Dilatancy-controlled gas flow in preferential pathways plays a key role in the safety analysis of radioactive waste repositories.This is particularly the case for bentonite,an often-preferred barrier material.Gas flow...Dilatancy-controlled gas flow in preferential pathways plays a key role in the safety analysis of radioactive waste repositories.This is particularly the case for bentonite,an often-preferred barrier material.Gas flow in preferential pathways is characterized by localization and spontaneous behavior,which is challenging to simulate in numerical models due to strong hydro-mechanical coupling.To analyze a laboratory experiment in the framework of the DECOVALEX-2023 project,this study introduced a new approach of combining continuous modelling methods with spatial material properties derived from material heterogeneities and experimental observations.The proposed model utilized hydro-mechanical spatial distributions,namely Young’s modulus and gas entry pressure,and elastoplasticity combined with a linear swelling model.A conceptual strain-dependent permeability approach simulated dilatancycontrolled gas flow based on hydro-mechanical coupling.To test the effectiveness of the presented approach,a gas injection test in a compacted,saturated bentonite sample was simulated using the opensource code OpenGeoSys 5.8 and compared with experimental observations.The presented methodology is capable of simulating localized gas flow in preferential pathways.The spatial distributions of Young’s modulus and gas entry pressure affect the swelling pressure,relative permeability and,in combination with the strain-dependent permeability model,also the intrinsic permeability.展开更多
As is known, high-level radioactive waste (HLW) is commonly heat-emitting. Heat output from HLWwilldissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical(THMC) processes. In hi...As is known, high-level radioactive waste (HLW) is commonly heat-emitting. Heat output from HLWwilldissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical(THMC) processes. In highly consolidated clayey rocks, thermal effects are particularly significantbecause of their very low permeability and water-saturated state. Thermal impact on the integrity of thegeological barriers is of most importance with regard to the long-term safety of repositories. This studyfocuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using acoupled thermo-mechanical multiphase flow (TH2M) model which is implemented in the finite elementprogramme OpenGeoSys (OGS). The material properties of the numerical model are characterised by atransversal isotropic elastic model based on Hooke's law, a non-isothermal multiphase flow model basedon van Genuchten function and Darcy's law, and a transversal isotropic heat transport model based onFourier's law. In the numerical approaches, special attention has been paid to the thermal expansion ofthree different phases: gas, fluid and solid, which could induce changes in pore pressure and porosity.Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in thepresent model. The model has been applied to simulate a laboratory heating experiment on claystone.The numerical model gives a satisfactory representation of the observed material behaviour in thelaboratory experiment. The comparison of the calculated results with the laboratory findings verifies thatthe simulation with the present numerical model could provide a deeper understanding of the observedeffects. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.展开更多
1.Introduction The availability of reliable information describing our natural and anthropogenic environment—and its changes in particular—is crucial for understanding the complexity of structures and processes with...1.Introduction The availability of reliable information describing our natural and anthropogenic environment—and its changes in particular—is crucial for understanding the complexity of structures and processes within environmental systems.Modern remote sensing and monitoring methods provide an increasing amount of environmental data that can be used for a variety of management purposes[1,2].展开更多
The water quality of all rivers into the Qinhuangdao coastal water was below the grade V in 2013. In this study, an inte- grated MIKE 1 l water quality model is applied to deal with the water environment in the rivers...The water quality of all rivers into the Qinhuangdao coastal water was below the grade V in 2013. In this study, an inte- grated MIKE 1 l water quality model is applied to deal with the water environment in the rivers into the Qinhuangdao coastal water. The model is first calibrated with the field measured chemical oxygen demand (COD) concentrations. Then the transport of the COD in the rivers into the Qinhuangdao coastal water is computed based on the model in the water environmental monitoring process. Numerical results show that the COD concentration decreases dramatically in the estuaries, from which we can determine the positions of long-term monitoring stations to monitor the river pollutions into the coastal water. Furthermore, different scenarios about the inputs of the point sources and the non-point sources are simulated to discuss the model application in the water enviro- nmental control, and simplified formula are derived for assessing the water quality and the environmental management of rivers.展开更多
