To evaluate the columnar jointed basalts in the dam site of Baihetan hydropower station in southwest China, we developed a basic conceptual model of single jointed rock mass. Considering that the rock mass deformation...To evaluate the columnar jointed basalts in the dam site of Baihetan hydropower station in southwest China, we developed a basic conceptual model of single jointed rock mass. Considering that the rock mass deformation consists of rock block deformation and joints deformation, the linear mechanical characteristics of the cell (including the elastic joints and the nonlinear mechanical behaviors of the cell) with a combined frictional-elastic interface were analyzed. We developed formulas to calculate the rock block deformation, which can be adapted for multiple jointed rock mass and columnar jointed basalts. The formulas are effective in calculating the equivalent modulus of multiple jointed rock mass, and precisely reveal the anisotropic properties of columnar jointed basalts. Furthermore, the in situ rigid bearing plate tests were analyzed and calculated, and the types of loading-unloading curves and the equivalent modulus along different directions of columnar jointed basalts were obtained. The analytical results are in close compliance with the test results.展开更多
It is becoming an important social problem to make maintenance and rehabilitation of existing short and medium span(10-20 m)bridges because there are a huge amount of short and medium span bridges in service in the wo...It is becoming an important social problem to make maintenance and rehabilitation of existing short and medium span(10-20 m)bridges because there are a huge amount of short and medium span bridges in service in the world.The kernel of such bridge management is to develop a method of safety(condition)assessment on items which include remaining life and load carrying capacity.Bridge health monitoring using information technology and sensors is capable of providing more accurate knowledge of bridge performance than traditional strategies.The aim of this paper is to introduce a state-of-the-art on not only a rational bridge health monitoring system incorporating with the information and communication technologies for lifetime management of existing short and medium span bridges but also a continuous data collecting system designed for bridge health monitoring of mainly short and medium span bridges.In this paper,although there are some useful monitoring methods for short and medium span bridges based on the qualitative or quantitative information,mainly two advanced structural health monitoring systems are described to review and analyse the potential of utilizing the long term health monitoring in safety assessment and management issues for short and medium span bridge.The first is a special designed mobile in-situ loading device(vehicle)for short and medium span road bridges to assess the structural safety(performance)and derive optimal strategies for maintenance using reliability based method.The second is a long term health monitoring method by using the public buses as part of a public transit system(called bus monitoring system)to be applied mainly to short and medium span bridges,along with safety indices,namely,"characteristic deflection"which is relatively free from the influence of dynamic disturbances due to such factors as the roughness of the road surface,and a structural anomaly parameter.展开更多
Twinning-detwinning(TDT)behavior in a strongly basal-textured Mg-Li alloy during two-step compression(RD)-compression(ND)process was investigated using quasi-in-situ EBSD.TDT behavior and TDT variants selection were s...Twinning-detwinning(TDT)behavior in a strongly basal-textured Mg-Li alloy during two-step compression(RD)-compression(ND)process was investigated using quasi-in-situ EBSD.TDT behavior and TDT variants selection were statistically discussed with the loading path for the first time.Non-Schmid twinning behavior was observed in the first step compression,owing to the local stress fluctuations by neighboring twins;in contrast,Schmid’s law well predicted the detwinning variants selection.This asymmetrical TDT behavior was first investigated to date related with the strong basal texture and loading path.Besides,with the progress of compression,Schmid factors for twinning demonstrated a decreasing tendency;however,those for detwinning during the second step displayed an abnormally increasing trend,fundamentally stemming from prior twinning behavior.展开更多
基金Project (Nos. 50911130366 and 2011CB013504) supported by the National Natural Science Foundation of Chinathe Postdoctoral Advanced Research Programs Class Ⅱ of Zhejiang Province (No. BSH1302013), China
文摘To evaluate the columnar jointed basalts in the dam site of Baihetan hydropower station in southwest China, we developed a basic conceptual model of single jointed rock mass. Considering that the rock mass deformation consists of rock block deformation and joints deformation, the linear mechanical characteristics of the cell (including the elastic joints and the nonlinear mechanical behaviors of the cell) with a combined frictional-elastic interface were analyzed. We developed formulas to calculate the rock block deformation, which can be adapted for multiple jointed rock mass and columnar jointed basalts. The formulas are effective in calculating the equivalent modulus of multiple jointed rock mass, and precisely reveal the anisotropic properties of columnar jointed basalts. Furthermore, the in situ rigid bearing plate tests were analyzed and calculated, and the types of loading-unloading curves and the equivalent modulus along different directions of columnar jointed basalts were obtained. The analytical results are in close compliance with the test results.
文摘It is becoming an important social problem to make maintenance and rehabilitation of existing short and medium span(10-20 m)bridges because there are a huge amount of short and medium span bridges in service in the world.The kernel of such bridge management is to develop a method of safety(condition)assessment on items which include remaining life and load carrying capacity.Bridge health monitoring using information technology and sensors is capable of providing more accurate knowledge of bridge performance than traditional strategies.The aim of this paper is to introduce a state-of-the-art on not only a rational bridge health monitoring system incorporating with the information and communication technologies for lifetime management of existing short and medium span bridges but also a continuous data collecting system designed for bridge health monitoring of mainly short and medium span bridges.In this paper,although there are some useful monitoring methods for short and medium span bridges based on the qualitative or quantitative information,mainly two advanced structural health monitoring systems are described to review and analyse the potential of utilizing the long term health monitoring in safety assessment and management issues for short and medium span bridge.The first is a special designed mobile in-situ loading device(vehicle)for short and medium span road bridges to assess the structural safety(performance)and derive optimal strategies for maintenance using reliability based method.The second is a long term health monitoring method by using the public buses as part of a public transit system(called bus monitoring system)to be applied mainly to short and medium span bridges,along with safety indices,namely,"characteristic deflection"which is relatively free from the influence of dynamic disturbances due to such factors as the roughness of the road surface,and a structural anomaly parameter.
基金supported by the grant from the Natural Science Foundation of China(51871244)the Hunan Provincial Innovation Foundation for Postgraduate(CX20200172)the Fundamental Research Funds for the Central Universities of Central South University(1053320190103)。
文摘Twinning-detwinning(TDT)behavior in a strongly basal-textured Mg-Li alloy during two-step compression(RD)-compression(ND)process was investigated using quasi-in-situ EBSD.TDT behavior and TDT variants selection were statistically discussed with the loading path for the first time.Non-Schmid twinning behavior was observed in the first step compression,owing to the local stress fluctuations by neighboring twins;in contrast,Schmid’s law well predicted the detwinning variants selection.This asymmetrical TDT behavior was first investigated to date related with the strong basal texture and loading path.Besides,with the progress of compression,Schmid factors for twinning demonstrated a decreasing tendency;however,those for detwinning during the second step displayed an abnormally increasing trend,fundamentally stemming from prior twinning behavior.
