穿越断层带隧道结构动态力学特性试验研究

Experimental study on dynamic mechanical characteristics of tunnel structure passing through fault zone

为了揭示隧道穿越断层期间结构力学响应特性,通过室内模型试验研究断层倾角为45°、60°、75°时采用台阶法进行开挖施工的围岩压力、围岩位移和衬砌应力变化情况。结果表明:断层倾角越大,围岩压力值越高,断层倾角为75°、60°时围岩压力分别为45°的1.169倍、1.089倍;拱部围岩压力影响范围达1.0倍洞径,拱腰、边墙处影响范围为0.5倍洞径;断层倾角越大,围岩径向位移值越高,断层倾角为75°、60°时径向位移达45°的1.112倍、1.057倍;拱部围岩位移影响范围达1.0倍洞径,拱腰、边墙处影响范围为0.5倍洞径;由于存在断层结构,隧道开挖后形成较大松散压力,衬砌结构呈“扁坦式”受力状态,边墙位置衬砌应力最大,拱顶、拱腰处次之;断层倾角越大,衬砌应力值越高,第一施工循环拱顶位置衬砌应力在断层倾角75°、60°时分别为45°的1.176倍、1.079倍,拱腰处为1.187倍、1.089倍,边墙处为1.169倍、1.082倍;第二循环拱顶位置衬砌应力在断层倾角75°、60°时分别为45°的1.136倍、1.067倍,拱腰处为1.158倍、1.075倍,边墙处为1.156倍、1.077倍。

In order to reveal the structural mechanical response characteristics of the tunnel during passing through fault zone,indoor model tests were conducted to study the changes in surrounding rock pressure,surrounding rock displacement,and lining stress during excavation construction using the step method with fault dip angles of 45°,60°,and 75°.The results show that the larger the dip angle of the fault,the higher the surrounding rock pressure value.When the dip angle of the fault is 75°and 60°,the surrounding rock pressure is 1.169 times and 1.089 times that of 45°,respectively.The influence range of surrounding rock pressure at the arch is 1.0 time of the tunnel diameter,and the influence range at the arch waist and side walls is 0.5 times of the tunnel diameter.The larger the dip angle of the fault,the higher the radial displacement value of the surrounding rock.When the fault dip angle is 75°and 60°,the radial displacement reaches 1.112 times and 1.057 times that of 45°.The displacement of the surrounding rock at the arch has an impact range of 1.0 time of the tunnel diameter,and the impact range at the arch waist and side walls is 0.5 times of the tunnel diameter.Due to the presence of fault structures,a large amount of loose pressure is formed after tunnel excavation,and the lining structure is in a“flat and flat”stress state.The lining stress is highest at the side wall position,followed by the arch crown and arch waist.The larger the dip angle of the fault,the higher the stress value of the lining.The stress of the lining at the arch crown position in the first construction cycle is 1.176 times and 1.079 times that of 45°when the fault dip angle is 75°and 60°,1.187 times and 1.089 times at the arch waist,and 1.169 times and 1.082 times at the side wall.The stress of the lining at the arch crown position in the second cycle is 1.136 times and 1.067 times that of 45°when the fault dip angle is 75°and 60°,1.158 times and 1.075 times at the arch waist,and 1.156 times and 1.077 times at the side wall.