This dissertation, "Failure of Saturated Sandy Soils Due to Increase in Pore Water Pressure" by Sainulabdeen Mohamed, Junaideen, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled FAILURE OF SATURATED SANDY SOILS DUE TO INCREASE IN PORE WATER PRESSURE Submitted by Sainulabdeen Mohamed Junaideen for the degree of Doctor of Philosophy at The University of Hong Kong in January 2005 Most slope failures are attributable to an increase in pore water pressure during or following periods of intense rainfall. These failures are induced by reduction of effective confining stress whilst shear stress remains nearly constant, as opposed to the failures caused by increasing shear stress in standard laboratory tests. Although the significance of the different stress paths has been recognized, studies of soil behaviour in constant shear stress path, which closely represents conditions during a rise in pore water pressure, have been scarce. Furthermore, past studies suggest that the steady state line is not unique and the volume change tendency of soils is stress path-dependent. These findings make it difficult to predict the behaviour of soils during a rise in pore water pressure. Nevertheless, there is an urgent need to study such behaviour as rainfall-induced slope failures occur in various types of soils and occasionally turn into debris flows, posing a serious risk to both life and property. The principal objectives of this study were to characterize the soil behaviour during a rise in pore water pressure and to examine existing theories in respect of the instability of soils. A comprehensive testing program, which included load-controlled constant shear stress path tests and standard strain rate-controlled undrained tests, was conducted on completely decomposed granites. Specimens prepared at various densities were used for the tests. A fast data-acquisition system was utilized so that readings during rapid deformations could also be recorded. The study's findings showed that the steady state line was reasonably unique for a given soil and that the volume change tendency was not path-dependent. The steady state concept could be used to explain soil behaviour during a rise in pore water pressure; and the difference between the current void ratio and the void ratio at the steady state at the current stress level could be used to characterize soil behaviour. Instability of the soils occurs at higher stress ratios in the constant shear stress path than in the undrained loading stress path. To define the instability state due to a rise in pore water pressure, the post-peak portion of undrained effective stress paths is of very limited use for this type of soil. Conversely, using the constant shear test results, the instability state can be adequately defined for soils of various densities. Furthermore, the concept of collapse surface can be extended to define the instability state of soils of various densities due to undrained loading. DOI: 10.5353/th_b3070854 Subjects: Shear strength of soils Slopes (Soil mechanics) Sandy soils - Testing

Sand, clay and rock have to be excavated for a variety of purposes, such as dredging, trenching, mining (including deep sea mining), drilling, tunnel boring and many other applications. Many excavations take place on dry land, but they are also frequently required in completely saturated conditions, and the methods necessary to accomplish them consequently vary widely. This book provides an overview of cutting theories. It begins with a generic model, valid for all types of soil (sand, clay and rock), and continues with the specifics of dry sand, water-saturated sand, clay, atmospheric rock and hyperbaric rock. Small blade angles and large blade angles are discussed for each soil type, and for each case considered the equations/model for cutting forces, power and specific energy are given. With models verified by laboratory research, principally from the Delft University of Technology, and data from other recognized sources, this book will prove an invaluable reference for anybody whose work involves major excavations of any kind.

While many introductory texts on soil mechanics are available, most are either lacking in their explanations of soil behavior or provide far too much information without cogent organization. More significantly, few of those texts go beyond memorization of equations and numbers to provide a practical understanding of why and how soil mechanics work.

Progressive failure has been a classical problem in the field of geotechnical engineering and has attracted considerable attention in connection with slope stability and foundation problems. It is associated with strain localization or shear banding and is also related to damage in material structures. As knowledge of the progressive failure mechanism increases, it is now necessary to establish effective communications between researchers and engineers. The International Symposium on Deformation and Progressive Failure in Geomechanics provided an opportunity for discussing recent advances in this area. A total of 136 papers were contributed from 22 countries. As well as these, the symposium proceedings also contain 8 interim technical reports on the subject by the members of the Asian Technical Committee of the International Society for Soil Mechanics and Foundation Engineering and the Japanese Geotechnical Society National Committee on Progressive Failure in Geo-structures.

Landslides triggered by rainfall cause significant damage to infrastructure annually and affect many lives in several parts of the world, including Switzerland. These landslides are initiated by a decrease in the effective stresses, and hence the shear strength of the soil, as a result of the increase in pore water pressure. The frequency of their occurrence is directly affected by the climatic and hydrological conditions in the region. Therefore, it is expected that the predicted rise in the number of extreme meteorological events, accompanied by the concentration of population and infrastructure in mountainous regions, will result in an increased number of casualties associated with landslides in the future. The main goal of this doctoral project was to study the effects of pore water pressure perturbations on the stability of unsaturated silty sand slopes and to investigate the mechanisms leading to the initiation and propagation of the shear deformations and eventually possible rapid mass movements. The behaviour of the test slope prior to the failure induced by the artificial rainfall event was investigated using analytical and numerical methods. The mechanical features of unsaturated soils and reinforcing effects of the vegetation were implemented in 2D and 3D limit equilibrium analysis. The possible depth of the failure surface was calculated based on these simplified models and was compared with the depth of the real failure surface in the landslide triggering experiment. The soil-bedrock interactions, in terms of the pattern of pore pressure distributions and their influence on stabilising or destabilising the slope, were studied and the results were compared to the field measurements.

