Research On Dynamic Risk-warning Of Metro Tunnel During Construction By CD-Bench Cut Composite Method

In recent years,with the sustained and rapid development of China’s national economy,pace of urbanization is accelerating.As a modern urban transport force, subway construction is speeding up in major cities across the country.But China’s topography is varied and geological conditions is complex.Therefore it will have great risk in construction process.Once the accident happens, the project cost will increased or it will damage the construction machinery and will cause great casualties, the post-processing are extremely hard with tremendous negative social effects.So taking risk early warning problem of subway tunnel construction as the object of study,which encounters complicated geological conditions and a special method,based on risk warning and by means of extension theory, dynamic risk early warning research of subway tunnel construction is carried out. The feedback of risk early warning signal is timely,in order to reduce the risk accidents and improve project the management level.This research mainly includes the following four aspects:(1) Depend on CD-Bench cut composite method of Changping section of Guanhui intercity rapid railway,which is in VI level weak surrounding rock area,this paper proposes the combination of the risk analyze and construction monitoring measurement system under complex situations at risk early warning process.Risk factor is identified and risk early warning index system is established,which includes geological and supporting condition observation,vault settlement,convergence deformadon,ground settlement and building settlement as five-level indexes and the corresponding thirteen secondary indexes.This ensures systematization and scientificity of index system and can also describe alarm size quantitatively.(2) Extension theory is applied to the risk assessment,correlation function matrix is established and combination weight is calculated by improved analytic hierarchy process(AHP) and entropy weight method.Then fuzzy comprehensive evaluation theory is introduced to determine the final overall risk level.Finally, the level of risk is associated with the five-color warning system,mapping relation is formatted between them,so as to establish dynamic risk-warning model of metro tunnel during construction by CD-Bench cut composite method and achieve dynamic warning during construction.(3) Based on the above research,this paper combines with the ongoing construction of the inter city section of Changping Guanhui,try to evaluate the construction risk and make the early warning signal by using this model. As can be seen from a comprehensive risk index that warning signal is yellow,it indicates that risk level of subway tunnel under construction is grade 3, is urgent and partial collapse and sudden inrush of water mud emerges.It will havebad impact on tunnel construction, but it won’t produce big accident.The risk level of vault settlement,convergence deformadon and ground settlement are much higher,is grade 4.The risk level of vault settlement rate,convergence deformadon rate, ground settlement rate and building settlement rate are middle,is grade 3.The example responses alarm size during tunnel construction intuitively and timely.At the same time,it verifies feasibility and practicability of dynamic risk-warning model of metro tunnel during construction by CD-Bench cut composite method,and it is worth spreading in similar engineering and application.(4) Object-oriented visual programming tool Visual Basic 6.0 is adopted to complete dynamic risk-warning system of metro tunnel during construction by CD-Bench cut composite method.Thus human-computer interaction platform is established.