| 摘要: |
| 钙质砂受力后易产生颗粒破碎，从而使其力学性质发生变化。对取自我国南沙某岛礁的钙质砂样进行了不同正压力下的直剪试验。分析了钙质砂颗粒剪切破碎特性，并就不同试验压力下剪切后钙质砂样的颗粒破碎程度通过筛分试验进行了粒径级配分析。结果表明，在不同正压力下进行直剪试验，钙质砂存在一定的颗粒破碎现象，随着正压力增大，颗粒破碎越来越严重；由于钙质砂颗粒破碎的影响，剪切后钙质砂的颗粒级配性质发生改变，随正压力增大钙质砂由级配良好逐渐变得级配不良。钙质砂直剪试验强度包络线为峰值强度包络线，而非残余强度包络线。钙质砂残余强度的摩擦角数值等于或接近砂的天然休止角。从工程安全角度考虑，选用钙质砂的内摩擦角应等于或接近天然休止角。 |
| 关键词: 正压力 钙质砂 剪切 颗粒破碎 |
| DOI： |
| 分类号:TU411 |
| 基金项目:江苏省自然科学基金资助项目（BK2015071）；江苏省交通科技项目（2017T12）;江苏省研究生科研与实践创新计划项目（KYCX18_2336） |
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| Shear breakage characteristics of calcareous sand particles under different normal pressures |
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QI Yongzheng1,2, YUAN Zirui1, YANG Yongheng1
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1.Faculty of Civil Engineering and Architecture, Jiangsu University of Science and Technology, Zhenjiang;2.College of Civil and Transportation Engineering, Hohai University, Nanjing
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| Abstract: |
| The particles of the calcareous sands are easily broken under the conditions of high stresses. Consequently, the mechanical properties of the calcareous sands will change under the action of different pressures. The shear breakage characteristics of the calcareous sand particles under different normal pressures are examined and analyzed in this paper. Several direct shear tests on the calcareous sands from Nansha’s island of the South China Sea are conducted under different positive pressures. The particle breakage degrees of the sand samples under different positive pressures are studied through the sieving tests. The analysis results show that the calcareous sands can be broken to some extent after the direct shear tests under different positive pressures. The content of the coarse particles reduces and the content of the fine particles increases accordingly. As the positive pressures increase, the particle breakage becomes more and more serious. The grain grading properties of the calcareous sands change after the crushing of the calcareous sand particles. As the normal pressures increase, the gradation of the sand samples becomes poor gradually from its original gradation. The strength envelope of the calcareous sands is the peak strength instead of the residual strength. The friction angle of the residual strength of the calcareous sand is equal to or close to the natural repose angle of the sand. From the point of view of engineering safety, the internal friction angle of the calcareous sands should be equal to or close to the natural repose angle. |
| Key words: normal pressure calcareous sand shear particle breakage |