This book presents a one-stop reference to the empirical correlations used extensively in geotechnical engineering. Empirical correlations play a key role in geotechnical engineering designs and analysis. Laboratory and in situ testing of soils can add significant cost to a civil engineering project. By using appropriate empirical correlations, it is possible to derive many design parameters, thus limiting our reliance on these soil tests. The authors have decades of experience in geotechnical engineering, as professional engineers or researchers. The objective of this book is to present a critical evaluation of a wide range of empirical correlations reported in the literature, along with typical values of soil parameters, in the light of their experience and knowledge. This book will be a one-stop-shop for the practising professionals, geotechnical researchers and academics looking for specific correlations for estimating certain geotechnical parameters. The empirical correlations in the forms of equations and charts and typical values are collated from extensive literature review, and from the authors' database.

This book presents 09 keynote and invited lectures and 177 technical papers from the 4th International Conference on Geotechnics for Sustainable Infrastructure Development, held on 28-29 Nov 2019 in Hanoi, Vietnam. The papers come from 35 countries of the five different continents, and are grouped in six conference themes: 1) Deep Foundations; 2) Tunnelling and Underground Spaces; 3) Ground Improvement; 4) Landslide and Erosion; 5) Geotechnical Modelling and Monitoring; and 6) Coastal Foundation Engineering. The keynote lectures are devoted by Prof. Harry Poulos (Australia), Prof. Adam Bezuijen (Belgium), Prof. Delwyn Fredlund (Canada), Prof. Lidija Zdravkovic (UK), Prof. Masaki Kitazume (Japan), and Prof. Mark Randolph (Australia). Four invited lectures are given by Prof. Charles Ng, ISSMGE President, Prof.Eun Chul Shin, ISSMGE Vice-President for Asia, Prof. Norikazu Shimizu (Japan), and Dr.Kenji Mori (Japan).

Doctoral Thesis / Dissertation from the year 2010 in the subject Engineering - Geotechnology, , course: Civil Engineering, language: English, abstract: With growing infrastructure developments in hilly areas and due to economical constraints of using locally available rockfill materials for construction of embankments, practicing engineers must be acquainted with geotechnical response of non-conventional granular soils. These materials are most likely to disintegrate with time due to physical and chemical weathering. In general, the laboratory investigations on durability characteristics of such materials are only made through simple slaking tests. However, studies examining the effects of slaking-induced disintegration of soil grains on the geotechnical engineering analysis and design parameters are rather limited. This is essentially due to the reason that the grains of standard laboratory sands are mostly durable and hence, the stress-strain response is considered to be unaffected by the presence of water. In order to explore the possible effects of deterioration of soil grains on static and dynamic properties of granular soils, a series of consolidated drained torsional shear tests on various crushed soft rocks were performed under saturated and dry conditions and compared with a well reported Toyoura silica sand consisting of durable grains. Due to the sensitivity of crushed rockfill to deteriorate upon water-submergence, test under dry conditions represented the response of a soil with intact grains, whereas a similar test under saturated condition simulated the potential reduction in strength and stiffness of the soil with time. From the grain size distributions determined after each test, a degradation index was defined to quantify the degree of disintegration of grains. Strength and deformation properties determined from monotonic as well as cyclic shear tests were then compared with this index. Possible correlations of water-induced deterioration of soil grains with consolidation behaviour, peak shear strengths, friction angles, dynamic shear stiffness, and volume-change characteristics during shearing were explored. In addition, the effects of confining stress and shear strain level on particle breakage were also investigated. It was concluded that time-dependent characterization of rockfill materials by monitoring the degree of deterioration can be helpful to avoid catastrophic geotechnical failures. Nonetheless, this study is a caution to conventional soil mechanics in which decay of grains and loss of soil strength with time are often uncared.

Unsaturated Soil Mechanics is the first book to provide a comprehensive introduction to the fundamental principles of unsaturated soil mechanics. * Offers extensive sample problems with an accompanying solutions manual. * Brings together the rapid advances in research in unsaturated soil mechanics in one focused volume. * Covers advances in effective stress and suction and hydraulic conductivity measurement.