Based on the research method of combining simulation analysis with field testing by distinct element process UDEC, we have analyzed the roof deformation and failure laws and roadway support technology of gob-side entr...Based on the research method of combining simulation analysis with field testing by distinct element process UDEC, we have analyzed the roof deformation and failure laws and roadway support technology of gob-side entry retaining in a thin seam with a large inclined angle. The results show that during exploitation in seams with large inclined angle, rotational subsidence of the main roof under the gob area is small and can maintain balance, so there is no need to provide artificial permanent support resistance for the main roof near the upper side to control rotational subsidence. Obstructed by the dense scrap rail,waste rock from the immediate roof caving slides from the upper gob area to the lower area and fills it,which strikes a balance between the immediate roof under the goaf after it fractures into large pieces and filling waste rocks.展开更多
The Wenchuan earthquake on May 12,2008 caused numerous collapses,landslides,barrier lakes,and debris flows.Landslide susceptibility mapping is important for evaluation of environmental capacity and also as a guide for...The Wenchuan earthquake on May 12,2008 caused numerous collapses,landslides,barrier lakes,and debris flows.Landslide susceptibility mapping is important for evaluation of environmental capacity and also as a guide for post-earthquake reconstruction.In this paper,a logistic regression model was developed within the framework of GIS to map landslide susceptibility.Qingchuan County,a heavily affected area,was selected for the study.Distribution of landslides was prepared by interpretation of multi-temporal and multi-resolution remote sensing images(ADS40 aerial imagery,SPOT5 imagery and TM imagery,etc.) and field surveys.The Certainly Factor method was used to find the influencial factors,indicating that lithologic groups,distance from major faults,slope angle,profile curvature,and altitude are the dominant factors influencing landslides.The weight of each factor was determined using a binomial logistic regression model.Landslide susceptibility mapping was based on spatial overlay analysis and divided into five classes.Major faults have the most significant impact,and landslides will occur most likely in areas near the faults.Onethird of the area has a high or very high susceptibility,located in the northeast,south and southwest,including 65.3% of all landslides coincident with the earthquake.The susceptibility map can reveal the likelihood of future failures,and it will be useful for planners during the rebuilding process and for future zoning issues.展开更多
Continental orogens on Earth can be classified into accretionary orogen and collisional orogen.Magmatism in orogens occurs in every periods of an orogenic cycle,from oceanic subduction,continental collision to orogeni...Continental orogens on Earth can be classified into accretionary orogen and collisional orogen.Magmatism in orogens occurs in every periods of an orogenic cycle,from oceanic subduction,continental collision to orogenic collapse.Continental collision requires the existence of prior oceanic subduction zone.It is generally assumed that the prerequisite of continental deep subduction is oceanic subduction and its drag force to the connecting passive-margin continental lithosphere during continental collision.Continental subduction and collision lead to the thickening and uplift of crust,but the formation time of the related magmatism in orogens depends on the heating mechanism of lithosphere.The accretionary orogens,on the other hand,have no strong continental collision,deep subduction,no large scale of crustal thrusting,thickening and uplift,and no UHP eclogite-facies metamorphic rocks related to continental deep subduction.Even though arc crust could be significantly thickened during oceanic subduction,it is still doubtful that syn-or post-collisional magmatism would be generated.In collisional orogens,due to continental deep subduction and significant crustal thickening,the UHP metamorphosed oceanic and continental crusts will experience decompression melting during exhumation,generating syn-collisional magmatism.During the orogen unrooting and collapse,post-collisional magmatism develops in response to lithosphere extension and upwelling of asthenospheric mantle,marking the end of an orogenic cycle.Therefore,magmatism in orogens can occur during the continental deep subduction,exhumation and uplift after detachment of subducted oceanic crust from continental crust,and extensional collapse.The time span from continental collision to collapse and erosion of orogens(the end of orogenic cycle)is 50–85 Myr.Collisional orogens are the key sites for understanding continental deep subduction,exhumation,uplift and orogenic collapse.Magmatism in collisional orogens plays important roles in continental reworking and net growth.展开更多
基金Financial support for this work was provided by the National Natural Science Foundation of China(No.51104176)
文摘Based on the research method of combining simulation analysis with field testing by distinct element process UDEC, we have analyzed the roof deformation and failure laws and roadway support technology of gob-side entry retaining in a thin seam with a large inclined angle. The results show that during exploitation in seams with large inclined angle, rotational subsidence of the main roof under the gob area is small and can maintain balance, so there is no need to provide artificial permanent support resistance for the main roof near the upper side to control rotational subsidence. Obstructed by the dense scrap rail,waste rock from the immediate roof caving slides from the upper gob area to the lower area and fills it,which strikes a balance between the immediate roof under the goaf after it fractures into large pieces and filling waste rocks.
