Thesis (M. Sc.)--University of Hong Kong, 2003.

The purpose of this thesis is to show, using computer simulation of flow systems in a variety of hypothetical slopes, how different geological environments affect the groundwater flow regime, which in turn is fundamental to the stability of a slope. Galerkin's method is used to derive a finite element program to model two dimensional, saturated, steady state flow through anisotropic and heterogeneous rigid porous media. An understanding of the regional geology is required in order to understand the regional flow system. The following points are illustrated. a. In anisotropic media, the most adverse groundwater condition for slope stability occurs when the major axis of conductivity lies down the dip of the slope. b. Depending on their characteristics, faults, contacts and dykes can be either detrimental or favourable in their effect on the flow system. Careful field investigation is required to establish that effect. c. Deep weathering commonly causes a confining zone of low conductivity, a situation very detrimental to stability. d. Stress relief fractures on valley walls can adversely influence the effect of groundwater on stability. e. A regional aquifer can cause high pore pressure development beneath a valley. f. Fluctuations in the regional groundwater system can cause instability in Pleistocene terraces. g. The presence of an underlying less conductive zone or unit can have an adverse effect on the flow system. Conductivity contrasts of less than two orders of magnitude can cause pore pressure development critical to stability. Three other points are demonstrated which have direct application to slope stability analysis and control. 1. The pressure head distribution on rock wedges can be nonlinear rather than the commonly assumed linear distribution. 2. The introduction of a reservoir at the toe of a slope can influence the groundwater regime well above the reservoir surface; even a low reservoir can cause, the change required to cause instability. 3. Piezometric measurements and drainage systems must penetrate through any less conductive unit that might be acting as a slide plane. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

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

Mana computer programs have been developed for solving slope stability problems. Since slope stability problems can be characterized as optimization problems, many optimization techniques can be used for searching for the lowest safety factor for a given problem and the corresponding critical slip surface. Most of the slope stability programs use the direct search method which requires only the function value (i.e., safety factor value). In this thesis, a new optimization technique, the Broyden (1970), Fletcher (1970), Goldfarb (1970), and Shanno (1970) (BFGS) quasi-Newton optimization method, is used in conjunction with the STABR program of Lefebvre (1971) to solve slope stability problems. This method of optimization requires the function value and the first derivative value, which can be found by the finite difference method. A new program CSLIP3, incorporating the BFGS technique, is used to solve a variety of realistic slope stability problems. It is determined that CSLIP3 is reliable and efficient.

published_or_final_version / Civil Engineering / Master / Master of Science in Engineering

published_or_final_version / Applied Geosciences / Master / Master of Science

published_or_final_version / Applied Geosciences / Master / Master of Science

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.

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