Construction method for top arch of underground powerhouse under surrounding rock condition of extrusion fracture zone

The invention discloses a construction method for a top arch of an underground powerhouse under the surrounding rock condition of the extrusion fracture zone, which aims to solve the problems that the underground powerhouse surrounding rock condition under the extrusion fracture zone surrounding rock condition in a high seismic intensity area is poor, and the stability of the underground powerhouse surrounding rock is difficult to guarantee if the underground powerhouse is directly excavated. According to the construction method, consolidation grouting is carried out on the top arch of the underground powerhouse, a certain pressure is applied to a certain proportion of cement paste, the cement paste is pressed into rock cracks through drill holes, and a consolidated body with certain strength and impermeability is formed through cementation hardening of the cement paste, so that the strength of the surrounding rock is improved, and meanwhile the integrity and impermeability of the surrounding rock are improve