Abstract: Downhole acquisition of drilling parameters for geotechnical property analysis is a key component of intelligent engineering site investigation. To address the limitations of existing measurement-while-drilling (MWD) systems, which lack generalizability and cannot directly measure torque and thrust at the drill bit. A storage-based downhole MWD method is proposed. By introducing a measurement subassembly between the drill rod and drill bit, this method enables direct near-bit measurement of torque, thrust, rotational speed, and inclination. These measurements have clear physical significance and eliminate the need for rod-length corrections. The subassembly adopts a modular design, allowing flexible adaptation to different drill rod sizes and compatibility with various drilling rigs. This design ensures strong engineering applicability. The system independently collects data in a storage mode, while a depth counter performs data splicing and time–depth conversion. This process ensures data completeness and reliability. Field tests conducted at an industrial park in Wuhan demonstrate that the proposed method can clearly capture the drilling characteristics of soil and rock layers, as well as lithological transition zones and locations of discontinuities. Combined analysis of multiple parameters effectively reveals variations in rock integrity. Within the same lithology, the linear increase in thrust with drilling depth confirms that near-bit direct measurement mitigates rod-length effects. This technique provides a feasible, flexible, and high-precision approach for MWD data acquisition and geotechnical parameter inversion.

Key words: measurement-while-drilling (MWD), downhole measurement, drilling parameters, storage-based acquisition, lithology change identification