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Probabilistic outlier detection for sparse multivariate geotechnical Site investigation data using Bayesian learning

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Geoscience Frontiers 2021年第1期12卷 425-439页

作者： Shuo Zheng Yu-Xin Zhu Dian-Qing Li Zi-Jun Cao Qin-Xuan Deng Kok-Kwang Phoon State Key Laboratory of Water Resources and Hydropower Engineering Science Institute of Engineering Risk and Disaster PreventionWuhan University299 Bayi RoadWuhan 430072China Department of Civil and Environmental Engineering National University of SingaporeBlk E1A#07-031 Engineering Drive 2Singapore 117576Singapore

Various uncertainties arising during acquisition process of geoscience data may result in anomalous data instances(i.e.,outliers)that do not conform with the expected pattern of regular data instances.With sparse multivariate data obtained from geotechnical Site investigation,it is impossible to identify outliers with certainty due to the distortion of statistics of geotechnical parameters caused by outliers and their associated statistical uncertainty resulted from data sparsity.This paper develops a probabilistic outlier detection method for sparse multivariate data obtained from geotechnical Site investigation.The proposed approach quantifies the outlying probability of each data instance based on Mahalanobis distance and determines outliers as those data instances with outlying probabilities greater than 0.5.It tackles the distortion issue of statistics estimated from the dataset with outliers by a re-sampling technique and accounts,rationally,for the statistical uncertainty by Bayesian machine learning.Moreover,the proposed approach also suggests an exclusive method to determine outlying components of each outlier.The proposed approach is illustrated and verified using simulated and real-life dataset.It showed that the proposed approach properly identifies outliers among sparse multivariate data and their corresponding outlying components in a probabilistic manner.It can significantly reduce the masking effect(i.e.,missing some actual outliers due to the distortion of statistics by the outliers and statistical uncertainty).It also found that outliers among sparse multivariate data instances affect significantly the construction of multivariate distribution of geotechnical parameters for uncertainty quantification.This emphasizes the necessity of data cleaning process(e.g.,outlier detection)for uncertainty quantification based on geoscience data.

关键词： Outlier detection Site investigation Sparse multivariate data Mahalanobis distance Resampling by half-means Bayesian machine learning

An article on Site investigation with geophysical methods in Tangshan city of China

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An article on site investigation with geophysical methods in...

A generic framework for geotechnical subsurface modeling with machine learning

中国科学院地质与地球物理研究所第十届(2010年度)学...

作者： Qingyun Di,Diquan Li,Hui cheng & Changmin Fu Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,China

The proposed Tangshan Wanda Square will be built in the center of Tangshan city,China.In this area block collapse,karst collapse,zones of buried structural fracture and ground fissures have developed.All would be disadvantageous factors affecting the construction of high-rise buildings.Therefore,Site investigation using geophysical methods was performed to identify the extent of the potentially weak geological structure.This survey adopted the Controlled Source Audio-frequency Magnetotelluric method(CSAMT).The goal of CSAMT is to define the electrical characteristics,especially low resistivity anomalies, to a depth of 500 m.In view of the difficulty of data processing in a city with strong industrial interference,comparatively reliable 3D resistivity data sets in the investigated area were possible after removing the wild data,preserving the true data and comparing results among survey lines repeatedly.CSAMT result reveals the location,depth and distribution range of the karst,coal seam block,and karst fracture zone,and provides the geophysical evidence for risk assessment of the proposed high-rise building development.

关键词： CSAMT Site investigation Tangshan high-rise buildings Geophysical methods

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1366-1379页

作者： Jiawei Xie Jinsong Huang Cheng Zeng Shan Huang Glen J.Burton Discipline of Civil Surveying and Environmental EngineeringPriority Research Centre for Geotechnical Science and EngineeringThe University of NewcastleCallaghanNSW2308Australia ATC Williams Pty.Ltd. SingletonNSW2330Australia

