岛礁土体地下空间的主要土质为钙质砂。通过对两种不同相对密实度的钙质砂试样进行的常体积和常应力条件下的单剪试验,以及具有相同级配的石英砂的对比试验,对钙质砂的抗剪强度进行了研究。结果表明:在相同的颗粒级配条件下,钙质砂具有高于石英砂的临界内摩擦角及低于石英砂的相变角和最大剪胀角的特性;钙质砂的最大剪胀角、相变角及临界内摩擦角均受颗粒破碎的影响,其中最大剪胀角及临界内摩擦角随着破碎的增加而降低,而相变角随着破碎的增加而增加。最后,将临界内摩擦角和剪胀角视为颗粒破碎的“效果角”,通过引入影响颗粒破碎的相对密实度,提出了基于现有评价方法的钙质砂最大内摩擦角的计算模型。
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