Patent ID: 9732523
Date: 2017-08-15
CPC Classifications: E01C,E01F,E02D,E04C

Claim:
1. A connection surface disposed on a face of a structural unit, the face of the structural unit extending generally along a plane, the connection surface comprising: a first segment having a three dimensional surface profile including a plurality of positive outer surface features extending outwardly along a normal direction from the plane and a plurality of negative outer surface features extending inwardly along the normal direction from the plane, wherein at least two of the plurality of positive outer surfaces are separated from one another along both vertical and horizontal directions and at least two of the plurality of negative outer surfaces are separated from one another along vertical and horizontal directions; a second segment opposing the first segment with respect to an axis; wherein the second segment is a substantial reflection of the first segment across the axis, but reversed along the normal direction; wherein when identical connection surfaces face and engage one another in the same vertical orientation, the positive outer surfaces of the first segment nest with the negative outer surfaces of the second segment, and the positive outer surfaces of the second segment nest with the negative outer surfaces of the first segment.