敞开式TBM隧洞通风系统布置及除尘效果研究

Study on layout of ventilation system for open-type TBM Tunneling and its dust removal effect

为了研究敞开式TBM施工通风布置方案并提高通风除尘效果,以引汉济渭秦岭输水隧洞TBM工程为依托,利用数值计算软件FLUENT对不同送风风速,不同送风管位置下的洞内除尘效果进行了计算研究,并将模拟计算与现场实测结果对比,优化了施工通风系统布置。研究结果表明:粉尘质量浓度从拱架作业区至主控室逐渐增大,随着到掌子面的距离增加,粉尘浓度降低;送风风速越大,洞内粉尘危险浓度区域越广,敞开式TBM内人员集中作业区的粉尘质量浓度越小;送风管距掌子面越远,人员集中作业区粉尘浓度越高,送风管布置在距掌子面15 m时,作业区粉尘浓度最低。优化方案将送风风管和除尘风管分别布置在距掌子面15 m和25 m,送风风速和除尘风速为40 m/s和15 m/s时,作业区粉尘质量浓度可控制在2 mg/m^3规范限值以下。

In order to study the layout of the ventilation system for open-type TBM tunneling and enhance its dust removal effect, the in-tunnel dust removal effects under the different air blowing-in velocities and different positions of blast-pipe are calculated and studied herein with the numerical calculation software—FLUENT on the basis of the TBM construction of Qinling Water Conveyance Tunnel for Hanjiang River to Weihe River Water Transfer Project, and then the result from the simulative calculation is compared with that from the in-situ actual measured one;from which the layout of the construction ventilation system is optimized. The study result shows that the dust mass concentration is gradually increased from the arch centering working area to the main control room, while the dust concentration is decreased along with the increase of the distance to the tunnel excavation working face. The larger the air blowing-in velocity is, the wider the in-tunnel area with dangerous dust concentration is to be, while the smaller the dust mass concentration in the personnel concentration area of the open-type TBM is to be as well. The farther the distance of the blast-pipe to the tunnel excavation working face is, the higher the dust mass concentration in the personnel concentration area is to be, and then the dust concentration in the tunnel excavation working area is the lowest when the distance from the position of blast-in pipe to the working face is 15 m. In the optimized scheme, when both the blast-in pipe and the dust removal duct are arranged with the distances of 15 m and 25 m to the working face with the air blowing-in velocity and dust removal speed of 40 m/s and 15 m/s respectively, the dust mass concentration in the working area can be controlled to a range below the specified limit of 2 mg/m^3.