There is precedent for this - what we did to Aachen, Germany, during World War Two. We filled the underground utilities with concrete and turned 80% of all structures larger than outhouses into piles of rubble.
http://www.globalsecurity.org/military/library/report/2002/MOUTGabel.htm
"Knock 'em All Down: The Reduction of Aachen, October 1944
by Christopher R. Gabel, Ph.D."