The effectiveness of pressed-in ventilation system significantly affects the environmental condition inside the tunnel after blasting. Previous studies rarely focus on the ventilation scenario with two fans installed in series at a certain interval on the leaky ventilation ducting, which is very common for super long tunnel. The concept of the combined fan is introduced to consider the equivalent pressure rise created by the fan 1#, air leaky ducting 1 and the fan 2#. A theoretical model of long-distance air supply calculation suitable for this scenario is proposed to predict the flow rate to the working face and the fans’ actual operating parameters. The temporal-spatial gas distribution inside tunnel after blasting is predicted as well. This theoretical model is proven to be suitable for other ventilation scenarios in tunnel under construction. The accuracy of the theoretical model is verified by 4 tunnel on-site measurements data. Taking a tunnel project as illustration, this model is used to evaluate the air-supply effectiveness of the ventilation system during the construction period. With the increasing air supply length, the flow rate delivered to the working face is predicted. The maximum air supply length of fan 1# is determined under different fan’s rotating speed and air duct leakage situation. For three installation locations of fan 2#, the increased air supply length, the fans’ operating parameters and fans’ power are further compared. The rational installation location of fan 2# is given out. Under different air duct leakage situation, the temporal and spatial distributions of CO concentration inside the tunnel after blasting are predicted. The effect of air duct leakage situation on the safe re-entry time for the workers is given out. This research can provide theoretical support for engineers to evaluate the effectiveness of pressed-in ventilation system during the construction period.

中文翻译：

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施工期间压入式通风系统送风性能和 CO 稀释效应的理论预测


压入式通风系统的有效性对爆破后隧道内的环境条件有显著影响。以往的研究很少关注在漏气管道上以一定间隔串联安装两台风机的通风场景，这在超长隧道中很常见。引入组合风机的概念是为了考虑风机 1#、漏风管道 1 和风机 2# 产生的等效压力上升。提出了一种适用于此场景的长距离送风计算理论模型，用于预测流向工作面的流量和风机的实际运行参数。此外，还预测了爆破后隧道内的时空气体分布。该理论模型被证明适用于在建隧道中的其他通风场景。通过 4 条隧道现场测量数据验证了理论模型的准确性。以隧道工程为例，该模型用于评估通风系统在施工期间的供风效果。随着供气长度的增加，可以预测输送到工作面的流速。风扇 1# 的最大送风长度取决于不同风扇的转速和风道泄漏情况。对于风扇 2# 的三个安装位置，进一步比较了增加的送风长度、风扇的运行参数和风扇的功率。给出了风扇 2# 的合理安装位置。在不同风道泄漏情况下，预测爆破后隧道内部CO浓度的时空分布。给出了风道泄漏情况对工人安全重返时间的影响。 该研究可为工程师在施工期间评价压入式通风系统的有效性提供理论支持。