Foundation on soil - ABAQUS

Hi there,

 Recently I have modelled a 2D block of soil, at the first step of analysis the soil block subjected to a gravitational load (Gravity) and gravitational stresses generated in the soil block, at the second step, a little rectangular part of soil block removed and currently a concrete block with same size of removed soil embedded on the soil block. this concrete block to be subjected a surface loading.

but the problem is that when i remove the rectangular part of soil, and embed the concrete block instead, I see some space between concrete block and soil and i dont want this.

to solve this problem what should i do?

you can download my abaqus file using the link below :

 http://www.4shared.com/file/h0fsB_7X/Foundation_on_soil.html

thanks in advance,