Earth temperature is one of the most important factors influencing the mechanical properties of frozen soil. Based on the field investigation of the characteristics of ground deformation and ground failure caused by t...Earth temperature is one of the most important factors influencing the mechanical properties of frozen soil. Based on the field investigation of the characteristics of ground deformation and ground failure caused by the M S8 1 earthquake in the west of the Kunlun Mountain Pass, China, the influence of temperature on the dynamic constitutive relationship, dynamic elastic modulus, damping ratio and dynamic strength of frozen soil was quantitatively studied by means of the dynamic triaxial test. Moreover, the characteristics of ground motion on a permafrost site under different temperatures were analyzed for the four profiles of permafrost along the Qinghai Xizang(Tibet) Railway using the time histories of ground motion acceleration with 3 exceedance probabilities of the Kunlun Mountains area. The influences of temperature on the seismic displacement, velocity, acceleration and response spectrum on permafrost ground were studied quantitatively. A scientific basis was presented for earthquake disaster mitigation for engineering foundations, highways and underground engineering in permafrost areas.展开更多
黑土区土壤肥力一直是人们关心的问题。通过选择在黑土区典型县份-德惠市的调查表明,耕地土壤有机质、全氮、有效磷与1980年相比较,分别增加了3.2g kg-11,0.11 g kg-1和5.70 mg kg-1,但有效钾下降了33.3 mg kg-1。土壤中有机质2003年盈...黑土区土壤肥力一直是人们关心的问题。通过选择在黑土区典型县份-德惠市的调查表明,耕地土壤有机质、全氮、有效磷与1980年相比较,分别增加了3.2g kg-11,0.11 g kg-1和5.70 mg kg-1,但有效钾下降了33.3 mg kg-1。土壤中有机质2003年盈余量48.7kg hm-2,氮15.07 kg hm-2,磷25.35 kg hm-2;钾亏损量170.62 kg hm-2。笔者认为,单纯从土壤营养管理角度看,目前黑土区耕地土壤肥力状况似乎没有想象的那么坏。但已有的研究也表明,黑土区耕地肥力的变化与现行的耕作制度有很大的关系。展开更多
A strong Mw7.0 earthquake struck Pingtung offshore of Talwan on December 26, 2006. It consisted of two major events with an 8-minute interval. The first major shock occurred at 12：26 UTC. Focal mechanism results from...A strong Mw7.0 earthquake struck Pingtung offshore of Talwan on December 26, 2006. It consisted of two major events with an 8-minute interval. The first major shock occurred at 12：26 UTC. Focal mechanism results from Harvard, USGS, and BATS all indicated that the first major shock was a normal fault earthquake and the second one was dominated by strike-slip offsets. The location of the epicenter varied greatly in depth in different analyses. The latest results showed that the focal depth of the first shock was most probably around 40-44 km, placing the epicenter in the lithospheric mantle. However, this is not a location where earthquakes usually occur. To explore the geodynamical mechanism of this event, we carded out 2D finite element method （FEM） numerical experiments. Our primary results indicate that the geodynamical background, as well as the formation of Pingtung earthquake, is a consequence of the collision between Luzon arc and Chinese continental margin. Although Taiwan Island is in the shadow of NW-SE trending compressive collision zone, the existence of ductile lower crust leads to the decoupling between upper crust and lithospheric mantle. As lithospheric mantle subducts to the depth of around 250 km, the upper part of the bending subduction slab puts itself in an extensional state. The extensional stress from bending induced the occurrence of this normal fault earthquake at the critical point.展开更多
文摘Earth temperature is one of the most important factors influencing the mechanical properties of frozen soil. Based on the field investigation of the characteristics of ground deformation and ground failure caused by the M S8 1 earthquake in the west of the Kunlun Mountain Pass, China, the influence of temperature on the dynamic constitutive relationship, dynamic elastic modulus, damping ratio and dynamic strength of frozen soil was quantitatively studied by means of the dynamic triaxial test. Moreover, the characteristics of ground motion on a permafrost site under different temperatures were analyzed for the four profiles of permafrost along the Qinghai Xizang(Tibet) Railway using the time histories of ground motion acceleration with 3 exceedance probabilities of the Kunlun Mountains area. The influences of temperature on the seismic displacement, velocity, acceleration and response spectrum on permafrost ground were studied quantitatively. A scientific basis was presented for earthquake disaster mitigation for engineering foundations, highways and underground engineering in permafrost areas.
文摘黑土区土壤肥力一直是人们关心的问题。通过选择在黑土区典型县份-德惠市的调查表明,耕地土壤有机质、全氮、有效磷与1980年相比较,分别增加了3.2g kg-11,0.11 g kg-1和5.70 mg kg-1,但有效钾下降了33.3 mg kg-1。土壤中有机质2003年盈余量48.7kg hm-2,氮15.07 kg hm-2,磷25.35 kg hm-2;钾亏损量170.62 kg hm-2。笔者认为,单纯从土壤营养管理角度看,目前黑土区耕地土壤肥力状况似乎没有想象的那么坏。但已有的研究也表明,黑土区耕地肥力的变化与现行的耕作制度有很大的关系。
基金supported by National Natural Science Foundation of China (Grant No. 40774048)Major Research of National Natural Science Foundation of China (Grant No. 90814014)Sino-Probe Project of China and Knowledge Innovation Program of Chinese Academy of Sciences (Grant No. KZCX2-YW-123)
文摘A strong Mw7.0 earthquake struck Pingtung offshore of Talwan on December 26, 2006. It consisted of two major events with an 8-minute interval. The first major shock occurred at 12：26 UTC. Focal mechanism results from Harvard, USGS, and BATS all indicated that the first major shock was a normal fault earthquake and the second one was dominated by strike-slip offsets. The location of the epicenter varied greatly in depth in different analyses. The latest results showed that the focal depth of the first shock was most probably around 40-44 km, placing the epicenter in the lithospheric mantle. However, this is not a location where earthquakes usually occur. To explore the geodynamical mechanism of this event, we carded out 2D finite element method （FEM） numerical experiments. Our primary results indicate that the geodynamical background, as well as the formation of Pingtung earthquake, is a consequence of the collision between Luzon arc and Chinese continental margin. Although Taiwan Island is in the shadow of NW-SE trending compressive collision zone, the existence of ductile lower crust leads to the decoupling between upper crust and lithospheric mantle. As lithospheric mantle subducts to the depth of around 250 km, the upper part of the bending subduction slab puts itself in an extensional state. The extensional stress from bending induced the occurrence of this normal fault earthquake at the critical point.
