By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hyd...By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hydro-fluctuation belt(Yunyang part) were analyzed.The relationship between the test parameters and the pollution degree in the region was discussed.The research results of UV spectrum data E3/E4 showed that in 4 sampling sites which included Huangshi Town,Gaoyang Town,Shuangjiang Town and Quma Town,the humification degree in the sediment of hydro-fluctuation belt in Shuangjiang Town sampling site was lower,and the aromaticity was smaller.Moreover,the effect of human factor was comparatively smaller.The fluorescence index value which represented the source of humus in DOM was 1.62-1.88.It showed that the biological and terrestrial source both existed.Three dimensional spectra results showed that the pollution degrees in 4 sampling sites were all smaller,and some prevention measures should be taken early.展开更多
Soils in the hydro-fluctuation belts of the reservoirs are most highly influenced by the special hydro-conditions and reservoir operation,leading to unique soil erosion process and largely accelerate soil erosion inte...Soils in the hydro-fluctuation belts of the reservoirs are most highly influenced by the special hydro-conditions and reservoir operation,leading to unique soil erosion process and largely accelerate soil erosion intensity.The present study aimed to estimate soil erosion rate in the hydro-fluctuation belt of the Pubugou Reservoir,Southwest China,based on the framework of Universal Soil Loss Equation(USLE).An attempt has been made to modify the original USLE by including the reservoir water erosivity(W),a new factor into the model.Soil erosion rate from different land use types were quantitatively estimated,using the USLE and the modified USLE respectively.Field observation showed that soil erosion rate in dry farmland,bare land and grassland was 4700,44600 and 5050 t/km2,respectively.The erosion rate assessed by the modified USLE was closely related to that recorded from the field monitoring data.The findings of this study clearly highlight the importance of inclusion of the W factor to the original USLE model while assessing soil erosion in the reservoir hydro-fluctuation belt.展开更多
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
Through the Betula nigra afforestation test in the engineering treatment area of the Wuxi Section of the Daning River in Chongqing,the feasibility of arbor vegetation restoration in the comprehensive management of the...Through the Betula nigra afforestation test in the engineering treatment area of the Wuxi Section of the Daning River in Chongqing,the feasibility of arbor vegetation restoration in the comprehensive management of the engineering treatment areas of the Three Gorges Reservoir was explored.The results showed that:(1)before the flooding in the project area,the survival rate of B.nigra seedlings was high,over 95%,and(2)in 2021,after a water storage period,affected by factors such as seedling specifications,flood and flooding time,the survival rate of the seedlings planted in 2020 was low,and the one-year-old seedlings were greatly competed by weeds and grew less.Two-year-old B.nigra seedlings were replanted in 2021,and the survival rate of the B.nigra seedlings was 100%in 2022.Two-year-old B.nigra seedlings have strong adaptability and have little impact on the stability of the engineering treatment area,and can be used as afforestation tree species in engineering treatment areas of hydro-fluctuation zones.展开更多
Setting monitoring transect in the middle and shallow water area(altitude 156-172 m) in Three Gorges reservoir hydro-fluctuation belt to research the changing characteristics of the contents of N, P,K,pH and organic m...Setting monitoring transect in the middle and shallow water area(altitude 156-172 m) in Three Gorges reservoir hydro-fluctuation belt to research the changing characteristics of the contents of N, P,K,pH and organic matter of the soil which experienced the influence of fluctuation the first time. The results showed that by the influence of water level fluctuating,contents of soil N,P,K,pH and organic matter had reduced in different soil layers in hydro-fluctuation belt.The available N decreased by 41.53%-59.87%,available P decreased by 5.26%- 36.76%,available K decreased by 3.55%-45.56%, total N decreased by 9.52%-40.00%,total P had no change generally,total K had decreased a little, content of organic material decreased by 7.62%- 37.83%%,pH value turned to neutral,changed by 1.73%-9.58%.展开更多
Fresh water microplastic pollution is of pressing concern globally,but its distribution and sources in reservoirs are poorly documented.Danjiangkou Reservoir is the second largest reservoir in China and is divided int...Fresh water microplastic pollution is of pressing concern globally,but its distribution and sources in reservoirs are poorly documented.Danjiangkou Reservoir is the second largest reservoir in China and is divided into the Han Reservoir and Dan Reservoir.In this work,microplastic abundances and morphological characteristics of the reservoir were investigated.The microplastic abundance of 15 main tributaries of the reservoir was also measured.The vertical distribution(in water column and sediment),horizontal distribution(in Han Reservoir and Dan Reservoir)and source of microplastics were analyzed.Microplastics accumulated in the middle layer of the reservoir,and the size and color of the microplastic particles changed from the surface to the bottom,which implies that surveys of surface water are not enough to determine the microplastic contamination for deep water reservoirs.In the surface water,the microplastic abundance in the Han Reservoir was lower than that in the Dan Reservoir(p<0.05),but microplastic abundance did not differ significantly in the intermediate and bottom water.Tributaries were one of the main sources of microplastics for Han Reservoir but not for Dan Reservoir.Agricultural cultivation in the hydro-fluctuation belt might be an important source of microplastics in the Dan Reservoir,which should be given additional attention.The results of this study can provide valuable information for developing microplastic sampling strategies in deep water reservoirs.Further studies are recommended to investigate the process through which microplastics in the hydro-fluctuation belt enter the reservoir and the sinking behavior of microplastics in the reservoir.展开更多
