The seven long tunnels of Jinping II hydropower station are deeply buried.The width and evolution characteristics of excavation damaged zone(EDZ) are the key problem to the design of tunnels excavation and supports.In...The seven long tunnels of Jinping II hydropower station are deeply buried.The width and evolution characteristics of excavation damaged zone(EDZ) are the key problem to the design of tunnels excavation and supports.In order to study this problem,several specific experimental tunnels with different overburden and geometric sizes were excavated at this site.Digital borehole camera,sliding micrometer,cross-hole acoustic wave equipment and acoustic emission apparatus were adopted.This paper introduced the comprehensive in situ experimental methods through pre-installed facilities and pre-drilled boreholes.Typical properties of the surrounding rock mass,including cracks,deformation,elastic wave and micro fractures,were measured during the whole process of the tunnel excavation.The width and characteristics of formation and evolution of tunnels EDZ were analyzed under different construction methods involving of TBM and drilling and blasting,the test tunnels were excavated by full-face or two benches.The relationships between EDZ and tunnel geometry sizes,overburden and excavation method were described as well.The results will not only contribute a great deal to the analysis of rock mass behavior in deeply buried rock mass,but also provide direct data for support design and rockburst prediction.展开更多
Nanoscale electrocatalysts have exhibited promising activity and stability,improving the kinetics of numerous electrochemical reactions in renewable energy systems such as electrolyzers,fuel cells,and metal-air batter...Nanoscale electrocatalysts have exhibited promising activity and stability,improving the kinetics of numerous electrochemical reactions in renewable energy systems such as electrolyzers,fuel cells,and metal-air batteries.Due to the size effect,nano particles with extreme small size have high surface areas,complicated morphology,and various surface terminations,which make them different from their bulk phases and often undergo restructuring during the reactions.These restructured materials are hard to probe by conventional ex-situ characterizations,thus leaving the true reaction centers and/or active sites difficult to determine.Nowadays,in situ techniques,particularly X-ray absorption spectroscopy(XAS),have become an important tool to obtain oxidation states,electronic structure,and local bonding environments,which are critical to investigate the electrocatalysts under real reaction conditions.In this review,we go over the basic principles of XAS and highlight recent applications of in situ XAS in studies of nanoscale electrocatalysts.展开更多
Automated EBSD or Orientation Imaging Microscopy (OIM) systems are being used in combination with other equipment within the scanning electron microscope (SEM) to perform in-situ measurements. This paper briefly revie...Automated EBSD or Orientation Imaging Microscopy (OIM) systems are being used in combination with other equipment within the scanning electron microscope (SEM) to perform in-situ measurements. This paper briefly reviews OIM studies of in-situ experiments performed using tensile and heating stages as well as in-situ serial sectioning. In particular, in-situ OIM scan results on an aluminum alloy sample deformed in tension; phase transformations in a cobalt sample, recrystallization and grain growth in a copper sample and serial sectioning of a nickel super-alloy sample are reviewed.展开更多
In the context of radioactive waste disposal,an underground research laboratory(URL)is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a radioactive waste dis...In the context of radioactive waste disposal,an underground research laboratory(URL)is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a radioactive waste disposal facility within a geological formation.The Meuse/Haute-Marne URL is a sitespecific facility planned to study the feasibility of a radioactive waste disposal in the Callovo-Oxfordian(COx)claystone.The thermo-hydro-mechanical(THM)behaviour of the host rock is significant for the design of the underground nuclear waste disposal facility and for its long-term safety.The French National Radioactive Waste Management Agency(Andra)has begun a research programme aiming to demonstrate the relevancy of the French high-level waste(HLW)concept.This paper presents the programme implemented from small-scale(small diameter)boreholes to full-scale demonstration experiments to study the THM effects of the thermal transient on the COx claystone and the strategy implemented in this new programme to demonstrate and optimise current disposal facility components for HLW.It shows that the French high-level waste concept is feasible and working in the COx claystone.It also exhibits that,as for other plastic clay or claystone,heating-induced pore pressure increases and that the THM behaviour is anisotropic.展开更多
基金supported by the National Basic Research Program of China("973"Program)(Grant No.2010CB732006)the National Natural Science Foundation of China(Grant No.40902091)supported by the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘The seven long tunnels of Jinping II hydropower station are deeply buried.The width and evolution characteristics of excavation damaged zone(EDZ) are the key problem to the design of tunnels excavation and supports.In order to study this problem,several specific experimental tunnels with different overburden and geometric sizes were excavated at this site.Digital borehole camera,sliding micrometer,cross-hole acoustic wave equipment and acoustic emission apparatus were adopted.This paper introduced the comprehensive in situ experimental methods through pre-installed facilities and pre-drilled boreholes.Typical properties of the surrounding rock mass,including cracks,deformation,elastic wave and micro fractures,were measured during the whole process of the tunnel excavation.The width and characteristics of formation and evolution of tunnels EDZ were analyzed under different construction methods involving of TBM and drilling and blasting,the test tunnels were excavated by full-face or two benches.The relationships between EDZ and tunnel geometry sizes,overburden and excavation method were described as well.The results will not only contribute a great deal to the analysis of rock mass behavior in deeply buried rock mass,but also provide direct data for support design and rockburst prediction.
