Optimization Research Of Ladder Track And Its CRC Foundation Based On An Improved Ant Colony Algorithm

In recent years, subway vibration problem has become increasingly severe as China’s rapid development of subway construction. Vibration induced by the subway train will affect not only the normal use of precision instruments, but also the normal life of residents along the subway lines. Ladder track, as a new vibration-reduced track, has solved some above problems, but there are still many issues to be analyzed.In view of this, laying type of sleeper-pads, length of ladder track, vertical stiffness of fasteners and equivalent vertical stiffness of sleeper-pads were analyzed. We mainly focused on the relationship between the vibration-reduced effect and the displacement of rail. In addition, we developed the CRC foundation which expands the damping capabilities of ladder track used in urban subway.The main contents are as follows:(1) By studying different ant colony optimization algorithms, a single-objective "foraging-homing" mechanism continuous domain colony algorithm (SO-FHACO) was proposed. And through the functional tests, SO-FHACO shows great abilities in global search, premature convergence and slow convergence. Then, multi-objective "foraging-homing" mechanism continuous domain colony algorithm (MO-FHACO) was obtained based on the Pareto principle by SO-FHACO.(2) The laboratory test of ladder track was carried out to study the dynamical characteristics of ladder track by different laying types of sleeper-pads. The results show that, additional sleeper-pads should be set at the end of ladder track for better ability of controlling vibration.(3) Vibration modes and corresponding natural frequencies of3.65/6.15/8.65m ladder track were obtained by the numerical modal analysis. Through time history analysis, spectrum analysis, transfer rate analysis and transmission loss analysis, we think6.15m ladder track has better damping properties.(4) FHACO was grafted onto Ls-Dyna dynamic finite element software. Matlab was employed to exchange the data between FHACO and commercial software Ls-Dyna. Thus, software FHACO&Ls-Dyna was developed. Using FHACO&Ls-Dyna, vertical stiffness of fasteners and equivalent vertical stiffness of sleeper-pads were optimized considering the balance of damping effect and train operation safety. Then, the parameters of CRC foundation for improving damping abilities of ladder track were optimized.