珊瑚混凝土（CAC）作为一种新型建筑材料，已经在岛礁工程结构建设领域引起了极大的关注。为了研究CAC的静态劈裂抗拉性能，本文提出了一种考虑骨料形状和空间分布随机性的三维（3D）随机混凝土细观模型，影响因素包括试件形状和支承垫片尺寸。我们建立了12 个不同的混凝土细观模型，按照试件形状可分为两种，即边长为150 mm的立方体和尺寸为ϕ150 mm×300 mm的圆柱体。其中，支承垫片宽度为6 mm、9 mm、12 mm、15 mm、18 mm和20 mm。本文系统分析和讨论了试件几何形状和垫片宽度对CAC劈裂抗拉性能的影响规律，研究内容包括混凝土开裂过程、最终破坏模式和劈裂抗拉强度（f_st）。结果表明：本文所开发的细观模型具有很高的可靠性，并确定了适用于CAC劈裂抗拉性能模拟和预测的最优计算参数。CAC的f_st值与试件形状和垫片宽度直接相关。其中，在垫片尺寸相同的情况下，立方体CAC试件的f_st值要略高于圆柱体模型，表明可以采用断裂面积的差异来解释试件形状效应对CAC f_st值的影响规律。此外，当垫片的相对宽度由0.04 增加到0.13 时，CAC的f_st值会呈现逐渐增大的趋势。基于弹性力学理论，本文初步确定了不同垫片宽度条件下CAC f_st的取值范围，这对于研究CAC的抗拉性能具有重要意义。

The use of coral aggregate concrete (CAC) as a novel construction material has attracted significant attention for the construction of reef engineering structures. To investigate the static splitting-tensile behaviors of CAC under the influence of two factors, namely specimen geometry and bearing strip size, a three-dimensional (3D) mesoscale modeling approach with consideration for aggregate randomness in shape and distribution was adopted in this study. We established 12 different specimen models with two specimen shapes (i.e., a cube with an edge length of 150 mm and a cylinder with dimensions of ϕ150 mm × 300 mm) and six strip widths (i.e., 6, 9, 12, 15, 18, and 20 mm) for calculation. The effects of specimen geometry and strip width on the splitting-tensile properties of CAC, such as failure processes, final failure patterns, and splitting-tensile strength (fst), are analyzed and discussed systematically. The results indicate the high reliability of the developed mesoscale modeling approach and reveal the optimal computational parameters for simulating and predicting the splitting-tensile properties of CAC. The fst values of CAC are associated with both the specimen geometry and width of the bearing strip. The fst values of the cube model are slightly higher than those of the cylinder model for the same bearing strip size, representing geometry effects that can be explained by differences in fracture area. Additionally, the fst value of CAC gradually increases with the relative width of the bearing strip ranging from 0.04 to 0.13. Based on the elastic solution theory, the variation area of CAC fst values with the relative width of the bearing strip was determined preliminarily, which has great significance for studying the tensile performance of CAC.