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Machine learning prediction of methane,ethane,and propane solubility in pure water and electrolyte solutions:Implications for stray gas migration modeling

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Acta Geochimica 2024年第5期43卷 971-984页

作者： Ghazal Kooti Reza Taherdangkoo Chaofan Chen Nikita Sergeev Faramarz Doulati Ardejani Tao Meng Christoph Butscher Institute of geotechnics TU Bergakademie FreibergGustav-Zeuner-Str.109599 FreibergGermany department of Petroleum Engineering Amirkabir University of TechnologyTehranIran Freiberg Center for Water Research ZeWaF TU Bergakademie Freiberg09599 FreibergGermany School of Mining College of EngineeringUniversity of TehranTehranIran Taiyuan University of Science and Technology Taiyuan 030024China

Hydraulic fracturing is an effective technology for hydrocarbon extraction from unconventional shale and tight gas reservoirs.A potential risk of hydraulic fracturing is the upward migration of stray gas from the deep subsurface to shallow *** stray gas can dissolve in groundwater leading to chemical and biological reactions,which could negatively affect groundwater quality and contribute to atmospheric *** knowledge oflight hydrocarbon solubility in the aqueous environment is essential for the numerical modelling offlow and transport in the ***,we compiled a database containing 2129experimental data of methane,ethane,and propane solubility in pure water and various electrolyte solutions over wide ranges of operating temperature and *** machine learning algorithms,namely regression tree(RT)and boosted regression tree(BRT)tuned with a Bayesian optimization algorithm(BO)were employed to determine the solubility of *** predictions were compared with the experimental data as well as four well-established thermodynamic *** analysis shows that the BRT-BO is sufficiently accurate,and the predicted values agree well with those obtained from the thermodynamic *** coefficient of determination(R2)between experimental and predicted values is 0.99 and the mean squared error(MSE)is 9.97×10^(-8).The leverage statistical approach further confirmed the validity of the model developed.

关键词： Gas solubility Hydraulic fracturing Thermodynamic models Regression tree Boosted regression tree Groundwater contamination

Integrated hazard assessment of rockfall incidents in the Cap Aokas Cliff Region

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Journal of Mountain Science 2024年第6期21卷 1916-1929页

作者： Zohra LADJEL Farid ZAHRI Riheb HADJI Younes HAMED Karim ZIGHMI Kaddour BENMARCE department of Earth Sciences Institute of Architecture and Earth SciencesFerhat Abbas UniversitySetif 19137Algeria Unit of Emerging Materials Research Ferhat Abbes UniversitySétif 19137Algeria Laboratory of Applied Research in Engineering Geology GeotechnicsWater Sciencesand EnvironmentFerhat Abbas UniversitySetif 19137Algeria International Association of Water Resources in the Southern Mediterranean Basin Gafsa 2112Tunisia department of Earth Sciences Faculty of SciencesUniversity of GafsaGafsa 2112Tunisia

Rock fall accidents in mountainous cliff areas have significant consequences for human life and *** study aimed to evaluate the rockfall hazard in the Cap Aokas cliff region located along the northeast coast of Algeria by identifying the key factors contributing to rockfall *** employed a combination of kinematic analysis,Matterocking method,and 3D trajectory simulations to determine zones that are susceptible to rockfall *** using a probabilistic and structural approach in conjunction with photogrammetry,we identified the controlling *** kinematic analysis revealed the presence of five discontinuity families,which indicated both plane and wedge failure *** 3D trajectory simulations demonstrated that the falling blocks followed the stream *** then validated the susceptibility maps generated from the analysis using aerial photos and historical rockfall *** findings of this study enhance our understanding of rockfall phenomena and provide valuable insights for the development of effective strategies to mitigate rockfall hazards.

关键词： Trajectory simulations Probabilistic analysis Structural approach Rockfall hazard Cap Aokas cliff

Shared mooring systems for offshore floating wind farms: A review

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Energy Reviews 2024年第1期3卷 76-89页

作者： Hang Xu Shengjie Rui Kanmin Shen Liangliang Jiang Haojie Zhang Long Teng Zhejiang Key Laboratory of Offshore geotechnics and Material College of Civil Engineering and ArchitectureZhejiang UniversityHangzhou310058China Norwegian Geotechnical Institute Sandakerveien 140Oslo0484Norway PowerChina Huadong Engineering Corporation Limited Hangzhou311122China department of Chemical and Petroleum Engineering The University of CalgaryCalgaryAlbertaCanada

