This study shows one construction example which overcomes NATM's defect by Ground Improvement.
That is to say, the ground which is difficult to construct NATM tunnel because of ground weakness e.g. a sream on the ground, loose soil, shallow overburden can be changed to suitable ground by Ground Improvement.
In this study, We used a Compaction grouting for ground improvement, Monitoring for a stabiltiy analysis of shallow NATM tunnel and the results are follows.
1.The stiffness of loose shallow ground increased up to 30% by ground improvement.
2.The increased stiffness enabled us to construct NATM tunnel in the loose shallow soil ground and the stability of this NATM tunnel was almost same like safe tunnel in the good soil condition.
3.The important parameter on the NATM is the ground stiffness as well as ground overburden height.
4.In the future, the study how to overcome NATM's limit should be more developed.