To study the damage mechanism of multi‐anchor piles in tunnel crossing landslide area under earthquake,the damping performance of multi‐anchor piles was discussed.The energy dissipation springs were used as the opti...To study the damage mechanism of multi‐anchor piles in tunnel crossing landslide area under earthquake,the damping performance of multi‐anchor piles was discussed.The energy dissipation springs were used as the optimization device of the anchor head to carry out the shaking table comparison test on the reinforced slope.The Hilbert spectrum and Hilbert marginal spectrum were proposed to analyze the seismic damage mechanism of the multi‐anchor piles,and the peak Fourier spectrum amplitude(PFSA)was used to verify the effectiveness of the method.The results show that the seismic energy is concentrated in the high‐frequency component(30-40Hz)of the Hilbert spectrum and the low‐frequency component(12-30 Hz)of the marginal spectrum.This indicates that they can be combined with the distribution law of the PFSA to identify the overall and local dynamic responses of the multi‐anchored piles,respectively.The stretchable deformation of the energy‐dissipation springs improves the coordination of the multi‐anchor piles,resulting in better pile integrity.The damage mechanism of the multi‐anchor piles is elucidated based on the energy method:local damage at the top and middle areas of the multi‐anchor piles is mainly caused by the low‐frequency component(12-30 Hz)of the marginal spectrum under the action of 0.15g and 0.20g seismic intensities.As the seismic intensity increases to 0.30g,the dynamic response of the slope is further amplified by the high‐frequency component(30-40 Hz)of the Hilbert energy spectrum,which leads to the overall damage of the multi‐anchor piles.展开更多
AIM:To compare the feature of ocular trauma between normalized period and the COVID-19 epidemic period in China,and to provide a profile for eye injuries in special times in future.METHODS:This is a multi-center cross...AIM:To compare the feature of ocular trauma between normalized period and the COVID-19 epidemic period in China,and to provide a profile for eye injuries in special times in future.METHODS:This is a multi-center cross-sectional study with 30 participated hospitals involving the China Ocular Trauma Society members.All hospitalized cases who visited the Ophthalmology Department in participated hospitals with eye injuries during the normalized period(2019)and the COVID-19 epidemic period(2020)were included in this study.Demographic characteristic of cases,date of injury,sites and types of injury were collected.RESULTS:This study involved 13525(61 cases with both eyes)injured cases.There were 7269(53.74%)eyeinjured cases and 6256(46.26%)eye-injured cases in 2019 and 2020 separately.Compared with 2019,the incidence of ocular trauma in retirees,housewives and unemployed increased with year-on-year of 4.96%,102.67%,and 11.64%among all occupations.In 2020,the incidence of eye injuries decreased in all injury sites except for an increase in home(30.29%year-on-year).The incidence of mechanical eye injuries decreased,while that of nonmechanical eye injuries(chemical/thermal/radiation)increased(47.45%year-on-year).There were 255(3.51%,255/7269)and 376(6.01%,376/6256)non-mechanical injured cases in 2019 and 2020(Pearson Chi^(2)=47.33,P<0.001)separately.CONCLUSION:During the COVID-19 epidemic period,the total cases of ocular trauma decrease but the proportion of non-mechanical ocular trauma increase.Penetrating is still the highest proportion among all types of mechanical ocular trauma.From a preventive point of view,protection for retired persons,housewives and unemployed persons should be improved during public health events period.展开更多
基金Science and technology development project of China Railway Ninth Bureau Group Co.,Ltd,Grant/Award Number:DLF‐ML‐JSFW‐2021‐09Science and Technology Development Project of China Railway Research Institute Co.Ltd,Grant/Award Number:2017‐KJ008‐Z008‐XB+2 种基金Gansu Province Youth Science and Technology Fund program,China,Grant/Award Number:21JR7RA739Natural Science Foundation of Gansu Province,China,Grant/Award Number:21JR7RA738National Key R&D Program of China,Grant/Award Number:2018YFC1504901。
文摘To study the damage mechanism of multi‐anchor piles in tunnel crossing landslide area under earthquake,the damping performance of multi‐anchor piles was discussed.The energy dissipation springs were used as the optimization device of the anchor head to carry out the shaking table comparison test on the reinforced slope.The Hilbert spectrum and Hilbert marginal spectrum were proposed to analyze the seismic damage mechanism of the multi‐anchor piles,and the peak Fourier spectrum amplitude(PFSA)was used to verify the effectiveness of the method.The results show that the seismic energy is concentrated in the high‐frequency component(30-40Hz)of the Hilbert spectrum and the low‐frequency component(12-30 Hz)of the marginal spectrum.This indicates that they can be combined with the distribution law of the PFSA to identify the overall and local dynamic responses of the multi‐anchored piles,respectively.The stretchable deformation of the energy‐dissipation springs improves the coordination of the multi‐anchor piles,resulting in better pile integrity.The damage mechanism of the multi‐anchor piles is elucidated based on the energy method:local damage at the top and middle areas of the multi‐anchor piles is mainly caused by the low‐frequency component(12-30 Hz)of the marginal spectrum under the action of 0.15g and 0.20g seismic intensities.As the seismic intensity increases to 0.30g,the dynamic response of the slope is further amplified by the high‐frequency component(30-40 Hz)of the Hilbert energy spectrum,which leads to the overall damage of the multi‐anchor piles.
基金Supported by National Natural Science Foundation of China(No.82020108007,No.81830026)Beijing-Tianjin-Hebei Special Project(No.20JCZXJC00180)。
文摘AIM:To compare the feature of ocular trauma between normalized period and the COVID-19 epidemic period in China,and to provide a profile for eye injuries in special times in future.METHODS:This is a multi-center cross-sectional study with 30 participated hospitals involving the China Ocular Trauma Society members.All hospitalized cases who visited the Ophthalmology Department in participated hospitals with eye injuries during the normalized period(2019)and the COVID-19 epidemic period(2020)were included in this study.Demographic characteristic of cases,date of injury,sites and types of injury were collected.RESULTS:This study involved 13525(61 cases with both eyes)injured cases.There were 7269(53.74%)eyeinjured cases and 6256(46.26%)eye-injured cases in 2019 and 2020 separately.Compared with 2019,the incidence of ocular trauma in retirees,housewives and unemployed increased with year-on-year of 4.96%,102.67%,and 11.64%among all occupations.In 2020,the incidence of eye injuries decreased in all injury sites except for an increase in home(30.29%year-on-year).The incidence of mechanical eye injuries decreased,while that of nonmechanical eye injuries(chemical/thermal/radiation)increased(47.45%year-on-year).There were 255(3.51%,255/7269)and 376(6.01%,376/6256)non-mechanical injured cases in 2019 and 2020(Pearson Chi^(2)=47.33,P<0.001)separately.CONCLUSION:During the COVID-19 epidemic period,the total cases of ocular trauma decrease but the proportion of non-mechanical ocular trauma increase.Penetrating is still the highest proportion among all types of mechanical ocular trauma.From a preventive point of view,protection for retired persons,housewives and unemployed persons should be improved during public health events period.
