Research On Oxygen Supply Technology For Tunnel During Construction At The High Altitude Based On Alveolar Oxygen Tension

With Chinese government putting forward a series of policies for the benefit of the western region, such as "western development", "The Belt and Road", China western area has ushered in unprecedented development opportunities of infrastructure construction. Water conservancy construction projects, transportation infrastructure of railway and highway and other key field are being carried out in full swing. The infrastructure construction of the western provinces, involves a total of 12 provinces, whose area is about 6850000km2 and the Qinghai Tibet plateau area is about 2570000km2 accounting for 37.5%. The western infrastructure construction activities are inevitable to carry out in high altitude area, among them, the hypoxia problem during construction is a seriously problem restricting the building of extra-long tunnel at high altitude needing to be solved urgely.The thesis is based on in the construction of Queershan tunnel, the elevation of which is the highest among the extra-long highway tunnels in the world. The research firstly established the alveolar oxygen partial pressure, an important physiological indicators of oxygen lack in body, as the foundation of the whole study. Then, the hypoxia condition evaluation method during tunnel construction, the control standard of oxygen concentration, the anoxic condition of workers in tunnel, the law of hypoxia, the comprehensive oxygen supply program of tunnel were discussed and reasearched. And the main work and conclusions of the study are as follows:(1) Through the investigation and research on the mechanism of the body oxygen circulation system, the hypoxic classification applicable in tunnel construction in high altitude was concluded. And environment evaluation methods as well as oxygen concentration standard was put forwaded combined with graded hypoxia which were applied in the supporting project.(2) According to the analysis of environment and people hypoxia by the site test data, the evaluation of environmental hypoxia and the rating of oxygen level in body were done. And the correctness of evaluation method for the high altitude tunnel construction hypoxia was verified, indicating the importance of oxygen supplyment during high altitude tunnel construction process.(3) The numerical simulation for the flow field of Queershan tunnel under the condition of ventilation was completed, the distribution of wind speed of the outflow from the wind p(?)pe and the distance between wind pipe outlet and tunnel working face was discussed. The suitable distance between tunnel wind pipe and tunnel face and the importance of wind speed of outflow from the wind pipe was proved, and the key hypoxia region was obtained.(4) The way of oxygen supply for the tunnel were compared by the numerical simulation. The numerical simulation results showed that the centralized oxygen supply for high altitude oxygen supply in tunnel is not feasible, the diffusion type of oxygen supply at the tunnel face has the advantages of less oxygen consumption, beteer oxygen environment. Finally the recommendations for oxygen supply during high-altitude tunnel construction was proposed:firstly, the area near the construction bench using the diffusion type of oxygen supply system and other regions using mobile car as oxygen bar or portable oxygen bottles to provide oxygen inside the tunnel, secondly, it is beteer to adopt indoor dispersion oxygen supply scheme at the bunkhouse and equip the hyperbaric oxygen chamber at the medical room to guarantee the construction personnel security outside the tunnel.