After water is impounded in a reservoir, rock mass in the hydro-fluctuation belt of the reservoir bank slope is subject to water saturation- dehydration circulation （WSDC）. To quantify the rate of change of rock mec...After water is impounded in a reservoir, rock mass in the hydro-fluctuation belt of the reservoir bank slope is subject to water saturation- dehydration circulation （WSDC）. To quantify the rate of change of rock mechanical properties, samples from the Longtan dam area were measured with uniaxial compression tests after different numbers （1, 5, 10, 15, and 20） of simulated WSDC cycles. Based on the curves derived from these tests, a modified Hock- Brown failure criterion was proposed, in which a new parameter was introduced to model the cumulative damage to rocks after WSDC. A case of an engineering application was analyzed, and the results showed that the modified Hock-Brown failure criterion is useful. Under similar WSDC-influenced engineering and geological conditions, rock mass strength parameters required for analysis and evaluation of rock slope stability can be estimated according to this modified Hoek-Brown failure criterion.展开更多
To investigate the dynamic damage evolution characteristics of bank slopes with serrated structural planes,the shaking table model test and the numerical simulation were utilized.The main findings indicate that under ...To investigate the dynamic damage evolution characteristics of bank slopes with serrated structural planes,the shaking table model test and the numerical simulation were utilized.The main findings indicate that under continuous seismic loads,the deformation of the bank slope increased,particularly around the hydro-fluctuation belt,accompanying by the pore water pressure rising.The soil pressure increased and then decreased showed dynamic variation characteristics.As the undulation angle of the serrated structural planes increased(30°, 45°, and 60°),the failure modes were climbing,climbinggnawing,and gnawing respectively.The first-order natural frequency was used to calculate the damage degree(Dd)of the bank slope.During microseisms and small earthquakes,it was discovered that the evolution of Dd followed the“S”shape,which was fitted by a logic function.Additionally,the quadratic function was used to fit the Dd during moderately strong earthquakes.Through the numerical simulation,the variation characteristics of safety factors(Sf)for slopes with serrated structural planes and slopes with straight structural planes were compared.Under continuous seismic loads,the Sf of slopes with straight structural planes reduce stalely,whereas the Sf for slopes with serrated structural planes was greater than the former and the reduction rate was increasing.展开更多
The reservoir operation awakens numerous landslides with multiple sliding surfaces known as reservoir landslides,and the systematic stability analysis for such landslides is becoming increasingly urgent.Taking the Maj...The reservoir operation awakens numerous landslides with multiple sliding surfaces known as reservoir landslides,and the systematic stability analysis for such landslides is becoming increasingly urgent.Taking the Majiagou landslide as an example,this paper analyses the comprehensive performance of the landslide from a probabilistic point of view.Under a reservoir operation cycle,a series of numerical analyses are carried out to simulate the migration of the seepage field,then the dynamic stability of the landslide is quantified accordingly.Subsequently,the wetting-drying cycles test is used to model the weakening of strength parameters in hydro-fluctuation belt under the long-term reservoir operation.Considering the weakening effect of long-term reservoir operation on the hydrofluctuation belt,the system reliability is evaluated using the Ditlevsen's bounds.The results suggest that the reservoir operation can affect the stability of the landslide by changing the seepage field.The system failure probability gradually rises as the number of wetting-drying cycles increases.Compared with conventional probabilistic analysis that calculates the failure probability of each sliding surface mechanically,analyzing the landslide in terms of system reliability can effectively narrow the failure probability range,which provides an insightful idea for evaluating the systematic stability of analogous reservoir landslides.展开更多
基金Supported by Talent Introduction Talent Plan of Chongqing ThreeGorge University(2007-SXXYRC-006)Accented Term of ChongqingThree Gorge University(10ZD-14)+1 种基金Special Term of National Water Body Pollution Control and Treatment Major Project(2009ZX07104-003-02)Special Term of National Science and Technology Supportm Plan Major Project(2008BAD98B04)
文摘By using the ultraviolet absorption spectrum,the fluorescence spectrum and three dimensional fluorescence spectra,the composition of dissolved organic matter(DOM) and the humification degree,etc.in the sediment of hydro-fluctuation belt(Yunyang part) were analyzed.The relationship between the test parameters and the pollution degree in the region was discussed.The research results of UV spectrum data E3/E4 showed that in 4 sampling sites which included Huangshi Town,Gaoyang Town,Shuangjiang Town and Quma Town,the humification degree in the sediment of hydro-fluctuation belt in Shuangjiang Town sampling site was lower,and the aromaticity was smaller.Moreover,the effect of human factor was comparatively smaller.The fluorescence index value which represented the source of humus in DOM was 1.62-1.88.It showed that the biological and terrestrial source both existed.Three dimensional spectra results showed that the pollution degrees in 4 sampling sites were all smaller,and some prevention measures should be taken early.
