Drainage board capable of lapping hermetically

The utility model relates to a drainage board. The middle part at one side of a base board is provided with a drum-shaped lug boss, the lower part of the base board is in a cylindrical shape, and the upper part is in a circular arc shape. The edge point of the base board is provided with four to six rows of cylindrical lug bosses used for lapping and connecting, a row of lug bosses with small diameter is also arranged between two rows of lapping and connecting lug bosses, and sealed adhesive is arranged at the lapping and connecting point of two drainage boards at both sides of each of the lug bosses with small diameter. In addition, the side surfaces of the lug bosses are also provided with stiffening ribs. The drainage board has the advantages of reasonable structure, firmness of mutual lapping and connecting and good sealing performance, is widely used for various basic construction situations, and is especially suitable for road engineering.