Abstract：In the seaside of Qinhuangdao，the surface soil usually consists of 2–5 meters of very soft soil layer. Its inner friction angle is very small or zero. The deformations of above saturated soil often lead to cracks in the building. In order to investigate its physical and mechanical properties，large numbers of undisturbed soil samples have been obtained with the rigid steel ring from the test pit. Laboratory tests including confined compression test and triaxial test are carried out. The seadside soft clay can be defined as silty clay，for its water content is 37%–44%. The shear strength，sensitivity，and bearing capacity of seaside soft clay are determined in-situ by using plate loading test，cone penetration test，and vane shear test. The test results show that the shear strength of field vane test can be determined as a function of testing depth with specific penetration resistance and shear strength. The average value of undrained shear strength is 27 kPa with medium or even higher sensitivity of 2.4–12.5. The characteristic values of subgrade bearing capacity are less than 80 kPa. Based on the field test，allowable loads and settlements of the foundation for some buildings during consolidation are theoretically analyzed. Problems arising from some buildings constructed on the soft clay in Qinhuangdao district are presented.
