The material point method(MPM)has been gaining increasing popularity as an appropriate approach to the solution of coupled hydro-mechanical problems involving large deformation.In this paper,we survey the current stat...The material point method(MPM)has been gaining increasing popularity as an appropriate approach to the solution of coupled hydro-mechanical problems involving large deformation.In this paper,we survey the current state-of-the-art in the MPM simulation of hydro-mechanical behaviour in two-phase porous geomaterials.The review covers the recent advances and developments in the MPM and their extensions to capture the coupled hydro-mechanical problems involving large deformations.The focus of this review is aiming at providing a clear picture of what has or has not been developed or implemented for simulating two-phase coupled large deformation problems,which will provide some direct reference for both practitioners and researchers.展开更多
Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study pr...Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.展开更多
Water spewing and muck plugging often occur during earth pressure balance(EPB)shield machines tunnelling in water-rich sandy strata,even though the conventional foam has been employed to condition sandy soils.In this ...Water spewing and muck plugging often occur during earth pressure balance(EPB)shield machines tunnelling in water-rich sandy strata,even though the conventional foam has been employed to condition sandy soils.In this study,a novel thickened foaming agent suitable for EPB shield tunnelling in water-rich sandy strata is developed.In contrast to conventional foam-conditioned sands,the thickened foam-conditioned sand has a low permeability due to the consistent filling of soil pores with the thickened foam,and the initial permeability coefficient decreases by approximately two orders of magnitude.It also exhibits a suitable workability,which is attributed to the enhanced capability of the thickened foam to condition sandy soils.In addition,the effect of concentration on the stability of the foam is explained by the Gibbs-Marangoni effect,and conditioning mechanisms for the thickened foam on sands are discussed from the evolution of foam bubbles.展开更多
Bio-cemented soils can exhibit various types of microstructure depending on the relative position of the carbonate crystals with respect to the host granular skeleton.Different microstructures can have different effec...Bio-cemented soils can exhibit various types of microstructure depending on the relative position of the carbonate crystals with respect to the host granular skeleton.Different microstructures can have different effects on the mechanical and hydraulic responses of the material,hence it is important to develop the capacity to model these microstructures.The discrete element method(DEM)is a powerful numerical method for studying the mechanical behaviour of granular materials considering grain-scale features.This paper presents a toolbox that can be used to generate 3D DEM samples of bio-cemented soils with specific microstructures.It provides the flexibility of modelling bio-cemented soils with precipitates in the form of contact cementing,grain bridging and coating,and combinations of these distribution patterns.The algorithm is described in detail in this paper,and the impact of the precipitated carbonates on the soil microstructure is evaluated.The results indicate that carbonates precipitated in different distribution patterns affect the soil microstructure differently,suggesting the importance of modelling the microstructure of bio-cemented soils.展开更多
The simulation of slope failures,including both failure initiation and development,has been modelled using the material point method（MPM）.Numerical case studies involving various slope angles,heterogeneity and rainf...The simulation of slope failures,including both failure initiation and development,has been modelled using the material point method（MPM）.Numerical case studies involving various slope angles,heterogeneity and rainfall infiltration are presented.It is demonstrated that,by utilising a constitutive model which encompasses,in a simplified manner,both pre-and post-failure behaviour,the material point method is able to simulate commonly observed failure modes.This is a step towards being able to better quantify slope failure consequence and risk.展开更多
Because of the deltaic nature of the Netherlands,deep soft soil deposits are widespread.Due to the population density exploitation of underground space is vital for commercial developments and transport networks.Piles...Because of the deltaic nature of the Netherlands,deep soft soil deposits are widespread.Due to the population density exploitation of underground space is vital for commercial developments and transport networks.Piles are used as primary support elements in deep excavations,cut and cover tunnels,quay walls,flood defences and to provide uplift resistance to the base of tunnels and basements.This paper examines empirical correlations linking the Cone Penetration Test(CPT)end resistance qc and the resistance of deep foundations in sand.It is found that correlations between qc and pile end resistance are independent of pile diameter.However,the impact of installation method,residual load,plugging and sand creep should be considered.In the case of shaft resistance,constant correlation factors between qc and average shaft resistance are possible for non-displacement piles.For the case of displacement piles,correlations that include the effects of friction fatigue and pile plugging during installation are recommended.展开更多
基金The financial supports from National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(Grant No.52022112)the International Postdoctoral Exchange Fellowship Program(Talent-Introduction Program,Grant No.YJ20220219)。
文摘The material point method(MPM)has been gaining increasing popularity as an appropriate approach to the solution of coupled hydro-mechanical problems involving large deformation.In this paper,we survey the current state-of-the-art in the MPM simulation of hydro-mechanical behaviour in two-phase porous geomaterials.The review covers the recent advances and developments in the MPM and their extensions to capture the coupled hydro-mechanical problems involving large deformations.The focus of this review is aiming at providing a clear picture of what has or has not been developed or implemented for simulating two-phase coupled large deformation problems,which will provide some direct reference for both practitioners and researchers.