Offshore wind energy,as a form of renewable power,has seen rapid development in recent *** fixedbottom wind turbines are typically used in water depths less than 50 m,the utilization of floating offshore wind turbines(FOWTs)becomes essential for deeper *** and effective mooring systems play a crucial role in making FOWTs commercially *** concept of a shared mooring system offers an innovative solution for deploying floating wind farms in clusters or arrays,which can reduce overall construction costs for large-scale floating wind *** is imperative to optimize the shared mooring arrangement for maximum cost-effectiveness and wind farm ***,implementing a shared mooring system introduces complexity to the dynamics of FOWTs,requiring the development of advanced simulation tools to meet modelling *** the shared mooring arrangement,mooring lines and anchors face more significant challenges,such as chain-seabed interactions,soil cyclic weakening,and anchor out-of-plane loading,which underscore the need for innovative,reliable,and efficient shared anchor *** article offers an overview of the current research status on shared mooring systems for floating wind farms,which might serve as a valuable reference for the construction of large-scale floating wind farms worldwide.

关键词： Floating offshore wind turbines Wind farm Shared mooring Shared anchor Renewable energy

Random checkerboard based homogenization for estimating effective thermal conductivity of fully saturated soils

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第1期9卷 18-28页

作者： Dariusz Lydzba Adrian Rózanski Magdalena Rajczakowska Damian Stefaniuk department of geotechnics HydrotechnicsUnderground and Hydraulic StructuresFaculty of Civil EngineeringWroclaw University of Science and TechnologyWybrzeze Wyspianskiego 27Wrocw50-370Poland

This paper proposes homogenization scheme for estimating the effective thermal conductivity of fully saturated soils. This approach is based on the random checkerboard-like microstructure. Two modeling scales and two modeling approaches are distinguished and used, i.e. microscale and mesoscale and 1-step and 2-step homogenizations, respectively. The 2-step homogenization involves sequential averaging procedure, i.e. first, at microscale, a mineralogical composition of soil skeleton is considered and averaging process results in estimation of the skeleton effective thermal conductivity, and then, at mesoscale, a random spatial packing of solid skeleton and pores via random checkerboard microstructure is modeled and leads to evaluation of the soil overall thermal conductivity. The 1-step homogenization starts directly at the mesoscale and homogenization procedure yields evaluation of the overall soil thermal conductivity. At the mesoscale, the distinct nature of soil skeleton, as composed of soil separates,is considered and random variability of soil is modeled via enriched random checkerboard-like *** approaches, i.e. 1-step and 2-step homogenizations, interrelate mineralogical composition with the soil texture characterized by the volume fractions of soil separates, i.e. sand, silt and clay. The probability density functions(PDFs) of thermal conductivity are assumed for each of the separates. The soil texture PDF of thermal conductivity is derived taking into consideration the aforementioned functions. Whenever the random checkerboard-like structure is used in averaging process, the Monte Carlo procedure is applied for estimation of homogenized thermal conductivity. Finally, the proposed methodology is tested against the laboratory data from our measurements as well as those available from literature.

关键词： Soil mechanics Micromechanics Effective thermal conductivity

Determination of pile failure mechanism under pullout test in loose sand

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Journal of Central South University 2015年第4期22卷 1490-1501页

作者： K.Faizi R.Kalatehjari R.Nazir A.S.A.Rashid department of geotechnics and Transportation Universiti Teknologi Malaysia

Estimating the deformation of soil around the pile contributes to reliable design of structures under pullout force. This work presents the results of a series of small-scale physical modelling tests designed to investigate the uplift resistance of piles with diameter of 5 cm and slenderness ratios of 1, 2, 3 and 4 in loose sand. Close photogrammetric technique and particle image velocimetry(PIV) were employed to observe the failure patterns due to uplift force on piles. The results show that the shear zones curve slightly outward near the ground surface. After peak resistance, the shear strain concentrates into a pair of narrow shear bands,then a flow around mechanism is formed accompanied by a reduction in the uplift resistance. The results from the laboratory tests were verified by analytical method proposed by Chattopadhyay and PLAXIS 2D and 3D finite element method software. It is found that the depth and width of the failure surface increase with the increment of the slenderness ratio. A good agreement is observed among the measured bearing capacity and obtained failure surface of the models and the results of numerical modelling. Finally, the maximum deformation of loose and dense sand respectively with densities of 25% and 75% were compared in the stage of fully removing pile. The results shows that the deformation of the soil is related to its density, therefore it depends on its dilatancy.

