Research On Time-space Effect Evolution Characteristic And Excavating&Supporting Structure Optimization Of Deep Pit Of Subway Station

Introduction of the author:Yuanping，female，was born in June，1973，whose tutorwas Professor Xuqiang. She graduated from Chengdu University of Technology inArchitecture and Civil Engineering major and was granted the Master Degree inJune，2013.The project of deep foundation pit for subway station is very comprehensive andgreatly risky. It must be attracted vital attention to avoid any engineering accident. Itis a key issue that how to control the soil deformation when processing the deepfoundation pit excavation. In the research field of deep foundation pit, conventionalstrength control theory is more mature than the deformation theory aboutspatial-temporal effect and reasonable control. There are many gaps and deficienciesin the area of the latter research topic.Relying on the project of deep foundation pit at Yangxi2^ndring Road Station ofChengdu Metro Line2#, based on the foundation pit deformation monitoring data, asystemic integrative research method is present, combined with the numericalsimulation as a means to analyze universal law qualitatively. With the existing designof retaining structure, the time and space effect of wall deformation, has beenanalyzed systematically and thoroughly. The deformation law of each pit section issummarized during the excavation phase. The validity of the existing retainingstructures is verified. Finally, the corresponding way about support timing andmeasure strength has been proposed. Main contents and conclusions as follows:（1）Carried on an explaination for Yangxi2^ndring Road station deep foundationpit engineering of Chengdu subway, including the geology environment condition, the foundation pit engineering design, the foundation pit engineering construction and thefoundation pit engineering monitor etc.（2）Carried on analysis to the monitor data of the Yangxi2^ndring Road stationdeep foundation pit, emphatically analysis the horizontal displacement, analysisshows: Stick out angles、intermediate place of the long side and near the prominentplace have large horizontal displacement should pay special attention to thestrengthen retaining and deformation monitoring.As the largest horizontaldisplacement during the monitoring period, the foundation pit long sidemidpoint’s（215#） is5.04mm.（3）On the spatial distribution, pit adjacent strata stress-strain analysis showedthat, the plastic area mainly appear in the bottom of the pile and the weakness sandlayer and other parts; In the time distribution, the second and third excavation is themain period of deformation during the entire pit excavation system, in this time, theplastic area of foundation pit minimum principal stress is obvious differentiation,some local place even appear tensile stress.Depending on the monitoring results andnumerical calculation, this thesis analyzes the space effect of the transform offoundation pit, the result is that the space effect was very obvious in the foundation pitengineering.