There are many fracture zones crossing the dam foundation of the Xiangjiaba Hydropower Project in southwestern China. Clastic rock is the main media of the fracture zone and has poor physical and mechanical properties...There are many fracture zones crossing the dam foundation of the Xiangjiaba Hydropower Project in southwestern China. Clastic rock is the main media of the fracture zone and has poor physical and mechanical properties. In order to investigate the creep behavior of clastic rock, triaxial creep tests were conducted using a rock servo-controlling rheological testing machine. The results show that the creep behavior of clastic rock is significant at a high level of deviatoric stress, and less time-dependent deformation occurs at high confining pressure. Based on the creep test results, the relationship between axial strain and time under different confining pressures was investigated, and the relationship between axial strain rate and deviatoric stress was also discussed. The strain rate increases rapidly, and the rock sample fails eventually under high deviatoric stress. Moreover, the creep failure mechanism under different confining pressures was analyzed. The main failure mechanism of clastic rock is plastic shear, accompanied by a significant compression and ductile dilatancy. On the other band, with the determined parameters, the Burgers creep model was used to fit the creep curves. The results indicate that the Burgers model can exactly describe the creep behavior of clastic rock in the Xiangjiaba Hydropower Project.展开更多
To deal with the construction difficulties of Xiangjiaba underground hydropower station,such as complex geological conditions,narrow rock bench,high loading,high quality requirements and urgent time limit,the project ...To deal with the construction difficulties of Xiangjiaba underground hydropower station,such as complex geological conditions,narrow rock bench,high loading,high quality requirements and urgent time limit,the project adopted the concept of precision blasting.The explosive energy and rock mass fragmentation were well controlled by taking reasonable excavation sequence,designing steel pipe drilling frame,the additional techniques of double layer smooth blasting,evenly micro charge,staggered arrangement of boreholes and pre-stressed anchors.These technologies ensured the excavation quality of the rock face beam,achieving successful blasting results:Semi hole ratio was 100%in Ⅱ surrounding rock,99.2%in Ⅲ surrounding rock and 90%~ 97.3%in Ⅳ surrounding rock;underbreak was avoided and the average backbreak was only2.9 cm;the unevenness was 0 ~ 4 cm;the influence depth of blasting and unloading was 0.2 ~ 0.7 cm.展开更多
The lower Jinsha River basin is located at the junction of Sichuan and Yunnan provinces in Southwest China,a region with intense tectonic movements and frequent moderate to strong seismic activities.Cascade hydropower...The lower Jinsha River basin is located at the junction of Sichuan and Yunnan provinces in Southwest China,a region with intense tectonic movements and frequent moderate to strong seismic activities.Cascade hydropower stations have been constructed along the lower Jinsha River since 2012.However,research on the effect of the impoundment of large-scale cascade reservoirs in a river basin on local seismic activities is currently lacking.Accurately identifying earthquake locations is essential for studying reservoir-induced earthquakes.Analyzing the spatiotemporal migration process of seismic activities based on complete and precise earthquake relocation is fundamental for determining the fluid diffusion coefficient,constructing fault models for reservoir areas,identifying earthquake types,exploring earthquake mechanisms,and evaluating seismic hazards.The seismicity pattern in the Xiangjiaba and Xiluodu reservoir areas,where seismic activities had been weak for a long time,has changed with the successive impoundment of the two reservoirs,showing microseismic events and seismic clusters.We investigated the spatiotemporal characteristics of seismic activities in the Xiangjiaba and Xiluodu reservoir areas using the waveform cross-correlation-based double-difference relocation technique and the b-value analysis method.We discovered that seismic events after the impoundment of these two reservoirs exhibited different characteristics in different