Work

Experimental study on the fundamental properties of coral-reef limestone and the vertical bearing behavior of post-grouted rock-socketed shafts

Year: 2025

Type: article

Abstract: The development of reclaimed islands and reefs has emerged as an important strategic measure for coastal nations. This paper systematically investigates the mechanical properties and engineering characteristics of coral-reef limestone in the proposed area for Male-Airport Island cross-sea bridge project. Based on the results of static load tests and core drilling conducted on post-grouted rock-socketed drilled shafts，this study provides a comprehensive analysis of the bearing deformation characteristics of the shaft embedded in coral-reef limestone before and after grouting. Additionally，the integrity of the shaft and the permeation diffusion range of the grouting are thoroughly evaluated. The test results reveal that the coral-reef limestone exhibits notable characteristics，including low density，large pore sizes，unique structure，strength anisotropy，and uneven cementation. Furthermore，large-diameter post-grouted rock-socketed drilled shafts demonstrate promising application potential in the coral-reef limestone strata. The post-grouting technique enhances the bearing deformation capacity of shaft foundations in coral-reef limestone，with the ultimate bearing capacity of the test shaft increasing by 3.6% after grouting，and the displacement of the shaft head decreasing by 33.53% compared to before grouting. Core drilling tests indicate that the grouting at the shaft tip penetrates approximately 3 m(around 2D) downward，which significantly improves the pore structure of the coral-reef limestone. Finally，by correlating the unconfined compressive strength of intact coral-reef limestone with the ultimate side resistance and tip resistance，this paper develops a computational method for calculating the load capacity of grouted rock-socketed drilled shafts in coral-reef limestone formations. This methodology offers a robust scientific foundation and theoretical basis to guide subsequent engineering applications.

Source: Chinese journal of rock mechanics and engineering

DOI: 10.3724/1000-6915.jrme.2024.0650