The invention belongs to the technical field of tunnel portal reinforcement, and discloses a construction method for reinforcement of an open
cut tunnel portal. The method comprises the steps of anchor cables; frame beam construction; anti-slide
pile construction; biased
retaining wall construction; lining formwork, wherein trolley positioning, lining
steel bar, concrete construction, disassemblyand maintenance are carried out; tunnel structure
waterproofing drainage, wherein tunnel
waterproofing drainage, water-stop band construction, water-stop strip construction, construction joint construction and deformation joint construction are carried out; and
ditch and cable groove construction, wherein a
ditch groove adopts ejecting set-shaped steel formworks, concrete is manually poured, tamping compaction is carried out by a plug-in vibrator, and a water
ditch, a cable groove and a side ditch are constructed by using a whole mobile formwork. The construction method for reinforcement of the open
cut tunnel portal is small in portal excavation amount, good in reinforcing effect and low in cost, and can ensure the safety stability of tunnel portal construction; and the problem of tunnelportal entrance is effectively solved, economy, rationality, safety and efficiency are achieved as best possible, and the scientific basis is provided for the design of the method for reinforcement ofthe open
cut tunnel portal.