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Abstract f5 Fault is the largest fault in the dam area of Jinping I hydropower station。In order to improve the quality of rock mass of dam abutment，adits f5–1，f5–2 and 4 inclined shaft were used to replace the fault f5. Based on the extensive research，the necessity of replacement grid setting was discussed. 3D finite element method was employed to simulate natural topography and geological conditions and excavation. The stability of replacement grid was evaluated by stress and deformation，and compared with measured data. The results show that the adits f5–1and f5–2 meet the stability requirement of the construction period，but supporting force in local tunnel is insufficient. For adit f5–2，two kinds of reinforced measures，prestressed anchor bolt，steel arch centering，thick shotcret and lining in advance，were adopted，these measures can makes the adit to meet stability requirements. Taking the other factors into consideration，it is believed that lining in advance is more reasonable. For cross parts of adit and inclined shaft，inclined shaft were excavated after lining before and after 10 m of cross parts of adit were completed，the maximum compressive stress of lining is less than 6.5 MPa and the maximum tensile stress is less than 1.7 MPa. For cross parts of adit f5–1 and force transmission tunnel # 5，first proposed in # 5 tunnel applied lining，then consolidation grouting on the thinner rock pillar，last for the construction of the adit. The numerical analysis results provide a scientific basis for the design of lining in replacement tunnel，and has guiding meaning to the other similar projects.
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Received: 11 April 2012
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2012, Vol. 31 
