Objective Pipeline trench earthwork measurement is a critical component of oil and gas pipeline construction, as its results directly influence resource allocation and progress management. Therefore, selecting an efficient and accurate measuring method is essential.

Methods Using the laser point cloud direct measurement method, both the primary substratum before pipeline trench excavation and the excavated trench area were scanned with airborne radar to obtain two point cloud datasets: one for the foundation and one for the pipeline trench. High-altitude noise was then filtered using the radius filtering method. After refinement of the point cloud data, the point cloud was sliced transversely along the pipe centerline based on construction chainage, followed by vertical slicing of each transverse slice. Two point cloud datasets were then traversed according to the height of the lower surface layer in the vertical slices, allowing for the extraction of the pipeline trench profile point cloud. The slicing results were treated as infinitesimal volume elements, with the infinitesimal volumes of both straight and arc sections calculated and aggregated to determine the earth-rock volume using the infinitesimal integration method.

Results The method was implemented in 13 testing areas along a pipeline in the Shaanxi–Gansu–Ningxia region, with algorithm parameters tested in areas 1–5. The optimal parameters determined were a transverse slice thickness of 0.20 m, a vertical slice thickness of 0.10 m, and a lower surface layer height of 0.05 m for vertical slices. The algorithm’s repeatability was tested in areas 6–7, yielding a total average error of 4.72％ and demonstrating effective measurement performance. Comparison tests conducted in areas 8–13 with DJI, Global Mapper Pro, and oblique photography demonstrated that the laser point cloud method achieved a high measurement accuracy, with an average error of only 5.84％.

Conclusion Utilizing LiDAR for point cloud collection offers higher measurement accuracy and broader applicability across varying conditions. The direct method eliminates the modeling accuracy loss associated with indirect methods, and using the primary landform as the datum plane reduces errors typically introduced by using the pithead plane as the base in conventional direct methods.