During the later period of construction of Tianshengqiao concrete faced rockfill dam(CFRD), cracks appeared in the upstream fill slope. The main reason was the nonuniform deformation. The treatment methods were: for c...During the later period of construction of Tianshengqiao concrete faced rockfill dam(CFRD), cracks appeared in the upstream fill slope. The main reason was the nonuniform deformation. The treatment methods were: for cracks with opening less than 1 cm, the cracked slope was compacted with added effort to eliminate cracks; for cracks with opening greater than 1 cm , crack grouting was carried out . The practice demonstrated the treatment was successful. Careful analysis of the relation between sectionalized filling and crack emergence is of significance in guiding the construction design and drawing out filling plan for a high CFRD.展开更多
Due to a large number of high concrete face rockfill dams(CFRDs) being constructed, the seismic safety is crucially important and seismic performance assessment must be performed for such dams. Fragility analysis is a...Due to a large number of high concrete face rockfill dams(CFRDs) being constructed, the seismic safety is crucially important and seismic performance assessment must be performed for such dams. Fragility analysis is a method of great vitality for seismic performance assessment; it can intuitively forecast the structural effects of different ground motion intensities and provide an effective path for structure safety assessment. However, this method is rarely applied in the field of high earth dam risk analysis.This paper introduces fragility analysis into the field of high CFRD safety assessment and establishes seismic performance assessment methods. PGA, Sa(T1, 5%), PGV and PGD are exploited as the earthquake intensity measure(IMs). Relative settlement ratio of dam crest, cumulative sliding displacement of dam slope stability and a new face-slab destroying index(based on DCR and COD) are regarded as the dam damage measures(DMs). The dividing standards of failure grades of high CFRDs are suggested based on each DM. Fragility function is estimated according to incremental dynamic analysis(IDA) and multiple stripes analysis(MSA) methods respectively from a large number of finite element calculations of a certain CFRD, and seismic fragility curves are determined for each DM. Finally, this study analyzes the failure probabilities of the dam under different earthquake intensities and can provide references and bases for the seismic performance design and safety risk assessment of high CFRDs.展开更多
Numerical simulation of concrete-faced rockfill dams(CFRDs)considering the spatial variability of rockfill has become a popular research topic in recent years.In order to determine uncertain rockfill properties effici...Numerical simulation of concrete-faced rockfill dams(CFRDs)considering the spatial variability of rockfill has become a popular research topic in recent years.In order to determine uncertain rockfill properties efficiently and reliably,this study developed an uncertainty inversion analysis method for rockfill material parameters using the stacking ensemble strategy and Jaya optimizer.The comprehensive implementation process of the proposed model was described with an illustrative CFRD example.First,the surrogate model method using the stacking ensemble algorithm was used to conduct the Monte Carlo stochastic finite element calculations with reduced computational cost and improved accuracy.Afterwards,the Jaya algorithm was used to inversely calculate the combination of the coefficient of variation of rockfill material parameters.This optimizer obtained higher accuracy and more significant uncertainty reduction than traditional optimizers.Overall,the developed model effectively identified the random parameters of rockfill materials.This study provided scientific references for uncertainty analysis of CFRDs.In addition,the proposed method can be applied to other similar engineering structures.展开更多
文摘During the later period of construction of Tianshengqiao concrete faced rockfill dam(CFRD), cracks appeared in the upstream fill slope. The main reason was the nonuniform deformation. The treatment methods were: for cracks with opening less than 1 cm, the cracked slope was compacted with added effort to eliminate cracks; for cracks with opening greater than 1 cm , crack grouting was carried out . The practice demonstrated the treatment was successful. Careful analysis of the relation between sectionalized filling and crack emergence is of significance in guiding the construction design and drawing out filling plan for a high CFRD.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFC0404904)the National Natural Science Foundation of China(Grant Nos.51679029,51508071 and 51779034)
文摘Due to a large number of high concrete face rockfill dams(CFRDs) being constructed, the seismic safety is crucially important and seismic performance assessment must be performed for such dams. Fragility analysis is a method of great vitality for seismic performance assessment; it can intuitively forecast the structural effects of different ground motion intensities and provide an effective path for structure safety assessment. However, this method is rarely applied in the field of high earth dam risk analysis.This paper introduces fragility analysis into the field of high CFRD safety assessment and establishes seismic performance assessment methods. PGA, Sa(T1, 5%), PGV and PGD are exploited as the earthquake intensity measure(IMs). Relative settlement ratio of dam crest, cumulative sliding displacement of dam slope stability and a new face-slab destroying index(based on DCR and COD) are regarded as the dam damage measures(DMs). The dividing standards of failure grades of high CFRDs are suggested based on each DM. Fragility function is estimated according to incremental dynamic analysis(IDA) and multiple stripes analysis(MSA) methods respectively from a large number of finite element calculations of a certain CFRD, and seismic fragility curves are determined for each DM. Finally, this study analyzes the failure probabilities of the dam under different earthquake intensities and can provide references and bases for the seismic performance design and safety risk assessment of high CFRDs.
基金supported by the National Natural Science Foundation of China(Grants No.51879185 and 52179139)the Open Fund of the Hubei Key Laboratory of Construction and Management in Hydropower Engineering(Grant No.2020KSD06).
文摘Numerical simulation of concrete-faced rockfill dams(CFRDs)considering the spatial variability of rockfill has become a popular research topic in recent years.In order to determine uncertain rockfill properties efficiently and reliably,this study developed an uncertainty inversion analysis method for rockfill material parameters using the stacking ensemble strategy and Jaya optimizer.The comprehensive implementation process of the proposed model was described with an illustrative CFRD example.First,the surrogate model method using the stacking ensemble algorithm was used to conduct the Monte Carlo stochastic finite element calculations with reduced computational cost and improved accuracy.Afterwards,the Jaya algorithm was used to inversely calculate the combination of the coefficient of variation of rockfill material parameters.This optimizer obtained higher accuracy and more significant uncertainty reduction than traditional optimizers.Overall,the developed model effectively identified the random parameters of rockfill materials.This study provided scientific references for uncertainty analysis of CFRDs.In addition,the proposed method can be applied to other similar engineering structures.
