Study On The Construction Technology Of The Steel Cofferdam In Complicated Hydro-Geological Conditions

Steel cofferdam is a temporary structure of bridge foundation construction,which has been widely used.The purpose of steel cofferdam is mainly cap and foundation construction in cofferdam,which can block the water and the soil into the Steel cofferdam and not affect construction,When after the foundation and the pier constructed above the water level and can be removed.Among them,the double wall steel cofferdam is a kind of water retaining cofferdam used in the deep water construction of bridge foundation,which is widely used at present.In this paper,one bridge that across the Yangtze River be used to study.Firstly,it introduced the construction technology of cofferdam in deep foundation of the bridge in detail.According to the actual construction situation,this paper expounds the construction elements and construction technology of double wall steel cofferdam.Due to the double wall steel cofferdam belongs large temporary steel structure and constructed in deep water.Its special position and stress complex,high level of structure importance.Therefore,it is necessary to calculate the strength of the every components of the steel cofferdam in different construction stages.Based on the construction process,it divided into four calculation conditions.Cofferdam sinking and positioning,concrete bottoming,pumping,pile caps concrete placement is required to calculate the strength of the structure;cofferdam will suffer from the erosion of water When it in sinking,so it need to scour resistance calculation.When after the steel cofferdam pouring bottom concrete,it need to check the strength of subsealing concrete and anti floating.The calculation results show that the steel cofferdam can meet the requirements in each construction stage.Concrete pile cap blongs mass concrete,so deal with the construction method,especially we should carry on the special research of temperature control,by the large-scale general finite element software ANSYS,wen can analyze the temperature and stress in the concrete,and choose one reasonable temperature control measures.In this paper,it also studied that construction process of monitoring technology and risk analysis.When steel cofferdam in construction and use can not completely consistent with the state of the design.Therefore,we should real-time monitoring all parameters of the of steel cofferdam.Because of the special construction environment,a lot of uncertain factors directly affects the construction safety and quality,by choosing a reasonable monitoring means and accurate analysis of risks existing in the construction,and take some corresponding measures,in order to ensure the safety of steel cofferdam in construction process.