TY JOUR TI Frost Heave and Its Influence on Spacer System of Enclosing Constructions of Deep Ditches KW frost heave KW ditch fencing KW spacer system KW nature experiment KW numerical modelling JO Proceedings of Petersburg Transport University AU Metelkin, S.V. AU Paramonov, V.N. PY 2022 IS 19 PB FSBEI HE "Emperor Alexander I St. Petersburg State Transport University"