Design charts for the stability analysis of unsaturated soil slopes
- Authors: Gavin, Kenneth , Xue, Jianfeng
- Date: 2010
- Type: Text , Journal article
- Relation: Geotechnical and Geological Engineering Vol. 28, no. 1 (2010), p. 79-90
- Full Text: false
- Reviewed:
- Description: Simple limit equilibrium analyses can be performed to determine the Factor of Safety (FOS) against slope failure of unsaturated soil slopes. However, many of the input parameters needed for these analyses are highly variable, and the FOS value obtained is critically dependent on assumptions made by the designer. This paper describes a suite of reliability analyses on unsaturated soil slopes performed using an invariant reliability model. The results are presented in design charts from which a designer can choose the FOS value required to ensure a given target reliability index for a slope. The approach ensures that despite the variability of input parameters the slope will have a probability of failure of 2.23% or less.
Deterministic and probabilistic multi-modal analysis of slope stability
- Authors: Reale, Cormac , Xue, Jianfeng , Pan, Zhangming , Gavin, Kenneth
- Date: 2015
- Type: Text , Journal article
- Relation: Computers and Geotechnics Vol. 66, no. (2015), p. 172-179
- Full Text: false
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- Description: Traditional slope stability analysis involves predicting the location of the critical slip surface for a given slope and computing a safety factor at that location. However, for some slopes with complicated stratigraphy several distinct critical slip surfaces can exist. Furthermore, the global minimum safety factor in some cases can be less important than potential failure zones when rehabilitating or reinforcing a slope. Existing search techniques used in slope stability analysis cannot find all areas of concern, but instead converge exclusively on the critical slip surface. This paper therefore proposes the use of a holistic multi modal optimisation technique which is able to locate and converge to multiple failure modes simultaneously. The search technique has been demonstrated on a number of benchmark examples using both deterministic and probabilistic analysis to find all possible failure mechanisms, and their respective factors of safety and reliability indices. The results from both the deterministic and probabilistic models show that the search technique is effective in locating the known critical slip surface while also establishing the locations of any other distinct critical slip surfaces within the slope. The approach is of particular relevance for investigating the stability of large slopes with complicated stratigraphy, as these slopes are likely to contain multiple failure mechanisms. © 2015 Elsevier Ltd.
Kinematic assessment of slopes at handlebar hill open cut mine, Mt. Isa, Queensland, Australia
- Authors: Almandalawi, Maged , You, Greg , Dowling, Kim , Dahlhaus, Peter
- Date: 2016
- Type: Text , Journal article
- Relation: International Journal of GEOMATE Vol. 10, no. 1 (2016), p. 1575-1583
- Full Text: false
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- Description: A complete kinematic analysis was conducted for the west slope at the Handlebar Hill mine using the Rocscience/Dips 6.0 software. The west slope was divided into three zones: W1 (south-west), W2 (mid-west) and W3 (north-west), which were then subdivided into nine small elements to increase the certainty of parameters. This enabled the analysis to define the potential kinematics of motions of critical structures. Small scale joints, bedding, faults, shears along the discontinuities were plotted and the data were analysed systematically. The results indicated that the potential toppling mode created by discontinuities can lead to direct/flexural toppling failure. The kinematic feasibility also revealed that the intersections of the discontinuities within the critical zone can structurally control the wedge planar failure modes. The results will assist the mine geotechnical engineers to understand the potential slope failure mechanisms and their locations. © 2016, International Journal of GEOMATE.
Optimisation of strength reduction finite element method codes for slope stability analysis
- Authors: Dyson, Ashley , Tolooiyan, Ali
- Date: 2018
- Type: Text , Journal article
- Relation: Innovative Infrastructure Solutions Vol. 3, no. 1 (2018), p. 1-12
- Full Text: false
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- Description: One of the modern methods for estimating the factor of safety for the stability of slopes is the strength reduction method. In recent times, computer codes have utilised the strength reduction method in conjunction with finite element analysis. This paper explores the implementation of a strength reduction finite element method with FORTRAN and Python codes in conjunction with the computer-aided engineering package Abaqus, incorporating a modified strength reduction definition, allowing for a refinement of the factor of safety search space. The computational efficiency of the modified method is compared with the traditional technique, for both 2D and 3D analysis. The algorithm results are compared for contrasting FEM element types and geometries and benchmarked against proprietary geotechnical finite element solvers.
