受控三轴应力-应变下沉积物声速与物理力学性质的关系

发布时间：2018-07-29 10:05

【摘要】：对南海某海域深度100~400m的海底浅层(约2m埋深范围)沉积物柱状样在接近海底水压力下进行三轴应变-声学同步测量,结果表明沉积物纵波声速有两个特征:(1)从应变过程开始到结束,沉积物纵波声速不断变化;(2)平均声速随着平均静弹性模量的增加,由大变小又由小变大,存在声速最小值。这些结果与海底浅表层沉积物的物理力学性质、围压、颗粒的结合状态改变有关。此外,沉积物动弹性模量和孔隙度呈良好的负相关性,这与孔隙度增大含水量增大有关;动弹性模量是静弹性模量的10~100倍,这主要与三轴应变试验的应变数量级与声波振动产生的应变数量级的差异大有关。采用本论文实验测量的数据分别建立了双复合参数-声速和孔隙度-声速经验公式,分析结果表明双复合参数-声速公式声速预报误差约是孔隙度-声速公式的1/4,表明双复合参数-声速公式更加有效。
[Abstract]:A triaxial strain-acoustic synchronous measurement of sediment columnar samples at a depth of 100m to 400m in a certain sea area of the South China Sea is carried out under the pressure of water near the sea floor. The results show that the velocity of longitudinal wave in sediment has two characteristics: (1) from the beginning to the end of the strain process, the sound velocity of the longitudinal wave of sediment changes continuously, and (2) with the increase of the mean static modulus of elasticity, the mean velocity of sound changes from large to small to large, and there exists the minimum sound velocity. These results are related to the change of physical and mechanical properties, confining pressure and particle binding state of shallow surface sediments. In addition, there is a good negative correlation between dynamic elastic modulus and porosity of sediment, which is related to the increase of porosity, and the dynamic modulus of elasticity is 10 ~ 100 times that of static modulus of elasticity. This is mainly related to the difference between the magnitude of strain in triaxial strain test and the magnitude of strain produced by acoustic vibration. Based on the experimental data measured in this paper, the empirical formulas of double composite parameters-sound velocity and porosity-sound velocity are established, respectively. The results show that the prediction error of sound velocity is about 1 / 4 of the formula of porosity and sound velocity, which indicates that the formula of double composite parameter and sound velocity is more effective.
【作者单位】：广东工业大学机电工程学院;中国科学院南海海洋研究所中科院边缘海地质重点实验室;
【基金】：国家自然科学基金(41176034,41476028)
【分类号】：P733.23

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