The text compares the shield exacation on two jobs sites. Geological layers are simmilar although the rates of each kind of soil are different. Fine Alluvial deposits, Tertiary sands and clays are encoutered. The tow job sites differ in shield technology: (slurry shield versus Eath Pressure Balanced Shield) and nearly 10 yaers elapsed betwwen the two excavations. So we size the opporunity to compare the ways the two technologies faced with the different soil layers.