小净距隧道施工方法优化研究

On construction method optimization of small clear distance tunnel

以河源洞小净距隧道为工程背景,通过模拟研究比较不同施工方法下的塑性区、位移、应力情况.研究结果表明:侧壁导坑法施工中对围岩开挖次数较多,围岩受到的扰动较大,塑性区范围比台阶法大;在相同的开挖次数下,CRD(中隔墙)法施工产生的塑性区范围又大于侧壁导坑法.对于围岩条件较差的情况,控制位移是施工中应该注意的一项重要工作,侧壁导坑法施工对于控制位移的增量有明显优越性,所以在软弱地层可以优先考虑采用.

The simulation research was studied for comparing plastic zone, displacement and stress conditions in different constructions methods in small clear distance tunnel in Heyuandong. The results show that the method of double side excavation excavates many more times in the rock, and it leads to more disturbance suffered by the surrounding rock, so the scope of the plastic zone is larger than excavated by the way of steps excavation; in the same excavation times, CRD （mid-partition） method get larger scope of plastic zone than double side excavation. In poor condition of surrounding rock, controlling displacement is an important job that should be paid attention to in the construction. The method of double side excavation has obvious advantages in order to control the displacement of the delta, so it has priority to be considered to use in weak stratum.