Due to extensive water pollution in Chinese rivers and lakes,large efforts have to be made to improve the quality of drinking water and manage the sewage water treatment process.We propose a general workflow for integ...Due to extensive water pollution in Chinese rivers and lakes,large efforts have to be made to improve the quality of drinking water and manage the sewage water treatment process.We propose a general workflow for integrating a large number of heterogeneous data sets relating to various hydrological compartments into a Virtual Geographic Environment(VGE).This allows both researchers and stakeholders to easily access complex data collections in a unified context,find interrelations or inconsistencies between data sets and evaluate simulation results with respect to other observations or simulations in the same region.A prototype of such a VGE has been set up for the region around Chao Lake,containing more than 20 spatial data sets and collections as well as first simulation result.The prototype has been successfully presented to researchers and stakeholders from China and Germany.展开更多
The advent of information and communication technology and the Internet of Things have led our society toward a digital era.The proliferation of personal computers,smartphones,intelligent autonomous sensors,and pervas...The advent of information and communication technology and the Internet of Things have led our society toward a digital era.The proliferation of personal computers,smartphones,intelligent autonomous sensors,and pervasive network interactions with individuals have gradually shifted human activities from offline to online and from in person to virtual.This transformation has brought a series of challenges in a variety of fields,such as the dilemma of placelessness,some aspects of timelessness(no time relevance),and the changing relevance of distance in the field of geographic information science(GIScience).In the last two decades,“cyber thinking”in GIScience has received significant attention from different perspectives.For instance,human activities in“cyberspace”need to be reconsidered when coupled with the geographic space to observe the first law of geography.展开更多
基金This research was conducted within the DECOVALEX-2023 projectDECOVALEX is an international research project comprising participants from industry,government,and academia,focusing on development of understanding,models and codes in complex coupled problems in sub-surface geological and engineering applications.DECOVALEX-2023 is the current phase of the project.The authors appreciate the DECOVALEX-2023 Funding Organisations Andra,BASE,BGE,BGR,CAS,CNSC,COVRA,US DOE,ENRESA,ENSI,JAEA,KAERI,NWMO,RWM,SÚRAO,SSM and Taipower for their financial and technical support of the work described in this paper.The statements made in the paper are,however,solely those of the authors and do not necessarily reflect those of the Funding Organisations.This work was further supported by the German Federal Ministry for Economic Affairs and Climate Action(BMWK).
文摘Dilatancy-controlled gas flow in preferential pathways plays a key role in the safety analysis of radioactive waste repositories.This is particularly the case for bentonite,an often-preferred barrier material.Gas flow in preferential pathways is characterized by localization and spontaneous behavior,which is challenging to simulate in numerical models due to strong hydro-mechanical coupling.To analyze a laboratory experiment in the framework of the DECOVALEX-2023 project,this study introduced a new approach of combining continuous modelling methods with spatial material properties derived from material heterogeneities and experimental observations.The proposed model utilized hydro-mechanical spatial distributions,namely Young’s modulus and gas entry pressure,and elastoplasticity combined with a linear swelling model.A conceptual strain-dependent permeability approach simulated dilatancycontrolled gas flow based on hydro-mechanical coupling.To test the effectiveness of the presented approach,a gas injection test in a compacted,saturated bentonite sample was simulated using the opensource code OpenGeoSys 5.8 and compared with experimental observations.The presented methodology is capable of simulating localized gas flow in preferential pathways.The spatial distributions of Young’s modulus and gas entry pressure affect the swelling pressure,relative permeability and,in combination with the strain-dependent permeability model,also the intrinsic permeability.
