【摘要】 乌鞘岭长大深埋隧道横穿祁连山东麓,长达20050m,最大埋深1050m。在于枚岩夹板岩及构造角砾岩等软弱岩层洞段的隧道开挖过程中,围岩强烈变形,水平最大变形达1034mm,拱顶最大下沉量达1053mm,由此导致支护失效甚至型钢钢架被严重扭曲,且持续变形不收敛。原地应力测量研究表明,该洞段具有明显的现今构造应力作用,最大主应力的作用强度为20～22MPa,现今地应力状态的总体特征为σ_H≥σ_V＞σ_h。分析认为,隧道围岩的变形是在较强的构造应力与垂直重力的共同作用下,由于未及时支护,软弱围岩不能承受该作用力,以致产生持续性流变大变形。工程实践表明,围岩应力状态是支护设计的依据,而适时支护是非常重要的。允许围岩适度变形,使围岩应力得以适度释放。选择在流变大变形尚未形成,围岩尚未丧失其抗载能力的时刻,及时进行衬砌支护,这对确保围岩稳定和支护安全具有重要意义。更多还原

【Abstract】 Wushaoling long and deep-buried tunnel passes through the east foot of Qilian Mountain,with the length of 20 050 m and the maximum burial depth of 1 050 m.During the excavation of tunnel in the soft rock such as phyllite,plywood rock and tectonic breccia,the surrounding rock was deformed severely,with the maximum horizontal deformation magnitude of 1 034 mm and the arch top subsidence magnitude of 1 053 ram, which led to that not only supports lost their effects,but steel frames were distorted heavily.Moreover,the deformation lasted and could not converge.The testing results of original field stress show that these tunnel sections are under the action of clear modem tectonic stresses with the maximum principal stress of 20 - 22 MPa, and that the general feature of modem ground stress field is thatσ_H≥σ_V≥σ_h.According to the analysis,it is considered that the strong deformation of surrounding rock of tunnel results from the joint actions of rather strong tectonic stress and vertical gravity stress;and that the tunnel has not be supported in time and soft surrounding rock can not bear such actions,which causes continuous large theological deformation.Engineering practice indicates that the stress state of surrounding rock is the basis of support design;and that the timely support is very critical.However,proper deformation of surrounding rock is allowed,which can make the stress of surrounding rock release properly.Carrying out lining support construction in time when the large rheological deformation has not been formed and the surrounding rock has not lost its bearing capacity is of great significance to assure the stability of surrounding rock and the safety of supports.更多还原