Stability Analysis Of The Unfavorable Geologic Section With Pre-grouting Reinforcement In Subsea Tunnel At Jiaozhou Bay

For the tunnel construction in unfavorable geological section, we often use pre-grouting to reinforce it. Then it is important for our research to identify grouting design parameters, examine the grouting effectiveness and analyze the stability of tunnel in fore-and-aft pre-grouting reinforcement. Due to specificity of the condition, fractured rocks and unlimited supply of water, it is especially important for the tunnel construction. Tunnel water-gushing damage and the instability of surrounding rock which will bring incurable consequences. Therefore, in view of the complex traits of tunnel surrounding rock in unfavorable geologic sections, there is very important practical significance to study the grouting rules of fractured rock mass and the influence of grouting in unfavorable geologic sections.This paper relies on the Subsea Tunnel Project at QinDao Jiaozhou Bay. On the base of field survey and literature research, I study the stability of surrounding rock with theoretical analysis and numerical simulation when the tunnel passes though fault fracture zone. The main research as follows: First, study the grouting rules of fractured rock mass and the splitting grouting technique when tunnel pass though unfavorable geologic sections; Second, analyze field pre-grouting experiments in Harbor Tunnel at Jiaozhou Bay and some issues of the grouting design during tunnel passing though faultagef4-4. Third, analyze the stability of tunnel surrounding rock in unfavorable geologic section using numerical analysis, and summarize out a series of grouting parameters, which is suited to Harbor Tunnel in unfavorable geologic section at Jiaozhou Bay. Fourth, study the examination of the grouting effectiveness, use theoretical formula and numerical analysis to calculate tunnel water-gushing amount during fore-and-aft grouting on the base of the first cycle grouting data of faultagef4-4. At last, I combined the calculated water-gushing amount with the measured water-gushing amount to get a series of important grouting parameters which is suited to tunnel passing though fault facture zone. It is all for providing guidance of constructing Harbor Tunnel at Jiaozhou Bay in safety.