The invention provides a double-layer outer-rigid inner-flexible composite lining drainage
system and a construction method thereof, and belongs to the technical field of high-water-pressure tunnel drainage type lining design and construction. The outer-layer rigid drainage
system is arranged in a full-
ring mode, the radial water guide blind pipes are vertically inserted into surrounding rock, the annular water guide blind pipes and the longitudinal water guide blind pipes are pre-buried in a secondary lining, the water guide blind pipes are connected through five-way connectors, and the
tail ends of the annular water guide blind pipes are connected into an inverted arch center
ditch. The inner-layer flexible drainage
system is arranged in a semi-
ring mode, the planar geotechnical cloth is located on the outer side of the annular drainage blind
pipe, the annular drainage blind
pipe is connected with the longitudinal
water collection blind
pipe through the three-way connector, the two ends of the transverse drainage blind pipe are connected with the longitudinal
water collection blind pipe and the drainage side
ditch respectively, and the drainage side
ditch is communicated with the inverted arch center ditch through the transverse drainage blind pipe. The method has the advantages that a large amount of underground water is drained before entering the primary support, the drainage and
pressure reduction effects are very obvious, the safety reserve is high, the structural durability is remarkably improved, and the service life of a tunnel is prolonged.