Soft rock TBM , Slurry shield when the ground conditions are granular with very high water pressure slurry shield TBMs are used and by filling the cutter head with pressurized slurry, hydrostatic pressure is applied to the excavation. ,Earth pressure balance In soft ground with less than 7 bar of pressure, earth pressure balance machines are used and the cutter head is also a combination of tungsten carbide cutting bits, carbide disc cutters, and drag picks.t is a method of excavating, where the excavated material supports the tunnel face. It later gets plasticized with the help of slurry such that it is transportable.