A case study for mapping of spatial distribution of free surface heave in alluvial soils (Yalova, Turkey) by using GIS software

A procedure for producing a surface heave map using GIS package in clayey alluvial soils is proposed. An active zone was first defined, and the layers in the active zone were subdivided according to their swelling characteristics. The free surface heave values for each cell of the digitized map of the study area were calculated by using the available equation in the literature, and a spatial distribution map was then constructed interpolating the data belonging to each borehole location. Soils having a high swelling capacity are widely distributed in the study area, and will cause serious heave problems on light structures. Clayey soils in the study area have generally moderate-very high swelling potentials, and swell pressures in many locations are much higher (up to 98 kPa) for low-rise structures. Moreover, differential movements sourced from surface heave are also expected in many locations. It was calculated that the minimum expected heave was 0.00 cm while the maximum was 12.24 cm, indicating "very severe" differential movement. The results obtained in this paper can be used as basic data to assist surface heave hazard management and land use planning. The information derived from this study also has a special importance for assessing the probable deformations on intended light construction applications in Yalova city. The methods used in this study will be valid for generalized planning and assessment purposes; although they may be less useful on the site-specific scale, where local geology and geographic heterogeneities may prevail. (C) 2007 Elsevier Ltd. All rights reserved.