TY JOUR TI Investigation of Subgrade Construction on Pile Foundation with Flexible Grillage KW Weak soils KW subgrade construction KW pile foundation KW flexible grillage KW geosynthetic materials JO Bulletin of scientific research results AU Serebryakov, D.V. PY 2023 IS 2023 PB FSBEI HE "Emperor Alexander I St. Petersburg State Transport University"