ABSTRACT: this study, swelling properties of fine grained soils that surfacing around Güdül and its environments were

studied in order to determine causes of cracks and plaster spills on 1 and 3 storey buildings in Güdül district of

Ankara. 19 boreholes with a depth of 5 m to 15 m were drilled. Groundwater was not observed except BH-4, BH-9

and BH-16. 21 standard penetration test samples and 30 undisturbed soil samples were taken from these boreholes.

Swelling pressure tests, swelling percent tests, soil classification and index tests were carried out with these samples.

The SPT N60 blow counts from which samples were taken are ranging between 12 and 49 and the mean average

N60values are determined as 25 blow counts.%59 of the soil samples are determined as low plastic clay (CL) low

plastic silt (ML) or low plastic organic material (OL). %41 of the soil samples are determined as high plastic clay

(CH)- High plastic organic material (OH) or high plastic silt (MH). The mean swelling pressure is 45.83 kPa and

the highest swelling pressure is 111.29 kPa determined from the swelling pressure tests. Activity, swelling potential,

swelling pressure maps of Güdül and its surrounding were prepared. While the activity of soil is 0.5 arround the

Emirler district, the activity of the soils is 1.4 arround Yeni district which locates 5 km north of Emirler district.

Likewise, the swelling potential and swelling pressure values are 1.5% and 25 kPa around Emirler district, while 6% and 65 kPa around Yeni district. Except for the location of BH-17, there is a significant increase in swelling

percentage and swelling pressure values from south to north direction. If the foundation soils interact with water,

swelling pressure may cause risk for 1-3 storey buildings.