XU Shiliang, CUI Zhendong. 2010: ANALYSIS OF INSITU GEOSTRESS AND ROCKBURST |AT NO.2 VENTILATION SHAFT TUNNEL OF QINLING HIGHWAY TUNNEL. JOURNAL OF ENGINEERING GEOLOGY, 18(3): 407-412.
    Citation: XU Shiliang, CUI Zhendong. 2010: ANALYSIS OF INSITU GEOSTRESS AND ROCKBURST |AT NO.2 VENTILATION SHAFT TUNNEL OF QINLING HIGHWAY TUNNEL. JOURNAL OF ENGINEERING GEOLOGY, 18(3): 407-412.

    ANALYSIS OF INSITU GEOSTRESS AND ROCKBURST |AT NO.2 VENTILATION SHAFT TUNNEL OF QINLING HIGHWAY TUNNEL

    • The No.2 ventilation shaft of Qinling highway tunnel is mainly located in the mixed gneiss stratum. The main technical problems encountered in the shaft excavation are high insitu geostress and rockburst. The paper examined the engineering geology of the shaft and the geostress measurement results of nearby engineering by hydraulic fracturing method. Then, the geostress field in the shaft area is calculated and regressed with 3D finite element method. It is shown that the geostress in the shaft area has a high horizontal geological structure stress and is ly distributed in zones. The maximum horizontal geostress is 28.7 MPa. The vertical geostress is controlled by weight of rockmass. Based on the geostress field, the rockburst prediction in the shaft is made according to the Tao's rockburst criteria. The depth of rockburst failure area is estimated with the constantdeviatoricstresscriterion of brittle rock mass. The results show that there are high possibilities of occurring weak and moderate rockbursts. The maximum depth of failure is 0.6 m in the surrounding rocks of the shaft. The results from the geostress and rockburst analysis are well compared with the actual situations of rockbursts after shaft excavation.
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