| Shield tunneling machine on which mechanical, electrical, information, measurement, hydraulic and control techniques were applied has features of high efficiency, quickness, high quality and safety, which made it be the most widely used construction equipment in underground tunneling project in the world. The drive system of its cutterhead is with the features of large inertia, high power and variable load. Since the electro-hydraulic control techniques closely integrated with electronic technology, it has become the new trend of the driving mode. Based on the actual working conditions, aiming at impact load and cutterhead deadlocking, the problems of existing driving mode were analyzed, a driving system with higher reliability and higher energy efficiency was put forward, the system's dynamic performance and impact adaptability were mainly studied. The main research work is as follows:1. The development course and research status of shield technology were reviewed. The existing driving mode of cutterhead was analyzed. Variable-frequency driving mode was compared with hydraulic driving mode.2. From the perspective of load, the basic properties of rock and soil were discussed, the cutting mechanical model and the physical phenomena in cutting process were expounded. The composition of torque and its research method was described in detail. The impact load and its effect as well as the reason of cutterhead deadlocking were mainly studied. Based on the shield tool cutting experiment and the data collected from the shield site, the causes of the load's randomness and impact were verified and analyzed.3. Shield cutter drive system's structure was analyzed. The advantages and disadvantages of existing shield cutter drive hydraulic system has been studied. The design ideas of shield driven hydraulic system was proposed under the environment for load.Based on the load,a volume motor control loop of variable pump-variable motor was proposed.The combination of proportional valve and accumulator was used to control the dynamic impact loads.4. Based on fluid mechanics, the mathematical model of the cutterhead's hydraulic driving system was established. Starting at system dynamic characteristics, the effects of the parameters of the system on the system itself under heavy impact load were studied. Hydraulic impact and the calculation method of its peak were elaborated. Based on the model of hydraulic accumulator, its dynamic characteristics were analyzed.5. Based on the mathematical model established, the simulation model of cutterhead's hydraulic system was built by use of the software AMESim. The dynamic characteristics of the system and adaptability of the impact were studied by simulation. The results show that the shield rotary cutter drive hydraulic system can absorb load impact well,avoid the overflow loss effectively and recover part of the impact energy by using the proportional valve to contral accumulator. It has better energy efficiency and reliability. |
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