Construction Effects and Technical Measures During Traversing the Deep Weathered Rock Trough of Xiamen Xiang'an Sub-sea Tunnel

Based on the general situation and geology condition of the Xiamen Xiang'an sub-sea tunnel,the construction effects on different methods of excavation and pre-supporting were simulated by FLAC.The rational method of excavation and pre-supporting was proposed through analysis and comparison of the computed results.The construction technology of double-side pilot heading excavation method and full-section curtain grouting was introduced.The simulated results of the double-side pilot heading excavation method show that the deflections of arch crown,side wails,and bottom plate will be reduced obviously;the tunnel section will be forced in much more rational distribution;and there will not be large areas of stress concentration.The suggestions include:1)to select the double-side pilot heading excavation method,2)to adopt full-face curtain grouting for advanced consolidation,3)and to apply grouting by small diameter steel tubes and other supple- mentary reinforced measures during the excavation.