Prediction and classification for finite element slope stability analysis by random field comparison
- Authors: Dyson, Ashley , Tolooiyan, Ali
- Date: 2019
- Type: Text , Journal article
- Relation: Computers and Geotechnics Vol. 109, no. (2019), p. 117-129
- Full Text: false
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- Description: This paper considers probabilistic slope stability analysis using the Random Finite Element Method (RFEM) combined with processes to determine the level of similarity between random fields. A procedure is introduced to predict the Factor of Safety (FoS) of individual Monte Carlo Method (MCM) random field instances prior to finite element simulation, based on random field similarity measures. Previous studies of probabilistic slope stability analysis have required numerous MCM instances to reach FoS convergence. However, the methods provided in this research drastically reduce computational processing time, allowing simulations previously considered too computationally expensive for MCM analysis to be simulated without obstacle. In addition to computational efficiency, the comparison based procedure is combined with cluster analysis methods to locate random field characteristics contributing to slope failure. Comparison measures are presented for slope geometries of an Australian open pit mine to consider the impacts of associated factors such as groundwater on random field similarity predictors, while highlighting the capacity of the similarity procedure for prediction, classification and computational efficiency.
Probabilistic investigation of RFEM topologies for slope stability analysis
- Authors: Dyson, Ashley , Tolooiyan, Ali
- Date: 2019
- Type: Text , Journal article
- Relation: Computers and Geotechnics Vol. 114, no. (2019), p. 1-15
- Full Text: false
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- Description: The Random Finite Element Method (RFEM) is an increasingly popular tool in geotechnical engineering, especially for analysis of spatial variation and uncertainty in slope stability. Although the method has gained prominence in recent years, topological effects of strong and weak zones and the impact of their locations remain largely unknown. Although numerous potential slip surface realisations can be generated with RFEM, probabilistic failure statistics are often governed by several representative slip surfaces (RSS). In this research, random field similarity methods and clustering techniques are coupled with RFEM slope stability simulation to determine the impact of shear strength spatial patterns on slope failure mechanisms and safety factors. Regions of significance are highlighted within a case study of a Victorian open-cutbrown coal mine, with particular attention given to the effects on the slope failure surface as well the factor of safety. Results are presented of Factor of Safety distributions when particular slip surfaces and clustering constraints are imposed, providing further understanding of the impacts of shear strength characteristics on probabilistic simulation results.
Random finite element method prediction and optimisation for open pit mine slope stability analysis
- Authors: Dyson, Ashley
- Date: 2020
- Type: Text , Thesis , PhD
- Full Text:
- Description: Inherent soil variability can have significant effects on the stability of open-pit mine slopes. In practice, the spatial variability of materials is not commonly considered as a routine component of slope stability analysis. The process of quantifying spatially variable parameters, as well as the modelling of their behaviour is often a complex undertaking. Currently, there are no large-scale commercial software packages containing in-built methods for modelling spatial variability within the Finite Element environment. Furthermore, conventional Limit Equilibrium Methods (LEM) incorporating spatial variability are unable to consider the stress/strain characteristics of these materials. The following research seeks to accurately model the slope mechanics of spatially variable soils, adopting The Random Finite Element Method (RFEM) developed by Griffiths and Fenton (2004) to determine slope failure mechanisms and safety factors. Techniques are developed to produce a set of optimised Random Finite Element Method simulations using the Monte Carlo Method. Additionally, random field analysis techniques are investigated to compare and categorise soil parameter fluctuation, providing a direct relationship between random field properties and slope failure surfaces. Optimisation and analysis techniques are implemented to examine the effects of cross-sectional geometries and input parameter distributions on failure mechanisms, safety factors and probabilities of failure. Cross-sectional RFEM analysis is performed in the Finite Element Method (FEM) software package Abaqus, with the techniques of this research demonstrated for a large open-pit brown coal mine located in the state of Victoria, Australia. The outcome of this research is a comprehensive procedure for optimised RFEM simulation and analysis.
- Description: Doctor of Philosophy
Sensitivity of the stability assessment of a deep excavation to the material characterisations and analysis methods
- Authors: Ghadrdan, Mohsen , Shaghaghi, Tahereh , Tolooiyan, Ali
- Date: 2020
- Type: Text , Journal article
- Relation: Geomechanics and Geophysics for Geo-Energy and Geo-Resources Vol. 6, no. 4 (2020), p.
