The utility model provides a but depth measurement type drainage member and soft foundation structure belongs to building construction field, including drainage core, filter layer and plain conductor, be provided with a plurality of water drainage tank on two faces of drainage core respectively, the length direction extension of drainage core is followed to a plurality of water drainage tank's on the same face length, is provided with the mounting groove on the face of drainage core, and the length direction of mounting groove is on a parallel with the length direction of drainage core, and installation slot position in arbitrary water drainage tank's tank bottom is in the plain conductor embedding mounting groove. But be somebody's turn to do the depth of inter fit that depth measurement type drainage member detected plain conductor's length through special detecting instrument and then obtained the drain bar, plain conductor is straight, and it is more accurate to detect the result that obtains, is close to the actual degree of depth of drainage core male more, and the inspection and the test of the construction of being convenient for improve construction quality, improve the security.