高海拔隧道施工氧含量变化及供氧方法

Oxygen Content Change and Oxygen Supply Method in High Altitude Tunnel Construction

针对高海拔隧道低压缺氧威胁施工安全的问题,基于氧气质量守恒和等效气管氧分压两种方法分析了高海拔隧道施工供氧标准;并在海拔4 232 m的雀儿山隧道开展洞口与掌子面温度、气压和氧含量长期监测。结果表明:实测洞口氧气密度比理论分析低4. 93%;而实测气管氧分压比理论分析低0. 6%,等效气管氧分压方法更适用于高海拔缺氧程度预测。洞口与掌子面温度和大气压力呈夏季高、冬季低的季节性波动。隧道掘进1 500 m以后,在保证良好通风条件下,掌子面比洞口气管气氧分压平均低0. 46 k Pa;随着推进距离继续增大,气管氧分压降低不明显。现场测试发现弥散式供氧方法能够有效增加施工区域的氧气含量,但由于供氧需求量大,施工建议采取弥散式供氧、个人携氧与移动式吸氧车供氧相结合的方式,保障隧道施工人员的氧气需求。

Aiming at the construction risk of high-altitude tunnel with low-pressure and oxygen-deficient,the oxygen supply standard for high-altitude tunnel construction was analyzed based on oxygen mass conservation and equivalent tracheal oxygen partial pressure,and long-term monitoring of temperature,pressure and oxygen content were carried out at the Queershan tunnel with an altitude of 4 232 m.The results show that the actual measured oxygen density is 4.93%lower than the theoretical analysis,while the actual measured oxygen partial pressure of the trachea is 0.6%lower than the theoretical analysis.The equivalent tracheal oxygen partial pressure method is more suitable for the prediction of high altitude hypoxia.The temperature and atmospheric pressure of the tunnel portal and the tunnel face are seasonally high in summer and low in winter.After tunneling for 1 500 m,under the condition of ensuring good ventilation,the tracheal oxygen partial pressure of the tunnel face is 0.46 kPa lower than the tunnel portal.The distance continues to increase,and the tracheal oxygen partial pressure is not significantly reduced.On-site test found that the diffuse oxygen supply method can effectively increase the oxygen content in the construction area,but the oxygen demand is large.The construction proposal adopts a combination of diffused oxygen supply,personal oxygen carrying and mobile oxygen pump to ensure the oxygen demand of construction workers.