Creating 2D and 3D mesh in a single geometry

I'm currently doing a project that analyses a component which requires integrated 2D and 3D meshing. I'm somehow able to create two separate types of mesh in a single geomtry but I'm constantly failing in having connectivity between the created 2D and 3D mesh which is resulting in very high values of displacement when solved. Could any of you please help me in sorting out this problem??