Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads....Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads.Three models of typical bedded rock slopes(BRSs),i.e.gently(GIS),moderately(MIS),and steeply(SIS)inclined slopes,were proposed according to field investigations.The dynamic response mechanism and stability of the BRSs,affected by the rock mass deterioration of the HFB,were investigated by the shaking table test and the universal distinct element code(UDEC)simulation.Specifically,the amplification coefficient of the peak ground acceleration(PGA)of the slope was gradually attenuated under multiple seismic loads,and the acceleration response showed obvious“surface effect”and“elevation effect”in the horizontal and vertical directions,respectively.The“S-type”cubic function and“steep-rise type”exponential function were used to characterize the cumulative damage evolution of the slope caused by microseismic waves(low seismic waves)and high seismic waves,respectively.According to the dynamic responses of the acceleration,cumulative displacement,rock pressure,pore water pressure,damping ratio,natural frequency,stability coefficient,and sliding velocity of the slope,the typical evolution processes of the dynamic cumulative damage and instability failure of the slope were generalized,and the numerical and experimental results were compared.Considering the dynamic effects of the slope height(SH),slope angle(SA),bedding plane thickness(BPT),dip angle of the bedding plane(DABP),dynamic load amplitude(DLA),dynamic load frequency(DLF),height of water level of the hydro-fluctuation belt(HWLHFB),degradation range of the hydro-fluctuation belt(DRHFB),and degradation shape of the hydro-fluctuation belt(DSHFB),the sensitivity of factors influencing the slope dynamic stability using the orthogonal analysis method(OAM)was DLA>DRHFB>SA>SH>DLF>HWLHFB>DSHFB>DABP>BPT.展开更多
Phosphorus concentration on the surface of seawater varies greatly with different environments,especially in coastal.The molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is st...Phosphorus concentration on the surface of seawater varies greatly with different environments,especially in coastal.The molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is still unclear.In this study,transcriptomes and gene knockouts were used to investigate the adaptive molecular mechanism of a model coastal cyanobacterium Synechococcus sp.PCC 7002 during periods of phosphorus starvation and phosphorus recovery(adding sufficient phosphorus after phosphorus starvation).The findings indicated that phosphorus deficiency affected the photosynthesis,ribosome synthesis,and bacterial motility pathways,which recommenced after phosphorus was resupplied.Even more,most of the metabolic pathways of cyanobacteria were enhanced after phosphorus recovery compared to the control which was kept in continuous phosphorus replete conditions.Based on transcriptome,54 genes potentially related to phosphorusdeficiency adaptation were selected and knocked out individually or in combination.It was found that five mutants showed weak growth phenotype under phosphorus deficiency,indicating the importance of the genes(A0076,A0549-50,A1094,A1320,A1895)in the adaptation of phosphorus deficiency.Three mutants were found to grow better than the wild type under phosphorus deficiency,suggesting that the products of these genes(A0079,A0340,A2284–86)might influence the adaptation to phosphorus deficiency.Bioinformatics analysis revealed that cyanobacteria exposed to highly fluctuating phosphorus concentrations have more sophisticated phosphorus acquisition strategies.These results elucidated that Synechococcus sp.PCC 7002 have variable phosphorus response mechanisms to adapt to fluctuating phosphorus concentration,providing a novel perspective of how cyanobacteria may respond to the complex and dynamic environments.展开更多
With the construction of the Xiluodu hydropower station on the Jinsha River,the reservoir impoundment began in 2013 and the water level fluctuates annually between 540 m and 600 m above sea level.The Yanjiao rock slop...With the construction of the Xiluodu hydropower station on the Jinsha River,the reservoir impoundment began in 2013 and the water level fluctuates annually between 540 m and 600 m above sea level.The Yanjiao rock slope which is located on the left bank of the Jinsha River 75 km upstream of the Xiluodu dam site,began to deform in 2014.The potential failure of the slope not only threatens Yanjiao town but also affects the safe operation of the Xiluodu reservoir.This paper is to find the factors influencing the Yanjiao slope deformation through field investigation,geotechnical reconnaissance,and monitoring.Results show that the Yanjiao slope can be divided into a bank collapse area(BCA)and a strong deformation area(SDA)based on the crack distribution characteristics of the slope.The rear area of the slope has been experiencing persistent deformation with a maximum cumulative displacement(GPS monitoring point G4)of 505 mm and 399 mm in the horizontal and vertical directions,respectively.The potential failure surface of the slope is formed 36 m below the surface based on the borehole inclinometer.The bank collapses of the Yanjiao slope are directly caused by the reservoir impoundment while the deformation area of the slope is affected by the combination of the rainfall and reservoir water level fluctuation.Based on mechanism of the Yanjiao slope,prestressed anchor combined with the surface drainage and slope unloading are recommended to prevent potential deformation.展开更多
基金the China Postdoctoral Science Foundation(Grant No.2023M730432)the Special Funding for Chongqing Postdoctoral Research Project(Grant No.2022CQBSHTB1010)the Chongqing Postdoctoral Science Foundation(Grant No.CSTB2023NSCQ-BHX0223).
