DOCSLIB.ORG

UNIVERSITY of CALIFORNIA Santa Barbara an Analysis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
UNIVERSITY of CALIFORNIA Santa Barbara an Analysis UNIVERSITY OF CALIFORNIA Santa Barbara An Analysis of Landslide Risk and Vulnerability in Distinct Realities: Low-Income Communities in Brazil and a Wealthy Community in the United States A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Geography by Erica Akemi Goto Committee in charge: Professor Keith Clarke, Committee Co-Chair Professor Edward Keller, Committee Co-Chair Professor Hugo Loáiciga Professor Summer Gray March 2021 The dissertation of Erica Akemi Goto is approved. _____________________________________________ Hugo Loáiciga _____________________________________________ Summer Gray _____________________________________________ Keith Clarke, Committee Co-Chair _____________________________________________ Edward Keller, Committee Co-Chair February 2021 An Analysis of Landslide Risk and Vulnerability in Distinct Realities: Low-Income Communities in Brazil and a Wealthy Community in the United States Copyright © 2020 by Erica Akemi Goto iii ACKNOWLEDGMENTS I would like to thank everyone that made this research possible. Many thanks to Dr. Eduardo Soares Macedo who helped me with the AHP variables and helped me reach out to other experts, to all the other IPT technicians who took the time to answer the AHP questionnaire, to all the technicians at the São Bernardo do Campo Municipality, especially Luiz Antonio Neves Costa and Fabiana Mendez de Souza, who guided me on choosing the best neighborhood for conducting my research in their city and local residents, who kept me safe during the fieldwork, to the Laboratório de Mecânica de Rochas of the University of São Paulo, especially Eduardo Carlos Heitzmann who guided me in the lab and Maria Eugenia Boscov who allow me to use their laboratory to perform part of my research, and to colleagues and friends who helped me conduct fieldwork at São Bernardo do Campo (Paul Alessio, Lucas Ciola, Carlos Eduardo Silva, Mauricio Hirata, Danilo Lomonaco Vitorelli). I would like to thank my lab colleagues who supported my work by exchanging ideas and forming a writing group. Special thanks to Rafael, Marcela, Haiyun, and Mike. I would like to thank my committee members, Hugo Loáiciga and Summer Gray, for taking the time to meet with me, criticize my work, and give suggestions. I also would like to thank Summer Gray for the opportunity to work closely with her, mentor me, and offer support during difficult times during the last two years. A special thank you to Robby Nadler, who helped me in my writing trajectory and always knew when and how to criticize in a nice way. Special thanks to my advisors, Keith Clarke and Edward Keller, for guiding and supporting me during my research. I would like to thank my parents and my sister for supporting me in all moments. I also would like to thank the Brazilian Government and the Science Without Borders Fellowship that supported me financially for 4 years. iv VITA OF ERICA AKEMI GOTO December 2020 EDUCATION Bachelor of Social Communication, University of Sao Paulo, Sao Paulo, 2006 Bachelor of Teaching Geoscience and Environmental Education, University of Sao Paulo, Sao Paulo, 2013 Master of Geoscience, University of Campinas, Campinas, 2014 Doctor in Geography, University of California, Santa Barbara, June 2020 (expected) PROFESSIONAL EMPLOYMENT Summer 2020: Research Assistant, Department of East Asian Language & Cultural Studies, University of California, Santa Barbara Summer 2000, 2019, 2018: Graduate Student Research, Earth Research Institute – University of California, Santa Barbara 2019-2020: Teaching Assistant, Department of Environmental Studies, University of California, Santa Barbara 2020: Instructor, Department of Environmental Studies, University of California, Santa Barbara 2015-2018: Teaching Assistant, Department of Geographyt, University of California, Santa Barbara PUBLICATIONS “Ordinal Logistic Regression to automatic classify shallow landslide risk level in Sao Paulo city, Brazil,” Landslide inventory mapping and vulnerability assessment (2020) “A mixed-methods approach to understanding debris flow vulnerability in Montecito, CA. Landslide inventory mapping and vulnerability assessment,” Landslide inventory mapping and vulnerability assessment (2020) “Using Expert’s Knowledge based on the Analytical Hierarchical Process (AHP) and the Brazilian Government Methodology (BGM) to map and compute the level of risk for shallow landslides in Brazil.,” submitted (2019) “A tool to compute the landslide degree of risk using R-Studio and R-Shiny,” Proceedings of the 4th ACM SIGSPATIAL International Workshop on Safety and Resilience (2018), ACM, New York. v AWARDS WLF5 Travel and Registration Support, 2019 Conference Grant - Dangermond Travel Funds Award, University