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• Using spring sets and built-in water bag to simulate aquifer; embedding guide lift hose and branch conduit as prefabricated water-conducting channel; Using "cutting-support-blocking" integrated device to simulate key equipment of ARFMP. • The floor failure characteristics of ARFMP are obtained and its effectiveness in preventing water inrush is verified. • An engineering treatment scheme combining ARFMP and floor regional control is proposed, and reliability of the model test results is verified after field application. The coal mining in North China is seriously threatened by floor water inrush from the Ordovician limestone, so it is particularly important to explore failure characteristics. Automatic roadway formation mining without pillars (ARFMP) provides an effective method for reducing floor failure. To explore failure characteristics above confined water, a two-dimensional model test system is built up. Such a system can be applied to compare the difference of floor failure between ARFMP above confined water and traditional retained coal pillar mining, and to intuitively analyze the lifting law of confined water under dynamic disturbance. The core features of this system include the customized spring sets and water bag adopted as materials to simulate the floor aquifer, the guide lift hose and branch conduit used as the lifting channel of confined water, and the flow rate and cumulative volume monitored in real time. The customized "cutting-support-blocking" integrated device is the key equipment to simulate ARFMP. Then, the model test is conducted on a typical engineering case. By comparing stress, displacement, and water inrush characteristics of floor in different areas, failure characteristics of the roof-cutting side, the middle of working face, the collapse column area, and the coal pillar side were obtained, and it was clarified that ARFMP can effectively prevent floor water inrush. According to the results of model test, a comprehensive treatment scheme combining ARFMP with the floor regional control is proposed to ensure the safe mining of working face. [ABSTRACT FROM AUTHOR]

• Fastener stiffness increases with service time in high-speed railway. • Fastener stiffness is sensitive to low temperature and high frequency. • The temperature- and frequency-dependent characteristics of fastener affect rail vibration and decay rate. • PUEP composed of PTMG1000 and NDI has wide temperature range stiffness characteristics. The operation line of China's high-speed railway has exceeded 40,000 km. The performance decay and even failure to some fastener systems could be caused by complex terrain (mountain and plain), variable environment (−50 °C to 50 °C), high speed (300–350 km/h) and high frequency (500–700 Hz). Herein, the W300-1 fastener is taken as the research object to test and conclude the service performance and online track modal recognition. The comprehensive test system is used to obtain the dynamic characteristics of fasteners with the preload under the temperature-dependent (−70 °C to 50 °C) and frequency-dependent (10–1250 Hz) coupling conditions. It is found that the elastic pad stiffness in fastener system is sensitive to the low temperature and high frequency. In order to study the influences of temperature- and frequency-dependent dynamic characteristics of fasteners on track system, the dynamics analysis model of track system is constructed. The rail receptance curve under constant working condition is verified by the online track recognition. Simultaneously, the dynamic characteristics of the rail under constant working condition (4 Hz) and temperature-/frequency-dependent conditions are contrastively analyzed. The results indicate that the frequency-dependent characteristics of elastic pad enable the first-order modal frequency to shift toward a higher frequency, accompanied by the amplitude increase. The temperature-dependent characteristics of elastic pad make the medium- and high-frequency decay rate of rail wider but smaller. Due to the adverse effects of above conclusions, the polymer materials of elastic pad in fastener system are modified and optimized from two perspectives of polyol type and crosslinking agent type. Based on the standard requirements of Q/CR7-2014, it is certain that the dynamic performances of PUEP samples prepared by PTMG1000 and NDI together can meet the requirements of safety and stability of high-speed railway. [ABSTRACT FROM AUTHOR]