prevention pyramid 4 and the driving piles 3 are driven into the ground in a substantially radial pattern although it is desirable to drive the driving piles 3 into the hard ground below the soft ground if the ground is a soft ground the sedimentation suppression plate 5 suppresses sedimentation and tilt of the pile foundation 1 a even if the driving piles 3 cannot be driven into the ground with sufficient strength specifically the sedimentation suppression plate 5 resists the sedimentation because the installation area with respect to the ground surface f and the underground is wide and large buoyance is generated in a soft ground close to liquid therefore the resistance to the sedimentation and the buoyance of the sedimentation suppression plate 5 can suppress the sedimentation of the entire pile foundation 1 a and the structural object o placed on the pile foundation 1 a the sedimentation suppression and the buoyance of the sedimentation suppression plate 5 can be appropriately adjusted by changing the size of the sedimentation suppression plate 5 therefore when the load on the plurality of pile foundations la varies due to the weight balance according to the parts supporting the structural object o or due to wind pressure on the structural object or when the softness level of the ground varies due to the installation location the size of the sedimentation suppression plate 5 can be appropriately adjusted to control the amount of sedimentation and the sedimentation speed to suppress the tilt of the mounted structural object o since the frost heaving prevention pyramid 4 is made of a thermally insulated material the heat of the air is not easily transmitted to the soil and the effect of frost heaving in a winter term in a cold region such as.