of California, Santa Barbara, 2018, 2019 Student best paper - 4th ACM SIGSPATIAL International Workshop on Safety and Resilience, 2018 Conference Grant - UCSB GSA,2018 Summer fellowship – Earth Research Institute (ERI), 2016, 2017 Field Work Grant - Leal Anne Kerry Mertes Scholarship Award, 2016-2017 Ph.D. fellowship - Science Without Borders, CAPES, Brazilian Government, 2014-2018 FIELDS OF STUDY Major Field: Geography vi ABSTRACT by Erica Akemi Goto Landslides are natural events that occur in many parts of the world in both developed and developing countries. They can be triggered by rainfall, earthquakes, volcanos, and a combination of post-fire and rainfall. However, the impact they cause in a community can be very different, based on how the community can anticipate and respond. They can cause material losses and some minor property damage, but also, they can become natural disasters, resulting in significant material and human losses. One way to avoid and mitigate landslide disasters is by implementing Disaster Risk Reduction measures, such as risk mapping or developing an evacuation plan. These measures help municipalities plan before an event occurs, thereby protecting their communities and being proactive. In this doctoral dissertation, the focus is on two of these Disaster Risk Reduction measures: risk and vulnerability assessments. In the first part, the study is conducted in the Metropolitan Area of Sao Paulo, Brazil. In these urban areas, shallow landslides are frequent in low-income neighborhoods on hillslopes, especially during summer months, when intense rainfall frequently occurs. Chapters 2 and 3 propose two distinct methodologies to quantify an inventory-based shallow landslide risk mapping. The quantification is intended to reduce bias and standardize risk mapping methodology. In chapter 2, experts’ knowledge and the Analytical Hierarchical Process (AHP) method is applied to compute weights for variables, and application is developed and used to calculate the risk level automatically. In this study, variables that vii illustrate instability in the terrain were the ones with the highest contribution for a higher risk. In chapter 3, a large dataset from a previous mapping of Sao Paulo city and Ordinal Logistic Regression (OLR) was used to select essential variables and to compute their weights. The equation calculated can be used in the developed application to compute the risk level automatically. In chapter 4, a spatial analysis of the slope stability using SHALSTAB and Factor of Safety and saturated hydraulic conductivity was computed in two hillslopes of São Bernardo do Campo, in the Metropolitan area of Sao Paulo. In one of these sites, the hillslope is disturbed by human activities (previous homes, cut and filling, landfill), and in the second site, the hillslope is undisturbed. The saturated hydraulic conductivity and the slope stability analysis illustrate that the disturbed site has less homogeneous soil than does the undisturbed site. Additionally, based on the soil characteristics and results from SHALSTAB and Factor of Safety analysis, the undisturbed hillslope is more stable than the disturbed hillslope. The second part of the study was conducted in Montecito, California. The study was proposed after the 2018 Montecito debris flows that killed 23 people and damaged more than 400 homes. In this study, I used a parallel mixed-methods approach and a temporal-spatial analysis to understand the main factors that made the community vulnerable to debris-flows and to determine who were the most vulnerable people. The study concludes that the most vulnerable people were informal workers (gardens, housekeepers, caretakers, nannies), renters, and residents of areas that were in the voluntary evacuation zone. Lack of education about debris-flows and previous debris-flows in the region by the community increased the vulnerability of the entire community. Moreover, the institutional vulnerability was high for the entire community, but county measures in the aftermath contributed to the community viii resilience. Keywords: landslide, debris-flows, risk, landslide assessment, weights of evidence, SHALSTAB, vulnerability, AHP, OLR, mixed-methods. ix TABLE OF CONTENTS ACKNOWLEDGMENTS ..................................................................................................... iv ABSTRACT ........................................................................................................................... vii ABBREVIATIONS ............................................................................................................... xii EQUATION SYMBOLS ..................................................................................................... xiii LIST OF EQUATIONS ......................................................................................................
