MULTI-SHAFT EXCAVATING DEVICE AND TORSION SENSING METHOD FOR OBLONG EXCAVATION HOLE FORMED BY MULTI-SHAFT EXCAVATING DEVICE

PURPOSE: To measure torsion of an oblongly excavated hole by calculating the torsional angle of the hole using signals given by an azimuth meter and a non-touch type object sensor installed at the tip of one excavating shaft. CONSTITUTION: A non-touch type object sensor 3 is installed on a recess 12 provided at the tip of one of a plurality of excavating shafts 1 laid in line. An azimuth meter 4 measures the angle formed by the direction of the sensor 3 viewed from the center of the excavating shaft to the reference direction toward the center of the on-the-ground termination of adjoining excavating shaft 1. The signal emitted when the sensor 3 is positioned the closest to the adjoining shaft 1. When the output of the sensor 3 maximizes, the azimuth meter 4 emits azimuth, and a oblongly excavated hole torsional angle calculating means 5 indicates the torsional angle of an oblongly excavated hole.