- Full Text: false
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- Description: Due to the spatial variability of material characterisations in deep and large scale excavations, stability assessment is often a challenging task. Numerous slope stability analysis methods based on a range of assumptions and principles are implemented in commercial software packages to ease the process of stability assessment of non-homogeneous and multi-layered slopes. However, the selection of a suitable method remains crucial as the application of an unrealistic or unsuitable method may lead to catastrophic consequences. Besides material shear strength parameters, and analysis methods, non-strength characterisations such as permeability and creep can affect the result of slope stability analysis significantly. In this study, the sensitivity of the stability assessment of a deep excavation in Australia to material characterisations such as friction angle, cohesion and permeability and creep is investigated by the use of different formulations and assumptions of the Limit Equilibrium Method (LEM) and the Finite Element Method (FEM) as the two most common slope stability methods. The results show that the stability assessment is highly sensitive to the applied method and assumptions. Moreover, the role of material strength and non-strength parameters and the selection of a suitable constitutive model in slope stability assessment is presented. © 2020, Springer Nature Switzerland AG.
Stability prediction of Himalayan residual soil slope using artificial neural network
- Authors: Ray, Arunava , Kumar, Vikash , Kumar, Amit , Rai, Rajesh , Khandelwal, Manoj , Singh, T.
- Date: 2020
- Type: Text , Journal article
- Relation: Natural Hazards Vol. 103, no. 3 (2020), p. 3523-3540
- Full Text:
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- Description: In the past decade, advances in machine learning (ML) techniques have resulted in developing sophisticated models that are capable of modelling extremely complex multi-factorial problems like slope stability analysis. The literature review indicates that considerable works have been done in slope stability using ML, but none of them covers the analysis of residual soil slope. The present study aims to develop an artificial neural network (ANN) model that can be employed for evaluating the factor of safety of Shiwalik Slopes in the Himalayan Region. Data obtained from numerical analysis of a residual soil slope were used to develop two ANN models (ANN1 and ANN2 utilising eleven input parameters, and scaled-down number of parameters based on correlation coefficient, respectively). A four-layer, feed-forward back-propagation neural network having the optimum number of hidden neurons is developed based on trial-and-error method. The results derived from ANN models were compared with those achieved from numerical analysis. Additionally, several performance indices such as coefficient of determination (R2), root mean square error, variance account for, and residual error were employed to evaluate the predictive performance of the developed ANN models. Both the ANN models have shown good prediction performance; however, the overall performance of the ANN2 model is better than the ANN1 model. It is concluded that the ANN models are reliable, valid, and straightforward computational tools that can be employed for slope stability analysis during the preliminary stage of designing infrastructure projects in residual soil slope. © 2020, Springer Nature B.V.
Analytical and numerical approaches to evaluate the effect of time-dependent and time-independent soil characteristics on the stability of deep excavations
- Authors: Ghadrdan, Mohsen
- Date: 2021
- Type: Text , Thesis , PhD
- Full Text:
- Description: Excavating the ground for different purposes, such as extracting valuable materials or undertaking urban construction, may cause concerns regarding the stability of the formed slopes, which can affect the environment, the economy, and human lives. Slope stability analysis in large-scale and deep excavations such as open-pit mines is challenging due to uncertainties regarding varying material parameters, complex field conditions and lack of or insufficient data such as pore water pressure distribution, in-situ stress conditions, and discontinuities. Despite different advanced analytical and numerical slope stability techniques having been developed, slope stability analysis may produce unreliable conclusions due to these uncertainties and challenges. This study’s objective is to investigate the effect of different factors associated with slope stability through a case study of the Yallourn brown coal open pit mine in Australia. In this study, the two most common slope stability methods—the Limit Equilibrium Method (LEM) and the Finite Element Method (FEM)—were employed. A comprehensive study was conducted to determine how the generation and dissipation of Negative Excess Pore-Water Pressure (NEPWP) affect slope stability assessments. Additionally, due to the complex geological stratigraphy of the site, different scenarios for geological layering were defined and investigated for the slope stability analyses. Moreover, the sensitivity of the slope stability assessment to not only different material characteristics but also different formulations and assumptions of LEM and FEM are presented.
- Description: Doctor of Philosophy
Slope stability analysis using deterministic and probabilistic approaches for poorly defined stratigraphies
- Authors: Ghadrdan, Moshen , Dyson, Ashley , Shaghaghi, Tahereh , Tolooiyan, Ali
- Date: 2021
- Type: Text , Journal article
- Relation: Geomechanics and Geophysics for Geo-Energy and Geo-Resources Vol. 7, no. 1 (2021), p.