Load more

Recommended publications
  • Hydraulic Conductivity and Shear Strength of Dune Sand–Bentonite Mixtures
    Hydraulic Conductivity and Shear Strength of Dune Sand–Bentonite Mixtures M. K. Gueddouda Department of Civil Engineering, University Amar Teledji Laghouat Algeria [email protected] [email protected] Md. Lamara Department of Civil Engineering, University Amar Teledji Laghouat Algeria [email protected] Nabil Aboubaker Department of Civil Engineering, University Aboubaker Belkaid, Tlemcen Algeria [email protected] Said Taibi Laboratoire Ondes et Milieux Complexes, CNRS FRE 3102, Univ. Le Havre, France [email protected] [email protected] ABSTRACT Compacted layers of sand-bentonite mixtures have been proposed and used in a variety of geotechnical structures as engineered barriers for the enhancement of impervious landfill liners, cores of zoned earth dams and radioactive waste repository systems. In the practice we will try to get an economical mixture that satisfies the hydraulic and mechanical requirements. The effects of the bentonite additions are reflected in lower water permeability, and acceptable shear strength. In order to get an adequate dune sand bentonite mixtures, an investigation relative to the hydraulic and mechanical behaviour is carried out in this study for different mixtures. According to the result obtained, the adequate percentage of bentonite should be between 12% and 15 %, which result in a hydraulic conductivity less than 10–6 cm/s, and good shear strength. KEYWORDS: Dune sand, Bentonite, Hydraulic conductivity, shear strength, insulation barriers INTRODUCTION Rapid technological advances and population needs lead to the generation of increasingly hazardous wastes. The society should face two fundamental issues, the environment protection and the pollution risk control.
    [Show full text]
  • Hydraulic Conductivity of Composite Soils
    This is a repository copy of Hydraulic conductivity of composite soils. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/119981/ Version: Accepted Version Proceedings Paper: Al-Moadhen, M orcid.org/0000-0003-2404-5724, Clarke, BG orcid.org/0000-0001-9493-9200 and Chen, X orcid.org/0000-0002-2053-2448 (2017) Hydraulic conductivity of composite soils. In: Proceedings of the 2nd Symposium on Coupled Phenomena in Environmental Geotechnics (CPEG2). 2nd Symposium on Coupled Phenomena in Environmental Geotechnics (CPEG2), 06-07 Sep 2017, Leeds, UK. This is an author produced version of a paper presented at the 2nd Symposium on Coupled Phenomena in Environmental Geotechnics (CPEG2), Leeds, UK 2017. Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Proceedings of the 2nd Symposium on Coupled Phenomena in Environmental Geotechnics (CPEG2), Leeds, UK 2017 Hydraulic conductivity of composite soils Muataz Al-Moadhen, Barry G.
