Underground wall construction method and apparatus

Excavating apparatus for making an excavation in rock in substantially vertical columns, said vertical columns having lower ends, comprising in combination,

• a frame having upper and lower ends and a substantially vertical bearing surface for bearing against a vertical surface opposite a substantially vertical reaction surface in said excavation, means on said frame for coupling to a source of vertical lift force,
• a rotary rock cutting mill and means for rotating said mill,
• a link member and pivot means pivotally mounting said link member proximate the lower end of said frame, means mounting said rotating rock cutting mill on said link member,
• motor means for pivoting said link member on said pivot means from a stowed position at the lower end of said frame outwardly toward the lower end of a vertical column of rock to be excavated to form cuttings by said rotary rock cutting mill, and
• fluid lift means for removing cuttings from said excavation.

A method of excavating a trench along a selected line in rocky terrain,

• forming an initial bore hole having a bottom,
• providing a rotary rock milling tool on a frame such that said rotary rock milling tool is laterally extendable relative to said frame,
• lowering said rotary rock milling tool and said frame to the bottom of said initial bore hole,
• laterally extending said rotary rock milling tool in a direction to extend said trench along said selected line and simultaneously discharging the reaction forces against a wall surface opposite the direction of said rotary rock milling tool is extended to form a trench bottom,
• gradually raising said frame and rotary rock milling tool to excavate an adjacent column of earth from the bottom upwards and allowing the cuttings to fall clear to the bottom of said trench without impeding the excavation, and removing the cuttings from the bottom of said trench.