Construction of diaphragm wall panels may cause considerable stress changes in heavily overconsol- idated soil deposits and can induce substantial ground movement. The 3D Lagrangian method was adopted to model the mec...Construction of diaphragm wall panels may cause considerable stress changes in heavily overconsol- idated soil deposits and can induce substantial ground movement. The 3D Lagrangian method was adopted to model the mechanical response of ground, including horizontal normal stress and shear stress, lateral ground displacement and vertical ground surface settlement, during the slurry trenching and concreting of diaphragm wall panels. Numerical results show that slurry trenching leads to horizontal stress relief of ground, reducing the horizontal stress of the ground from initial K0 pressure to hydrostatic betonite pressure. Wet concrete pressure lies between the hydrostatic bentonite pressure and the initial K0 pressure, so it can compensate partially the horizontal stress loss of the ground adjacent to the trench and thus reduce the lateral movement of the trench face as well as the vertical settlement of the ground surface.展开更多
Exploitation technology of pressure relief coalbed methane in vertical surface wells is a new method for exploration of gas and coalbed methane exploitation in mining areas with high concentrations of gas, where tecto...Exploitation technology of pressure relief coalbed methane in vertical surface wells is a new method for exploration of gas and coalbed methane exploitation in mining areas with high concentrations of gas, where tectonic coal developed. Studies on vertical surface well technology in the Huainan Coal Mining area play a role in demonstration in the use of clean, new energy resources, preventing and reducing coal mine gas accidents and protecting the environment. Based on the practice of gas drainage engineering of pressure relief coalbed methane in vertical surface wells and combined with relative geological and exploration en- gineering theories, the design principles of design and structure of wells of pressure relief coalbed methane in vertical surface wells are studied. The effects of extraction and their causes are discussed and the impact of geological conditions on gas production of the vertical surface wells are analyzed. The results indicate that in mining areas with high concentrations of gas, where tectonic coal developed, a success rate of pressure relief coalbed methane in surface vertical well is high and single well production usually great. But deformation due to coal exploitation could damage boreholes and cause breaks in the connection between aquifers and bore-holes, which could induce a decrease, even a complete halt in gas production of a single well. The design of well site location and wellbore configuration are the key for technology. The development of the geological conditions for coalbed methane have a significant effect on gas production of coalbed methane wells.展开更多
This article examines the spatial characteristics of public service supply and the factors influencing such supply in cities of Sichuan Province, China using spatial-autocorrelation and spatial econometric models with...This article examines the spatial characteristics of public service supply and the factors influencing such supply in cities of Sichuan Province, China using spatial-autocorrelation and spatial econometric models with statistical data in 2012. The results demonstrate that expenditures on different types of public services present different spatial autocorrelation patterns. Although the spatial differences in basic public service expenditures are relatively small, a clear fan-shaped spillover to the east can be seen in Chengdu City. Chengdu also shows high clustering of advanced public service expenditures, being a typical core-periphery pattern. Post-earthquake reconstruction expenditures are clustered in the "5.12 Wenchuan earthquake" region and spill over toward cities to the east. The efficiency of public services in the mountainous areas in western Sichuan is low and exhibits a pattern of low-low spatial autocorrelation. The efficiency of public service supply is affected by economic, social, political and geographical factors. Based on the results of this analysis, we recommend a supply strategy that incorporates different types of public services and a specialized public service supply strategy for mountainous areas. Overall public service efficiency should be enhanced by focusing on narrowing the gap in farmers' income among regions and accelerating urbanization. Decision-makers should consider moresupportive policies with regard to providing basic public services in mountainous areas to ensure an equalized supply of basic public services. To enhance the efficiency of advanced public service supply, additional growth pole should be encouraged and incentivized; however, investments are required to drive the development of the peripheral regions through regional economic integration. Both software and hardware types of infrastructure are required to supply services efficiently during post-disaster reconstruction.展开更多
