Study And Optimization On Deformation In Chengdu Subway Station Foundation Pit

In subways'construction, a question in geotechnical engineering is the design and the construction of the deep foundation pit, accommodating the demand of econimic and safety.As a kind of supporting type with large application range,row piles with inner support get more and more approval these years.Chengdu new east station No.7 subway pit has a depthe of 36m.It is crossed by the No.7 subway station,and has a big Excavation range.The field has a unfavorable geology.The pit get through several stratum,including miscellaneous fill,clay,silt, Chengdu clay and medium weathering mudstone.The Chengdu-Kunming railway which is in operation crosses the filed near the pit,so it has a limit to the settlement caused by the pit construction.The scale of the subway station pit is rare in Chengdu geotechnical engineering.This thesis analyzes the deformation and stress of the row piles with inner support system, according to the monitoring resules and the Plaxis simulation.It shows the regularity of the soil and piles'displacement, steel stress, earth pressure and the stress of the inner support in important construction steps.And get more specific Regularity with the Plaxis simulation and calculation.lt optimizes the supporting system by changing the parameters of the piles'diameter and spacing or the supports'pre-stress.CoMPared with others supporting systems's features,it puts forward a new supporting scheme of the bolt-shotcrete.It meets the demands of displacement,overcoming some disadvantages of the original design,as the difficult of pre-lording the supports,the hinder to the construction space, the stacking of the steel pipes and temperature effect to the supports'stress.