- Full Text: false
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- Description: The stability of slopes directly affects human lives, the environment, and the economy. Inaccurate geological profiles within numerical slope stability models can lead to potentially catastrophic consequences when model conditions do not appropriately reflect real-life stratigraphy. In cases where localised deposits are prevalent, probabilistic methods are often necessary to accommodate for unknown or poorly defined stratigraphies. Currently, there are no commercial geotechnical software packages that simulate probabilistic constitutive behaviour of materials within finite element methods for large-scale stratigraphic analysis. Instead, commercially available probabilistic methods such as the random limit equilibrium method are incapable of incorporating non-linear constitutive soil behaviour. For this reason, advanced constitutive models are seldom coupled with probabilistically varying soil layers or spatially variable soil parameters. The objective of this research is the implementation of a simplified method for probabilistic stratigraphic analysis within a commercially available FE environment, providing a technique to assess the effects of stratigraphic uncertainty on slope stability. The proposed method is presented, highlighting the impact of localised thin layers of soft material as well as their frequency and location on the slope of an operational open-pit mine. The significance of these stratigraphic effects is presented through a case study of Australia’s second-largest open-pit mine, at which the stability of a collapsed coal slope is analysed. To improve the reliability of the finite element method for slope stability assessment, the Monte Carlo approach has been incorporated to consider varying shear strength distributions for models incorporating advanced constitutive behaviour. Thicker probabilistically generated deposits of silty material resulted in increased slope Factors of Safety. Similarly, greater proportions of silty deposits within a predominantly clayey interseam produced larger safety factors than slopes without localised thin silty layers. Stratigraphic analysis indicated that the Factor of Safety was most sensitive to localised silt layers at depths greater than 83 m below ground level. © 2020, Springer Nature Switzerland AG.
Application of slope mass rating and kinematic analysis along road cut slopes in the Himalayan terrain
- Authors: Siddique, Tariq , Sazid, Mohammed , Khandelwal, Manoj , Varshney, Harsh , Irshad, Sayem
- Date: 2022
- Type: Text , Conference paper
- Relation: International Conference on Geotechnical challenges in Mining, Tunneling and Underground structures, ICGMTU 2021, Virtual, Online, 20-21 December 2021, Lecture Notes in Civil Engineering Vol. 228, p. 697-708
- Full Text: false
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- Description: Hundreds of fatalities are being reported every year due to rampant slope failures along road-cut engineered slopes in the Himalayan region. Prevailing perilous conditions of cut slopes are mainly due to adverse geological attributes and ever-rising anthropogenic factors. To procure a landslide resilient design along roads in mountainous regions, a systematic geotechnical investigation is required. In this regard, the characterization of vulnerable slopes through empirical classification systems is of paramount importance for geotechnical appraisal. Eleven vulnerable road cut slopes along national highway-5 (NH-5), from Solan to Shimla have been studied herein. The present study incorporates the application of Slope Mass Rating (SMR) and its extensions, including Continuous Slope Mass Rating (CSMR) and Chinese Slope Mass Rating (ChSMR) to study various slopes. The outcomes of SMR and its extensions are used to classify cut slopes into different stability grades. In addition, prevailing structurally controlled failures have also been assessed by kinematic analysis. The majority of slopes are liable to undergo planar and wedge failures. The outcomes obtained by kinematic analysis, SMR and its extensions are used to propose adequate remedial measures. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
Development of the scaled boundary finite element method for image-based slope stability analysis
- Authors: Wijesinghe, Dakshith , Dyson, Ashley , You, Greg , Khandelwal, Manoj , Song, Chongmin , Ooi, Ean Tat
- Date: 2022
- Type: Text , Journal article
- Relation: Computers and Geotechnics Vol. 143, no. (2022), p.