This study introduces a generic framework for geotechnical subsurface modeling, which accounts for spatial autocorrelation with local mapping machine learning(ML) methods. Instead of using XY coordinate fields directly as model input, a series of autocorrelated geotechnical distance fields(GDFs) is designed to enable the ML models to infer the spatial relationship between the sampled locations and unknown locations. The whole framework using GDF with ML methods is named GDF-ML. This framework is purely data-driven which avoids the tedious work in the scale of fluctuations(SOFs)estimating and data detrending in the conventional spatial interpolation methods. Six local mapping ML methods(extra trees(ETs), gradient boosting(GB), extreme gradient boosting(XGBoost), random forest(RF), general regression neural network(GRNN) and k-nearest neighbors(KNN)) are compared in the GDF-ML framework. The results show that the GDFs are better than the conventional XY coordinate fields based ML methods in both accuracy and spatial continuity. GDF-ML is flexible which can be applied to high-dimensional, multi-variable and incomplete datasets. Among these six methods, GDF with ET method(GDF-ET) clearly shows the best accuracy and best spatial continuity. The proposed GDF-ET method can provide a fast and accurate interpretation of the soil property profile. Sensitivity analysis shows that this method is applicable to very small training dataset size. The associated statistical uncertainty can also be quantified so that the reliability of the subsurface modeling results can be estimated objectively and explicitly. The uncertainty results clearly show that the prediction becomes more accurate when more sampled data are available.

关键词： Site investigation Machine learning(ML) Spatial interpolation Geotechnical distance fields(GDFs) Tree-based models

Uncertainty quantification and reduction in the characterization of subsurface stratigraphy using limited geotechnical investigation data

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Underground Space 2020年第2期5卷 125-143页

作者： Xiangrong Wang Department of Civil and Environmental Engineering and Engineering Mechanics The University of DaytonDaytonOH 45469-0243USA

Subsurface stratigraphy is critical to the design,construction,and subsequent performance of geotechnical structures.However,in practice it is impossible to identify the stratigraphy of a subsurface geological domain with absolute certainty,due to the limitations imposed by geotechnical investigation techniques and project budgets.This paper presents a subsurface stratigraphic modeling and uncertainty quantification approach,which is established based on an improved and extended geological modeling technique previously established by the author and others,for simulating the stratigraphy of both two-dimensional(2D)and three-dimensional(3D)cases with more complex geological features.Furthermore,this approach provides quantitative evaluation of the amount of stratigraphic uncertainty in the current interpretation and enables the systematic reduction of stratigraphic uncertainty through the investigation of additional targeted borehole drilling locations.Illustrative examples,including artificial cases as well as two real cases from existing geotechnical projects,are presented in this study to demonstrate the use of the proposed analysis approach.

关键词： Site investigation Stratigraphy Stochastic modeling Uncertainty quantification Borehole drilling

Seasonal influence on cone penetration test: An unsaturated soil site example

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第2期11卷 361-368页

作者： Heraldo Luiz Giacheti Renan Cravera Bezerra Breno Padovezi Rocha Roger Augusto Rodrigues Department of Civil and Environmental Engineering Sao Paulo State UniversityBauruBrazil Department of Geotechnical Engineering University of Sao PauloSao CarlosBrazil

Interpretation of electric cone penetration test(CPT) based pore water pressure measurement(CPTu) is well established for soils with behavior that follows classical soil mechanics. The literature on the interpretation of these tests performed on unsaturated tropical soils is limited, and little is known about the influence of soil suction on in situ test data. In this context, the CPT data are presented and discussed to illustrate the seasonal variability in an unsaturated tropical soil site. The test data show that soil suction significantly influenced CPT data up to a depth of 4 m at the study site. It shows the importance of considering seasonal variability in unsaturated soil sites caused by soil suction, which was related to water content through a soil-water retention curve(SWRC). It is also important to consider this aspect in the interpretation of CPT data from these soils.

关键词： Site investigation In situ testing Cone penetration test (CPT) Unsaturated soil Suction Variability

Post-analysis simulation of the collapse of an open sabo dam of steel pipes subjected to boulder laden debris flow

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International Journal of Sediment Research 2020年第6期35卷 621-635页

作者： Toshiyuki Horiguchi Vincent Richefeu Department of Civil Engineering National Defense Academy Universite Grenoble Alpes Laboratoire 3SR (solsSolidesStructuresRisques)

The objective of the proposed method is to utilize a Site investigation of a debris flow disaster and verify a real scale analysis to evaluate the impulsive load on an open sabo dam.The Nagiso debris flow disaster which occurred in Nagano in 2014,where damage caused by Typhoon Neogri was studied.The verification result of the Site investigation demonstrated the weak components of the open Sabo dam experienced damage owing to the debris flow.A discrete element method is normally applied to a solid body to calculate an interaction function force with respect to the contact point between boulders and the dam.The numerical method initially concatenates elements that model the open Sabo dam.Moreover,the stiffness coefficient of flanges and coupling joints between pipes was expressed to utilize the sectional partition method to determine the structural characteristics.The method was improved to separate from the connecting elements beyond the boundary conditions.The debris flow model uses a water flow distribution model,and the debris flow flowed from 200m upstream of the open sabo dam.Accordingly,the proposed method was examined to verify the primary cause of damage to the open sabo dam and used to reproduce the circumstances that evaluated the impulsive load occurrence mechanism in the case of a real disaster.In addition,the coupling joints between the hollow steel pipes utilized a’reproduction analysis’ for a real sabo dam and a‘reinforced analysis’ for a reinforced sabo dam were applied to assess the weak point of the dam.

