Lubrication and heat transfer control are two significant functions of mold fluxes. In order to coordinate the contradiction between lubrication and heat transfer, the effects of BaO and Li2O on basic characteristics of CaO-SiO2 based mold fluxes were studied by hemispherical melting temperature instrument, rotating cylinder method, X-ray diffractometer (XRD) in present study. The results show that the melting temperature and viscosity at 1300°C all represent a downward trend with BaO and Li2O enhancement at different basicity, and the break temperature decrease with BaO addition while decrease and then increase with Li2O addition, which illustrates that Li2O content should be no more than 0.8 wt% for the purpose of lubrication. Meanwhile, to ensure a sufficient thickness of the liquid slag film and avoid discontinuity of the liquid slag film, the BaO content is better to be 10 wt% with low melting temperature and viscosity. The main crystalline phase in the mold fluxes is cuspidine (3CaO·2SiO2·CaF2), and the crystallization ratio rises sharply when basicity increased to 1.65. For better deal with the contradiction of lubrication and heat transfer, the mold fluxes composition w(BaO) = 10 wt%, w(Li2O) = 0.8 wt%, R ≥1.65 is reasonable, which has a profound impact on high crystallization and lubricity mold fluxes.

In order to obtain the change rule of surrounding rock structure displacement and supporting structure internal force with time during the construction of the low mountain ridge tunnel, this paper relies on the Xishan Tunnel Project as the background. During tunneling, the displacement around the tunnel, the subsidence of the surface, the internal force of the steel arch and the pressure between the two layers of support are monitored dynamically. According to the above monitoring and measurement data, and the monitoring data analysis and nonlinear regression fitting, the predicted trend curve is obtained, the displacement change rules and characteristics of various surrounding rocks of the tunnel are obtained, to ensure the construction safety and stability requirements of supporting structure, and to provide a reasonable opportunity for the construction of secondary lining.