Research On Oxygen Supply Index And Oxygen Supply Technology Applicability In High Altitude Tunnel Construction

In order to realize the national "Western Development" policy and the economic strategic concept of "One Belt,One Road,Joint Construction and Prosperity",it is an important task to improve the transportation infrastructure in the western region.However,there are many plateaus in the western region,and the high-altitude areas are faced with problems such as high cold,low pressure,and low oxygen,which have brought great difficulties to the construction and operation of the project.In addition,the terrain in the western region is undulating,and a large number of tunnels need to be constructed.Therefore,the problem of oxygen supply in high-altitude tunnel construction needs to be solved urgently.Relying on some places along National Highway 318(Chengdu-Lhasa section)and Guigala Tunnel of S5 Lhasa-Zedang Expressway in Tibet,By means of data investigation,power bicycle riding test and numerical simulation,The evaluation index of personnel labor intensity in high altitude environment is analyzed and determined,The law between altitude,oxygen concentration,labor power and labor intensity is studied,and the standard of oxygen supply height and concentration in high altitude tunnel is determined.At the same time,the distribution law of oxygen concentration in high altitude tunnel is tested and studied,and the influence of different working conditions on the effect of dispersive oxygen supply and centralized oxygen supply is discussed.The main research contents and conclusions of this paper are as follows:(1)Based on the experimental data of power bicycle riding,by means of variance analysis,it is determined that heart rate,blood pressure and blood oxygen saturation can evaluate labor intensity and altitude alone,and lung ventilation can evaluate labor intensity,altitude and the interaction between labor intensity and altitude.(2)Through the oxygen supply riding test,the variation law of labor intensity of personnel under different altitude,different riding power and different oxygen concentration was obtained.Referring to the measured value of average energy metabolism rate of tunnel workers in previous studies,the riding power of riding test is related to tunnel construction intensity.Based on the average energy metabolism rate and blood oxygen saturation index required by the code,the height standard and concentration standard of oxygen supply in high altitude tunnel are determined.(3)By means of data investigation and field measurement,it is determined that the oxygen concentration in the tunnel decreases obviously with the increase of excavation length when the tunnel is not ventilated at high altitude;Under the condition of good ventilation conditions,the oxygen concentration in the tunnel has no obvious change with the increase of excavation length.(4)Based on the numerical simulation method,it is determined that the change of the wind speed of the air duct has little effect on the diffused oxygen supply effect near the secondary lining and the tunnel face..When the air duct is close to the working face,a vortex will be formed near the working face,which helps to prevent the supplied oxygen from escaping around,thus improving the effect of the diffusion type of oxygen supply in this area.In the centralized oxygen supply system,when the oxygen supply pipeline is arranged on the same side as the ventilation pipeline,and the oxygen supply pipeline is closer to the working face than the ventilation pipeline,the oxygen supply effect is better.However,the height of oxygen supply pipeline has little effect on oxygen supply effect.