特大型圆筒式尾水调压室穹顶施工通风技术

施工通风是影响地下洞室开挖施工安全和设备效率的重要因素。白鹤滩水电站特大型圆筒式尾水调压室规模大,埋深深,无通风竖井,穹顶施工通风十分困难。为确定穹顶施工通风关键因素,制定针对性的通风方案,采用流体数值软件构建了地下洞室三维非稳态湍流模型,分析了压入、压出和混合式通风的特点,提出了一套适用于穹顶施工期的高效循环置换通风技术;研究了穹顶开挖爆破污染物时空分布特点和逸散规律,并进行了现场污染物测试。数值计算和测试结果证明:洞室群内气流组织顺畅,污染物能及时排至排风洞内,通风10 min后污染物浓度可达到规范要求,循环置换通风技术高效可行。

Huge Cylindrical Tailrace Surge Chamber Dome Construction Ventilation Technology

Construction ventilation problem is an important factor, which influences construction safety and equipments efficiency. The cylindrical tailrace surge chamber of Baihetan hydropower station is huge, deep buried and have no ventilation well, the dome construction ventilation problem is difficult. In order to determine the key factor of dome construction ventilation and formulate targeted ventilation plan, this paper used fluid numerical calculation software, established three dimensional unsteady turbulent caverns model, analyzed the characteristics of press-in, press-out and hybrid ventilation, put forward an efficient cycle replacement ventilation technology which is suitable for dome construction period. Moreover, it studied pollutants distribution characteristic and loss law of tailrace surge chamber dome excavation blasting, and carried out pollutant concentration field test. Numerical calculation and test results show that the air distribution of caverns is smooth, pollutants can discharge into dedicated exhaust tunnel timely. After blasting ventilating 10 min, it can meet national standards, and the cycle replacement ventilation technology is efficient and feasible.