engleski

Conditions of building foundations in old urban areas

Free sites inside old urban areas are very rare and they existence is only within some unfavorable geotechnical conditions, where in past there was no possibility to construct. Presence of surrounding buildings and lack of space needed for good construction site organization is main problem due projecting and construction of new buildings. In this paper it will be shown project solution and construction of accommodation business building in center of city Rijeka, Croatia. Location predicted for construction is surrounded with old masonry buildings, builded in second half of 19th century, and new underground garage. In geological point of view, new building is constructed on alluvial deposits on Riječina river mouth covered with artificial embankment old nearly 200 years. Layers of clay, sand and gravel are exchanged through depth. Water level is very high and located 1m below existed ground surface and is equal to sea level increased with inflow from mainland. The main problem of construction of foundation was construction of underground part of complex in purpose of garage below water level, but also below existing foundation of surrounding buildings. Projected foundation construction predicts boring piles that goes down to depth of 22 m and finishes in layer of gravel to decrease settlement of surrounding buildings. Construction of excavation pit is predicted with jet-grouting pile wall. The lowering of ground water level inside excavation pit is predicted with system of drainage wells below the pile cap construction, during construction works until the weight of construction overload buoyancy. Project is made according with Eurocode EC7 using observational methods. During construction, system of monitoring was set up by constructing piezometers for monitoring groundwater level, inclinometers for monitoring displacements during excavation of pit, clinometers for monitoring slope of nearby buildings and with system of surveying points for monitoring settlements during and after construction. All measured values were in range with predicted values gained by geostatic analyses.

foundation ; design ; urban areas ; analysis ; monitoring

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