    [Show full text]
  • Vertical Hydraulic Conductivity of Soil and Potentiometric Surface of The
    Vertical Hydraulic Conductivity of Soil and Potentiometric Surface of the Missouri River Alluvial Aquifer at Kansas City, Missouri and Kansas August 1992 and January 1993 By Brian P. Kelly and Dale W. Blevins__________ U.S. GEOLOGICAL SURVEY Open-File Report 95-322 Prepared in cooperation with the MID-AMERICA REGIONAL COUNCIL Rolla, Missouri 1995 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director For additional information Copies of this report may be write to: purchased from: U.S. Geological Survey District Chief Earth Science Information Center U.S. Geological Survey Open-File Reports Section 1400 Independence Road Box 25286, MS 517 Mail Stop 200 Denver Federal Center Rolla, Missouri 65401 Denver, Colorado 80225 II Geohydrologic Characteristics of the Missouri River Alluvial Aquifer at Kansas City, Missouri and Kansas CONTENTS Glossary................................................................................................................~^ V Abstract.................................................................................................................................................................................. 1 Introduction ................................................................................................................................................................^ 1 Study Area..................................................................................................................................................................
    [Show full text]
  • Transmissivity, Hydraulic Conductivity, and Storativity of the Carrizo-Wilcox Aquifer in Texas
    Technical Report Transmissivity, Hydraulic Conductivity, and Storativity of the Carrizo-Wilcox Aquifer in Texas by Robert E. Mace Rebecca C. Smyth Liying Xu Jinhuo Liang Robert E. Mace Principal Investigator prepared for Texas Water Development Board under TWDB Contract No. 99-483-279, Part 1 Bureau of Economic Geology Scott W. Tinker, Director The University of Texas at Austin Austin, Texas 78713-8924 March 2000 Contents Abstract ................................................................................................................................. 1 Introduction ...................................................................................................................... 2 Study Area ......................................................................................................................... 5 HYDROGEOLOGY....................................................................................................................... 5 Methods .............................................................................................................................. 13 LITERATURE REVIEW ................................................................................................... 14 DATA COMPILATION ...................................................................................................... 14 EVALUATION OF HYDRAULIC PROPERTIES FROM THE TEST DATA ................. 19 Estimating Transmissivity from Specific Capacity Data.......................................... 19 STATISTICAL DESCRIPTION ........................................................................................
    [Show full text]
  • Method 9100: Saturated Hydraulic Conductivity, Saturated Leachate
    METHOD 9100 SATURATED HYDRAULIC CONDUCTIVITY, SATURATED LEACHATE CONDUCTIVITY, AND INTRINSIC PERMEABILITY 1.0 INTRODUCTION 1.1 Scope and Application: This section presents methods available to hydrogeologists and and geotechnical engineers for determining the saturated hydraulic conductivity of earth materials and conductivity of soil liners to leachate, as outlined by the Part 264 permitting rules for hazardous-waste disposal facilities. In addition, a general technique to determine intrinsic permeability is provided. A cross reference between the applicable part of the RCRA Guidance Documents and associated Part 264 Standards and these test methods is provided by Table A. 1.1.1 Part 264 Subpart F establishes standards for ground water quality monitoring and environmental performance. To demonstrate compliance with these standards, a permit applicant must have knowledge of certain aspects of the hydrogeology at the disposal facility, such as hydraulic conductivity, in order to determine the compliance point and monitoring well locations and in order to develop remedial action plans when necessary. 1.1.2 In this report, the laboratory and field methods that are considered the most appropriate to meeting the requirements of Part 264 are given in sufficient detail to provide an experienced hydrogeologist or geotechnical engineer with the methodology required to conduct the tests. Additional laboratory and field methods that may be applicable under certain conditions are included by providing references to standard texts and scientific journals. 1.1.3 Included in this report are descriptions of field methods considered appropriate for estimating saturated hydraulic conductivity by single well or borehole tests. The determination of hydraulic conductivity by pumping or injection tests is not included because the latter are considered appropriate for well field design purposes but may not be appropriate for economically evaluating hydraulic conductivity for the purposes set forth in Part 264 Subpart F.
