公路隧道互补结合竖井送排的改进型混合通风方式研究

针对特长公路隧道常规分段纵向式通风系统运营费用昂贵的问题，提出采用双洞互补与竖井送排相结合的改进型混合通风方式。在理论分析的前提下给出换气横通道与竖井的合理结合方案，详细推导适用于超出常规双洞互补通风方式限制长度的隧道的改进型混合通风方式计算方法；通过比较传统分段通风方式和改进型混合通风方式的交通风与隧道结构利用效率，对改进型混合通风方案的经济效益进行工程实例分析。结果表明：改进型混合通风方式与常规分段纵向式通风方式相比，前者有效地提高了交通风的利用率，降低了由于交通风太过富余而对隧道通风产生的不利影响，同时减少了资源的浪费；在最不利的行车阻滞工况下，改进型混合通风方式需要通过竖井进行送排的风量之和由1 723.06 m³·s^-1降至804.62 m³·s^-1，降幅达53.3％，有效地减少了轴流风机的功率，降低了对竖井的设计要求；在隧道通风最不利工况下，射流风机的配机功率提高了84%，轴流风机配机功率降低了52.4%，虽然射流风机购置费用增加，但总配机功率仍然减少13.1%，极大地节省了运营费用；在土建方面，改进型混合通风方式增加了2个横风道，取消了部分送排联络通道，相互抵消，但竖井的规模减小，土建费用有所下降；改进型混合通风方式增加了2条排烟通道，解决了双洞互补通风方式中火灾排烟困难的问题。

Improved Mixed Ventilation Mode Combined Double-hole Complementarity with Blowing and Exhausting Shaft in Highway Tunnel

In order to address the problem of expensive operating costs of conventional segmental longitudinal ventilation systems in long highway tunnels, an improved mixed ventilation mode combined double-hole complementarity with the blowing and exhausting shaft was proposed. On the basis of theoretical analysis, a reasonable combination scheme for ventilation cross passage and shaft was provided. Furthermore, a calculation method for an improved mixed ventilation mode was derived in detail, which is applicable to tunnels beyond the limit of the conventional double-hole complementary ventilation mode. By comparing the utilization efficiency of traffic wind and tunnel structure between the traditional segmental ventilation method and the improved mixed ventilation mode, the economic benefits of the improved mixed ventilation scheme were analyzed with the help of an example. Results showed that as compared to conventional segmental longitudinal ventilation, the improved mixed ventilation can effectively improve the utilization rate of traffic wind, reduce the adverse effect of excessive traffic wind on tunnel ventilation, and reduce wastage of resources. Under the most unfavorable traffic blocking conditions, the entire air volume is sent and discharged by the improved mixed ventilation method through the shaft; a decrease from 1 723.06 m³·s^-1 to 804.62 m³·s^-1, i.e., 53.3% decrease, was recorded that effectively reduces the power of the axial flow fan, as well as the design requirements of the shaft. Under the most unfavorable conditions of tunnel ventilation, the power of the jet fan increases by 84%, while that of the axial fan reduces by 52.4%. Although the purchasing cost of the jet fan increases, the power of the total fan reduces by 13.1%, which greatly reduces the operating costs. Form the aspect of civil engineering, the improved mixed ventilation mode involves the use of two cross air ducts and canceling of a part of the connection channel for transmission and exhaust, both of which offset each other. However, as the scale of vertical shafts is reduced, the civil engineering costs are also reduced. The use of two smoke exhaust channels in the improved mixed ventilation system therefore addresses the problem of fire smoke exhaust in the dual hole complementary ventilation system.