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珊瑚碎屑钙质砂是海洋沉积物中的一种,其强度低、形状不规则、内孔隙多和易破碎等性质和普通石英砂有很大差异。通过对取自南沙群岛永暑礁附近海域的钙质砂进行大型剪切试验,分析得到轴压、剪切速率和级配对钙质砂力学特性的影响。试验结果表明,钙质砂的抗剪强度在达到峰值之后都会出现应变软化现象,随后略微增长并且达到稳定。随着剪切速率的降低和轴压增大,试验土体的抗剪强度持续增加,出现的颗粒破碎增多,土体的剪胀量减小;随着级配粗颗粒的增加,土体的最大抗剪强度和颗粒破碎持续增加,并且在P5=65.14%情况下达到峰值,之后随着粗颗粒含量的增多而降低。
Coral clastic calcareous sand is a marine sediment, its low strength, irregular shape, many pores and easy to break and other properties and ordinary quartz sand are quite different. The effects of axial compression, shear rate and gradation on the mechanical properties of calcareous sand were analyzed by large shear tests of calcareous sand taken from the sea near Yongshu Reef of the Nansha Islands. The test results show that the shear softening of calcareous sand occurs after its peak value, then slightly increases and reaches a steady state. With the decrease of shear rate and the increase of axial pressure, the shear strength of the test soil increases continuously, the number of particles broken increases and the amount of dilatancy of soil decreases. With the increase of gradation coarse particles, The maximum shear strength and particle breakage continued to increase, reaching a peak at P5 = 65.14% and then decreasing with increasing coarse particle content.