摘要
针对Ⅲ级围岩,利用弹塑性三维有限元模型分析了小净距隧道在不同净距下隧道围岩、中隔墙、锚杆及初衬的受力性状。结果表明,两洞围岩应力终值不同,后行洞施工会造成中隔墙应力集中,其应力集中系数随净距减小而增大,应力峰值点位由拱腰与墙脚趋于起拱线;后行洞开挖使先行洞侧围岩松动区扩大,引起中隔墙内锚杆轴向应力增加,对其他部位锚杆受力影响很小;后行洞施工增加先行洞衬砌环向压力,但不会增加衬砌环向负弯矩。对于Ⅲ级围岩,隧道的最小净距取0.5B是合适的,在此净距下,两洞掌子面间的最小间距约为0.5B。
A three-dimensional FEM model was applied to simulate the mechanical behaviour of surrounding rock, middle rock wall, anchor and preceding lining of a neighbourhood tunnel with different clear intervals for grade Ⅲ surrounding rock based on elasto-plastic constitutive. The results show that （1） the final stress states of the two tunnel surrounding rock are different, the driving of succeeding tunnel mainly results in the stress concentration in the middle roek wall. When the clear interval decrease, the coefficient of stress concentration in the middle rock wall increases rapidly, meanwhile, the location of the maximum stress changes from footwall and hance to spring line gradually; （2） with the decreasing of clear interval, the driving of succeeding tunnel lead to enlarge of the loosed surrounding rock areas in the preceding tunnel; （3） the driving of succeeding tunnel mainly increases the axial stress of anchor embedded in the middle rock wall, the anchors at other parts are less affected; the driving also increases lining circumferential stress in the preceding tunnel but not increases the lining circumferential negative moment. The rational clear interval for grade Ⅲ surrounding rock is about 0.5 B, under this circumstance, the minimum distance of excavation face between the preceding tunnel and the succeeding tunnel is about 0.5 B.
出处
《公路交通科技》
CAS
CSCD
北大核心
2008年第12期138-145,共8页
Journal of Highway and Transportation Research and Development
关键词
隧道工程
施工力学
有限元
小净距隧道
围岩压力
tunnel engineering
constmction mechanics
FEM
small interval tunnel
surrounding roek pressure
