Safe and rapid construction method for direct conversion from step normal to CRD method

A safe and rapid construction method for direct conversion from a step method to a CRD method is characterized in that in shallow-buried excavation tunnel construction, pre-reinforcement, advance support measures and informatization construction measures are combined, and conversion from an upper step to a CRD method section is completed through gradual change expanding excavation of the upper step of the step method section and timely additional arrangement of a temporary mid-partition wall and a temporary inverted arch; and the lower step maintains the safe step pitch, and section and construction method conversion is completed in the same mode. According to the method, the time interval between construction method conversion is avoided, disturbance of benching method expanding excavation to surrounding rock is reduced, construction safety is guaranteed, meanwhile, the construction progress is accelerated, idling work is reduced, and the method has very important reference value and practical significance f