In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is...In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is often carried out in China,with water content and dry density of samples being assumed to be constant.However,an open frozeneheave test,all the factors of which change as the test goes on,can reflect the real frozeneheave damage more accurately.In this paper,the open frozeneheave test was carried out on five types frozen soil along the ChinaeRussia Crude Oil Pipeline to measure the frozeneheave factor and water content of each soil sample and accordingly analyze their relationship.Besides,its test results were compared with that of the closed frozeneheave test.Then,the normal frozeneheave force was measured by using the displacement limiting method,and this measurement was compared with the result of the static equilibrium test.Finally,a difference significance test was conducted.It is shown that the frozeneheave factor of the open test is higher than that of the closed test;the frozeneheave factor of fine grained soil has a significant effect on the frozeneheave factor of soils,and the frozeneheave factor increases as the capillary effect or the swabbing action of soil increases;the frozeneheave factor of coarse grained soil is mainly dependent on the mud content,and it is lower than that of fine grained soil;the value of frozeneheave force is in close relation with the test methods and the sample height;it is indicated that the open frozeneheave test is more applicable to the investigation on the frozeneheave of the foundation soils of pipelines in the Da Hinggan Mountains.It is concluded that the soils for the cushion and digging/packing layers of the pipelines in the permafrost regions shall be acted by the gravel or detritus with lower mud content,and waterproof and draining pipeline jetty shall be made from the clay soils with a higher plasticity.展开更多
The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Dat...The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database （GLCCD） that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are： （1） The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. （2） The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. （3） The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. （4） The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.展开更多
基金Project supported by the National Natural Science Foundation Project“Research on the Frozeneheave Mechanism of Marsh Turfy Soil in Seasonally Frozen Area”(No.41502272)Seed Fund Project of Changchun Institute of Technology,“Research on the FrozeneThaw Cycle Effect of Shallowly Buried Pipelines in the Permafrost Zone of Da Hinggan Mountains”(No.320160017).
文摘In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is often carried out in China,with water content and dry density of samples being assumed to be constant.However,an open frozeneheave test,all the factors of which change as the test goes on,can reflect the real frozeneheave damage more accurately.In this paper,the open frozeneheave test was carried out on five types frozen soil along the ChinaeRussia Crude Oil Pipeline to measure the frozeneheave factor and water content of each soil sample and accordingly analyze their relationship.Besides,its test results were compared with that of the closed frozeneheave test.Then,the normal frozeneheave force was measured by using the displacement limiting method,and this measurement was compared with the result of the static equilibrium test.Finally,a difference significance test was conducted.It is shown that the frozeneheave factor of the open test is higher than that of the closed test;the frozeneheave factor of fine grained soil has a significant effect on the frozeneheave factor of soils,and the frozeneheave factor increases as the capillary effect or the swabbing action of soil increases;the frozeneheave factor of coarse grained soil is mainly dependent on the mud content,and it is lower than that of fine grained soil;the value of frozeneheave force is in close relation with the test methods and the sample height;it is indicated that the open frozeneheave test is more applicable to the investigation on the frozeneheave of the foundation soils of pipelines in the Da Hinggan Mountains.It is concluded that the soils for the cushion and digging/packing layers of the pipelines in the permafrost regions shall be acted by the gravel or detritus with lower mud content,and waterproof and draining pipeline jetty shall be made from the clay soils with a higher plasticity.
文摘The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database （GLCCD） that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are： （1） The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. （2） The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. （3） The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. （4） The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.
