Exploring the Logic and Landscape of the Knowledge System＂ Multilevel Structures, Each Multiscaled with Complexity at the Mesoscale

1.Breaking habitual thinking patterns Breaking the patterns of habitual thinking is crucial in order to welcome a new revolution of science and technology(S&T)and to realize a new paradigm of scientific research.We are facing a new era for S&T,in which there are more opportunities than challenges.However,this new era calls for governments and

The Highest Dam in the World under Construction： The Shuan^iangkou Core-Wall Rockfill Dam

Dadu River is an important tributary of the Yangtze River in China. The Shuangjiangkou Hydropower Station is the control reservoir upstream of the main trunk of Dadu River. Located in the Aba Tibetan and Qiang Autonomous Prefecture of Sichuan Province, the project is mainly aimed at power generation and flood control.

Early demonstration and research on the key technical issues of large-basin hydropower development under the concept of harmony

As a typical representative of hydropower development in China,the Dadu River is characterized by abundant water resources,poor geological conditions,many resettlements and limited environmental capacity.Therefore,the technical problems faced by Dadu River hydropower development are numerous and complex.We analysed these technical problems,such as the hydropower-development mode,normal water level,dam-site selection,damming technology,migration resettlement and environmental protection.The concept and characteristics of harmonious hydropower development are identified.The harmonious hydropower-development concept has been applied to all aspects of the Dadu River hydropower-development feasibility study to solve the key technical problems of hydropower development on the Dadu River and to promote the development of China’s hydropower.

Failure precursor of surrounding rock mass around cross tunnel in high-steep rock slope

The stability of the surrounding rock mass around cross tunnel in the right bank slope of Dagangshan hydropower station, in the southwestern China, was analyzed by microseismic monitoring as well as numerical simulations. The realistic failure process analysis code （abbreviated as RFPA3D） was employed to reproduce the initiation, propagation, coalescence and interactions of micro-fractures, the evolution of associated stress fields and acoustic emission （AE） activities during the whole failure processes of the surrounding rock mass around cross tunnel. Combined with microseismic activities by microseismic monitoring on the fight bank slope, the spatial-temporal evolution and the micro-fracture precursor characteristics during the complete process of progressive failure of the surrounding rock mass around cross tunnel were discussed and the energy release law of the surrounding rock mass around the cross tunnel was obtained. The result shows that the precursor characteristic of microfractures occurring in rock mass is an effective approach to early warn catastrophic damage of rock mass around cross tunnel. Moreover, the heterogeneity of rock mass is the source and internal cause of the failure precursor of rock mass.

Excavation-induced microseismicity: microseismic monitoring and numerical simulation

The volume of influence of excavation at the right bank slope of Dagangshan Hydropower Station, southwest China, is essentially determined from microseismic monitoring, numerical modeling and conventional measurements as well as in situ observations. Microseismic monitoring is a new application technique for investigating microcrackings in rock slopes. A micro- seismic monitoring network has been systematically used to monitor rock masses unloading relaxation due to continuous exca- vation of rock slope and stress redistribution caused by dam impoundment later on, and to identify and delineate the potential slippage regions since May, 2010. An important database of seismic source locations is available. The analysis of microseismic events showed a particular tempo-spatial distribution. Seismic events predominantly occurred around the upstream slope of 1180 m elevation, especially focusing on the hanging wall of fault XL316-1. Such phenomenon was interpreted by numerical modeling using RFPA-SRM code （realistic failure process analysis-strength reduction method）. By comparing microseismic activity and results of numerical simulation with in site observation and conventional measurements results, a strong correlation can he obtained between seismic source locations and excavation-induced stress distribution in the working areas. The volume of influence of the rock slope is thus determined. Engineering practices show microseismic monitoring can accurately diagnose magnitude, intensity and associated tempo-spatial characteristics of tectonic activities such as faults and unloading zones. The integrated technique combining seismic monitoring with numerical modeling, as well as in site observation and conventional surveying, leads to a better understanding of the internal effect and relationship between microseismic activity and stress field in the right bank slope from different perspectives.