Mechanics Characteristic Analysis And Modeling For Load Of Shield Machine During Tunneling

Shield machine is a kind of typical equipment for tunneling, which hascharacteristics of heavy body, complex structure and high load. The load duringtunneling is a core mechanics parameter for the equipment. Mechanical modeling forthe reasonable calculation of the load is important in terms of positive equipmentdesign and load control of tunnel constructions with different geological conditions.A decoupled model of the cutterhead load is established, in which the interactionbetween the cutterhead and the soil on the excavation interface is considered. Thecoupled system between the cutterhead and the soil is considered as two correlativesubsystems. Equilibrium differential equations and boundary conditions areestablished for decoupled analysis. A constitutive model closer to the actual state ofthe soil based on the elastic-plastic yield damage theory is used. In addition, acomprehensive consideration of the contributions of the depth burial and thecutterhead topological structure to the interface load is made. Then nonlineardistributions of the normal and tangential loads on the cutterhead are presented. Thenormal and tangential stress expressions acting on the soil interface by the cutterheadare presented.Based on the decoupled model of the cutterhead load, the characteristic of totalloads is systematically analyzed. Load components on shield skin and follow-upequipment are taken into account. Then the dissertation establishes a predicting modelof total loads acting on the equipment interface. The model fully reflects theinfluences of geological parameters, operating parameters, and structural parameters.The effectiveness of the proposed model is verified by applying it to several metroengineering projects with three typical geological conditions in Tianjin, Beijing andShenzhen. According to the predicting model above, the rational analysis for theKrause empirical formulae is presented to classify various types of load impactparameters. Then the improved load formulae are provided for engineeringapplications.The inverse identification for on-site data during tunneling construction is carriedout. A new mechanical modeling method based on the combination of dimensional analysis and data mining techniques is proposed. The dimensional analysis based onthe intrinsic mechanical mechanism and data mining techniques are effectivelycombined for the identification and modeling of on-site data without a direct model.An identification and optimization model for the load and energy consumption ofshield machines can be worked out. Load variation characteristics and efficiencyoptimal ranges are discussed. The modeling method provides a new way for themechanical analysis of on-site data (experimental data) in the nonlinear,multi-parameter, multi-field coupling problems.