Seismic Response And Stablity Assessment Of Block In Dagangshan Powerstation Underground

Key Block Theory is a kind of method developed and perfected in recent years, which analyses the stability of engineering rock masses. According to the geologic data of Dagangshan hydropower station, analyzed stability of key blocks in underground plant, discussed support optimizations method base on Block Theory Used Newmark method and Discrete element method to study the seismic response and stability of key block in underground plant, established a multi-factor,multi-index evaluation method to judge the stability of blocks in large underground plants under seismic load, which expanded the application of block theory. Major works and its characteristics are summarized as follows:(1) Based on the geological data and design informations of Da-gangshan underground plants, studied the distribution characteristics of joints,dike and fault by Dips and Origin softs, through which, got the basic information for support optimizations and seismic response of key block.(2) Based on the key block theory, the corresponding support methods for cases of random block, positioned block and half-positioned block are obtained and compared. Thus, the support method is determined according to the range of different surrounding rock section, reducing the bolt number reasonably and reaching the safe and economic effect.(3) Based on the key block theory and Newmark sliding block method, seismic response and stability of key block in large underground plants are studied. It's found that inertia force of the key block which acting with short time and large force leads to generation of permanent displacement under three-direction seismic loads; seismic loads with different intensity cause the key block not only quantitative change of seismic response but also motion patterns; The result also shows that seismic response characteristics is related to depth and volume of key blocks, Finally, seismic response of the key block is studied considering cyclic degradation of structure plane strength. Through that, seismic stability evaluation method considering multiple factor and indexes is established.(4) Rock mass discontinuity will case earthquake wave transmission, refraction,reflection and other complex propagations, some blocks will Slip and even break down. Based on the geologic data of Da-gangshan hydropower station, build underground plant model by 3DEC to simulate digging process, and compared the simulate results to actual measurement to make sure model parameters rationality; and further study seismic response and dynamic stability of blocks under different support condition. According to results, using 3DEC to analyze seismic response of key blocks is feasible, and found Anchors have good antiknock quality for blocks.