- Full Text: false
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- Description: This paper presents a numerical technique for geotechnical slope stability analysis, integrating digital image meshing with the scaled boundary finite element method, allowing site conditions such as complex stratigraphies, surface and internal geometry evolution to be simulated in a robust and straightforward procedure. The quadtree decomposition technique is used to automatically discretise the geometry directly from digital images using pixel information to accurately capture boundaries with fine-scale elements. The process allows complex numerical models to be generated from cross-section images of slopes, capitalising on the combination of the scaled boundary finite element method and quadtree meshing. The spatial distribution of the soil material properties can be represented by the colour of each pixel. A mapping technique is developed to integrate these parameters into the computational mesh. The feasibility of the proposed method is presented through case study simulations of an active large Australian open-pit mine, considering various aspects of complex features such as geometry, stratigraphy and material behaviour. © 2021
Simultaneous slope design optimisation and stability assessment using a genetic algorithm and a fully automatic image-based analysis
- Authors: Wijesinghe, Dakshith , Dyson, Ashley , You, Greg , Khandelwal, Manoj , Song, Chongmin , Ooi, Ean Tat
- Date: 2022
- Type: Text , Journal article
- Relation: International Journal for Numerical and Analytical Methods in Geomechanics Vol. 46, no. 15 (2022), p. 2868-2892
- Full Text: false
- Reviewed:
- Description: Mine slope design is a complex task that requires consideration of geotechnical analysis, structural stability, economics and the environment. Economic factors usually drive mine slope design, particularly in the case of open-pit designs, where the process of steepening slope walls by several degrees can have profound financial implications. Due to the risks associated with catastrophic slope collapse, slope stability analysis is an integral component of open-pit engineering projects. However, initial design concepts and geotechnical assessments are often considered separately. In this study, a technique is developed that combines the scaled boundary finite element method (SBFEM) with genetic algorithms (GAs) to simultaneously perform slope stability analysis and optimise the slope profile. The iterative design approach optimises characteristics of the slope profile such as the slope height, width, angle and number of benches while ensuring the factor of safety (FoS) remains above a threshold value. A salient feature of the technique is the ability to automatically address the modifications to the geometry of the slope by updating the digital images used in the analysis to assess the stability of each instance in the optimisation process and determine the optimum slope geometry. The results highlight the application of the developed technique to determine appropriate slope excavation designs as well as slope backfilling scenarios. The method is exemplified in several cases where complex stratigraphies and spatially variable materials are considered. As such, the GA-driven slope design process conveys an optimised, automated tool, combining mine slope design and slope stability analysis. © 2022 John Wiley & Sons Ltd.
Development of scaled boundary finite element method for geotechnical and mining engineering
- Authors: Wijesinghe, Dakshith
- Date: 2023
- Type: Text , Thesis , PhD
- Full Text: false
- Description: Numerical methods are a mature field of research and have become an increasingly important tool in mining and geotechnical engineering design practices. Although the advantages of numerical methods in aiding the analysis and solving practical engineering problems have been widely accepted and recognised, there is still a gap for further improvements. One such area is the challenge to consider the complexities of geology and the lack of stratigraphic information in the numerical model. Failure to include geological complexities may lead to overestimating the analysis parameters, such as the safety factor. These difficulties mainly manifest in the form of complex mesh generation due to the need to integrate spatial variable material parameters, capturing complex geological features, requirement of additional meshing algorithms, high human involvement, and long processing time. The scaled boundary finite element method (SBFEM) is a semi-analytical method that has potential to address these types of problems. This thesis focuses on developing the SBFEM to address these challenges so that complex geotechnical and mining engineering can be better modelled. Optimisation problems in geotechnical and mining engineering are also considered by developing a combined SBFEM-genetic algorithm framework for the design and rehabilitation of slopes. To begin with, an image-based mesh generation procedure is developed to automatically integrate the spatially variable material parameters into a computational mesh. The procedure allows the input of large data sets of geological and geometrical information in image format, and the mapping procedure enables the concatenation of any number of material parameters into a single computational mesh. The scaled boundary finite element formulation is used to discretise the governing equations of elasto-plasticity considering a Mohr-Coulomb failure criterion, which is common in soils. A shear strength reduction technique is implemented to analyse the stability of slopes in the form of an output Factor of Safety. The developed method is shown to allow routine changes in the operation of the slopes to consider geometric changes, such as backfilling, excavation and updates to geological sublets, by simply editing the digital image inputs. To extend the SBFEM to more complex geotechnical and mining engineering applications, a formulation that considers the coupled effect of pore pressure and nonlinear deformation of the soil is