关键词： Open sabo dam Site investigation Damage verification Discrete element method

Reducing risks in the investigation, design and construction of large concrete dams

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 197-209页

作者： E.T.Brown Golder Associates Pty. Ltd. BrisbaneAustralia

An overview of the GeoSafe 2016 Symposium topic is provided using the example of large concrete dams for purposes of illustration.It is essential that the risks associated with large dams be evaluated rigorously and managed proactively at all stages of their lives so that the risk of failure remains As Low As Reasonably Practicable(ALARP).Rock engineering features of large concrete dams that require particular attention,assessment and monitoring during the investigation,design,construction,initial filling,inservice operation,and subsequent repair and upgrade stages of the lives of concrete dams are identified and illustrated by examples from recorded experiences.A number of major concrete dam failures,including that of the St.Francis dam,California,U.S.A.,in 1928,have led to significant developments in rock mechanics and rock engineering knowledge and techniques,as well as in dam design and review processes.More recent advances include a range of analytical,numerical modelling,probabilistic,reliability,failure mode and risk assessment approaches.

关键词： Concrete dam failure Dam engineering Risk assessment Rock engineering design Site investigation

50 years change in urban land use and ecological planning globally in the era of design with nature

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Ecosystem Health and Sustainability 2019年第1期5卷 185-198,I0001页

作者： Ian Douglas School of Environment Education and DevelopmentUniversity of ManchesterManchesterUK

Ian McHarg’s 1969 book,Design with Nature,was grounded in earlier good practice,especially the European vision of fitting cities into the regional landscape and carrying thorough surveys before planning commenced.The book emerged in the wake of publications that worried about the ability of the earth to support expanding populations and their growing impact on the environment.McHarg argued that ecological design should follow planning based on detailed site information.Although McHarg advised many urban authorities in the USA and other countries,especially in Africa,Asia and Europe,and his ideas had influenced some British new towns,they had little attention in the planning of Milton Keynes,England’s largest new urban settlement,where the initial geological surveys were inadequate,but a successful large tree-planting programhas created a“city in the forest.”McHarg was however closely involved in planning the Nigerian Capital city,Abuja,but his sound master plan was ill-equipped to provide for a nation undergoing post-conflict rebuilding and a local population more concerned with access to land than ecological planning.Nonetheless,McHarg helped us to promote,protect,and preserve urban green spaces.Although teams from different disciplines now work well together,the integrated thinking advocated by McHarg remains sometimes in short supply in local practice.

关键词： Planning design urban nature garden city Site investigation

Effect of trigger system on experimental dispersion characteristics of active surface wave testing

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 311-318页

作者： Lin Shibin Jeramy C.Ashlock Zhu Liming Qin Zexiang Li Bo Zhu Xingji Zhai Changhai State Key Laboratory of Precision Blasting Jianghan UniversityWuhan 430056China Hubei Key Laboratory of Blasting Engineering Jianghan UniversityWuhan 430056China Department of Civil Construction&Environmental EngineeringIowa State UniversityAmesIA 50010USA Wuhan Airport Road Development Co. Ltd.Wuhan 430065China School of Civil and Environmental Engineering Harbin Institute of TechnologyShenzhen 518055China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of TechnologyHarbin 150090China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disaster of the Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin 150090China

A trigger system is typically employed in active seismic testing to trigger and synchronize multichannel surface wave data acquisition.The effect of the trigger system on the dispersion image of surface waves is empirically known to be negligible,however,theoretical explanation regarding the effect of the trigger system is insufficient.This study systematically examines the theory for surface wave dispersion analysis and proves that the effect of the trigger system on a dispersion image is negligible via a solid theoretical explanation.Subsequently,based on the new theoretical explanation,an alternative method that uses only the relative phase difference between sensors to extract dispersion characteristics with better conceptual clarity is proposed.Two active surface wave testing cases are considered to validate the theory and method.The results indicate that(1)an accurate trigger system is not necessary for surface wave data acquisition,and(2)it is unnecessary to assume that the impact point is the generation point of the surface waves for the experimental dispersion analysis.

关键词： Site investigation surface waves data acquisition dispersion