Analysing Study Of The Underground Continuous Wall Construction Risks

Along with the gradual progress of the urban rail traffic construction development andengineering construction scale being expanded daily, the difficulty of engineeringconstruction is on the rise. The underground continuous wall is the common palisade structureof the subway deep foundation pit, the quality of which concerns not only the whole pit safetybut also the later metro station operation. As the quality of underground continuous wallproject has all the characteristics as large investment, grandeur scale, involvement of manyfactors, complicated construction process, serious consequences and profound influence, it isnecessary to recognize, analyze and evaluate the risks of the underground continuous wallconstruction to provide a reference for the smooth construction of the underground continuouswall. The main contents include the following respects:(1) A summary of the recent urban rail traffic engineering construction accidents toindicate the necessity to analyze the construction risks.(2) Using WBS-RBS method to indentify risk source of underground continuous wallconstruction process. Those main analysis process include: cutoff wall, steel reinforcementcage fabrication, locking pipe construction and underwater concrete casting. Also theinfluence of environment surrounding should be considered. Finally,The main risk source ofunderground continuous wall construction is obtained(3) Risk assessment method is introduced. Those method include decision tree method,fuzzy comprehensive evaluation method, monte carlo method, analytic hierarchy process withmore detail. The analytic hierarchy process and experts marking is combined to evaluate theconstruction risk sources and serve as the standards of the risk grade classification. The finalrisk index is work out. (4) A risk analysis of Ying Hua park station on the Ningbo subway line1is proceededwith above methods applied. This analysis is mostly focused on the calculation of the slot’sstability Fs and the critical excavation depth based on the soil data and mud index in theslotting period. The main risk sources is obtained on the basis of the safety in the davitprocess of the steel cage, the quality accidents in the concrete casting process and the in-siteinspection data of the surroundings with the experts experience combined. The analyticprocess and experts marking is combined to do quantitative calculation and evaluation tofinally obtain the risk levels while the risk-counter measures is adopted over the riskevaluation results.