Research Of The Risk And Control Of Water Burst In The Deep Foundation Construction Pit Of Subway Stations In Wuhan

In recent years,the urban subway construction in Wuhan has entered the golden age of rapid development.At present,the city has maked an urban panning of 26 metro lines,with 11 lines under construction and 5 lines which have builded.Most of the subway lines are through the high populated areas,transportation hub areas,Complex formation areas,etc.At the same time,the production safety accidents happen frequently,especially the water burst in deep foundation pit water accident.Without timely effective control measures,the accidents will bring serious consequences which maybe leading to collapse of foundation pit in severe cases,and the collapse will result to the damage of surrounding structures,casualties and other secondary disasters.This paper takes risk analysis and control of water burst in the deep foundation pit of Wuhan subway during the process of excavation ai the object of study,which has crucial instructive meaning.First,the risk analyzes method of dynamic fault tree has its unique advantage of handling the event with obvious time series over the traditional risk analysis methods.So this paper introduces the theory of dynamic fault tree and builds the dynamic fault tree model taking the water burst in foundation pit of Tangjiadun subway station in Wuhan as an example.The basic event probability of dynamic fault tree is uncertain.Bayesian,Markov chains,and other methods are unable to analyzes the dynamic fault tree quickly and efficiently,while quickly and monte carlo sampling method to calculate the dynamic fault tree,while the Monte carlo sampling method can make it.Therefore,the paper makes a simulation study about the possibility of water burst accident by citing the Monte Carlo sampling method,does deep analysis on the complexity of foundation pit water burst system and effectively analyzes the change rules of uncertain effect which top events affected by elementary events,providing a reliable basis to prevention of water burst in later period.Secondly,to effectively seek the consequences of the accident,this paper makes a comparative study on the deformation around the foundation pit uder two different state,normal excavation process and water burst state,using FLAC3 D and based on the impact model the surrounding environment affected by water burst accident and seepage theory of foundation pit.The paper also analyzes the sphere of influence of water burst combined with the actual environment around the foundation pit,and studies relative relationship between water burst and seepage field changes by GEO Studio.The study obtains the gushing water speed under the condition of water burst accident,which has important theoretical and practical significance to provide decision support to the accident emergency rescue.Thirdly,based on the analysis of the accident caused by water infiltration in deep foundation pit,aiming at the low efficiency and hysteresis of traditional monitoring and early warning of deep foundation pit engineering,combined with a large number of monitoring data,this paper uses the ARMA model to analyze the correlation of sequence data.At the same time,this paper summarizes the characteristics of gushing water accident in Wuhan area which is based on the geological condition of the backfill,and analyzes the deformation monitoring data of the gushing water accident before and after in the deep foundation pit of Wuhan Metro by using ARMA model.And this paper tries to predict and warn the risk of deep foundation pit gushing by studying the pattern fluctuation of the ARMA model,and analyzes the data of different monitoring points comprehensively to achieve the purpose of fully sensing the risk of water gushing.Compared with the conventional monitoring and traditional data analysis to achieve the prediction and early warning of the risk of water gushing,the optimized monitoring and early warning is more efficient and sensitive.Finally,this paper takes the optimization of emergency rescue as the main line,analyzes and summarizes the characteristics of emergency of deep foundation pit gushing,and includes short board of water gushing emergency in the space,time,material,manpower,cost,etc.Constructing the network diagram of the emergency response process of the deep foundation pit water gushing in accordance with the present situation of our country,and on the basis of the above,the paper constructs an emergency constraint model of water gushing accident based on multiple objective,which can effectively solve the constraint problem in the emergency process.In addition,the importance of material in the process of water gushing emergency is studied.By constructing the ISM model of emergency materials,it is determined that the hierarchical relationship of material and its relative importance in the emergency system of water gushing,and it effectively guide the storage and distribution of emergency supplies.Furthermore,the paper constructs the emergency dispatch network of water gushing,through the construction of the emergency dispatch network of water gushing emergency materials,and to optimize it,so as to improve the efficiency of emergency rescue of deep foundation pit.