TY JOUR TI Cavitiyless Drain of Composite Profile Reinforced with Drainage Pipe KW Cavityless drain KW hydraulic calculation KW drainage KW subgrade KW composite section JO Proceedings of Petersburg Transport University AU Shtykov, V.I. AU Ponomarev, A.B. PY 2022 IS 19 PB FSBEI HE "Emperor Alexander I St. Petersburg State Transport University"