Research On Risk Monitoring And Controlling System Throughout Shield Tunneling Based Soil Mechanical Characteristic

With the highly development of tunnel construction in China, the shield methodare being used extensively. Although we have accumulated abundant practicalexperience for shield tunneling, the risk still exist. According to statistics, more than70%of major accidents occurred while the shield is starting from shaft or reaching toshafted. Soil destabilization and hole leakage is common causes for risk in the shieldstarting and arriving construction, which maybe bring serious problems of safety andquality such as surface subsidence, tunnel collapsing and casualties.ConstructionSafety in the phase of starting and arriving shaft had been paid muchattention by state and local government in China.In this paper, based on theoretical study, mechanics and modeling experiments,we build a dynamic risk evaluation system with analytic hierarchy process, adaptiveweight adjusting method, improved clonal selection algorithm and fuzzy mathematicstheory. And we study pre-control and emergency measures to build a remote real-timerisk monitor and control system, which has been applied to the engineering practice toavoid accidents. The major achievements in this thesis are as follows1) According to the theoretical analysis, actual triaxial test, macrostructuremodeling experiments and failure modeling experiments, the discrimination indexesof stability and risk ranking of reinforced soil has been obtained. The paper alsopresents the model of multi-index threshold value analysis and the risk identificationmodel of stable state according to the fuzzy comprehensive evaluation method. Thusthe quantitative comprehensive identification and assessment of reinforced soil in thestarting and arriving construction stage has been achieved.2) Indoor freezing tests of single pipe, single row pipe and double row pipe forthree kinds of soil were made to analyze the temperature drop law and the failuremechanisms of frozen soil. Meanwhile, the stability evaluation index and the riskranking for freezing method are established.3) This paper proposes an improved clonal selection algorithm (ICSA) inspiredby biologocal immune principles, including negative selection, clone selection, votingmechanism and so on. Considering the features of the shield construction, thisimmune model is specified to implement real-time risk identification.4) In this paper, the analysis hierarchical process based on adaptive weightadjusting is used for establishing the structure and weight system of risk assessment models at the shield starting and arriving construction stage. Meanwhile, the dynamicrisk evaluation model is initialized through case analysis and modeling experiments.5) The risk intelligent surveillance system is utilized to monitor the wholeprocess in the shield starting and arriving construction, which not onlyincludsreal-time monitoring, intelligent judgment, risk assessment, hierarchy alarmand decision making aids, but also has self-learning ability and self-mending ability.The practical engineering application proved that this system can find potential risksand make some effective risk pre-control technical measures.