Zhang Hui, Ren Huiqi, Mu Chaomin, Wu Xiangyun, Huang Kui, Wang Fei
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan 232001, China.
Defense Engineering Institute, Academy of Military Sciences, People's Liberation Army, Luoyang 471023, China.
Materials (Basel). 2023 Feb 17;16(4):1683. doi: 10.3390/ma16041683.
Calcareous sand is one of the main building materials in the construction of islands and reefs, and its shear property is very important for predicting their strength and deformation. However, the correlation research on the shear properties of calcareous sand is limited. In this paper, a series of the triaxial consolidation drainage shear tests of calcareous sand with relative densities (Dr) of 70% and 90% under confining pressures of 100, 200, 400 and 800 kPa were carried out by a triaxial testing apparatus, and the effects of relative density and confining pressure on the deformation and strength characteristics of calcareous sand were analyzed. The results show that the stress-strain curves of calcareous sand show a strain softening characteristic, and both peak deviatoric stress and failure strain increase with confining pressure, but the increase in failure strain is restrained when the confining pressure is larger than 400 kPa. The initial shear modulus of calcareous sand is positively correlated with confining pressure. Additionally, the molar circular envelope of calcareous sand is linear in the range of 100~400 kPa, but it deviates from linear when confining pressure exceeds 400 kPa. The critical state line (CSL) of calcareous sand is nonlinear, with almost the same exponent for calcareous sand with different relative densities. The research results have important reference value for the foundation construction of islands and reefs.
钙质砂是岛礁建设的主要建筑材料之一，其抗剪特性对于预测岛礁的强度和变形非常重要。然而，关于钙质砂抗剪特性的相关研究较为有限。本文利用三轴试验仪对相对密实度（Dr）为70%和90%的钙质砂在100、200、400和800 kPa围压下进行了一系列三轴固结排水剪切试验，分析了相对密实度和围压对钙质砂变形和强度特性的影响。结果表明，钙质砂的应力 - 应变曲线呈现应变软化特征，峰值偏应力和破坏应变均随围压增大而增大，但当围压大于400 kPa时，破坏应变的增大受到抑制。钙质砂的初始剪切模量与围压呈正相关。此外，钙质砂的摩尔圆包线在100~400 kPa范围内呈线性，但当围压超过400 kPa时偏离线性。钙质砂的临界状态线（CSL）是非线性的，不同相对密实度的钙质砂指数几乎相同。研究成果对岛礁地基建设具有重要的参考价值。
