What Does Ground Loss Mean?
Ground loss can be defined as the volume of soil excavated in excess of designed excavation. While excavating a borehole or a tunnel an opening is initiated into which the soil can deform and make way for ground loss. Trenchless construction methods such as horizontal directional drilling (HDD) and microtunneling use drill bits and cutter heads to excavate the soil below the ground surface.
Excess overcut and improper filling of annular space can lead to ground loss overtime.
Trenchlesspedia Explains Ground Loss
Advances in trecnhless technology have reduced the time and consequently the cost required to install a pipeline considerably. However; it has been observed, especially in soft soil, that soil deformation due to tunneling and boring activities inevitably occur. During excavation, deformation of soil around the tunnel leads to ground loss. The undrained ground loss can take place ahead of the face, over the shield, and during lining erection.
Other factors that affect ground loss are elasto-plastic deformation at the tunnel face and excess overcut in the periphery of the tunnel shield.