基金supported by BMWi (Bundesministerium für Wirtschaft und Energie,Berlin)
文摘As is known, high-level radioactive waste (HLW) is commonly heat-emitting. Heat output from HLWwilldissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical(THMC) processes. In highly consolidated clayey rocks, thermal effects are particularly significantbecause of their very low permeability and water-saturated state. Thermal impact on the integrity of thegeological barriers is of most importance with regard to the long-term safety of repositories. This studyfocuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using acoupled thermo-mechanical multiphase flow (TH2M) model which is implemented in the finite elementprogramme OpenGeoSys (OGS). The material properties of the numerical model are characterised by atransversal isotropic elastic model based on Hooke's law, a non-isothermal multiphase flow model basedon van Genuchten function and Darcy's law, and a transversal isotropic heat transport model based onFourier's law. In the numerical approaches, special attention has been paid to the thermal expansion ofthree different phases: gas, fluid and solid, which could induce changes in pore pressure and porosity.Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in thepresent model. The model has been applied to simulate a laboratory heating experiment on claystone.The numerical model gives a satisfactory representation of the observed material behaviour in thelaboratory experiment. The comparison of the calculated results with the laboratory findings verifies thatthe simulation with the present numerical model could provide a deeper understanding of the observedeffects. 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
基金the German Federal Ministry of Education and Research(BMBF)for funding the Chaohu Lake project in the frame of the Chinese Major Water Program(02WCL1337A-E)the Sino-German Center for Science Promotion(CDZ)for the Poyang Lake project(GZ1167)+1 种基金the Helmholtz Association for supporting the establishment of Center for Environmental Information Science(HIRN 0002)the Chinese Academy of Sciences(CAS)for providing support to various activities through the CAS President’s International Fellowship Initiative(PIFI)
文摘1.Introduction The availability of reliable information describing our natural and anthropogenic environment—and its changes in particular—is crucial for understanding the complexity of structures and processes within environmental systems.Modern remote sensing and monitoring methods provide an increasing amount of environmental data that can be used for a variety of management purposes[1,2].
基金Project supported by the Marine Public Welfare Pro-gram of China(Grant No.201305003-5)the Science and Technology Program of the Oceanic Administration of Hebei Province of China
文摘The water quality of all rivers into the Qinhuangdao coastal water was below the grade V in 2013. In this study, an inte- grated MIKE 1 l water quality model is applied to deal with the water environment in the rivers into the Qinhuangdao coastal water. The model is first calibrated with the field measured chemical oxygen demand (COD) concentrations. Then the transport of the COD in the rivers into the Qinhuangdao coastal water is computed based on the model in the water environmental monitoring process. Numerical results show that the COD concentration decreases dramatically in the estuaries, from which we can determine the positions of long-term monitoring stations to monitor the river pollutions into the coastal water. Furthermore, different scenarios about the inputs of the point sources and the non-point sources are simulated to discuss the model application in the water enviro- nmental control, and simplified formula are derived for assessing the water quality and the environmental management of rivers.
基金provided by the German Federal Ministry of Education and Research(BMBF)CLIENT program‘International Partnerships for Sustainable Innovations’for the project‘Managing Water Resources for Urban Catchments’[grant number 02WCL1337A]the Helmholtz Research Network‘Research Centre for Environmental Information Science’[grant number HIRN0001].
文摘Due to extensive water pollution in Chinese rivers and lakes,large efforts have to be made to improve the quality of drinking water and manage the sewage water treatment process.We propose a general workflow for integrating a large number of heterogeneous data sets relating to various hydrological compartments into a Virtual Geographic Environment(VGE).This allows both researchers and stakeholders to easily access complex data collections in a unified context,find interrelations or inconsistencies between data sets and evaluate simulation results with respect to other observations or simulations in the same region.A prototype of such a VGE has been set up for the region around Chao Lake,containing more than 20 spatial data sets and collections as well as first simulation result.The prototype has been successfully presented to researchers and stakeholders from China and Germany.
文摘The advent of information and communication technology and the Internet of Things have led our society toward a digital era.The proliferation of personal computers,smartphones,intelligent autonomous sensors,and pervasive network interactions with individuals have gradually shifted human activities from offline to online and from in person to virtual.This transformation has brought a series of challenges in a variety of fields,such as the dilemma of placelessness,some aspects of timelessness(no time relevance),and the changing relevance of distance in the field of geographic information science(GIScience).In the last two decades,“cyber thinking”in GIScience has received significant attention from different perspectives.For instance,human activities in“cyberspace”need to be reconsidered when coupled with the geographic space to observe the first law of geography.