Foundation filling performance of calcareous soil on coral reefs in the South China Sea

Abstract

Atoll reef flats in the South China Sea are ideal sites for land reclamation and engineering construction. Calcareous soil deposited in atoll lagoons is an excellent filling material for land reclamation. This brittle material with irregular particle shapes is prone to obvious particle breakage under impact or vibration loads. First, this manuscript introduced the geomorphology and geological conditions of coral reefs, and explored the selection of reclamation sites and the source of filling materials. Then, compaction characteristics of calcareous soil were studied, and particle breakage was analyzed. On this basis, the optimal compaction test method was proposed based on the test results. Finally, a new method of “impact rolling + water spray” for coarse-grained calcareous soil, which proved effective in engineering practice in the South China Sea, was put forward. According to in-situ test results, after 20 passes of “impact rolling + water spray” on calcareous soil foundation, the compactness within the depth range of 1.0 m exceeded 80%; the foundation compactness at 0.3 m, 0.7 m, and 1.0 m deep increased by 8.4%, 4.8%, and 4.1%, respectively. This method significantly improved foundation compaction efficiency, offering important references for the compaction treatment of coarse-grained calcareous soil in coral reef regions.