Despite the continuous advancements of engineering construction in high-intensity areas,many engineering landslides are still manufactured with huge thrust force,and double-row piles are effective to control such larg...Despite the continuous advancements of engineering construction in high-intensity areas,many engineering landslides are still manufactured with huge thrust force,and double-row piles are effective to control such large landslides.In this study,large shaking table test were performed to test and obtain multi-attribute seismic data such as feature image,acceleration,and dynamic soil pressure.Through the feature image processing analysis,the deformation characteristics for the slope reinforced by double-row piles were revealed.By analyzing the acceleration and the dynamic soil pressure time domain,the spatial dynamic response characteristics were revealed.Using Fast Fourier Transform and half-power bandwidth,the damping ratio of acceleration and dynamic soil pressure was obtained.Following that,the Seism Signal was used to calculate the spectral displacement of the accelerations to obtain the regional differences of spectral displacement.The results showed that the overall deformation mechanism of the slope originates from tension failure in the soil mass.The platform at the back of the slope was caused by seismic subsidence,and the peak acceleration ratio was positively correlated with the relative pile heights.The dynamic soil pressure of the front row piles showed an inverted"K"-shaped distribution,but that of the back row piles showed an"S"-shaped distribution.The predominant frequency of acceleration was 2.16 Hz,and the main frequency band was 0.7-6.87 Hz;for dynamic soil pressure,the two parameters became 1.15 Hz and 0.5-6.59 Hz,respectively.In conclusion,dynamic soil pressure was more sensitive to dampening effects than acceleration.Besides,compared to acceleration,dynamic soil pressure exhibited larger loss factors and lower resonance peaks.Finally,back row pile heads were highly sensitive to spectral displacement compared to front row pile heads.These findings may be of reference value for future seismic designs of double-row piles.展开更多
Cotton (Gossypium hirsutum L.) is an economically important crop for the Southern United States. The southern US also has a long growing season suitable for double cropping a second crop after small grains;however, th...Cotton (Gossypium hirsutum L.) is an economically important crop for the Southern United States. The southern US also has a long growing season suitable for double cropping a second crop after small grains;however, the harvest date for the small grains typically occurs after the optimum planting window for cotton which reduces yield potential. A relay intercropping system was developed at Clemson University that allows interseeding of cotton into standing wheat 2 to 3 weeks before harvest with interseeded cotton yields similar to the conventional mono-cropped cotton. Therefore, the objectives of this study were 1) to determine the optimum tillage and planting methods for narrow row (76-cm) and wide row (97-cm) cotton, and 2) to compare narrow and wide row systems for conventional tillage cotton, cotton interseeded into standing wheat, and cotton planted into a terminated wheat cover crop on coastal plain soil. Two replicated tests were conducted to accomplish these objectives. In Study 1, conventional narrow row cotton combined with a deep tillage operation using Paratill yielded 23% more than conventional wide row cotton which had a deep tillage operation with a subsoiler just before planting. There were no differences between the conventional (97-cm row spacing) mono-crop and interseeded cotton yields. In Study 2, there was no significant difference in yield between narrow-row and wide-row cotton for each cropping system during the two years study. Both wide and narrow-row full season cotton had significantly higher yields than interseeded and cover crop planting systems in year two of the study. The two conservation cropping practices, wheat used as a cover crop and interseeding, showed considerable promise for reducing energy requirements, soil erosion, and wind-borne cotton damage associated with bare soil in conventional tillage. This research demonstrates the benefits of interseeding and narrow row spacing for sustainable cotton production in coastal plain soils of the Southern United States.展开更多
基金the financial support by the National Key R&D Program of China(No.2018YFC1504901)Gansu Province Youth Science and Technology Fund program,China(Grant No.21JR7RA739)+1 种基金Natural Science Foundation of Gansu Province,China(Grant No.21JR7RA738)Natural Science Foundation of Gansu Province,China(No.145RJZA068)。
文摘Despite the continuous advancements of engineering construction in high-intensity areas,many engineering landslides are still manufactured with huge thrust force,and double-row piles are effective to control such large landslides.In this study,large shaking table test were performed to test and obtain multi-attribute seismic data such as feature image,acceleration,and dynamic soil pressure.Through the feature image processing analysis,the deformation characteristics for the slope reinforced by double-row piles were revealed.By analyzing the acceleration and the dynamic soil pressure time domain,the spatial dynamic response characteristics were revealed.Using Fast Fourier Transform and half-power bandwidth,the damping ratio of acceleration and dynamic soil pressure was obtained.Following that,the Seism Signal was used to calculate the spectral displacement of the accelerations to obtain the regional differences of spectral displacement.The results showed that the overall deformation mechanism of the slope originates from tension failure in the soil mass.The platform at the back of the slope was caused by seismic subsidence,and the peak acceleration ratio was positively correlated with the relative pile heights.The dynamic soil pressure of the front row piles showed an inverted"K"-shaped distribution,but that of the back row piles showed an"S"-shaped distribution.The predominant frequency of acceleration was 2.16 Hz,and the main frequency band was 0.7-6.87 Hz;for dynamic soil pressure,the two parameters became 1.15 Hz and 0.5-6.59 Hz,respectively.In conclusion,dynamic soil pressure was more sensitive to dampening effects than acceleration.Besides,compared to acceleration,dynamic soil pressure exhibited larger loss factors and lower resonance peaks.Finally,back row pile heads were highly sensitive to spectral displacement compared to front row pile heads.These findings may be of reference value for future seismic designs of double-row piles.
文摘Cotton (Gossypium hirsutum L.) is an economically important crop for the Southern United States. The southern US also has a long growing season suitable for double cropping a second crop after small grains;however, the harvest date for the small grains typically occurs after the optimum planting window for cotton which reduces yield potential. A relay intercropping system was developed at Clemson University that allows interseeding of cotton into standing wheat 2 to 3 weeks before harvest with interseeded cotton yields similar to the conventional mono-cropped cotton. Therefore, the objectives of this study were 1) to determine the optimum tillage and planting methods for narrow row (76-cm) and wide row (97-cm) cotton, and 2) to compare narrow and wide row systems for conventional tillage cotton, cotton interseeded into standing wheat, and cotton planted into a terminated wheat cover crop on coastal plain soil. Two replicated tests were conducted to accomplish these objectives. In Study 1, conventional narrow row cotton combined with a deep tillage operation using Paratill yielded 23% more than conventional wide row cotton which had a deep tillage operation with a subsoiler just before planting. There were no differences between the conventional (97-cm row spacing) mono-crop and interseeded cotton yields. In Study 2, there was no significant difference in yield between narrow-row and wide-row cotton for each cropping system during the two years study. Both wide and narrow-row full season cotton had significantly higher yields than interseeded and cover crop planting systems in year two of the study. The two conservation cropping practices, wheat used as a cover crop and interseeding, showed considerable promise for reducing energy requirements, soil erosion, and wind-borne cotton damage associated with bare soil in conventional tillage. This research demonstrates the benefits of interseeding and narrow row spacing for sustainable cotton production in coastal plain soils of the Southern United States.
