长隧道独头掘进压入式施工通风数值模拟

在长隧道施工中,通风问题往往成为影响其爆破周期的重要因素。基于计算流体力学理论,对压入式通风气流运动采用三维紊态RNGk-ε湍流模型进行三维数值模拟。通过对某公路隧道模型的计算分析,得到了施工期隧道内流场和浓度场随时间在洞内的分布变化规律。研究表明,爆破后的有害气团在隧道内的运动可总结为＂移动＂和＂扩散＂的过程,移动的结果使有害气团从爆破掌子面向洞口排出,扩散的结果使有害气团在移动的过程中逐渐扩大范围并稀释。另外,根据CO的进入浓度和允许浓度对工作人员的进洞时间进行了研究。

Simulation of Values of Forced Ventilation for Construction of Long Tunnel Excavated from a Single End

In the long-tunnel excavation,ventilation usually becomes one important factor affecting the blasting-operation period.Based on theory of computational hydromechanics,the forded ventilation airflow movement is simulated in 3D values by applying the RNG k-εturbulent-flow model of 3D turbulent pattern.Through computation and analysis on one highway tunnel,law of distribution and variation of airflow field and concentration field with time change in tunnel during construction period is obtained.The study shows that movement of the harmful air mass in tunnel after blasting operation includes Shifting and Diffusing processes.The shifting movement results in the harmful mass being discharged from the blasting front to the tunnel portal.The diffusing movement results in the harmful mass enlarging in scope and being diluted during the shifting process.In addition,time for entering into tunnel is studied in accordance with CO concentration and its allowable concentration.