含橡胶纤维钙质砂的渗透和固结特性试验研究

Experimental study on permeability and consolidation of calcareous sand mixed with rubber fiber

珊瑚岛礁常年处于复杂的海洋动力环境中,岛上堤坝围堰、基坑等构筑物的地基渗透变形甚至破坏会导致地基承载力失效的可能性变高。为探究橡胶纤维固化钙质砂的渗透特性和固结特性,采用常水头渗透试验和固结试验研究不同纤维含量下钙质砂的渗透规律和固结变形规律,并设置含纤维玻璃珠对照组。钙质砂具有颗粒形状极不规则、多棱角、内孔隙多等特点,为进一步研究颗粒形状的影响,采用高速动态图像粒度分析仪对钙质砂和玻璃珠的颗粒形状和粒径进行分析。试验结果表明,纤维含量对钙质砂试样渗透特性几乎无影响,但是含纤维玻璃珠试样中,随着纤维含量的增加,渗透系数先增加后减小。由于形状不规则橡胶纤维的加入,一定程度上填补了钙质砂之间的孔隙;钙质砂试样存在800 kPa的压力阈值,当压力超过800 kPa后,其压缩模量增幅变缓;不同纤维含量试样的e-lg p曲线可以用Harris模型表示,钙质砂组的材料系数c=5,玻璃珠组材料系数c=3,此外,材料参数a、b与纤维含量有较好的线性关系。提出了合理的预测模型指导地基加固,具有十分重要的理论价值与工程实际意义。

Coral islands and reefs are always in a complex marine dynamic environment.Seepage deformation or even damage of foundation of embankment cofferdam,foundation pit and other structures on the island will increase the possibility of subsoil bearing capacity failure.In order to explore the permeability and consolidation of calcareous sand mixed with rubber fiber,constant head permeability test and consolidation test were used to study the permeability and consolidation deformation of calcareous sand with different fiber contents,and the control group containing fiber glass beads was set.Calcareous sand has extremely irregular particle shape,ultra-high non sphericity and abnormal rich edges and corners,further study was carried out by a high-speed dynamic image particle size analyzer to analyze the particle shape and size of the calcareous sand and glass bead.The test results show that the fiber content hardly affect the permeability of calcareous sand samples,but the permeability coefficient first increases and then decreases with the increase of fiber content in the glass beads containing fiber.To some extent,the addition of rubber fiber shortens the water passage in the calcareous sand sample.Calcareous sand sample has a pressure threshold of 800 kPa.When the pressure exceeds 800 kPa,the increase of compression modulus slows down.The e-lg p curve of the mixture sample with different fiber contents can be expressed by the Harris model.The material coefficient of the calcareous sand-rubber fiber mixture is c = 5,and that of the glass bead-rubber fiber mixture is c = 3.Meanwhile,there is a good linear relationship between material parameters a and b and fiber content.