regions.The seismic activities at the Xiluodu dam quickly responded to the rising water level,with the seismic intensity decaying rapidly afterward.These events were concentrated in the limestone strata along both sides of the Jinsha River,with a shallow focal depth,generally within 5 km,and a high b-value of approximately 1.2.Such features are close to those of karst-type earthquakes.Microseismic activities frequent occur on the eastern bank of the Yongshan reservoir section downstream of the Xiluodu dam,with two parallel NW-trending earthquake strips visible after precise earthquake relocation.The M_(S)5.2 earthquake near Wuji town on August 17,2014,had prominent foreshocks and aftershocks distributed in a clear NW-trending 20-km-long strip,perpendicular to the riverbank.These seismic events had a low b-value of approximately 0.7.The orientation of the node plane revealed by the strike-slip focal mechanism of the mainshock is consistent with that of the strip formed by the foreshock-mainshock-aftershock sequence,indicating the existence of a NW-striking concealed fault.Seismic activities near the Yanjin-Mabian fault upstream of the Xiangjiaba reservoir area since 2013 were concentrated in a NW-trending strip,with several near EW-trending seismic clusters on its western side,and with the largest event having a magnitude of M_(L)3.7.So far,the impoundment of the Xiangjiaba and Xiluodu reservoirs has not triggered seismic activities on the large Jinyang-Ebian and Yanjin-Mabian faults nearby.展开更多
为检验向家坝升船机通航条件,协调部、省、市三级航运主管部门,明确实船试航工作流程及组织实施模式,对“船-机-水”相互适应性进行了枯水期、丰水期实船试航试验。结果表明,升船机及助导航设备设施性能良好,船舶安检调度及航路航法科...为检验向家坝升船机通航条件,协调部、省、市三级航运主管部门,明确实船试航工作流程及组织实施模式,对“船-机-水”相互适应性进行了枯水期、丰水期实船试航试验。结果表明,升船机及助导航设备设施性能良好,船舶安检调度及航路航法科学合理。泄洪工况下,下游引航道及口门区通航水流条件较差,对通航影响较大,研究应用“无人机+自动跟踪浮子”及“三维立体视觉”水流条件观测新方法,提出电站出流8500 m 3 s,泄洪不超2200 m 3 s双控通航流量标准,试航成果为后续升船机试通航运行及通航验收提供数据支撑。展开更多
基金supported by the National Natural Science Foundation of China(Grants No.51409261 and 11172090)the Natural Science Foundation of Shandong Province(Grants No.ZR2014EEQ014)the Applied Basic Research Programs of Qingdao City(Grant No.14-2-4-67-jch)
文摘There are many fracture zones crossing the dam foundation of the Xiangjiaba Hydropower Project in southwestern China. Clastic rock is the main media of the fracture zone and has poor physical and mechanical properties. In order to investigate the creep behavior of clastic rock, triaxial creep tests were conducted using a rock servo-controlling rheological testing machine. The results show that the creep behavior of clastic rock is significant at a high level of deviatoric stress, and less time-dependent deformation occurs at high confining pressure. Based on the creep test results, the relationship between axial strain and time under different confining pressures was investigated, and the relationship between axial strain rate and deviatoric stress was also discussed. The strain rate increases rapidly, and the rock sample fails eventually under high deviatoric stress. Moreover, the creep failure mechanism under different confining pressures was analyzed. The main failure mechanism of clastic rock is plastic shear, accompanied by a significant compression and ductile dilatancy. On the other band, with the determined parameters, the Burgers creep model was used to fit the creep curves. The results indicate that the Burgers model can exactly describe the creep behavior of clastic rock in the Xiangjiaba Hydropower Project.
文摘To deal with the construction difficulties of Xiangjiaba underground hydropower station,such as complex geological conditions,narrow rock bench,high loading,high quality requirements and urgent time limit,the project adopted the concept of precision blasting.The explosive energy and rock mass fragmentation were well controlled by taking reasonable excavation sequence,designing steel pipe drilling frame,the additional techniques of double layer smooth blasting,evenly micro charge,staggered arrangement of boreholes and pre-stressed anchors.These technologies ensured the excavation quality of the rock face beam,achieving successful blasting results:Semi hole ratio was 100%in Ⅱ surrounding rock,99.2%in Ⅲ surrounding rock and 90%~ 97.3%in Ⅳ surrounding rock;underbreak was avoided and the average backbreak was only2.9 cm;the unevenness was 0 ~ 4 cm;the influence depth of blasting and unloading was 0.2 ~ 0.7 cm.
