特长公路隧道通风竖井施工阶段稳定性分析

结合某隧道2#通风竖井施工项目,采用数值模拟的方法,分析了竖井及风道的施工对围岩衬砌稳定性的影响。研究结果表明：竖井开挖初期,衬砌压应力、壁座拉应力和位移量均随着竖井的开挖逐步增大,最大值分别为8.1 MPa、1.03 MPa和2.62 mm。开挖到第五步和第六步时对衬砌的应力和位移影响最为不利,应采取相应的保护措施。风道开挖后拱底上抬、拱顶下沉,拱底衬砌最大位移量为3.2 mm,临近竖井部位衬砌拉应力值达到3.76 MPa,可能对初期衬砌造成局部破坏。竖井和风道连接部位衬砌和围岩均出现拉应力集中,最大拉应力值分别达到3.8 MPa和1.6 MPa,围岩最大上抬位移为2.66 mm,竖井和风道连接部位出现局部破损,在实际工程的施工中需予以加固。

Analysis the Stability of Construction Stage of Extra-long Highway Tunnel Ventilation Shaft

The influence of the construction of shaft and air on the stability of rock-lining is analyzed with simulation method which combine the construction project of a tunnel 2# ventilation shaft. Resuits show ＂that compressive stress, walling crib tensile stress and displacement increase gradually with the excavation of shaft on the beginning of vertical shaft excavation, and the maximum is 8.1 MPa, 1.03 MPa and 2.62 mm respectively. The effects on stress and displacement of the lining is adverse at step 5 and step 6 that should take protection measures corresponding. The maximum displacement of arch bottom lining is 3.2 mm, and tensile stress value of lining near to shaft is 3.76 MPa caused by arch bottom up and vault subsidence after wind tunnel excavation, which may lead local damage to the lining. Stress concentration occurs in the lining and surrounding rock on the connection parts of shaft and wind tunnel, and the maximum tensile stress value reach to 3.8 MPa and 1.6 MPa, the largest lift displacement of surrounding rock is 2.66 mm,which lead a local damage on the connection parts of shaft and wind tunnel, and it need to be reinforced in actual construction project.