Abstract Calcareous sand containing weak particles originated from the deposition of skeletal residue of marine organisms is susceptible to significant particle crushing under compression and shearing. The breakage of grains results in excessive deformation and foundation failure. This study focuses on the mechanical properties and particle crushing of calcareous sand retrieved from Nansha Island, South China Sea. A series of isotropically drained and undrained triaxial compression tests were performed on reconstituted calcareous sand samples at different initial densities and at a wide range of confining stresses. The amount of particle crushing for calcareous sand after shearing was measured and quantified. Experimental results demonstrate that the shear response of calcareous sand had been well interpreted within the critical state framework. The amount of particle crushing for calcareous sand increases with increasing density and confining stress. Compared with the undrained condition, a larger amount of particle crushing of calcareous sands is observed in the drained triaxial compression test. Stress-dilatancy curves exhibit similar varying tendency for calcareous sand. Multiple critical state lines for calcareous sands with different initial densities are identified in the void ratio and logarithm of the mean stress plane. Considering the variation in stress ratio at the critical state induced by particle crushing, all stress paths are normalized to determine the state bounding surface for calcareous sand at varying densities and stresses.

中文翻译：

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南海回收钙质砂力学行为及颗粒破碎试验研究

摘要 来自海洋生物骨骼残渣沉积的含有弱颗粒的钙质砂在压缩和剪切作用下容易受到显着的颗粒破碎。晶粒的破碎导致过度变形和地基破坏。本研究重点研究了南海南沙岛回收的钙质砂的力学特性和颗粒破碎情况。在不同初始密度和大范围围压条件下，对重构钙质砂样品进行了一系列各向同性排水和不排水三轴压缩试验。对剪切后钙质砂的颗粒破碎量进行测量和量化。实验结果表明，钙质砂的剪切响应在临界状态框架内得到了很好的解释。钙质砂的颗粒破碎量随着密度和围压的增加而增加。与不排水条件相比，在排水三轴压缩试验中观察到更多的钙质砂颗粒破碎。钙质砂的应力-剪胀曲线表现出类似的变化趋势。通过孔隙比和平均应力平面的对数确定了不同初始密度的钙质砂的多条临界状态线。考虑到由颗粒破碎引起的临界状态下应力比的变化，所有应力路径都被归一化以确定不同密度和应力下钙质砂的状态边界面。在排水三轴压缩试验中观察到大量的钙质砂颗粒破碎。钙质砂的应力-剪胀曲线表现出类似的变化趋势。通过孔隙比和平均应力平面的对数确定了不同初始密度的钙质砂的多条临界状态线。考虑到由颗粒破碎引起的临界状态下应力比的变化，所有应力路径都被归一化以确定不同密度和应力下钙质砂的状态边界面。在排水三轴压缩试验中观察到大量的钙质砂颗粒破碎。钙质砂的应力-剪胀曲线表现出类似的变化趋势。通过孔隙比和平均应力平面的对数确定了不同初始密度的钙质砂的多条临界状态线。考虑到由颗粒破碎引起的临界状态下应力比的变化，所有应力路径都被归一化以确定不同密度和应力下钙质砂的状态边界面。通过孔隙比和平均应力平面的对数确定了不同初始密度的钙质砂的多条临界状态线。考虑到由颗粒破碎引起的临界状态下应力比的变化，所有应力路径都被归一化以确定不同密度和应力下钙质砂的状态边界面。通过孔隙比和平均应力平面的对数确定了不同初始密度的钙质砂的多条临界状态线。考虑到由颗粒破碎引起的临界状态下应力比的变化，所有应力路径都被归一化以确定不同密度和应力下钙质砂的状态边界面。