基金funded by the project of"The Seismogenesis and Discrimination Methods of Cascade Reservoir in the Lower reaches of Jinsha River"(No.JG/20023B)from the China Three Gorges Construction Engineering Corporationthe National Key R&D Program project(No.2021YFC3000703)。
文摘The lower Jinsha River basin is located at the junction of Sichuan and Yunnan provinces in Southwest China,a region with intense tectonic movements and frequent moderate to strong seismic activities.Cascade hydropower stations have been constructed along the lower Jinsha River since 2012.However,research on the effect of the impoundment of large-scale cascade reservoirs in a river basin on local seismic activities is currently lacking.Accurately identifying earthquake locations is essential for studying reservoir-induced earthquakes.Analyzing the spatiotemporal migration process of seismic activities based on complete and precise earthquake relocation is fundamental for determining the fluid diffusion coefficient,constructing fault models for reservoir areas,identifying earthquake types,exploring earthquake mechanisms,and evaluating seismic hazards.The seismicity pattern in the Xiangjiaba and Xiluodu reservoir areas,where seismic activities had been weak for a long time,has changed with the successive impoundment of the two reservoirs,showing microseismic events and seismic clusters.We investigated the spatiotemporal characteristics of seismic activities in the Xiangjiaba and Xiluodu reservoir areas using the waveform cross-correlation-based double-difference relocation technique and the b-value analysis method.We discovered that seismic events after the impoundment of these two reservoirs exhibited different characteristics in different regions.The seismic activities at the Xiluodu dam quickly responded to the rising water level,with the seismic intensity decaying rapidly afterward.These events were concentrated in the limestone strata along both sides of the Jinsha River,with a shallow focal depth,generally within 5 km,and a high b-value of approximately 1.2.Such features are close to those of karst-type earthquakes.Microseismic activities frequent occur on the eastern bank of the Yongshan reservoir section downstream of the Xiluodu dam,with two parallel NW-trending earthquake strips visible after precise earthquake relocation.The M_(S)5.2 earthquake near Wuji town on August 17,2014,had prominent foreshocks and aftershocks distributed in a clear NW-trending 20-km-long strip,perpendicular to the riverbank.These seismic events had a low b-value of approximately 0.7.The orientation of the node plane revealed by the strike-slip focal mechanism of the mainshock is consistent with that of the strip formed by the foreshock-mainshock-aftershock sequence,indicating the existence of a NW-striking concealed fault.Seismic activities near the Yanjin-Mabian fault upstream of the Xiangjiaba reservoir area since 2013 were concentrated in a NW-trending strip,with several near EW-trending seismic clusters on its western side,and with the largest event having a magnitude of M_(L)3.7.So far,the impoundment of the Xiangjiaba and Xiluodu reservoirs has not triggered seismic activities on the large Jinyang-Ebian and Yanjin-Mabian faults nearby.
文摘为检验向家坝升船机通航条件,协调部、省、市三级航运主管部门,明确实船试航工作流程及组织实施模式,对“船-机-水”相互适应性进行了枯水期、丰水期实船试航试验。结果表明,升船机及助导航设备设施性能良好,船舶安检调度及航路航法科学合理。泄洪工况下,下游引航道及口门区通航水流条件较差,对通航影响较大,研究应用“无人机+自动跟踪浮子”及“三维立体视觉”水流条件观测新方法,提出电站出流8500 m 3 s,泄洪不超2200 m 3 s双控通航流量标准,试航成果为后续升船机试通航运行及通航验收提供数据支撑。