Planation surfaces （PS） play a major role in reconstruction of the evolutionary history of landforms in local areas. Thus, objective and consistent mapping of planation surfaces from remotely sensed data （e.g., sat...Planation surfaces （PS） play a major role in reconstruction of the evolutionary history of landforms in local areas. Thus, objective and consistent mapping of planation surfaces from remotely sensed data （e.g., satellite imagery, digital elevation models （DEMs）） is paramount for interpreting the geomorphological evolution. Due to the lack of dated sedimentary covers and the difficulties of com-prehensive field work, the number and age of planation surfaces in the Southwest Hubei （湖北） Prov-ince of China are still controversial. In order to map the PS in the study area, four data visualization techniques including ETM＋ false color composite, grey-scale DEM, shaded relief model （SRM） and painted relief model （P M） were examined. It is found that the PRM is the most optimal technique for planation surface mapping. The study area was successfully mapped by visual interpretation of a PRM derived from ASTER GDEM. The mapped PS was divided into five classes in terms of elevation ac-cording to previous studies, varying from 1 700-2 000 （PS1）, 1 300-1 500 （PS2）, 1 000-1 200 （PS3）, 800-900 （PS4） to 500-600 （PS5） m. The results were partially compared with the published works. It is revealed that this method of mapping enjoys a higher accuracy and can reduce the time and ef- fort required in the traditional mapping to a large extent. The results also demonstrated that the PRM is an effective tool for geomorphological fea-ture mapping with considerable accuracy. The pre- liminary results can serve to facilitate locating rep-resentative samples for the planation surfaces dating, thus to determine the ages of PS in the study areas.展开更多
Combining the loaded tooth contact analysis(LTCA)method and the gear dynamic model,a wear prediction model for spur gears with tip relief is established.The simulated wear depth is verified by the experimental results...Combining the loaded tooth contact analysis(LTCA)method and the gear dynamic model,a wear prediction model for spur gears with tip relief is established.The simulated wear depth is verified by the experimental results in a published reference.Based on the wear profile,the mesh stiffness and the tooth root stress obtained from the proposed model are compared with those obtained from the finite element model.Relative to the finite element method,the proposed method can greatly reduce the computation time.The effects of the tip relief and surface wear on the meshing and the dynamic characteristics are discussed.The tip relief can greatly decelerate the surface wear.Appropriate tip relief and slight wear can decrease the tooth interference and reduce the system vibration.Furthermore,the effects of the rotational speed on the wear depth are also studied and it is found that the quasi-static model is applicable to wear prediction when the rotational speed is away from the harmonic resonance peak.展开更多
The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with t...The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter(d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth(h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.展开更多
基金the National Natural Science Foundation of China (No. 50679041)the Shanghai Leading Academic Discipline Project (No. B208)
文摘Construction of diaphragm wall panels may cause considerable stress changes in heavily overconsol- idated soil deposits and can induce substantial ground movement. The 3D Lagrangian method was adopted to model the mechanical response of ground, including horizontal normal stress and shear stress, lateral ground displacement and vertical ground surface settlement, during the slurry trenching and concreting of diaphragm wall panels. Numerical results show that slurry trenching leads to horizontal stress relief of ground, reducing the horizontal stress of the ground from initial K0 pressure to hydrostatic betonite pressure. Wet concrete pressure lies between the hydrostatic bentonite pressure and the initial K0 pressure, so it can compensate partially the horizontal stress loss of the ground adjacent to the trench and thus reduce the lateral movement of the trench face as well as the vertical settlement of the ground surface.
基金Projects 2007AA06Z220 supported by the Hi-tech Research and Development Program of China307014 by the Key Science and Technology Program of the Ministry of Education
文摘Exploitation technology of pressure relief coalbed methane in vertical surface wells is a new method for exploration of gas and coalbed methane exploitation in mining areas with high concentrations of gas, where tectonic coal developed. Studies on vertical surface well technology in the Huainan Coal Mining area play a role in demonstration in the use of clean, new energy resources, preventing and reducing coal mine gas accidents and protecting the environment. Based on the practice of gas drainage engineering of pressure relief coalbed methane in vertical surface wells and combined with relative geological and exploration en- gineering theories, the design principles of design and structure of wells of pressure relief coalbed methane in vertical surface wells are studied. The effects of extraction and their causes are discussed and the impact of geological conditions on gas production of the vertical surface wells are analyzed. The results indicate that in mining areas with high concentrations of gas, where tectonic coal developed, a success rate of pressure relief coalbed methane in surface vertical well is high and single well production usually great. But deformation due to coal exploitation could damage boreholes and cause breaks in the connection between aquifers and bore-holes, which could induce a decrease, even a complete halt in gas production of a single well. The design of well site location and wellbore configuration are the key for technology. The development of the geological conditions for coalbed methane have a significant effect on gas production of coalbed methane wells.
