Construction method for long-distance large-span tunnel and ultra-small clear distance tunnel

The invention relates to the technical field of tunnel construction, and discloses a long-distance and large-span tunnel ultra-small clear distance tunnel construction method, which comprises the following steps of: firstly excavating parts I and II by adopting a controlled blasting method for a first tunnel, then excavating parts III and IV by adopting the controlled blasting method, and forming a blasting free face after excavating the parts I and II; in the excavation engineering of the part III and the part IV, a reinforcing measure is adopted for conducting grouting reinforcement on a middle rock clamping arch part, after first support construction of the first tunnel is completed, foam concrete with the damping effect of the first tunnel is poured, after the tunnel strength meets the design requirement, a second lining structure of the first tunnel is poured, and the excavation step sequence of the later tunnel is similar to that of the first tunnel; the V and the VI are excavated through a controlled b