| Shield tunneling machine (STM) is a full-face tunneling machine dedicated to tunnel construction. STM can perform excavation, supporting, lining, slaging and other procedures to facilitate the automation and factorization of tunnel construction. The designed tunnel axis is the ideal trajectory by taking into account the requirements of train safety, geological conditions and surface structures. Attitude control technology is the key technology to keep the shield machine move forward in the right attitude, reduce the deviation between of the shield trajectory and the designed tunnel axis, and improve the quality and efficiency of lining construction.In the thesis, the workspace and minimum turning radius of shield machine were analyzed under different structural parameter conditions. Then, mathematic relationship between the workspace of thrust mechanism and its structural parameters was revealed The method of determining key structural parameters of thrust mechanism was proposed based on workspace analysis of parallel mechanism. This work provides an effective method of choosing the right structural parameters of shield thrust mechanism for specific tunnel construction. With this method, the structural parameters of the STM with outer diameter6.34m was designed in order to make the shield machine meet the requirement of the specific tunnel construction-the minimum radius of tunnel axis is175m and the maximum fitting error is less than10mm. By analyzing the variation of the attitude of STM when it excavates along straight curve, circular curve and easement curve, the method of performing precise calculation of the target attitude of shield machine and target motion features of thrust cylinders was proposed according to the parametric equation of designed tunnel axis. With this method, the existing attitude control system based on displacement control of thrust cylinders, which can only be used on the straight tunnel construction before, can be used on the shield machine when it excavates along the circular curve and easement curve now. Based on mathematical modeling of thrust motion dynamics, electro-hydraulic control system, and the load exerted on shield machine by stratum, another shield machine attitude automatic control system with the goal of tracking the designed tunnel axis was proposed. As the performance of this control system is independent of the recognition and prediction of stratum condition, it has strong anti-interference capability. Aimed at the position and posture control of segment, high efficiency segment erecting technology was developed based on position and speed compound control technology and the difficulties of controlling the large inertia segment erector under high moving speed condition were overcome. According to the experimental results from the2.2m segment erection test rig, the revolution speed of segment erector can reach up to4.73r/min which is3times of the highest speed (1.5r/min) of existing segment erector. More importantly, the precision of segment position was not adversely affected by the increased motion speed, and the impact torque of the segment erector using position and speed compound control was only about30%of the impact torque that in the position control system.The major contents are summarized as follows:In chapter1, the operating principle and the general development situation of shield tunneling machine in domestic and overseas were introduced. The current research status of shield thrust electro-hydraulic control technology, shield machine attitude control technology, trajectory tracking control technology, and segment erection control technology were analyzed. In the end, the research background, main content and the significance of this thesis were presented.In chapter2, the degree of freedom of shield machine was analyzed, and the constraint equations for the workspace analysis of shield machine were constructed. The workspaces of common and passive-hinged shield machines with different structural parameters were analyzed. The relationship between the workspace and the minimum turning radius of shield machine was uncovered. Based on the analysis of the workspace of shield machine, an effective method for determining the key parameters of shield machine was promoted. This method simultaneously considered multiple factors including the minimum curvature radius of designed tunnel axis, the fitting error of tunnel axis, and diameter of hydraulic cylinder distribution circle. Finally, this method was employed to determine the parameters for a certain shield machine used for the construction of a specific tunnel.In chapter3, the parametric equation of typical tunnel axis was established. A calculation model was developed for determining the displacement of each hydraulic cylinder during the shield machine excavates along typical tunnel axis. The speed and acceleration of each of thrust cylinder piston, as well as the angular velocity and acceleration of each hydraulic cylinder were analyzed when shield machine moved forward along straight curve, circular curve and easement curve. The research provided target parameters for the attitude control system of shield machine. In chapter4, the attitude adjustment motion of shield machines were analyzed, and kinetic equations for the adjustment motion were established. Based on mathematical modeling of electro-hydraulic control system of shield thrust system and analyzing the load exerting on shield machine, we promoted two kinds of shield machine attitude automatic control systems which were suitable for different geological conditions. The performances of the proposed shield machine attitude automatic control systems were evaluated by simulation and experiments carried out on a shield machine test rig.In chapter5, the working principles of segment erection were analyzed, and a highly efficient segment erection technology with high erection precision and erection efficiency was promoted. The mathematical model of the electro-hydraulic control system of segment erector was established and four control systems was designed to meet the requirements of high-speed and high-precision segment erection. In order to verify the validity of each control system and evaluate their performances, experiments of segment erection were carried out on a test rig.In chapter6, the major research work and results of the thesis were summarized.In addition, suggestions for further study on the subject were provided. |
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