基金financially supported by the National Key Research and Development Program of China(Grant No.SQ2018YFD080041)the Sichuan Science and Technology Program(Grant No.2017SZ0188)。
文摘Soils in the hydro-fluctuation belts of the reservoirs are most highly influenced by the special hydro-conditions and reservoir operation,leading to unique soil erosion process and largely accelerate soil erosion intensity.The present study aimed to estimate soil erosion rate in the hydro-fluctuation belt of the Pubugou Reservoir,Southwest China,based on the framework of Universal Soil Loss Equation(USLE).An attempt has been made to modify the original USLE by including the reservoir water erosivity(W),a new factor into the model.Soil erosion rate from different land use types were quantitatively estimated,using the USLE and the modified USLE respectively.Field observation showed that soil erosion rate in dry farmland,bare land and grassland was 4700,44600 and 5050 t/km2,respectively.The erosion rate assessed by the modified USLE was closely related to that recorded from the field monitoring data.The findings of this study clearly highlight the importance of inclusion of the W factor to the original USLE model while assessing soil erosion in the reservoir hydro-fluctuation belt.
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Supported by Chongqing Technology Innovation and Application Development General Project(cstc2019jscx-msxmX0335)。
文摘Through the Betula nigra afforestation test in the engineering treatment area of the Wuxi Section of the Daning River in Chongqing,the feasibility of arbor vegetation restoration in the comprehensive management of the engineering treatment areas of the Three Gorges Reservoir was explored.The results showed that:(1)before the flooding in the project area,the survival rate of B.nigra seedlings was high,over 95%,and(2)in 2021,after a water storage period,affected by factors such as seedling specifications,flood and flooding time,the survival rate of the seedlings planted in 2020 was low,and the one-year-old seedlings were greatly competed by weeds and grew less.Two-year-old B.nigra seedlings were replanted in 2021,and the survival rate of the B.nigra seedlings was 100%in 2022.Two-year-old B.nigra seedlings have strong adaptability and have little impact on the stability of the engineering treatment area,and can be used as afforestation tree species in engineering treatment areas of hydro-fluctuation zones.
文摘Setting monitoring transect in the middle and shallow water area(altitude 156-172 m) in Three Gorges reservoir hydro-fluctuation belt to research the changing characteristics of the contents of N, P,K,pH and organic matter of the soil which experienced the influence of fluctuation the first time. The results showed that by the influence of water level fluctuating,contents of soil N,P,K,pH and organic matter had reduced in different soil layers in hydro-fluctuation belt.The available N decreased by 41.53%-59.87%,available P decreased by 5.26%- 36.76%,available K decreased by 3.55%-45.56%, total N decreased by 9.52%-40.00%,total P had no change generally,total K had decreased a little, content of organic material decreased by 7.62%- 37.83%%,pH value turned to neutral,changed by 1.73%-9.58%.
基金supported by the Fundamental Research Funds for Central Public Welfare Research Institutes of China(Nos.CKSF2019380/SH,CKSF2017062/SH)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23040303)。
文摘Fresh water microplastic pollution is of pressing concern globally,but its distribution and sources in reservoirs are poorly documented.Danjiangkou Reservoir is the second largest reservoir in China and is divided into the Han Reservoir and Dan Reservoir.In this work,microplastic abundances and morphological characteristics of the reservoir were investigated.The microplastic abundance of 15 main tributaries of the reservoir was also measured.The vertical distribution(in water column and sediment),horizontal distribution(in Han Reservoir and Dan Reservoir)and source of microplastics were analyzed.Microplastics accumulated in the middle layer of the reservoir,and the size and color of the microplastic particles changed from the surface to the bottom,which implies that surveys of surface water are not enough to determine the microplastic contamination for deep water reservoirs.In the surface water,the microplastic abundance in the Han Reservoir was lower than that in the Dan Reservoir(p<0.05),but microplastic abundance did not differ significantly in the intermediate and bottom water.Tributaries were one of the main sources of microplastics for Han Reservoir but not for Dan Reservoir.Agricultural cultivation in the hydro-fluctuation belt might be an important source of microplastics in the Dan Reservoir,which should be given additional attention.The results of this study can provide valuable information for developing microplastic sampling strategies in deep water reservoirs.Further studies are recommended to investigate the process through which microplastics in the hydro-fluctuation belt enter the reservoir and the sinking behavior of microplastics in the reservoir.
