Quaternary silt is widely distributed in China and easily liquefies during earthquakes. To identify the influence of the dry density on the liquefaction behaviour of Quaternary silt, 40 cyclic triaxial liquefaction te...Quaternary silt is widely distributed in China and easily liquefies during earthquakes. To identify the influence of the dry density on the liquefaction behaviour of Quaternary silt, 40 cyclic triaxial liquefaction tests were performed on loose silt(dry density rd=1.460 g/cm^3) and dense silt(rd=1.586 g/cm^3) under different cyclic stress ratios(CSRs) to obtain liquefaction assessment criteria, determine the liquefaction resistance, improve the excess pore water pressure(EPWP) growth model and clarify the relationship between the shear modulus and damping ratio. The results indicate that the initial liquefaction assessment criteria for the loose and dense silts are a double-amplitude axial strain of 5% and an EPWP ratio of 1. The increase in the anti-liquefaction ability for the dense silt is more significant under lower confining pressures. The CSR of loose silt falls well within the results of the sandy silt and Fraser River silt, and the dense silt exhibits a higher liquefaction resistance than the sand-silt mixture. The relationships between the CSR and loading cycles were obtained at a failure strain of 1%. The EPWP development in the dense and loose silts complies with the "fast-stable" and "fast-gentle-sharp" growth modes, respectively. The power function model can effectively describe the EPWP growth characteristics of the dense silt. Finally, based on the liquefaction behaviour of silt, a suggestion for reinforcing silt slopes or foundations is proposed.展开更多
With the income increase of elderly people in Beijing and the improvement of leisure facilities since 2000, the quality of elderly people leisure life in Beijing has obviously increased com- pared to ten years ago. Ac...With the income increase of elderly people in Beijing and the improvement of leisure facilities since 2000, the quality of elderly people leisure life in Beijing has obviously increased com- pared to ten years ago. According to the investigation and com- parative analysis on more than 900 elderly people, who usually exercise in public parks in Beijing City, we have found out several new features of elderly people＇s outdoor recreation in Belting： the increase of the leisure time, the expansion of leisure space, the in- dividuation of interest and the diversification of consumption. The leisure life quality evaluation index system of urban elderly people can be built based on these analyses. In order to accommodate the development tendency of elderly people＇s demand for leisure diversification, we should strengthen the organization and manage- ment of elderly people＇s leisure activity in urban construction, and pay more attention to function complementation between commu- nities and parks.展开更多
This explorative study investigates 1） whether and how quantitative measures of writing can be applied in finding out about scoring raters＇ specific tendency in their scoring of EFL writing; 2） how the knowledge of...This explorative study investigates 1） whether and how quantitative measures of writing can be applied in finding out about scoring raters＇ specific tendency in their scoring of EFL writing; 2） how the knowledge of raters＇ tendency and scoring results would help verify the best way of combining raters＇ scores; and 3） how the prediction of the writing scores of EFL writing obtained by quantitative writing performance measures would match the real scores given by raters. Based on a tentative CAF framework of writing measures, raters＇ performance or tendency in their scoring was observed and certain patterns of similarities as well as differences were found among the raters. The resuks of multiple linear regressions indicate that all raters give prior attention to the aspect of accuracy in their scoring. Differences among raters are also obvious. When it comes to the combination of different raters＇ scores, the study also finds that weighted average is the best of the three ways of combining scores for this group of raters because it has yielded the best predicting scores than the ＂pure average＂. It is even slightly better than the results obtained by facet analysis in terms of some important indices such as R square and Durbin-Watson value. The matching of the predicted scores with the real scores is well over 50 percent. The results of the study are further discussed in relation to the application of wpm and the possible improvement of wpm framework. The methodological, theoretical and practical implications of the study have also been touched upon in the relevant part of the article.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No.41761144077)the CAS “Light of West China” Program (Grant No.Y6R2240240)+1 种基金the Key Research Program of Frontier Sciences,CAS (Grant No.QYZDB-SSW-DQC010)the Sichuan science and technology plan project (Grant No.2017JY0251)
文摘Quaternary silt is widely distributed in China and easily liquefies during earthquakes. To identify the influence of the dry density on the liquefaction behaviour of Quaternary silt, 40 cyclic triaxial liquefaction tests were performed on loose silt(dry density rd=1.460 g/cm^3) and dense silt(rd=1.586 g/cm^3) under different cyclic stress ratios(CSRs) to obtain liquefaction assessment criteria, determine the liquefaction resistance, improve the excess pore water pressure(EPWP) growth model and clarify the relationship between the shear modulus and damping ratio. The results indicate that the initial liquefaction assessment criteria for the loose and dense silts are a double-amplitude axial strain of 5% and an EPWP ratio of 1. The increase in the anti-liquefaction ability for the dense silt is more significant under lower confining pressures. The CSR of loose silt falls well within the results of the sandy silt and Fraser River silt, and the dense silt exhibits a higher liquefaction resistance than the sand-silt mixture. The relationships between the CSR and loading cycles were obtained at a failure strain of 1%. The EPWP development in the dense and loose silts complies with the "fast-stable" and "fast-gentle-sharp" growth modes, respectively. The power function model can effectively describe the EPWP growth characteristics of the dense silt. Finally, based on the liquefaction behaviour of silt, a suggestion for reinforcing silt slopes or foundations is proposed.
基金support of Key Project of Chinese Ministry of Education (Grant No. 170170)
文摘With the income increase of elderly people in Beijing and the improvement of leisure facilities since 2000, the quality of elderly people leisure life in Beijing has obviously increased com- pared to ten years ago. According to the investigation and com- parative analysis on more than 900 elderly people, who usually exercise in public parks in Beijing City, we have found out several new features of elderly people＇s outdoor recreation in Belting： the increase of the leisure time, the expansion of leisure space, the in- dividuation of interest and the diversification of consumption. The leisure life quality evaluation index system of urban elderly people can be built based on these analyses. In order to accommodate the development tendency of elderly people＇s demand for leisure diversification, we should strengthen the organization and manage- ment of elderly people＇s leisure activity in urban construction, and pay more attention to function complementation between commu- nities and parks.
基金funded by China National Planning Office of Philosophy and Social Science(No.08XYY007)
文摘This explorative study investigates 1） whether and how quantitative measures of writing can be applied in finding out about scoring raters＇ specific tendency in their scoring of EFL writing; 2） how the knowledge of raters＇ tendency and scoring results would help verify the best way of combining raters＇ scores; and 3） how the prediction of the writing scores of EFL writing obtained by quantitative writing performance measures would match the real scores given by raters. Based on a tentative CAF framework of writing measures, raters＇ performance or tendency in their scoring was observed and certain patterns of similarities as well as differences were found among the raters. The resuks of multiple linear regressions indicate that all raters give prior attention to the aspect of accuracy in their scoring. Differences among raters are also obvious. When it comes to the combination of different raters＇ scores, the study also finds that weighted average is the best of the three ways of combining scores for this group of raters because it has yielded the best predicting scores than the ＂pure average＂. It is even slightly better than the results obtained by facet analysis in terms of some important indices such as R square and Durbin-Watson value. The matching of the predicted scores with the real scores is well over 50 percent. The results of the study are further discussed in relation to the application of wpm and the possible improvement of wpm framework. The methodological, theoretical and practical implications of the study have also been touched upon in the relevant part of the article.
