FIELD: construction industry, construction of sewage and water supply purification works erected on heaving ground bases. SUBSTANCE: underground structure of type of settling tank erected on heaving ground base includes monolithic reinforced concrete bottom and prefabricated outer and inner walls. Novelty of erection of underground structure consists in that its bottom is positioned directly on heaving ground base above depth of season freezing of ground. Thickness of bottom under outer walls around entire perimeter of structure is at least 2.5 times greater than thickness of bottom in center of span of underground structure. Thickened part of bottom has width six times as great as its thickness. Bearing walls are interjoined at top and bottom with the help of metal bars, area of each bar being determined by mathematical dependencies. Technical result of invention lies in development and erection of underground structure which can be positioned directly on heaving ground base, without erection of artificial base from unheaving materials above depth of season freezing of ground. EFFECT: substantially reduced usage of materials and labor input to erection of underground structure. 4 dwg _
