中文摘要：

立方体劈裂试验的应力公式借鉴于传统圆盘巴西试验，忽略了其三维效应，有效性难以保证。为了保证试验的有效性，得到更准确的应力公式，通过三维数值计算方法模拟立方体劈裂试验，结合 Griffith 强度理论分析其三维效应。分析得出，垫条比（垫条宽度和立方体边长的比值）和泊松比对立方体内应力分布影响较大。当垫条比取值一定时，泊松比取值越大，立方体内应力分布受应力集中影响越大，越难保证中心点起裂，而中心点起裂是立方体劈裂试验有效的前提，从而导致试验所测抗拉强度偏小；当泊松比取值一定时，垫条比取值越小，立方体内应力分布受应力集中影响越大，越容易在加载点附近出现应力凸起点，从而无法保证试验的有效性。为了保证试验的有效性，结合数值试验分析结果，对于不同的泊松比，推荐相应的垫条比取值范围，并在推荐范围内，建立考虑垫条比和泊松比的立方体劈裂强度修正公式。

英文摘要：

The formula of tensile strengths from the cubic splitting test ignores the three-dimensional effect. In order to obtain a more accurate stress formula,the cubic splitting test was simulated using the 3D numerical method to analyze the 3D effects based on the Griffith strength theory. It was found that the influences of the cushion-side ratio（the ratio of the width of cushion to the length of cube） and Poisson＆#39;s ratio on the stress of the cubic splitting test were significant. If the cushion-side ratio was constant,with the increase of the Poisson＆#39;s ratio, the influence of the stress concentration on the stress in the cubic specimen became larger,and the crack initiation at the center were not guaranteed. However,the center crack initiation is the premise of a valid test. The smaller tensile strength was obtained in this case. If Poisson′s ratio was constant,the smaller the cushion-side ratio the larger the influence of the stress concentration on the stress in the cubic specimen,the easier for a stress convex point to occur near the loading location. So the validity of the test was difficult to be guaranteed. In order to guarantee the validity of the tests,a revised 3D formula of tensile strengths was established considering the effect of cushion-side ratio and Poisson′s ratio with corresponding recommended range of cushion-side ratios for different Poisson′s ratios.