不排水条件下钙质砂声发射试验研究

通过对钙质砂进行不排水条件下声发射试验，探讨了不同围压、剪切速率、初始孔隙比和级配下钙质砂声发射规律。试验结果表明:低围压（围压低于400 kPa）时，钙质砂声发射活动频率随着围压的升高而增加；围压增至800 kPa时，声发射活动频率有所下降。低剪切速率下，钙质砂剪切试验明显分为颗粒破碎阶段和颗粒滑移阶段，随着剪切速率增大，二者之间较模糊，不能明显区分；松散和密实状态下，钙质砂声发射活动规律相似，钙质砂声发射活动频率均高于中密状态钙质砂；级配较好的钙质砂，声发射率峰值出现在试样发生剪切破坏前；级配稍差，试样声发射率相对均匀，声发射率峰值出现在邻近试验结束时。 

Acoustic emission test of calcareous sands under undrained condition

Calcareous sand acoustic emission was tested under undrained condition to study the law of acoustic emission with different confining pressure, shear rate, initial void ratio and grading. The results showed that when the confining pressure was lower than 400 kPa, calcareous sand acoustic emission event rate increased with confining pressure. But when the confining pressure was increased to 800 kPa, calcareous sand acoustic emission event rate decreased. The test of calcareous sand was divided into particle breakage stage and particle slip stage in low shear rate. Two stages can't be distinguished clearly as the shear rate increases. Loose and dense calcareous sands have similar acoustic emission activities which were higher than medium dense calcareous sand. When grading of calcareous sand was well, acoustic emission peak appeared at the early stage of shear failure rate. When grading calcareous sand was poor, acoustic emission rate was relatively uniform, and acoustic emission peak appeared at the end of the test.