| Focusing on the safety problem of shield tunnel construction,aiming at the problems of information perception of stratigraphic disaster source in front of shield tunnel,dynamic construction safety evaluation and critical safety distance identification of excavation into the nearby area,author first puts forward the applicable method of three-dimensional seismic wave in shield tunnel,and carries out field test exploration and outdoor comparative test analysis.By modifying the shield body,developing existing information perception technology,establishing the matching relationship between the geological conditions and gas occurrence,the linkage of sensing information of forward stratigraphic disaster source is realized.Then,the perception information index is quantified,and the dynamic safety evaluation method of shield tunnel construction is established to carry out the numerical calculation of the critical safe distance of the risk disaster source of shield tunnel,determining the engineering field application principle and technical scheme combined with the technical basis and engineering practice,so as to ensure the safe construction of shield tunnel.(1)The three-dimensional seismic reflection principle is used for geological information perception.The feasibility of three-dimensional seismic reflection method for geological information perception in shield tunnel is determined by carrying out three-dimensional seismic tomography shield tunnel field test,and the interference identification experiment of three-dimensional seismic wave signal segment is designed.The influence of segment factors on the geological information imaging in the application of three-dimensional seismic method in shield tunnel perception is studied through outdoor comparative experiments(2)Through the transformation of shield machine body and the development of geological information sensing equipment source trigger system,the shield machine is equipped with geological information sensing equipment,and the shield tunnel geological information sensing technology method is proposed;the shield machine is equipped with composite gas sensing equipment system,and the composite gas separation monitoring in front of the shield tunnel is realized,forming composite gas information sensing technology for shield tunnel.By studying the matching relationship between existing gas and geological conditions,the geological conditions corresponding to the type and concentration of target gas are analyzed,and the fusion application rules of gas information and geological information are established to realize the geology-gas information perception in front of shield tunnel(3)Based on the perception information obtained in the process of shield tunnel construction,a dynamic safety evaluation method for shield tunnel construction is established,which not only makes a comprehensive safety evaluation for the perception area in front of the shield tunnel,but also evaluates the main risk sources separately.It can reflect the overall risk level of the tunnel construction and the induced impact of various disasters at all times,and provide the basis for the decision-making of shield tunnel construction.(4)Based on the geological information and gas information perception of the front stratum and the dynamic safety evaluation of shield tunnel construction,aiming at the geological risk disaster sources such as karst cave and fault fracture zone which may induce water inrush in the process of shield tunneling,using numerical simulation and linear regression analysis and other means,the author studies various factors and their influence degree that may induce water inrush in the process of shield tunneling,and deduces the critical safe distance identification formula of water inrush disaster source in shield tunnel. |
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