Application of geostatistics to estimate the unit points and skin resistances as guidelines in deep foundation projects

Abstract

The kriging ordinary geostatistical methodology was used to estimate the values of strength and grain-size distribution of a sandstone residual soil, with the intention to obtain maps in various depth of the unit points and skin resistances according to the method proposed by Aoki and Velloso. The geostatistical mapping was prepared using 241 SPT boreholes of the studied area, where some maps of the unit point and skin resistances in depth were obtained. ln general, the results, showed that 82,3% of studied area (40,5 km2) occur aggregate soil formed for unit point resistance inferior to 15,0 MPa and 86,2% (42,4 km2) with unit skin resistance inferior to 0,4 MPa, on average, until 8,5 meters of depth. Analyzing all the maps, a spatial distribution of the aggregate soil more favorable to introduction of deep foundations in depth above 11,0 meters was verified.

Therefore, using the maps obtained by probabilistic estimations of the unit point and skin resistances of the soil aggregate, intended to indicate areas of the urban territory integrated, it is expect they met the necessary conditions of the foundation projects, mainly as preliminary implement to guide the geometric variability of the support surface of deep foundations.