基金financially supported by start-up funds from Oregon State UniversityPart of authors’ work using soft X-ray absorption spectroscopy was performed at beamline 6.3.1 of Advanced Light Source, which is an Office of Science User Facility operated for the U.S.DOE Office of Science by Lawrence Berkeley National Laboratory and supported by the DOE under Contract No. DEAC02-05CH11231
文摘Nanoscale electrocatalysts have exhibited promising activity and stability,improving the kinetics of numerous electrochemical reactions in renewable energy systems such as electrolyzers,fuel cells,and metal-air batteries.Due to the size effect,nano particles with extreme small size have high surface areas,complicated morphology,and various surface terminations,which make them different from their bulk phases and often undergo restructuring during the reactions.These restructured materials are hard to probe by conventional ex-situ characterizations,thus leaving the true reaction centers and/or active sites difficult to determine.Nowadays,in situ techniques,particularly X-ray absorption spectroscopy(XAS),have become an important tool to obtain oxidation states,electronic structure,and local bonding environments,which are critical to investigate the electrocatalysts under real reaction conditions.In this review,we go over the basic principles of XAS and highlight recent applications of in situ XAS in studies of nanoscale electrocatalysts.
基金The authors acknowledge the contribution of Seiichi Suzuki of TSL Japan for the engineering of the heating stage Robert Kubic and Raja Mishra of General Motors for providing access to the in-situ tensile stage+1 种基金 Michael Uchic and co-workers at the Air Force Research Laboratory for collecting and sharing the threedimensional data and Tom Lillo of Iaho National Engineering and Environmental Laboratory for providing the copper ECAE sample.
文摘Automated EBSD or Orientation Imaging Microscopy (OIM) systems are being used in combination with other equipment within the scanning electron microscope (SEM) to perform in-situ measurements. This paper briefly reviews OIM studies of in-situ experiments performed using tensile and heating stages as well as in-situ serial sectioning. In particular, in-situ OIM scan results on an aluminum alloy sample deformed in tension; phase transformations in a cobalt sample, recrystallization and grain growth in a copper sample and serial sectioning of a nickel super-alloy sample are reviewed.
文摘In the context of radioactive waste disposal,an underground research laboratory(URL)is a facility in which experiments are conducted to demonstrate the feasibility of constructing and operating a radioactive waste disposal facility within a geological formation.The Meuse/Haute-Marne URL is a sitespecific facility planned to study the feasibility of a radioactive waste disposal in the Callovo-Oxfordian(COx)claystone.The thermo-hydro-mechanical(THM)behaviour of the host rock is significant for the design of the underground nuclear waste disposal facility and for its long-term safety.The French National Radioactive Waste Management Agency(Andra)has begun a research programme aiming to demonstrate the relevancy of the French high-level waste(HLW)concept.This paper presents the programme implemented from small-scale(small diameter)boreholes to full-scale demonstration experiments to study the THM effects of the thermal transient on the COx claystone and the strategy implemented in this new programme to demonstrate and optimise current disposal facility components for HLW.It shows that the French high-level waste concept is feasible and working in the COx claystone.It also exhibits that,as for other plastic clay or claystone,heating-induced pore pressure increases and that the THM behaviour is anisotropic.
