Mechanical characteristics of reconstituted coral gravel soils with different fractions of finger-coral fragments and silt matrix
Mechanical characteristics of reconstituted coral gravel soils with different fractions of finger-coral fragments and silt matrix
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DOI：
10.1016/j.sandf.2015.09.022
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发表时间：
2015-10
影响因子：
3.7
通讯作者：
Y. Watabe;S. Sassa;T. Kaneko;Y. Nakata
中科院分区：
文献类型：
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作者：
Y. Watabe;S. Sassa;T. Kaneko;Y. Nakata
珊瑚砂砾土是指珊瑚碎块与粉砂基质组成的复合土，常见于亚热带海岛沿海地区。本研究以珊瑚碎片体积百分比最高可达44%（珊瑚颗粒分数59%）的复合土为研究对象，通过三轴CU-bar和CD试验，研究了考虑由珊瑚碎片组成的土壤骨架与粉土基质相互作用的土壤设计参数确定方法。对于珊瑚碎片体积百分比小于20%（珊瑚颗粒百分比为31%）的样品，CD试验获得的抗剪强度略大于CU-bar试验获得的抗剪强度；然而，两个测试之间的差异非常小。对于碎片体积百分比超过20%的样品（珊瑚颗粒比例为31%），CU-bar试验获得的抗剪强度被明显高估，因为现场存在不切实际的负超孔隙压力，对应于显著的膨胀。CD试验获得的抗剪强度也表现出与体积膨胀相对应的类似趋势；然而，这些值比从cu棒测试中得到的值要小得多。在珊瑚碎片密集包裹的土样中，抗剪角<e:1> (hz)远大于正常土样；然而，它倾向于与珊瑚碎片的颗粒粉碎有关。通过三轴试验前后的ct图像可以直观地证明颗粒破碎的趋势。当珊瑚碎块的体积百分比大于20%（珊瑚颗粒比例为31%）时，与颗粒相互作用和颗粒粉碎相关的土壤参数受到珊瑚碎块体积百分比的显著影响。
Coral gravel soils, which are composite soils consisting of finger-coral fragments and silt matrix, are often found in coastal regions of sub-tropical islands. In this study, for reconstituted soils with various volumetric percentages of coral fragments up to 44% (coral particle fraction of 59%) as the densest package, a series of triaxial CU-bar and CD tests was conducted to study the determination method for the soil design parameters in consideration of the interaction between the soil skeleton, consisting of coral fragments, and the silt matrix. For samples with volumetric percentages of coral fragments less than 20% (coral particle fraction of 31%), the shear strength obtained from the CD tests was slightly larger than that obtained from the CU-bar tests; however, the difference between the two tests was very small. For samples with volumetric percentages of fragments more than 20% (coral particle fraction of 31%), the shear strength obtained from the CU-bar tests was significantly overestimated because of the unrealistically large negative excess pore pressure in the field corresponding to significant dilation. The shear strength obtained from the CD tests also showed a similar tendency corresponding to volume expansion; however, these values are much smaller than those obtained from the CU-bar tests. For the samples with a dense package of coral fragments, shear resistance angleϕwas much larger than that for normal soils; however, it tended to decrease in association with the particle crush of coral fragments. The tendency of the particle crush was visually evidenced through CT-images taken before and after the triaxial tests. The soil parameters were significantly influenced by the volumetric percentages of the coral fragments in association with particle interaction and particle crush, when the percentage was more than 20% (coral particle fraction of 31%) for the coral gravel soils examined in this study.