膨胀土干湿循环过程中土体内部干缩裂缝的产生与其抗拉强度有关，且其在抵抗干缩裂缝发育时产生重要作用，所以在研究膨胀土胀缩机理时，必须考虑抗拉强度的影响。对南京高淳膨胀土压实圆柱样采用轴向压裂法进行抗拉强度试验，研究不同压实度、不同初始含水率、不同制样方法、饱和度以及吸力对压实圆柱样抗拉强度的影响。结果表明压实膨胀土的抗拉强度随着压实度的增大而增大，随着含水率的增大而减小;失水和吸水对压实膨胀土抗拉强度有削弱作用且吸水的削弱作用更加明显;试样从非饱和状态转变为饱和状态时抗拉强度减小极为明显，减小比率高达80%。

The generation of shrinkage cracks in expansive soil in wetting-drying cycle is related to its tensile strength, which must be considered in researching the swell-shrink mechanism of expansive soil as it plays an important role in resisting the development of dry shrinkage cracks. In this research, compacted cylindrical specimens of expansive soil from Gaochun, Nanjing are taken for tensile strength test with axial compress fracture method to investigate the influences of different factors such as degree of compaction, initial moisture content, specimen preparation method, degree of saturation and suction of compaction on tensile strength. Results show that 1) tensile strength of compacted expansive soil increases with the increase of degree of compaction, but decreases with the increase of moisture content; 2) tensile strength can be weakened both by losing water and absorbing water, and the weakening by the latter is more obvious; 3) when the sample changes from unsaturated state to saturated state, its tensile strength reduces remarkably with the reducing ratio up to 80%.