Extent of geotechnical site investigations for buildings in Estonia

Numerous researchers have described problems encountered during the construction and performance of a building that result from inadequate site investigations (SI). The type and coverage of in-situ tests can significantly affect the quality of SI results. The aim of this study is to explore the amount and methods of SI in Estonia during the last eleven years. Site investigations data from 92 private and public buildings were collected and analyzed. Both quantitative and qualitative research methods were adopted to identify the most commonly used in-situ and laboratory methods according to different soil types and building height. The impact of the SI contractor was analysed as well. It was found that the costs of investigations constituted approximately 0.1% of the building tender cost for two-to six-storey buildings. Almost half of the SI contractors were designers too. Regardless of the contractor of SI and the soil type, the extent of SI was always similar. The majority of the investigations were conducted only in one stage. Dynamic probing was the most frequent in-situ testing method. The amount and quality of SI was found to be too low for a reliable and optimum design.