developed. The image-based mesh generation procedure is incorporated to integrate the geological complexities, which include heterogeneity of strate and phreatic surfaces. The developed technique is applied to study complex case studies of a tailings dam embankment construction and a coal slope rehabilitation project with a construction period. The research also considers geometric optimisation problems within the context of geotechnical and mining engineering applications. Geometric optimisation of slopes such as those in open cut mines is important to reduce the overhead operational cost involved in construction, excavation and rehabilitation backfilling, while ensuring stability at an acceptable level. This is achieved by developing a unified platform combining genetic algorithm (GA) with scaled boundary finite element formulations and image-based meshing procedures. Since the image-based mesh generation procedure is an automatic process, it enables automation of the optimisation, which is an iterative proceeding. The capabilities of this technique are demonstrated by optimising the geometric parameters of complex slopes for given safety factors and rehabilitation geometries for given safety factors during a given construction period. The image-based SBFEM analysis platform is further developed to consider geological uncertainty, such as stratigraphic interfaces and phreatic surface fluctuations, so that their effect on slope stability can be studied. The Brownian bridge statistic technique is integrated into the pre-processing module to produce these instances reflecting the ranii dom fluctuations between two intervals and generate possible geological and hydrological cross-sections. This allows unknown geological stratigraphic interface fluctuation due to a lack of sublet information to be considered. The scaled boundary finite element formulations developed in the earlier parts of this thesis are used to discretise each generated profile and analysis probabilistically. Since the mesh generation method is fully automatic, this probabilistic analysis procedure enables to analyse of a large number of possible variations and their effect on geotechnical structures with limited human intervention. Few parametric studies were conducted on slopes to study the impact of stratigraphic and phreatic surface fluctuation on the probability of failure. Finally, the hydraulic fracture commonly seen in geotechnical and mining engineering applications is considered. The phase field has the potential to model complex fracture mechanisms including crack nucleation, branching and coalescence. However, it requires a very fine mesh in order to accurately regularise the energy resulting from the creation of new crack faces. This leads to longer processing time and high computational requirements. Moreover, fracture propagation modelling with phase field models requires equilibrium iterations and hence repetitive calculation of element matrices. This research develops a scaled boundary finite element formulation with phase field model to address hydraulic fracture problems in fully-saturated poro-elastic media. Adaptive meshing refinement based on quadtree meshes is applied. This restricts the fine mesh requirement to only the regions where damage is present and avoids the need for a very fine mesh throughout the structure. Further, leveraging from the unique number of patterns in a hierarchical mesh, an appropriate scaling technique is applied to transform the relevant matrices and vectors to the physical cell in the mesh. This avoids the need for repetitive calculations during the equilibrium iterations. These features increase the efficiency of fracture modelling while reducing the computational requirement. The benchmark problems and complex fracture network problems are provided to highlight the advantage of the method.
- Description: Doctor of Philosophy
Image based probabilistic slope stability analysis of soil layer interface fluctuations with Brownian bridges
- Authors: Wijesinghe, Dakshith , Dyson, Ashley , You, Greg , Khandelwal, Manoj , Ooi, Ean Tat
- Date: 2023
- Type: Text , Journal article
- Relation: Engineering Failure Analysis Vol. 148, no. (2023), p.
- Full Text: false
- Reviewed:
- Description: Accurate interpretation of stratigraphic profiles, the phreatic surface and the spatial variability of geomaterials are essential to produce representative behaviour of geomechanical systems through numerical simulations. When considering slope stability, variations in soil layer boundaries and the phreatic surface may result in misleading metrics such as the Factor of Safety (FoS) and the Probability of Failure (PoF). This paper presents an image-based technique for generating continuous stratigraphic profiles, including random fluctuations based on Brownian motion. Brownian bridges are used to produce random walks between known points on both soil layer boundaries and the phreatic level that overlap with the slope profile image. Quadtree decomposition is used to discretise the stratigraphy and the phreatic level through an automatic process using generated digital images for mesh generation while also integrating material properties. The Scaled Boundary Finite Element (SBFEM) is used to analyse the slope stability problem. Images based on random walks along an unknown stratigraphic material boundary and the phreatic surface are randomly generated and have many random possibilities, which are used to undertake probabilistic analysis to obtain PoF. This process is complex when using numerical methods, such as the Finite Element Method, as it requires mesh generation from different slope profiles with alternating material interfaces at each probabilistic instance. When the Scaled Boundary Finite Element Method is applied, probabilistic numerical analyses can be fully automated for randomly generated material interfaces. The feasibility of the proposed method is illustrated through several cases of a slope with multiple material layers, in addition to a slope incorporating a Brownian bridge phreatic surface formulation. © 2023 Elsevier Ltd