基金funding support from Rijkswaterstaat,the Netherlands,and European Union’s Horizon 2020 Research and Innovation Programme(Project SAFE-10-T under Grant No.723254)China Scholarship Council,and National Natural Science Foundation of China(Grant No.42225702).
文摘Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.
基金The financial support from the National Natural Science Foundation of China(Grant No.52022112)the Fundamental Research Funds for the Central South University(Grant No.2023ZZTS0366)are acknowledged and appreciated.The authors are also grateful for the help from Dr.Ji Zhao of China University of Mining and Technology.
文摘Water spewing and muck plugging often occur during earth pressure balance(EPB)shield machines tunnelling in water-rich sandy strata,even though the conventional foam has been employed to condition sandy soils.In this study,a novel thickened foaming agent suitable for EPB shield tunnelling in water-rich sandy strata is developed.In contrast to conventional foam-conditioned sands,the thickened foam-conditioned sand has a low permeability due to the consistent filling of soil pores with the thickened foam,and the initial permeability coefficient decreases by approximately two orders of magnitude.It also exhibits a suitable workability,which is attributed to the enhanced capability of the thickened foam to condition sandy soils.In addition,the effect of concentration on the stability of the foam is explained by the Gibbs-Marangoni effect,and conditioning mechanisms for the thickened foam on sands are discussed from the evolution of foam bubbles.
基金support from the China Scholarship Council(CSC)and the Geo-Engineering Section of Delft University of Technology.
文摘Bio-cemented soils can exhibit various types of microstructure depending on the relative position of the carbonate crystals with respect to the host granular skeleton.Different microstructures can have different effects on the mechanical and hydraulic responses of the material,hence it is important to develop the capacity to model these microstructures.The discrete element method(DEM)is a powerful numerical method for studying the mechanical behaviour of granular materials considering grain-scale features.This paper presents a toolbox that can be used to generate 3D DEM samples of bio-cemented soils with specific microstructures.It provides the flexibility of modelling bio-cemented soils with precipitates in the form of contact cementing,grain bridging and coating,and combinations of these distribution patterns.The algorithm is described in detail in this paper,and the impact of the precipitated carbonates on the soil microstructure is evaluated.The results indicate that carbonates precipitated in different distribution patterns affect the soil microstructure differently,suggesting the importance of modelling the microstructure of bio-cemented soils.
基金supported by the Marie Curie Career Integration Grant(No.333177)the "100 Talents" programme of the Chinese Academy of Science+1 种基金the China Scholarship Councilthe Geo-Engineering Section of Delft University of Technology
文摘The simulation of slope failures,including both failure initiation and development,has been modelled using the material point method（MPM）.Numerical case studies involving various slope angles,heterogeneity and rainfall infiltration are presented.It is demonstrated that,by utilising a constitutive model which encompasses,in a simplified manner,both pre-and post-failure behaviour,the material point method is able to simulate commonly observed failure modes.This is a step towards being able to better quantify slope failure consequence and risk.
基金Some of the work presented in this paper was completed together with a number of former research students and collaborators who include:Prof.Barry Lahane,Dr.Lisa Kirwan,Dr.Ali Tolooiyan,David Cadogan,Dr.Cormac Reale and others.The permission of the Port of Rotterdam and Funderingstechnieken Verstraeten bv.and BNED bv.to publish pile load test data is gratefully acknowledged.
文摘Because of the deltaic nature of the Netherlands,deep soft soil deposits are widespread.Due to the population density exploitation of underground space is vital for commercial developments and transport networks.Piles are used as primary support elements in deep excavations,cut and cover tunnels,quay walls,flood defences and to provide uplift resistance to the base of tunnels and basements.This paper examines empirical correlations linking the Cone Penetration Test(CPT)end resistance qc and the resistance of deep foundations in sand.It is found that correlations between qc and pile end resistance are independent of pile diameter.However,the impact of installation method,residual load,plugging and sand creep should be considered.In the case of shaft resistance,constant correlation factors between qc and average shaft resistance are possible for non-displacement piles.For the case of displacement piles,correlations that include the effects of friction fatigue and pile plugging during installation are recommended.
