LARGE DEFORMATION ANALYSIS AND FLOW MECHANISM STUDY OF THE SOIL DURING PILE PENETRATION

Large deformation of soil mass is a challenge in marine geotechnical engineering. Conventional geotechnical engineering analysis methods are limited to large deformation issues on account of complexity of flow mechanics and high gradient of deformation. The analytical methods solving the large soil deformation issues, Strain Path Method (SPM) and Shallow Strain Path Method (SSPM), are studied in the paper. The paper presents the calculated theory, analyzes the change rule and flowing mechanism of soil displacement field induced by pile penetration based on large and small strain theory under ideal soil conditions. Finally, the comprasions of calculation resultes by SPM and SSPM clarify the internal relation of both methods. Results show that the soil deformation field determined by using SSPM based on the large strain theory agrees well with that given by Sagaseta, which illustrates the validity of the calculated results. The soil upheaval occurs on the upper of the pile tip, but the soil moves downward in the vicinity and bottom of the pile tip. The settlement reaches the maximum value when the vertical position is equal to the depth of pile penetration. Calculating results based on the large and small strain theory are generally consistent when the radial position lies in the 3 times pile radius which is 1 times pile diameter away from the pile edge. Research findings in the paper help elucidate the large soil deformation behavior in a consistent and rational manner, and also provide the basic data for validating numerical simulations.