Study On Dynamic Behaviors Of Walking Sinking Platform For The Construction Of Shafts With Depth Over 1000 Meters

Sinking platform is the underground working stage in the construction of a shaft, whose capacities derectly determine available equipments and techniques, and are of significance to the safe and efficient execution of the well development. Along with the fast consuming of shallow resources of the earth, the mining depth of minerals extends downward gradually, and at present there have been more than 40 sets of mines with depth over 1000 meters in China. For the construction of these mines, conventional sinking platform of cable-hanging type exposes problems on leveling control and downhole arrangement, while the developing sinking platform of beam-inserted type needs massive beam nests and reduces the strength of the shaft wall, making it inappropriate to be widely promoted. Consequently, it has been an actual and urgent demand to research and develop new sinking platforms for the execution of deep shafts with depth over 1000 meters.This dissertation is supported by Changjiang Scholars and Innovative Research Team in University Program “Reliability of Large Electromechanical Equipments in Mines”(Grant No. IRT1292), where the walking sinking platform of frictional self-locking type is designed for the construction of deep shafts, and its working principle and dynamic behaviors are theoretically and experimentally studied in depth. The novel work is to provide a new underground working stage for the fast and efficient construction of shafts with depth over 1000 meters.Firstly, the study on physical design of the new sinking platform and its key patrmeters is carried out. The walking sinking platform of frictional self-locking type is designed for the construction of shafts with depth over 1000 meters, with its motion trajectory planed; Based on the friction cone model, research on working principle and key parameters about the self-locking and unlocking phenomenon are accomplished; Referring to the theory of layered elastic sytem and Hankel integral transformation, the stress distribution on the concret shaft wall under the action of the walking sinking platform is studied and the the design formulas is proposed for the imposed friction force intensity; The prototype test system is assembled to conduct functional experiments, which verify the feasibility of the designing scheme of the walking sinking platform of frictional self-locking type.Secondly, the study on dynamic features of the circle girder structure is carried out based on one-dimensional(1D) higher-order theory. The recognition algorithm of sectional deformation patterns based on free vibration modals of plate/shell elements is proposed to identify sectional deformation patterns of thin-walled rectangular section; Involved with the modal supoposition method, Kirchhoff hypothesis, Hamilton principle and Lagrange C0 interpolation function, the finite element model of the curved segment of the circle girder is built; Combining the lumped mass model of the flange end plate, the 1D higher-order model of the circle girder is established to study its dynamic behaviors; The modal test system of the circle girder is assembled to verify the practicability of its 1D higher-order theory using the test method.Next, the study on dynamic features of the main girder structure is carried out considering the constraints of semi-rigid connections. Sectional deformation patterns for thin-walled H section are identified to formulate the 1D higher-order model of the straight beam of the main girder structure; Component-based 1D modeling approach of the semi-rigid connection is proposed where the joint and connecting plates are respectively modeled adopting Bjerhammar pseudo-inverse matrix and the 1D higher-order theory; Using the energy principle, the 1D higher-order model of the main girder structure under semi-rigid constrains is established; Its dynamic features are studied with theoretical and experimental methods, and the practicability of the dynamic model is validated.Finally, the study on modeling approach and transient dynamic behaviors of the walking sinking platform in the steping process is carried out. The modeling approach of linearly superimposing symmetric and anti-symmetric half models of the bearing girder system to approximate arbitrary loading conditions of the sinking platform is proposed considering its structural symmetry; Referring to 1D higher-order models of thin-walled members and semi-rigid connections, the motion equations are deduced for the two half models; The force boundary formulation based on symmetry is defined with vector decomposition method, and the 1D higher-order model of the sinking platform is established consequently; The prototype test system of the sinking platform is assembled to study its transient dynamic behaviors in the stepping process, and to validate the practicability of the theoretical model.