By incorporating two different fracture mechanisms and salient unilateral effects in rock materials,we propose a thermomechanical phase-field model to capture thermally induced fracture and shear heating in the proces...By incorporating two different fracture mechanisms and salient unilateral effects in rock materials,we propose a thermomechanical phase-field model to capture thermally induced fracture and shear heating in the process of rock failure.The heat conduction equation is derived,from which the plastic dissipation is treated as a heat source.We then ascertain the effect of the non-associated plastic flow on frictional dissipation and show how it improves the predictive capability of the proposed model.Taking advantage of the multiscale analysis,we propose a phase-field-dependent thermal conductivity with considering the unilateral effect of fracture.After proposing a robust algorithm for solving involved three-field coupling and damage-plasticity coupling problems,we present three numerical examples to illustrate the abilities of our proposed model in capturing various thermo-mechanically coupled behaviors.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
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
In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar w...In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar weak structures.The failure may occur in two modes:a sliding failure on the weak plane or an intrinsic failure of the rock mass.The rock matrix is expected to behave elastically or fail in a brittle manner,being represented by a non-associated Mohr-Coulomb behavior,while the sliding failure is represented by the evaluation of the Coulomb criterion on an explicitly defined plane.Failure may furthermore affect the hydraulic properties of the rock mass:the shearing of the weakness plane may create a transmissive fluid pathway.Verification of the mechanical submodel is conducted by comparison with an analytical solution,while the coupled hydro-mechanical behavior is validated with field data and will be applied within a model and code validation initiative.The work presented here aims at documenting the progress in code development,while accurate match of the field data with the numerical results is current work in progress.展开更多
Due to the increase in open pit mining,pit lakes have become common surface water features,posing a potential risk to subsurface aquifer.In this study,a pit lake–groundwater interaction model is built based on the ge...Due to the increase in open pit mining,pit lakes have become common surface water features,posing a potential risk to subsurface aquifer.In this study,a pit lake–groundwater interaction model is built based on the general program MODFLOW with the LAK3 package.For the first time,the effects of lake-slope collapse and aquifer heterogeneity on pit lake–groundwater interactions are analyzed by dividing the lake into six water exchange zones based on the aquifer lithology and groundwater level.Our investigation and simulations reveal a total water exchange from groundwater to the lake of 349000 m3/a without collapse of the pit lake slope,while the total net water exchange under slope collapse conditions is 248000 m3/a(i.e.,a reduction of 1.40-fold).The monthly net water exchange per unit width from groundwater to the lake reaches the largest in April,shifting to negative values in zone IV from June to August and in zone V in June and July.Moreover,the monthly net water exchange per unit width decreases from north to south,and the direction and magnitude of water exchange are found to depend on the hydraulic gradients between the lake and groundwater and the hydraulic conductivity of the slope collapse.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
基金funding provided by the National Natural Science Foundation of China(No.12202137)TY's contribution is funded by the China and Germany Postdoctoral Exchange Program(Grant No.ZD202137).The first author(TY)would like to express his gratitude to Prof.Keita Yoshioka for reviewing this manuscript and for his invaluable feedback.
文摘By incorporating two different fracture mechanisms and salient unilateral effects in rock materials,we propose a thermomechanical phase-field model to capture thermally induced fracture and shear heating in the process of rock failure.The heat conduction equation is derived,from which the plastic dissipation is treated as a heat source.We then ascertain the effect of the non-associated plastic flow on frictional dissipation and show how it improves the predictive capability of the proposed model.Taking advantage of the multiscale analysis,we propose a phase-field-dependent thermal conductivity with considering the unilateral effect of fracture.After proposing a robust algorithm for solving involved three-field coupling and damage-plasticity coupling problems,we present three numerical examples to illustrate the abilities of our proposed model in capturing various thermo-mechanically coupled behaviors.
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the DECOVALEX-2019 funding organisations of Andra,BGR/UFZ,CNSC,US DOE,ENSI,JAEA,IRSN,KAERI,NWMO,RWM,SURAO,SSM and Taipower for their financial and technical support of the work described in this paper。
文摘In this paper,an elasto-plastic constitutive model is employed to capture the shear failure that may occur in a rock mass presenting mechanical discontinuities,such as faults,fractures,bedding planes or other planar weak structures.The failure may occur in two modes:a sliding failure on the weak plane or an intrinsic failure of the rock mass.The rock matrix is expected to behave elastically or fail in a brittle manner,being represented by a non-associated Mohr-Coulomb behavior,while the sliding failure is represented by the evaluation of the Coulomb criterion on an explicitly defined plane.Failure may furthermore affect the hydraulic properties of the rock mass:the shearing of the weakness plane may create a transmissive fluid pathway.Verification of the mechanical submodel is conducted by comparison with an analytical solution,while the coupled hydro-mechanical behavior is validated with field data and will be applied within a model and code validation initiative.The work presented here aims at documenting the progress in code development,while accurate match of the field data with the numerical results is current work in progress.
基金the National Key Research and Development Program of China(No.2016YFC0402810)the National Natural Science Foundation of China(Grant No.41731280).
文摘Due to the increase in open pit mining,pit lakes have become common surface water features,posing a potential risk to subsurface aquifer.In this study,a pit lake–groundwater interaction model is built based on the general program MODFLOW with the LAK3 package.For the first time,the effects of lake-slope collapse and aquifer heterogeneity on pit lake–groundwater interactions are analyzed by dividing the lake into six water exchange zones based on the aquifer lithology and groundwater level.Our investigation and simulations reveal a total water exchange from groundwater to the lake of 349000 m3/a without collapse of the pit lake slope,while the total net water exchange under slope collapse conditions is 248000 m3/a(i.e.,a reduction of 1.40-fold).The monthly net water exchange per unit width from groundwater to the lake reaches the largest in April,shifting to negative values in zone IV from June to August and in zone V in June and July.Moreover,the monthly net water exchange per unit width decreases from north to south,and the direction and magnitude of water exchange are found to depend on the hydraulic gradients between the lake and groundwater and the hydraulic conductivity of the slope collapse.
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.
