Based on the analysis of existing relevant research result, a theoretical basis for the defining freeze- thaw erosion zones of Qinghai-Tibet Plateau was been put forward, and a equation for calculating the altitude of...Based on the analysis of existing relevant research result, a theoretical basis for the defining freeze- thaw erosion zones of Qinghai-Tibet Plateau was been put forward, and a equation for calculating the altitude of the lower bound of the freeze-thaw erosion zones of Qinghai-Tibet Plateau was been established in this paper. Moreover, the freeze-thaw erosion zones in Tibet was been identified by using Geographical Information System (GIS) software. Next, based on the comprehensive analysis of impact factors of freeze-thaw erosion, this paper chooses annul temperature range, slop and vegetation as three indexes, works out the criteria for relative classification of freeze-thaw erosion, and realizes the relative classification of the freeze-thaw erosion in Tibet under the support of GIS software. Then, a synthetic assessment of freeze-thaw erosion in Tibet was been done according to the relative classification result.展开更多
Characteristics of plant species diversity of two types of grassland communities (alpine meadow and alpine grassland) was examined and the relationship between species diversity and community dynamics was determined u...Characteristics of plant species diversity of two types of grassland communities (alpine meadow and alpine grassland) was examined and the relationship between species diversity and community dynamics was determined using GPS positioning and in situscrutinization of community of alpine grassland in Nakchu prefecture of Tibet Autonomous Region. The result indicated that: ① there was an unobvious difference between grassland communities in terms of richness index of plant, evenness index, dominant index and diversity index. The species diversity index followed the order Kobresia humilis meadow >Stipa purpurea steppe>K. littledalei meadow; ② the original community created high diversity, while the degenerative community suffering from serious disturbance was of low diversity; ③ the diversity of community plants was closely related to changes of species biomass, and the growth and decline of species in the community; ④ grazing disturbance is a key factor of community dynamics, leading to coexistence of various secondary successions of communities, diversified suitable habitats and species diversity. improvements展开更多
It is analyzed that the impacts of vegetation type and soil moisture contenton shear strength of unsaturated soil through direct shearing tests for various vegetation types,different soil moisture contents and differe...It is analyzed that the impacts of vegetation type and soil moisture contenton shear strength of unsaturated soil through direct shearing tests for various vegetation types,different soil moisture contents and different-depth unsaturated soil. The results show that thecohesion of unsaturated soil changes greatly, and the friction angle changes a little with soilmoisture content. It is also shown that vegetation can improve shear strength of unsaturated soil,which therefore provides a basis thatvegetation can reinforce soil and protect slopes.展开更多
In this paper, taking railway flood in Xinjiang Line of New Eurasian Continental Bridge as an example, the dynamics mechanism of railway flood has been studied by using Chaotic Theory. During study, some nonlinear fea...In this paper, taking railway flood in Xinjiang Line of New Eurasian Continental Bridge as an example, the dynamics mechanism of railway flood has been studied by using Chaotic Theory. During study, some nonlinear features of railway flood, such as correlation dimension D2 and Kolomogorov entropy K, are analyzed based on time-series of railway flood in Xinjiang Line of New Eurasian Continental Bridge. Results show: time-series distribution of railway flood has some characteristics of Chaos dynamic system, and the variation of railway flood frequency is a definite low-dimension Chaotic attractor. The average length of Tp(Tp = 15d) calculated in this paper, which shows the time of forecasting by this Chaotic dynamic system, is close to the reality.展开更多
文摘Based on the analysis of existing relevant research result, a theoretical basis for the defining freeze- thaw erosion zones of Qinghai-Tibet Plateau was been put forward, and a equation for calculating the altitude of the lower bound of the freeze-thaw erosion zones of Qinghai-Tibet Plateau was been established in this paper. Moreover, the freeze-thaw erosion zones in Tibet was been identified by using Geographical Information System (GIS) software. Next, based on the comprehensive analysis of impact factors of freeze-thaw erosion, this paper chooses annul temperature range, slop and vegetation as three indexes, works out the criteria for relative classification of freeze-thaw erosion, and realizes the relative classification of the freeze-thaw erosion in Tibet under the support of GIS software. Then, a synthetic assessment of freeze-thaw erosion in Tibet was been done according to the relative classification result.
文摘Characteristics of plant species diversity of two types of grassland communities (alpine meadow and alpine grassland) was examined and the relationship between species diversity and community dynamics was determined using GPS positioning and in situscrutinization of community of alpine grassland in Nakchu prefecture of Tibet Autonomous Region. The result indicated that: ① there was an unobvious difference between grassland communities in terms of richness index of plant, evenness index, dominant index and diversity index. The species diversity index followed the order Kobresia humilis meadow >Stipa purpurea steppe>K. littledalei meadow; ② the original community created high diversity, while the degenerative community suffering from serious disturbance was of low diversity; ③ the diversity of community plants was closely related to changes of species biomass, and the growth and decline of species in the community; ④ grazing disturbance is a key factor of community dynamics, leading to coexistence of various secondary successions of communities, diversified suitable habitats and species diversity. improvements
文摘It is analyzed that the impacts of vegetation type and soil moisture contenton shear strength of unsaturated soil through direct shearing tests for various vegetation types,different soil moisture contents and different-depth unsaturated soil. The results show that thecohesion of unsaturated soil changes greatly, and the friction angle changes a little with soilmoisture content. It is also shown that vegetation can improve shear strength of unsaturated soil,which therefore provides a basis thatvegetation can reinforce soil and protect slopes.
基金Supponed by world Bank Project (Disaster Reduction in china) (NoA3) and"Xibuzhiguang"Project(Prevention of Railway Flood in xinjiang Line of New Eurasian Continental Bridge)(98013010)
文摘In this paper, taking railway flood in Xinjiang Line of New Eurasian Continental Bridge as an example, the dynamics mechanism of railway flood has been studied by using Chaotic Theory. During study, some nonlinear features of railway flood, such as correlation dimension D2 and Kolomogorov entropy K, are analyzed based on time-series of railway flood in Xinjiang Line of New Eurasian Continental Bridge. Results show: time-series distribution of railway flood has some characteristics of Chaos dynamic system, and the variation of railway flood frequency is a definite low-dimension Chaotic attractor. The average length of Tp(Tp = 15d) calculated in this paper, which shows the time of forecasting by this Chaotic dynamic system, is close to the reality.
