| Rock-burst is a very complicated dynamical instability phenomenon. High ground stress and its induced frequent rock-bursts are major influences of tunnel instability during the survey and design and construction stages.This paper combines closely with the engineering practice of the Jinpingâ…¡Hydropower Station, studies on rock-burst of the diversion tunnel of Jinpingâ…¡Hydropower Station. Study contents and conclusions acquired in this paper are mainly included as follows:(1) The engineering geological environmental conditions of study area explicated. Study the regional geology and the regional stability, landform conditions, strata lithology and the hydrological conditions and such in the study area.(2) This paper explicates mechanism of rock burst, at the same time, proposed graduation based on the rock-burst intensity, according to related information of transportation tunnel and exploration tunnel of Jinpingâ…¡Hydropower Station.(3)The maximum tangential stress value of tunnel wall is acquired through numerical calculation and 3D-sigma finite element analysis of tunnel excavation.(4)Forecast the probability, section and intensity of rock-burst emerging possibly during the diversion tunnel by tress-strength ratio method and geological comprehensive analysis.(5)Research on reinforcement measures, rockbolt play the role of preventing crack development and stress transfer to deep-seated rockmass. Reducing the spacing between of bolts has a better effect to prevent rock-burst than lengthening bolts. The hole for release of stress is an effective method to prevent heavy rock-burst because it make the stress transfer to deep-seated rockmass effectively. |
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