横跨色尔腾山山前断裂布设一条长10.77 km的浅层地震勘探测线L1,结果发现,色尔腾山山前断裂在剖面上清晰可见,其主断裂在上部存在分叉,由断层F_(P1.1)和F_(P1)组成,均为正断层,视倾向南;结合地质地貌调查认为,F_(P1.1)断层的最新活动时...横跨色尔腾山山前断裂布设一条长10.77 km的浅层地震勘探测线L1,结果发现,色尔腾山山前断裂在剖面上清晰可见,其主断裂在上部存在分叉,由断层F_(P1.1)和F_(P1)组成,均为正断层,视倾向南;结合地质地貌调查认为,F_(P1.1)断层的最新活动时代为全新世。针对色尔腾山山前断裂的F_(P1)断层开展钻孔联合地质剖面探测,划分出Fa、Fb两个断层,结合光释光测年结果发现,断层Fa和Fb为全新世断层,其最新活动时代晚于2.5±0.6 ka BP。色尔腾山山前断裂在近地表呈叉状结构,是该断裂在晚第四纪具有多次活动的反映。展开更多
The Yinchuan basin, located on the western margin of the Ordos block, has the characteristics of an active continental rift. A NW-striking deep seismic reflection profile across the center of Yinchuan basin precisely ...The Yinchuan basin, located on the western margin of the Ordos block, has the characteristics of an active continental rift. A NW-striking deep seismic reflection profile across the center of Yinchuan basin precisely revealed the fine structure of the crust. The images showed that the crust in the Yinchuan basin was characterized by vertical stratifications along a detachment located at a two-way travel time（TWT） of 8.0 s.The most outstanding feature of this seismic profile was the almost flat Mohorovicˇic′ discontinuity（Moho） and a high-reflection zone in the lower crust. This sub-horizontal Moho conflicts with the general assumption of an uplifted Moho under sedimentary basins and continental rifts, and may indicate the action of different processes at depth during the evolution of sedimentary basins or rifts.We present a possible interpretation of these deep processes and the sub-horizontal Moho. The high-reflection zone, which consists of sheets of high-density, mantlederived materials, may have compensated for crustal thinning in the Yinchuan basin, leading to the formation of a sub-horizontal Moho. These high-density materials may have been emplaced by underplating with mantlesourced magma.展开更多
To investigate the seismic behavior of I-section columns made of 460 MPa high strength steel （HSS）, six specimens were tested under constant axial load and cyclic horizontal load. The specimens were designed with di...To investigate the seismic behavior of I-section columns made of 460 MPa high strength steel （HSS）, six specimens were tested under constant axial load and cyclic horizontal load. The specimens were designed with different width-to-thickness ratios and loaded under different axial load ratios. For each specimen, the failure mode was observed and hysteretic curve was measured. Comparison of different specimens on hysteretic characteristic, energy dissipation capacity and deformation capacity were further investigated. Test results showed that the degradation of bearing capacity was due to local buckling of flange and web. Under the same axial load ratio, as width-to-thickness ratio increased, the deformation area of local buckling became smaller. And also, displacement level at both peak load and failure load became smaller. In addition, the full extent of hysteretic curve, energy dissipation capacity, ultimate story drift angle decreased, and capacity degradation occurred more rapidly with the increase of width-to-thickness ratio or axial load ratio. Based on the capacity of story drift angle, limiting values which shall not be exceeded are suggested respectively for flange and web plate of 460 MPa HSS I-section columns when used in SMFs and in IMFs in the case of axial load ratio no more than 0.2. Such values should be smaller when the axial load ratio increases.展开更多
文摘横跨色尔腾山山前断裂布设一条长10.77 km的浅层地震勘探测线L1,结果发现,色尔腾山山前断裂在剖面上清晰可见,其主断裂在上部存在分叉,由断层F_(P1.1)和F_(P1)组成,均为正断层,视倾向南;结合地质地貌调查认为,F_(P1.1)断层的最新活动时代为全新世。针对色尔腾山山前断裂的F_(P1)断层开展钻孔联合地质剖面探测,划分出Fa、Fb两个断层,结合光释光测年结果发现,断层Fa和Fb为全新世断层,其最新活动时代晚于2.5±0.6 ka BP。色尔腾山山前断裂在近地表呈叉状结构,是该断裂在晚第四纪具有多次活动的反映。
基金This study was financed jointly by the Sino Probe Project of China(Sinoprobe-02-01)the National Natural Science Foundation of China(Nos.41430213,41274097,and 41404072)+1 种基金Geological Investigation Project of China Geological Survey(Nos.1212011220260 and 12120115027101)‘‘Urban Active Fault Detection’’of National Development and Reform Commission(No.20041138)
文摘The Yinchuan basin, located on the western margin of the Ordos block, has the characteristics of an active continental rift. A NW-striking deep seismic reflection profile across the center of Yinchuan basin precisely revealed the fine structure of the crust. The images showed that the crust in the Yinchuan basin was characterized by vertical stratifications along a detachment located at a two-way travel time（TWT） of 8.0 s.The most outstanding feature of this seismic profile was the almost flat Mohorovicˇic′ discontinuity（Moho） and a high-reflection zone in the lower crust. This sub-horizontal Moho conflicts with the general assumption of an uplifted Moho under sedimentary basins and continental rifts, and may indicate the action of different processes at depth during the evolution of sedimentary basins or rifts.We present a possible interpretation of these deep processes and the sub-horizontal Moho. The high-reflection zone, which consists of sheets of high-density, mantlederived materials, may have compensated for crustal thinning in the Yinchuan basin, leading to the formation of a sub-horizontal Moho. These high-density materials may have been emplaced by underplating with mantlesourced magma.
基金the National Natural Science Foundation of China under Grant No.51478244
文摘To investigate the seismic behavior of I-section columns made of 460 MPa high strength steel （HSS）, six specimens were tested under constant axial load and cyclic horizontal load. The specimens were designed with different width-to-thickness ratios and loaded under different axial load ratios. For each specimen, the failure mode was observed and hysteretic curve was measured. Comparison of different specimens on hysteretic characteristic, energy dissipation capacity and deformation capacity were further investigated. Test results showed that the degradation of bearing capacity was due to local buckling of flange and web. Under the same axial load ratio, as width-to-thickness ratio increased, the deformation area of local buckling became smaller. And also, displacement level at both peak load and failure load became smaller. In addition, the full extent of hysteretic curve, energy dissipation capacity, ultimate story drift angle decreased, and capacity degradation occurred more rapidly with the increase of width-to-thickness ratio or axial load ratio. Based on the capacity of story drift angle, limiting values which shall not be exceeded are suggested respectively for flange and web plate of 460 MPa HSS I-section columns when used in SMFs and in IMFs in the case of axial load ratio no more than 0.2. Such values should be smaller when the axial load ratio increases.