基金supported by the National Natural Science Foundation of China under No. 41630639the National Basic Research Program of China (2014CB744703)+1 种基金Natural Science Basic Research Plan in Shaanxi Province of China (No. 2016JQ4014)China Postdoctoral Science Foundation (2016M602743)
文摘After water is impounded in a reservoir, rock mass in the hydro-fluctuation belt of the reservoir bank slope is subject to water saturation- dehydration circulation （WSDC）. To quantify the rate of change of rock mechanical properties, samples from the Longtan dam area were measured with uniaxial compression tests after different numbers （1, 5, 10, 15, and 20） of simulated WSDC cycles. Based on the curves derived from these tests, a modified Hock- Brown failure criterion was proposed, in which a new parameter was introduced to model the cumulative damage to rocks after WSDC. A case of an engineering application was analyzed, and the results showed that the modified Hock-Brown failure criterion is useful. Under similar WSDC-influenced engineering and geological conditions, rock mass strength parameters required for analysis and evaluation of rock slope stability can be estimated according to this modified Hoek-Brown failure criterion.
基金supported by the National Natural Science Foundation of China(No.41972266)the China Postdoctoral Science Foundation(No.2023M730432)+1 种基金the Special Funding for Chongqing Postdoctoral Research Project(No.2022CQBSHTB1010)the Chongqing Postdoctoral Science Foundation(No.CSTB2023NSCQBHX0223).
文摘To investigate the dynamic damage evolution characteristics of bank slopes with serrated structural planes,the shaking table model test and the numerical simulation were utilized.The main findings indicate that under continuous seismic loads,the deformation of the bank slope increased,particularly around the hydro-fluctuation belt,accompanying by the pore water pressure rising.The soil pressure increased and then decreased showed dynamic variation characteristics.As the undulation angle of the serrated structural planes increased(30°, 45°, and 60°),the failure modes were climbing,climbinggnawing,and gnawing respectively.The first-order natural frequency was used to calculate the damage degree(Dd)of the bank slope.During microseisms and small earthquakes,it was discovered that the evolution of Dd followed the“S”shape,which was fitted by a logic function.Additionally,the quadratic function was used to fit the Dd during moderately strong earthquakes.Through the numerical simulation,the variation characteristics of safety factors(Sf)for slopes with serrated structural planes and slopes with straight structural planes were compared.Under continuous seismic loads,the Sf of slopes with straight structural planes reduce stalely,whereas the Sf for slopes with serrated structural planes was greater than the former and the reduction rate was increasing.
基金supported by the Postdoctoral Fellowship Program of CPSF(No.GZB20230607)the Fundamental Research Funds for the Central Universities(No.2682024CX125)+3 种基金the National Key R&D Program of China(No.2023YFC3007201)the National Natural Science Foundation of China(No.42377161)the Natural Science Foundation of Hubei Province(No.2023AFB580)the Guizhou Provincial Science and Technology Project(No.QKHZC[2023]YB127)。
文摘The reservoir operation awakens numerous landslides with multiple sliding surfaces known as reservoir landslides,and the systematic stability analysis for such landslides is becoming increasingly urgent.Taking the Majiagou landslide as an example,this paper analyses the comprehensive performance of the landslide from a probabilistic point of view.Under a reservoir operation cycle,a series of numerical analyses are carried out to simulate the migration of the seepage field,then the dynamic stability of the landslide is quantified accordingly.Subsequently,the wetting-drying cycles test is used to model the weakening of strength parameters in hydro-fluctuation belt under the long-term reservoir operation.Considering the weakening effect of long-term reservoir operation on the hydrofluctuation belt,the system reliability is evaluated using the Ditlevsen's bounds.The results suggest that the reservoir operation can affect the stability of the landslide by changing the seepage field.The system failure probability gradually rises as the number of wetting-drying cycles increases.Compared with conventional probabilistic analysis that calculates the failure probability of each sliding surface mechanically,analyzing the landslide in terms of system reliability can effectively narrow the failure probability range,which provides an insightful idea for evaluating the systematic stability of analogous reservoir landslides.
