关键词: 南海钙质砂, 三轴蠕变试验, 蠕变特性, 蠕变数学模型

Abstract: Calcareous sand, a type of geo-material with special structure and mechanical properties formed due to the marine biological deposition process, is the material used in the dredger filling engineering of South China Sea. To further understand its creep properties, a series of long-term creep tests under different confining pressures were carried out using triaxial rheological apparatus on calcareous sand sampled from a coral reef island located at South China Sea. Experimental results show that the damping creep of saturated calcareous sand occurs under constant pressure load that is less than the failure strength. The deformation increases with time, while the deformation rate decreases until the deformation becomes stable. The larger the applied stress is, the longer the deformation becomes stable. The creep deformation is positively correlated with the deviatoric stress, while it is inversely correlated with the effective confining pressure. The relationships of strain-stress and strain-time are nonlinear. It is found that the strain-time relationship of calcareous sand can be described by power function. A new creep model of calcareous sand, considering the relationships of four parameters (i.e. creep strain, time, deviatoric stress and effective confining pressure), is proposed in this paper. Compared with the traditional empirical Mesri creep model, it is unnecessary to perform the conventional triaxial test to determine the peak failure strength in the proposed new model. Less experimental work is required and thus it is much easier to be used.

Key words: calcareous sand in South China Sea, triaxial creep tests, creep properties, creep mathematical model