Trajectory and Inclination Calculation of Cone Penetration Probe

Abstract – Cone penetration testing (CPT) is a fast and reliable means for exploring soils and soft ground (to 40 m depth) for support of buildings, retaining walls, pavement subgrades, and bridge foundations. A cone can deviate from verticality due to misalignment, a bent push rods, soil layering, or by being pushed off a vertical course during penetration if it encounters an obstacle such as a large rock. Deviation reduces probing accuracy, or large deviation from the initial alignment can cause breakage of the cone rods and loss of the cone down the hole. The inclination and trajectory calculation techniques of cone penetration test (CPT) probe are presented. Two-dimensional inclinometer was used on purpose to calculate probe trajectory and (if needed) to generate an alarm signal to avoid breakage of the cone rods.