关键词： pile uplift sand particle image velocimetry

Damage detection on framed structures: modal curvature evaluation using Stockwell Transform under seismic excitation

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Earthquake Engineering and Engineering Vibration 2015年第2期14卷 265-274页

作者： R.Ditommaso F.C.Ponzo G.Auletta department of Structures Geotechnics Engineering Geology University of Basilicata School of Engineering University of Basilicata

The key parameters for damage detection and localization are eigenfrequencies, related equivalent viscous damping factors and mode shapes. The classical approach is based on the evaluation of these structural parameters before and after a seismic event, but by using a modern approach based on time-frequency transformations it is possible to quantify these parameters throughout the ground shaking phase. In particular with the use of the S-Transform, it is possible to follow the temporal evolution of the structural dynamics parameters before, during and after an earthquake. In this paper, a methodology for damage localization on framed structures subjected to strong motion earthquakes is proposed based on monitoring the modal curvature variation in the natural frequency of a structure. Two examples of application are described to illustrate the technique: Computer simulation of the nonlinear response of a model, and several laboratory(shaking table) tests performed at the University of Basilicata(Italy). Damage detected using the proposed approach and damage revealed via visual inspections in the tests are compared.

关键词： damage detection S-transform band-variable fi lter

A comprehensive geomechanical method for the assessment of rockburst hazards in underground mining

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International Journal of Mining Science and Technology 2020年第3期30卷 345-355页

作者： Piotr Malkowski Zbigniew Niedbalski department of Geomechanics Civil Engineering and GeotechnicsAGH University of Science and Technology30-059 KrakowPoland

Rockburst hazard in mining industry all over the world is one of the most severe hazards. It is becoming increasingly common because of the ever-growing depths of mining operations accompanied by the increasing strength of rocks. One of the most difficult issues is to predict this hazard before the mining operations, whether geophysical investigations have been conducted or not. Polish experience in this field shows that in such cases an effective solution can be the geomechanical method. Therefore, extensive studies on rockburst hazard should focus on three main aspects:(1) rock mass and rock(and coal)predisposition to rockburst–laboratory tests and empirical analyses based on lithology,(2) identification of the potential places with stress and elastic energy concentration in the rock mass within the area planned for exploitation, and(3) the assessment of the impact of mining tremors on the surface. This preliminary geomechanical analysis assesses the propensity of the rock mass to dynamic breakage and provides quantitatively the level of rockburst hazard. The paper presents Polish experience in rockburst hazard assessment with the use of geomechanical method, as well as some solutions and examples of such analyses.

关键词： Hazards in underground mining Rockburst hazard assessment Rock mass propensity to rockburst Rock propensity to rockburst Geomechanical analysis

Biological process of soil improvement in civil engineering:A review

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Journal of Rock Mechanics and Geotechnical Engineering 2016年第5期8卷 767-774页

作者： Murtala Umar Khairul Anuar Kassim Kenny Tiong Ping Chiet department of geotechnics and Transportation Engineering Faculty of Civil EngineeringUniversiti Teknologi Malaysia

The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and environmental sustainability. This paper presents a review on the soil microorganisms responsible for this process, and factors that affect their metabolic activities and geometric compatibility with the soil particle sizes. Two mechanisms of biomineralization, i.e. biologically controlled and biologically induced mineralization, were also discussed. Environmental and other factors that may be encountered in situ during microbially induced calcite precipitation （MICP） and their influences on the process were identified and presented. Improvements in the engineering properties of soil such as strength/stiffness and permeability as evaluated in some studies were explored. Potential applications of the process in geotechnical engineering and the challenges of field application of the process were identified.

关键词： Bio-mediated soil improvement Microorganisms Metabolic activities BiomineralizationUrease activity

A one-dimensional strain-rate based model for soft structured clays

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Science China(Technological Sciences) 2012年第1期55卷 90-100页

作者： YIN ZhenYu WANG JianHua Center for Marine geotechnics Research Department of Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China

The paper aims to investigate the destructuration effect on the time-dependent behaviour of soft structured *** coupled with destructuration is analysed based on experimental observations.A strain-rate based model is developed to de-scribe the mechanical behaviour for both unstructured and structured clays under one-dimensional *** advantage of the proposed model lies in the determination of model parameters in a straightforward way,which leads to an easy use of the model for practical *** with consolidation,the model is used to simulate oedometer tests at constant rate of strain and long-term creep oedometer tests on two structured *** comparisons between predicted and measured results demonstrate that the proposed model can reasonably describe the effect of destructuration on the time-dependent behaviour of soft structured clay under one-dimensional *** the model is proposed for one-dimensional analysis,it can be a good base for developing a more general 3D model.

关键词： structured clays viscoplasticity consolidation creep strain.rate destructuration