文摘Reservoir-induced earthquakes(RIEs)occur frequently in the Three Gorges Reservoir Area(TGRA)and the rock mass strength of the hydro-fluctuation belt(HFB)deteriorates severely due to the reservoirinduced seismic loads.Three models of typical bedded rock slopes(BRSs),i.e.gently(GIS),moderately(MIS),and steeply(SIS)inclined slopes,were proposed according to field investigations.The dynamic response mechanism and stability of the BRSs,affected by the rock mass deterioration of the HFB,were investigated by the shaking table test and the universal distinct element code(UDEC)simulation.Specifically,the amplification coefficient of the peak ground acceleration(PGA)of the slope was gradually attenuated under multiple seismic loads,and the acceleration response showed obvious“surface effect”and“elevation effect”in the horizontal and vertical directions,respectively.The“S-type”cubic function and“steep-rise type”exponential function were used to characterize the cumulative damage evolution of the slope caused by microseismic waves(low seismic waves)and high seismic waves,respectively.According to the dynamic responses of the acceleration,cumulative displacement,rock pressure,pore water pressure,damping ratio,natural frequency,stability coefficient,and sliding velocity of the slope,the typical evolution processes of the dynamic cumulative damage and instability failure of the slope were generalized,and the numerical and experimental results were compared.Considering the dynamic effects of the slope height(SH),slope angle(SA),bedding plane thickness(BPT),dip angle of the bedding plane(DABP),dynamic load amplitude(DLA),dynamic load frequency(DLF),height of water level of the hydro-fluctuation belt(HWLHFB),degradation range of the hydro-fluctuation belt(DRHFB),and degradation shape of the hydro-fluctuation belt(DSHFB),the sensitivity of factors influencing the slope dynamic stability using the orthogonal analysis method(OAM)was DLA>DRHFB>SA>SH>DLF>HWLHFB>DSHFB>DABP>BPT.
基金the support from Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai,No.SML2021SP204)funded by the National Natural Science Founda-tion of China(Grant Nos.32170108,and 42188102)+1 种基金the Science and Technology Innovation 2025 Major Project of Ningbo City(Grant No.2022Z189)the Ningbo Public Welfare Science and Technology Program(Grant Nos.2023S068,2023S040).
文摘Phosphorus concentration on the surface of seawater varies greatly with different environments,especially in coastal.The molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is still unclear.In this study,transcriptomes and gene knockouts were used to investigate the adaptive molecular mechanism of a model coastal cyanobacterium Synechococcus sp.PCC 7002 during periods of phosphorus starvation and phosphorus recovery(adding sufficient phosphorus after phosphorus starvation).The findings indicated that phosphorus deficiency affected the photosynthesis,ribosome synthesis,and bacterial motility pathways,which recommenced after phosphorus was resupplied.Even more,most of the metabolic pathways of cyanobacteria were enhanced after phosphorus recovery compared to the control which was kept in continuous phosphorus replete conditions.Based on transcriptome,54 genes potentially related to phosphorusdeficiency adaptation were selected and knocked out individually or in combination.It was found that five mutants showed weak growth phenotype under phosphorus deficiency,indicating the importance of the genes(A0076,A0549-50,A1094,A1320,A1895)in the adaptation of phosphorus deficiency.Three mutants were found to grow better than the wild type under phosphorus deficiency,suggesting that the products of these genes(A0079,A0340,A2284–86)might influence the adaptation to phosphorus deficiency.Bioinformatics analysis revealed that cyanobacteria exposed to highly fluctuating phosphorus concentrations have more sophisticated phosphorus acquisition strategies.These results elucidated that Synechococcus sp.PCC 7002 have variable phosphorus response mechanisms to adapt to fluctuating phosphorus concentration,providing a novel perspective of how cyanobacteria may respond to the complex and dynamic environments.
基金the project of POWERCHINA Chengdu Engineering Corporation Limited,Power China under Grant No.P46220the Natural Science Foundation of Sichuan,China under Grant No.2022NSFSC0425the Science and Technology Department of Sichuan Province under Grant No.2021YJ0053。
文摘With the construction of the Xiluodu hydropower station on the Jinsha River,the reservoir impoundment began in 2013 and the water level fluctuates annually between 540 m and 600 m above sea level.The Yanjiao rock slope which is located on the left bank of the Jinsha River 75 km upstream of the Xiluodu dam site,began to deform in 2014.The potential failure of the slope not only threatens Yanjiao town but also affects the safe operation of the Xiluodu reservoir.This paper is to find the factors influencing the Yanjiao slope deformation through field investigation,geotechnical reconnaissance,and monitoring.Results show that the Yanjiao slope can be divided into a bank collapse area(BCA)and a strong deformation area(SDA)based on the crack distribution characteristics of the slope.The rear area of the slope has been experiencing persistent deformation with a maximum cumulative displacement(GPS monitoring point G4)of 505 mm and 399 mm in the horizontal and vertical directions,respectively.The potential failure surface of the slope is formed 36 m below the surface based on the borehole inclinometer.The bank collapses of the Yanjiao slope are directly caused by the reservoir impoundment while the deformation area of the slope is affected by the combination of the rainfall and reservoir water level fluctuation.Based on mechanism of the Yanjiao slope,prestressed anchor combined with the surface drainage and slope unloading are recommended to prevent potential deformation.
