岩石蠕变对隧道二衬结构影响的研究

岩石蠕变是岩石的重要力学特征之一。在隧道开挖完之后的很长时间内,围岩会因为蠕变而进行应力调整,蠕变产生的荷载由隧道的初衬和二衬联合承担。而当今隧道的使用寿命规定为100a,隧道设计中往往将二衬作为安全储备,没有通过分析围岩蠕变荷载对二次衬砌的影响对二衬进行设计。如不对此进行准确分析并采取有效的控制措施,长时间的蠕变将会对隧道二衬结构产生严重影响。因此,分析隧道二衬受力以及健康程度随时间的变化是十分有必要的。结合铜锣山隧道工程,利用大型有限差分软件FLAC3D的Bur-gers蠕变模型,分析了不同时间蠕变对围岩应力重分布以及对二衬的力学性能的影响,得出一些有价值的结论:岩石蠕变造成隧道断面围岩应力、作用弯矩的大小及位置发生变化,对衬砌的安全造成影响。

Study of the Effects of Rock Creep on the Structure of the Second Lining of a Tunnel

Rock creep is one of the important mechanical properties of rock.Within a very long period of time after the tunnel is excavated,the stress of the surrounding rock will be adjusted as a result of the rock creep,and the first lining and the second lining resists the loads of the creep in a cooperative way.However,because the lifespan of a tunnel nowadays is stipulated to be 100 years,the second lining is always used as the reserve of safety without analyzing the effects of loads of the rock creep on the second lining structure when the second lining is designed.If the effects are not accurately analyzed and effective control measures are not taken,the long-term creep may have a serious effect on the structure of the second lining,owing to which it is necessary to analyze the stress and the health of tunnels which vary with time.With the Tongluoshan Tunnel as a practical example,and by using the Burgers model of FLAC3D,the effects of rock creep on the stress redistribution of the surrounding rock and the mechanical behavior of the second lining at different times are analyzed in the paper,with some valuable conclusions obtained.It is found that the creep of rock causes changes in the amount of the surrounding rock stress,and both the amount and the position of the bending moment,which may have a great effect on the safety of the lining.