基金sponsored by the Knowledge Innovation Program of the Chinese Academy of Sciences,Research on the Residential Liveability and Reconstruction of Typical Mountainous Settlements in Southwest China(No.KZCX2-EW317)The Western Light Talent Training Program of the Chinese Academy of Sciences,Public services Efficiency of Central Towns in Western Mountainous Areas of Sichuan(NO.Y2R2230230)+1 种基金the Humanities and Social Sciences Youth Project of Ministry of Education in China,Evolution and Optimisation of Spatial Structure of Urbanisation in Mountainous Areas(No.14YJCZH130)"135"Directional Program of Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Study on the Development Type and Space Optimisation of Settlement and Urbanisation in Upper Reaches of Minjiang River Basin(No.SDS-135-1204-04 110ZK20013)
文摘This article examines the spatial characteristics of public service supply and the factors influencing such supply in cities of Sichuan Province, China using spatial-autocorrelation and spatial econometric models with statistical data in 2012. The results demonstrate that expenditures on different types of public services present different spatial autocorrelation patterns. Although the spatial differences in basic public service expenditures are relatively small, a clear fan-shaped spillover to the east can be seen in Chengdu City. Chengdu also shows high clustering of advanced public service expenditures, being a typical core-periphery pattern. Post-earthquake reconstruction expenditures are clustered in the "5.12 Wenchuan earthquake" region and spill over toward cities to the east. The efficiency of public services in the mountainous areas in western Sichuan is low and exhibits a pattern of low-low spatial autocorrelation. The efficiency of public service supply is affected by economic, social, political and geographical factors. Based on the results of this analysis, we recommend a supply strategy that incorporates different types of public services and a specialized public service supply strategy for mountainous areas. Overall public service efficiency should be enhanced by focusing on narrowing the gap in farmers' income among regions and accelerating urbanization. Decision-makers should consider moresupportive policies with regard to providing basic public services in mountainous areas to ensure an equalized supply of basic public services. To enhance the efficiency of advanced public service supply, additional growth pole should be encouraged and incentivized; however, investments are required to drive the development of the peripheral regions through regional economic integration. Both software and hardware types of infrastructure are required to supply services efficiently during post-disaster reconstruction.
基金supported by the National Basic Research Program of China (No. 2011CB710600)the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (No. CUGL100211)the National Natural Science Foundation of China (No. 91014002)
文摘Planation surfaces （PS） play a major role in reconstruction of the evolutionary history of landforms in local areas. Thus, objective and consistent mapping of planation surfaces from remotely sensed data （e.g., satellite imagery, digital elevation models （DEMs）） is paramount for interpreting the geomorphological evolution. Due to the lack of dated sedimentary covers and the difficulties of com-prehensive field work, the number and age of planation surfaces in the Southwest Hubei （湖北） Prov-ince of China are still controversial. In order to map the PS in the study area, four data visualization techniques including ETM＋ false color composite, grey-scale DEM, shaded relief model （SRM） and painted relief model （P M） were examined. It is found that the PRM is the most optimal technique for planation surface mapping. The study area was successfully mapped by visual interpretation of a PRM derived from ASTER GDEM. The mapped PS was divided into five classes in terms of elevation ac-cording to previous studies, varying from 1 700-2 000 （PS1）, 1 300-1 500 （PS2）, 1 000-1 200 （PS3）, 800-900 （PS4） to 500-600 （PS5） m. The results were partially compared with the published works. It is revealed that this method of mapping enjoys a higher accuracy and can reduce the time and ef- fort required in the traditional mapping to a large extent. The results also demonstrated that the PRM is an effective tool for geomorphological fea-ture mapping with considerable accuracy. The pre- liminary results can serve to facilitate locating rep-resentative samples for the planation surfaces dating, thus to determine the ages of PS in the study areas.
基金supported by the National Natural Science Foundation of China(Grant No.11772089)the Fundamental Research Funds for the Central Universities(Grant Nos.N170308028&N180708009)Program for the Innovative Talents of Higher Learning Institutions of Liaoning(Grant No.LR2017035)
文摘Combining the loaded tooth contact analysis(LTCA)method and the gear dynamic model,a wear prediction model for spur gears with tip relief is established.The simulated wear depth is verified by the experimental results in a published reference.Based on the wear profile,the mesh stiffness and the tooth root stress obtained from the proposed model are compared with those obtained from the finite element model.Relative to the finite element method,the proposed method can greatly reduce the computation time.The effects of the tip relief and surface wear on the meshing and the dynamic characteristics are discussed.The tip relief can greatly decelerate the surface wear.Appropriate tip relief and slight wear can decrease the tooth interference and reduce the system vibration.Furthermore,the effects of the rotational speed on the wear depth are also studied and it is found that the quasi-static model is applicable to wear prediction when the rotational speed is away from the harmonic resonance peak.
基金Projects(2013BAB02B01,2013BAB02B03)supported by the National Key Technology R&D Program of ChinaProject(N120801002)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(N20130042110010)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘The measurement of surface stresses in surrounding rocks with the use of a relief method of annular hole-drilling was studied by numerical analysis. The stress relief process by hole-drilling was then simulated with the use of finite element method. The influences of the borehole diameter(d), the initial stresses and the ratio of the initial principle stresses on the variations of the remained stress and the released stress in function of the relief depth(h) were discussed. The relation between the non-dimensional ratio of the released principle strains and that of the initial principle stresses, and the effect of the elastic modulus and the Poisson ratio of the rock mass on the stress relief curves were studied. The results show that the stress relief behavior formulated with the non-dimensional ratio of the released stress and the ratio of h/d is only sensitive to the ratio of the initial principle stresses and the Poisson ratio. The stresses are completely released when h equals 1.6d, and the tensile stresses take place on the bore core surface in the relief measurement process. Finally, a non-complete relief method of annular hole-drilling for measuring surface stress in surrounding rocks is proposed and the procedure is presented.
