STUDY OF ‘RAFT AND PILE RAFT FOUNDATION’ FOR ADDITIONAL FLOOR OF PARKING BUILDING, A STRUCTURAL AND GEOTECHNICAL OVERVIEW

ABSTRACT: Polytechnic of Sriwijaya (Polsri) will build a 2-story parking building, ground floor as car parking and upper floor as motorcycle parking. With the building load and soil conditions, it is planned to use bored pile as the foundation. But underneath the additional parking, the existing pool is to be preserved because the water will be used as a source of firefighting water. With this situation where 4 columns will be sitting on the pool slab, ‘raft foundations’ or ‘pile raft’ are considered. It should be calculated in advance, whether the allowable bearing capacity and settlement will be exceeded and whether the thickness pool floor strong enough to withstand the load of columns. This paper discuss the result of the study. Based on the CPT data, the estimated allowable bearing capacity ‘raft foundation’ at depth of 1,5 m is 0,5 kg/cm2, theoretically sufficient to carry out the load, but stress concentration should be analysed. Simple structural calculation and finite element analysis is carried out and the results of analysis show that the combination of pile foundation and the ‘raft foundation' can be implemented. Keywords: raft foundation, pile raft, foot plate, allowable bearing capacity, punching stress