    [Show full text]
  • Comparison of Hydraulic Conductivities for a Sand and Gravel Aquifer in Southeastern Massachusetts, Estimated by Three Methods by LINDA P
    Comparison of Hydraulic Conductivities for a Sand and Gravel Aquifer in Southeastern Massachusetts, Estimated by Three Methods By LINDA P. WARREN, PETER E. CHURCH, and MICHAEL TURTORA U.S. Geological Survey Water-Resources Investigations Report 95-4160 Prepared in cooperation with the MASSACHUSETTS HIGHWAY DEPARTMENT, RESEARCH AND MATERIALS DIVISION Marlborough, Massachusetts 1996 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director For additional information write to: Copies of this report can be purchased from: Chief, Massachusetts-Rhode Island District U.S. Geological Survey U.S. Geological Survey Earth Science Information Center Water Resources Division Open-File Reports Section 28 Lord Road, Suite 280 Box 25286, MS 517 Marlborough, MA 01752 Denver Federal Center Denver, CO 80225 CONTENTS Abstract.......................................................................................................................^ 1 Introduction ..............................................................................................................................................................^ 1 Hydraulic Conductivities Estimated by Three Methods.................................................................................................... 3 PenneameterTest.............................................................^ 3 Grain-Size Analysis with the Hazen Approximation............................................................................................. 8 SlugTest...................................................^
    [Show full text]
  • The Influence of Horizontal Variability of Hydraulic Conductivity on Slope
    water Article The Influence of Horizontal Variability of Hydraulic Conductivity on Slope Stability under Heavy Rainfall Tongchun Han 1,2,* , Liqiao Liu 1 and Gen Li 1 1 Research Center of Costal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China; [email protected] (L.L.); [email protected] (G.L.) 2 Key Laboratory of Soft Soils and Geoenvironmental Engineering, Ministry of Education, Zhejiang University, Hangzhou 310058, China * Correspondence: [email protected] Received: 5 August 2020; Accepted: 10 September 2020; Published: 15 September 2020 Abstract: Due to the natural variability of the soil, hydraulic conductivity has significant spatial variability. In the paper, the variability of the hydraulic conductivity is described by assuming that it follows a lognormal distribution. Based on the improved Green–Ampt (GA) model of rainwater infiltration, the analytical expressions of rainwater infiltration into soil with depth and time under heavy rainfall conditions is obtained. The theoretical derivation of rainfall infiltration is verified by numerical simulation, and is used to quantitatively analyze the effect of horizontal variability of the hydraulic conductivity on slope stability. The results show that the variability of the hydraulic conductivity has a significant impact on rainwater infiltration and slope stability. The smaller the coefficient of variation, the more concentrated is the rainwater infiltration at the beginning of rainfall. Accordingly, the wetting front is more obvious, and the safety factor is smaller. At the same time, the higher coefficient of variation has a negative impact on the cumulative infiltration of rainwater. The larger the coefficient of variation, the lower the cumulative rainwater infiltration.
    [Show full text]
  • Negative Correlation Between Porosity and Hydraulic Conductivity in Sand-And-Gravel Aquifers at Cape Cod, Massachusetts, USA
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by DigitalCommons@University of Nebraska University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln USGS Staff -- Published Research US Geological Survey 2005 Negative correlation between porosity and hydraulic conductivity in sand-and-gravel aquifers at Cape Cod, Massachusetts, USA Roger H. Morin Denver Federal Center, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/usgsstaffpub Part of the Earth Sciences Commons Morin, Roger H., "Negative correlation between porosity and hydraulic conductivity in sand-and-gravel aquifers at Cape Cod, Massachusetts, USA" (2005). USGS Staff -- Published Research. 358. https://digitalcommons.unl.edu/usgsstaffpub/358 This Article is brought to you for free and open access by the US Geological Survey at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in USGS Staff -- Published Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Journal of Hydrology 316 (2006) 43–52 www.elsevier.com/locate/jhydrol Negative correlation between porosity and hydraulic conductivity in sand-and-gravel aquifers at Cape Cod, Massachusetts, USA Roger H. Morin* United States Geological Survey, Denver, CO 80225, USA Received 3 March 2004; revised 8 April 2005; accepted 14 April 2005 Abstract Although it may be intuitive to think of the hydraulic conductivity K of unconsolidated, coarse-grained sediments as increasing monotonically with increasing porosity F, studies have documented a negative correlation between these two parameters under certain grain-size distributions and packing arrangements. This is confirmed at two sites on Cape Cod, Massachusetts, USA, where groundwater investigations were conducted in sand-and-gravel aquifers specifically to examine the interdependency of several aquifer properties using measurements from four geophysical well logs.
