1) Concentrated point arrangement, marine anchor chain is generally arranged under the column; The advantages of this arrangement are: the vertical force from the upper structure can be fully used to balance some of the water buoyancy; Because of the centralized arrangement of anchor bolts, it is also convenient for the external waterproof construction under the basement floor; The layout of the friction chain should also be noted. The failure is often the failure of the anchored rock mass; Because local anchor bolts are dense, anchor bolt construction is inconvenient.