基金supported by State Key Fundamental Research Program (973) project (2008CB425802)the National natural Science Foundation of China (Grant No. 40801009)
文摘The Wenchuan earthquake on May 12,2008 caused numerous collapses,landslides,barrier lakes,and debris flows.Landslide susceptibility mapping is important for evaluation of environmental capacity and also as a guide for post-earthquake reconstruction.In this paper,a logistic regression model was developed within the framework of GIS to map landslide susceptibility.Qingchuan County,a heavily affected area,was selected for the study.Distribution of landslides was prepared by interpretation of multi-temporal and multi-resolution remote sensing images(ADS40 aerial imagery,SPOT5 imagery and TM imagery,etc.) and field surveys.The Certainly Factor method was used to find the influencial factors,indicating that lithologic groups,distance from major faults,slope angle,profile curvature,and altitude are the dominant factors influencing landslides.The weight of each factor was determined using a binomial logistic regression model.Landslide susceptibility mapping was based on spatial overlay analysis and divided into five classes.Major faults have the most significant impact,and landslides will occur most likely in areas near the faults.Onethird of the area has a high or very high susceptibility,located in the northeast,south and southwest,including 65.3% of all landslides coincident with the earthquake.The susceptibility map can reveal the likelihood of future failures,and it will be useful for planners during the rebuilding process and for future zoning issues.
基金supported by the National Basic Research Program of China(Grant No.2015CB856105)the National Natural Science Foundation of China(Grant Nos.41372060,41430207,41130314,41121062)the Basic Geological Survey Programs of China Geological Survey(Grant No.1212011121258)
文摘Continental orogens on Earth can be classified into accretionary orogen and collisional orogen.Magmatism in orogens occurs in every periods of an orogenic cycle,from oceanic subduction,continental collision to orogenic collapse.Continental collision requires the existence of prior oceanic subduction zone.It is generally assumed that the prerequisite of continental deep subduction is oceanic subduction and its drag force to the connecting passive-margin continental lithosphere during continental collision.Continental subduction and collision lead to the thickening and uplift of crust,but the formation time of the related magmatism in orogens depends on the heating mechanism of lithosphere.The accretionary orogens,on the other hand,have no strong continental collision,deep subduction,no large scale of crustal thrusting,thickening and uplift,and no UHP eclogite-facies metamorphic rocks related to continental deep subduction.Even though arc crust could be significantly thickened during oceanic subduction,it is still doubtful that syn-or post-collisional magmatism would be generated.In collisional orogens,due to continental deep subduction and significant crustal thickening,the UHP metamorphosed oceanic and continental crusts will experience decompression melting during exhumation,generating syn-collisional magmatism.During the orogen unrooting and collapse,post-collisional magmatism develops in response to lithosphere extension and upwelling of asthenospheric mantle,marking the end of an orogenic cycle.Therefore,magmatism in orogens can occur during the continental deep subduction,exhumation and uplift after detachment of subducted oceanic crust from continental crust,and extensional collapse.The time span from continental collision to collapse and erosion of orogens(the end of orogenic cycle)is 50–85 Myr.Collisional orogens are the key sites for understanding continental deep subduction,exhumation,uplift and orogenic collapse.Magmatism in collisional orogens plays important roles in continental reworking and net growth.