    [Show full text]
  • Empirical Excess Pore Pressure Dissipation Model for Liquefiable Sands
    6th International Conference on Earthquake Geotechnical Engineering 1-4 November 2015 Christchurch, New Zealand Empirical Excess Pore Pressure Dissipation Model for Liquefiable Sands S.C. Chian1 ABSTRACT In the early phase of excess pore pressure dissipation, the excess pore pressure in a liquefied homogeneous soil stratum reduces most significantly at the base, leading to a curvature at the lower part of the initial isochrone while the upper half remains fairly unchanged. In the later phase, the curvature leaves the initial isochrone completely and progresses until excess pore pressure is fully dissipated. In this paper, a simplified exponential equation is introduced to capture the excess pore pressure dissipation over time. This equation is applied to several dynamic centrifuge tests and shown to depict a suitable fit to the dissipation time history over a wide range of hydraulic conductivity of sands. Introduction Soil liquefaction has been studied extensively over the past several decades since its field observation following the 1964 Niigata Earthquake. However, it still poses serious threats to infrastructure in earthquake prone areas to date, where liquefiable soil layers are present. This is evident in recent earthquakes such as the Christchurch Earthquake and the Great East Japan Earthquake in 2011. Numerous researchers have taken notice of the loss of shear strength due to generation of excess pore pressure during earthquake shaking, however not many have investigated the impact of dissipation of excess pore pressure as thoroughly. Severe ground displacement/settlement can occur during the dissipation of excess pore water pressure. This can lead to tilting of buildings, sliding/lowering of dam crest, lateral spreading of bridge abutment wall, etc.
    [Show full text]
  • Performance-Based Hydraulic Conductivity Models for Unbound Granular Materials
    Performance-Based Hydraulic Conductivity Models for Unbound Granular Materials Haithem Soliman, Ph.D. Assistant Professor Department of Civil & Geological Engineering University of Saskatchewan Email: [email protected] Ahmed Shalaby, P.Eng. Professor and Head Department of Civil Engineering University of Manitoba E-mail: [email protected] Paper prepared for presentation at the “Advanced Testing and Modeling of Road and Embankment Materials” Session of the 2016 Annual Conference of the Transportation Association of Canada Toronto, Ontario. 1 Abstract Specifications for unbound granular materials (UGM) must be based on the function of the unbound layer (drainable layer, high stiffness, or both). Using performance-based specifications that are based on laboratory performance of UGM (resilient modulus, permanent deformation, and permeability) provides durable and longer lasting unbound layers. This paper investigates the effect of fines content variation on the permeability (hydraulic conductivity) of two types of UGM, gravel and 100% crushed limestone. Hydraulic conductivity tests were conducted on compacted gravel UGM with 4.0% fines, 9.0% fines, and 14.5% fines. For 100% crushed limestone, hydraulic conductivity tests were conducted on compacted samples with 4.5% fines, 10.5% fines, and 16.0% fines. For gravel, the hydraulic conductivity decreased by 84% due to increasing fines content from 4.0% to 14.5%. For Limestone, the hydraulic conductivity decreased by 81% due to increasing fines content from 4.5% to 16.0%. For gradations with comparable fines content, limestone material showed higher hydraulic conductivity than that for gravel. The laboratory measured hydraulic conductivity was compared to Level 2 design inputs in the Mechanistic-Empirical Pavement Design Guide (Pavement ME).
