Development of high-precision drilling model test platform for sand and gravel formations

Compared to general static model tests, drilling type model tests require consideration of dynamic issues. The test theories are complex and the test control conditions are strict. On the basis of the static similarity ratio criterion, this article derives the dynamic similarity ratio criterion for drilling model tests and develops a matching model test platform. The platform uses surface vibration compaction method to prepare samples. By finely controlling the vibration conditions, it overcomes the shortcomings of traditional rain method and manual compaction method, and achieves the maximum dry density, higher density and uniformity of the samples. To address the issue of high stability requirements for monitoring data, a pressure monitoring sensor was installed at the bottom of the sample barrel to monitor drilling resistance and eliminate the influence of sliding friction between the guide rail and the rotary drilling platform. The new method provides more stable monitoring values, with residual squared values approximately one-third that of traditional methods. The experiment shows that the new model experimental platform and method can overcome the shortcomings of existing technology, distinguish the influence of subtle changes in experimental conditions on drilling efficiency, and can be used for research on the adaptability of pile drilling tools and tool selection.