珊瑚钙质砂体积蠕变初步试验研究

Preliminary Experimental Study on the Volumetric Creep of Calcareous Coral Sand

近几年来,我国在南海以吹填的方式建造或扩建了一系列陆域,所用的主要吹填材料是来源于泻湖的钙质砂。作为一种区别于普通陆源砂的海洋生物成因的特殊岩土材料,研究钙质砂与时间相关的蠕变特征对评价以其作为地基的灯塔、机场、防波堤等岛礁上重要结构物的长期工后沉降变形具有重要意义。利用三轴排水试验针对钙质砂开展了体积蠕变试验,发现在恒定围压条件下钙质砂的体积具有与时间相关的蠕变变形,且呈现衰减蠕变。采用一种改进的Burgurs软体元件模型对试验数据进行拟合,发现该蠕变模型可以很好的描述钙质砂的体积蠕变过程。

In recent years, a series of man-made lands have been built and extended by the means of hydraulic dredging in the South China Sea. The main dredging material used was the calcareous coral sand extracted from nearby lagoons. As a special geomaterial, the mechanical properties of calcareous coral soil are different from that of the conventional terrestrial soil. It is of great significance to study the time-dependent creep characteristics of the calcareous coral sand for evaluating the long-term post-construction deformation of lighthouses, airports, breakwaters and other structures constructed on dredged coral reefs. In this study, the volumetric creep test of the calcareous coral sand is carried out by the triaxial drainage test. It is found that the volume of the calcareous coral sand undergoes the significant creep deformation with time under constant loading of confining pressure and presents attenuation creep. Furthermore, a modified Burgers soft-matter model is adopted to fit the experimental data. It is observed that this creep model can describe volumetric creep process of calcareous coral sand very well.