Precise positioning core-pulling sampling process by Gongchi method

The invention discloses a precise positioning core-pulling sampling process by a Gongchi method. The process comprises the following steps: a, manufacturing a drilling positioning detection ruler: the drilling positioning detection ruler comprises a clamping plate, the lower surface of the clamping plate is provided with a positioning clamping groove, the upper surface of the clamping plate is provided with a horizontal ruler, and one end part of the clamping plate is provided with a plumb line; b, locally excavating a shallow soil layer above a to-be-detected pipeline, wherein the upper part of the to-be-detected pipeline is exposed out of the soil layer; c, clamping and mounting the drilling positioning detection ruler, aligning the positioning clamping groove to the upper part of the to-be-detected pipeline, calibrating the horizontal ruler and keeping the clamping plate at a horizontal position, and then determining a core-pulling central point through the plumb line; d, vertically driving positioning ste