.2 --- Implications of the study --- p.106 / Chapter 7.2.1 --- Use of exotic grasses and naturalness of bioengineered slopes --- p.106 / Chapter 7.2.2 --- Substrate thickness --- p.107 / Chapter 7.2.3 --- "Irrigation under the principle of ""low maintenance""" --- p.108 / Chapter 7.3 --- Limitations of the study --- p.108 / Chapter 7.4 --- Suggestions for further research --- p.110 / References --- p.112 / Appendices --- p.125

Volume 2 contains [51] coloured plates and [13] folded charts. / Bibliography : leaves 258-281. / 2 v. (xvi, 281 leaves, [51] leaves of plates) : col. ill., maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1993

Specialized techniques are needed to solve global optimization problems, due to the existence of multiple local optima or numerical noise in the objective function. The complexity of the problem is aggravated when discontinuities and constraints are present, or when evaluation of the objective function is computationally expensive. The global (minimization) programming problem is defined as finding the variable set for which the objective function obtains not only a local minimum, but also the smallest value, the global minimum. From a mathematical point of view, the global programming problem is essentially unsolvable, due to a lack of mathematical conditions characterizing the global optimum. In this study, the unconstrained global programming problem is addressed using a number of novel heuristic approaches. Firstly, a probabilistic global stopping criterion is presented for multi-start algorithms. This rule, denoted the unified Bayesian stopping criterion, is based on the single mild assumption that the probability of convergence to the global minimum is comparable to the probability of convergence to any other local minimum. This rule was previously presented for use in combination with a specific global optimization algorithm, and is now shown to be effective when used in a general multi-start approach. The suitability of the unified Bayesian stopping criterion is demonstrated for a number of algorithms using standard test functions. Secondly, multi-start global optimization algorithms based on multiple local searches, com¬bined with the unified Bayesian stopping criterion, are presented. Numerical results reveal that these simple multi-start algorithms outperform a number of leading contenders. Thirdly, parallelization of the sequential multi-start algorithms is shown to effectively re¬duce the apparent computational time associated with solving expensive global programming problems. Fourthly, two algorithms simulating natural phenomena are implemented, namely the rel¬atively new particle swarm optimization method and the well known genetic algorithm. For the current implementations, numerical results indicate that the computational effort associated with these methods is comparable. Fifthly, the observation that no single global optimization algorithm can consistently out¬perform any other algorithm when a large set of problems is considered, leads to the de¬velopment of a parallel competing algorithm infrastructure. In this infrastructure different algorithms, ranging from deterministic to stochastic, compete simultaneously for a contri¬bution to the unified Bayesian global stopping criterion. This is an important step towards facilitating an infrastructure that is suitable for a range of problems in different classes. In the sixth place, the constrained global programming problems is addressed using con¬strained algorithms in the parallel competing algorithm infrastructure. The developed methods are extensively tested using standard test functions, for both serial and parallel implementations. An optimization procedure is also presented to solve the slope stability problem faced in civil engineering. This new procedure determines the factor of safety of slopes using a global optimization approach. / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted