Abstract:A practice of a group of highrise buildings with raft foundation in karst region was introduced. There were 7 buildings in this group with 16 floors and one floor basement. The foundation was placed on a plastic silty clay layer whose beating counts of standard penetration test were 9–11. Under this layer was the karst region,and the altitude difference of rock surface reached to 15 m. It was more difficult to use the pile foundation than the raft foundation,so the latter was used. The bearing capacity of ground depends on the in-situ plate loading test,and it was found the in-situ results are larger than the values given in the report of geotechnical engineering exploration. The deformation moduli from the in-situ plate loading test were used to calculate the settlement,and they were 6 times of the compressing modulus. Based on the deformation modulus from the in-situ plate loading test,the settlement of each point on the raft foundation was calculated using spring model with concentrating force. Also,the raft foundation was analyzed using several methods including finite element method. The measured results show that the calculation results agree well with the measured settlements.