Process for excavating and constructing micro-steps of tunnels on basis of method for excavating steps

The invention provides a process for excavating and constructing micro-steps of tunnels. The process includes steps of excavating upper steps without reserved core soil, obliquely and downwardly drilling foot lock anchor rods at arch feet and hermetically attaching the foot lock anchor rods to base rock by means of grouting or by the aid of anchor agents; controlling and keeping the lengths of the upper steps, simultaneously excavating the upper steps and intermediate steps without reserved core soil and arranging foot lock steel pipes and lock anchor rods for the intermediate steps; circularly carrying out the steps by three times; keeping synchronously excavating the upper steps and the intermediate steps, simultaneously erecting trestles, starting to excavate lower steps and close inverted arches without reserved core soil, and then closing the inverted arches; synchronously advancing excavation of the upper steps, the intermediate steps and the lower steps, and carrying out alternate circular operation for synchronously excavating each upper step, the corresponding left intermediate step and the corresponding right lower step and synchronously excavating the upper step, the corresponding right intermediate step and the corresponding left lower step until the tunnels are completely integrally excavated. The process has the advantage that effects of guaranteeing the tunnel construction safety and increasing the construction speeds can be effectively realized.