    [Show full text]
  • Forecasting of Landslides Using Rainfall Severity and Soil Wetness: a Probabilistic Approach for Darjeeling Himalayas
    water Article Forecasting of Landslides Using Rainfall Severity and Soil Wetness: A Probabilistic Approach for Darjeeling Himalayas Minu Treesa Abraham 1 , Neelima Satyam 1 , Biswajeet Pradhan 1,2,3,* and Abdullah M. Alamri 4 1 Discipline of Civil Engineering, Indian Institute of Technology Indore, Madhya Pradesh 452020, India; [email protected] (M.T.A.); [email protected] (N.S.) 2 Centre for Advanced Modelling and Geospatial Information Systems (CAMGIS), Faculty of Engineering and Information Technology, University of Technology Sydney, Broadway, Sydney P.O. Box 123, Australia 3 Department of Energy and Mineral Resources Engineering, Sejong University, Choongmu-gwan, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Korea 4 Department of Geology & Geophysics, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; [email protected] * Correspondence: [email protected] Received: 18 February 2020; Accepted: 9 March 2020; Published: 13 March 2020 Abstract: Rainfall induced landslides are creating havoc in hilly areas and have become an important concern for the stakeholders and public. Many approaches have been proposed to derive rainfall thresholds to identify the critical conditions that can initiate landslides. Most of the empirical methods are defined in such a way that it does not depend upon any of the in situ conditions. Soil moisture plays a key role in the initiation of landslides as the pore pressure increase and loss in shear strength of soil result in sliding of soil mass, which in turn are termed as landslides. Hence this study focuses on a Bayesian analysis, to calculate the probability of occurrence of landslides, based on different combinations of severity of rainfall and antecedent soil moisture content.
    [Show full text]
  • Determining the Unsaturated Hydraulic Conductivity of a Compacted Sand-Bentonite Mixture Under Constant Volume and Free-Swell Conditions
    Determining the unsaturated hydraulic conductivity of a compacted sand-bentonite mixture under constant volume and free-swell conditions Y.J. Cui, A.M. Tang, C. Loiseau, P. Delage Université Paris Est, Ecole des ponts, I. Navier Corresponding author Prof. Yu-Jun Cui ENPC/CERMES 6 et 8 avenue Blaise Pascal, Cité Descartes, Champs-sur-Marne, 77455 MARNE-LA-VALLEE CEDEX 2, France. Tel: 33 1 64 15 35 50 Fax: 33 1 64 15 35 62 E-mail: [email protected] 1 Abstract Highly compacted sand-bentonite mixtures are often considered as possible engineered barriers in deep high-level radioactive waste disposals. In-situ, the saturation of these barriers from their initially unsaturated state is a complex hydro-mechanical coupled process in which temperature effects also play a role. The key parameter of this process is the unsaturated hydraulic conductivity of the barrier. In this paper, isothermal infiltration experiments were conducted to determine the unsaturated hydraulic conductivity according to the instantaneous profile method. To do so, total suction changes were monitored at different locations along the soil specimen by using resistivity relative humidity probes. Three constant volume infiltration tests were conducted showing, unexpectedly, a decrease of the hydraulic conductivity during infiltration. One test performed under free-swell conditions showed the opposite and standard trend. These observations were interpreted in terms of microstructure changes during wetting, both under constant volume and free swell conditions. Key-Words: Compacted sand/bentonite mixture, infiltration, instantaneous profile method, relative humidity, constant volume, free-swell, unsaturated hydraulic conductivity 2 Introduction In radioactive waste disposal at great depth, compacted expansive soils are sometimes considered as possible engineered barrier to be placed between the radioactive waste and the host rock.
    [Show full text]