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钙质土因其颗粒形状不规则、易破碎、高孔隙比等特征,其力学性质较为特殊。采用室内大型直接剪切试验设备,对取自南海珊瑚礁和三亚岸礁的粗颗粒钙质土进行了直剪试验,研究了粗颗粒钙质土在不同含水率、不同密度和不同矿物组成条件下的钙质土剪切特性。结果表明,粗颗粒钙质土表现出与常规无黏性土截然不同的力学性质,即(1)与石英砂相比,表观黏聚力较大,内摩擦角较高,软化性较弱;(2)表观黏聚力随着平均粒径的增大而增大,内摩擦角随着干密度的增大而增大;(3)与峰值强度相比,土体剪切破坏后其残余强度的表观黏聚力锐减而内摩擦角仅略有减小。研究成果可为岛礁工程建设提供借鉴,也可为其他粗颗粒土的研究提供参考。
Calcareous soil because of its irregular shape, fragile, high porosity and other characteristics, its mechanical properties are more special. The large-scale direct shear test equipment was used to test the coarse-grained calcareous soil from the coral reefs in the South China Sea and the Sanya shore reefs. The effects of different moisture content, density and composition of coarse-grained calcareous soils were studied. Calcareous soil shear characteristics. The results show that coarse-grained calcareous soil exhibits distinct mechanical properties compared with conventional non-clayey soils, namely (1) higher apparent cohesion, higher internal friction angle and softer softening than quartz sand ; (2) Apparent cohesion increased with the increase of average particle size, and the internal friction angle increased with the increase of dry density; (3) Compared with the peak intensity, The apparent cohesion of its residual strength dropped sharply while the internal friction angle decreased only slightly. The research results can provide reference for the construction of reefs and reefs, and provide reference for the research of other coarse-grained soils.