川藏铁路高地温隧道降温技术及效果分析

Cooling Technology and Effect Analysis for High Geothermal Tunnel on Sichuan-Tibet Railway

为改善位于青藏高原的高地温深埋特长隧道工作环境,防止高温热害发生,以川藏铁路桑珠岭隧道为工程依托,分析高地温的特征及其对工程的影响;考虑洞周围岩和掌子面的散热,以及人、机和炮碴释热等因素,给出通风降温时需风量和通风管数量的理论计算公式;在此基础上进一步提出综合立体降温技术,并分析降温效果。结果表明:桑珠岭隧道是典型的干热岩高地温隧道,通过地温测试数据反演得出隧道地温梯度为5.5℃·(100m)^-1,隧道埋深越大地温越高;理论计算得到隧道工作面需风量为324.10m3·s^-1,其中洞周岩壁散热需风量占86.21%,其余13.79%风量主要为人、机和炮碴释热所需;仅采用通风措施,持续通风3h后,洞周壁面温度降幅可达47%,但最低仍为32℃;再采用冷水喷洒和冰墙等辅助降温措施,可消减7.9×10^7kJ的热量。因此,对于高地温隧道,可采用以通风为主,结合喷洒冷水、设置冰墙等的综合立体降温技术。

In order to improve the working environment and prevent high temperature thermal damage in the extra-long and deep-buried tunnel with high ground temperature located on the Qinghai-Tibet Plateau, based on the Sangzhuling Tunnel of Sichuan-Tibet Railway, the high geothermal characteristics and the influence on engineering were analyzed. Considering such factors as the heat dissipation of both the surrounding rock and tunnel face as well as the heat release of human, machine and ballast, the theoretical formulas for calculating the air demand and the number of ventilation pipes in ventilation cooling were given . On this basis, an integrated three-dimensional cooling technology was put forward and the cooling effect was analyzed. Results show that the Sangzhuling Tunnel is a typical dry-hot rock and high geothermal tunnel. The inversion of geothermal test data shows that the geothermal gradient of the tunnel is 5.5 ℃·(100 m)^-1 , and the deeper the tunnel is buried, the higher the ground temperature is. Theoretical calculation shows that the air demand for tunnel working face is 324.10 m 3·s^-1 , in which, 86.21% is for the heat dissipation of surrounding rock, and the remaining 13.79% is mainly for the heat release of human, machine and ballast. Only with ventilation measures, after 3 hours of continuous ventilation, the wall temperature around the tunnel decreases by 47%, but the lowest temperature is still 32 ℃. 7.9×10 7 kJ heat can be reduced by auxiliary cooling measures, such as cold water spraying and ice wall. Therefore, for high geothermal tunnels, an integrated three-dimensional cooling technology can be adopted, which is ventilation mainly, combined with spraying cold water and setting up ice wall.