Analysis And Monitoring Of The Retaining Structure In Deep Excavation

In recent years, increasing scale and growing depth appears in excavationengineering to meet the needs of urban underground space development. Analysismethods of retaining structure and monitoring technology in deep excavation hasbecome an important part in the field of Civil Engineering. It is often difficult todetermine which impact should be included in the analysis of deep excavationproblems, which results in inefficiency and low-value. The law that internal force anddeformation of retaining structure follows and that soil deformation follows, wouldbe important reference for the retaining structure design and the monitoring program.Reliable and effective monitoring is necessary to ensure the safety of deep excavationconstruction, it is also necessary for the informationalized design and construction, aswell as the development of retaining structure design theory. Presently unreasonablemeasuring points arrangement, data processing methods and assessing methods hasbecome more and more common, reasonable and effective monitoring technologyhelps to improve the status quo.This paper takes the working shaft excavation in the South of Yangtze River asan example, which is part of Nanjing Weisan road tunnel across the Yangtze River.On the basis of the previous research, practical experience in deep excavation andmonitoring results of the working shaft excavation, this paper studies retainingstructure analysis method and monitoring technique, and achieved the followingresults:1) This paper explored and identified the various complex factors and theireffects, such as friction characteristics between the wall and soil, precipitation,groundwater seepage, time effect and space effects., And created a reasonable finiteelement analysis model for the process of deep excavation in soft-soil area.2) Based on the calculation results, on-site monitoring results and previousengineering, this paper summarized the law that internal force and deformation ofretaining structure follows and that soil deformation follows. 3) based on the law that internal force and deformation of the retaining structurefollows and that soil deformation follows, a series of recommendations are proposedfor the improvement of measuring points arrangement, data processing methods andassessing methods.4) A new warning criterion based on concrete cracking was proposed for theimprovement of safety assessing methods of retaining structure.Whether numerical simulation analysis is effective to a large extent depends onthe analysis model and soil parameters, the model and soil parameters should beoptimized based on pre-measured data in order to obtain a reasonable forecast results.Vast knowledge is required in excavation monitoring, and difficulty in monitoringvaries with engineering specifications. So improving monitoring arrangement isnecessary for specific specifications, on-site inspections should also be taking intoaccount.