High ground stress soft rock large deformation tunnel primary support and construction method thereof

The invention discloses a high ground stress soft rock large deformation tunnel primary support and a construction method thereof. The support is built on an excavation structural surface formed after the excavation of the high ground stress soft rock large deformation tunnel is completed, and the method comprises the steps of excavation surface concrete spraying, reinforcing mesh installation, steel arch installation, steel arch locking foot reinforcement and steel arch connection. In order to effectively restrain deformation of the soft rock tunnel, concrete is sprayed to the free face in time after tunnel excavation is completed, concrete spraying is carried out twice, falling of large-deformation surrounding rock of soft rock can be effectively controlled, then a steel arch is erected immediately, steel arch locking anchor pipe construction is carried out, and spraying is carried out again to the designed thickness; the reinforcing meshes are arranged on the inner side and the outer side of the steel arch