forepoling

Forepoling is a construction technique used in excavation, particularly in unstable ground conditions like quicksand or caving soil. It involves driving poles, planks, or sheathing into the ground ahead of or simultaneously with the excavation process. This method helps to support the ground and prevent collapses.12

A "forepole" itself can refer to the sharpened plank or pole used in this technique. An adaptation of forepoling is called "spiling," where poles are driven intermittently with gaps between them. This technique is crucial for safely advancing tunnels and underground excavations where the ground is prone to instability.32