Field Tests Study on Post-Grouting Cast-in-place Bored Piles in Soft Soil Area of Indonesia

Post-grouting bored piles are widely used in soft soil engineering in Indonesia, but the theoretical research on the bearing characteristics of post-grouting bored piles still lags behind engineering practice. Based on a project in Indonesia's soft soil region, field tests of bored piles with different pile lengths and post-grouting bored piles were carried out. The results show that the ultimate bearing capacity of post-grouting bored piles is 1.20 to 1.26 times that of bored piles, and the rebound rate and elastic deformation of post-grouting bored piles are correspondingly increased. Under the geological conditions of the study area, the upward flow height of post-grouting cement slurry is 12.4~13.8 m, and the downward penetration depth of cement slurry below the pile tip is 1.3~2.1 m, which is 1.6~2.6 times the pile diameter. The blow counts of the standard penetration test (SPT) of the rock and soil layers below the cement slurry return height of the post-grouting pile and below the pile end are significantly increased compared to those before grouting. The improvement of the pile side friction resistance and pile end resistance caused by post-grouting is the main factor for improving the bearing performance of the bored pile. The research results have reference significance for the design and construction of post-grouting in soft soil areas in Indonesia.