为研究冻结温度与尺寸效应耦合作用下的冻土石混合体巴西劈裂特性，分别对经过−10、−15、−20、−25、−30、−35、−40 ℃冻结处理后的5~10、10~15、15~20、5~20 mm粒径冻土石混合体试件进行巴西劈裂实验；研究冻结温度和不同粒径块石对试件劈裂抗拉强度的影响规律，并进一步通过数字图像相关技术（digital imagine correlation，DIC）再现了冻土石混合体在巴西劈裂实验过程中的应变场演化过程。实验结果表明：在劈裂拉应力作用下，试件从中心开裂并产生初始裂纹，沿着土石界面向两加载端贯穿试件，试件破裂面裂纹呈弯曲折线型，且块石粒径越大，裂纹越曲折；冻土石混合体在破坏时会经历线弹性变形阶段，并随着拉应力的增大和冻结温度的降低会经历塑性-脆性破坏阶段；试件劈裂抗拉强度具有强温度敏感性，会随着冻结温度的降低而近似线性增加；块石尺寸效应会导致试件强度的差异性，试件劈裂抗拉强度大小依次为5~10、5~20、10~15、15~20 mm粒径试件。

In order to study the Brazilian splitting characteristics of the frozen stone mixture under the coupling effect of freezing temperature and size effect, Brazilian splitting experiments were conducted on 5-10, 10-15, 15-20, and 5-20 mm particle size frozen soil-rock mixture samples after freezing at −10, −15, −20, −25, −30, −35, and −40 ℃ to investigate the effects of freezing temperature and different particle sizes on the splitting tensile strength of the samples. The effects of freezing temperature and different particle sizes on the splitting tensile strength of the samples were investigated, and the strain field evolution of the frozen soil-rock mixture during the Brazilian splitting experiments was further reproduced by digital imagine correlation (DIC). The experimental results show that the tensile strain is concentrated in the sample center with initial crack produced and the splitting damage pattern of the samples is curved and folded, and the larger the particle size is, the more curved the crack is; frozen soil-rock mixture goes through the linear elastic deformation stage when it breaks, and goes through the plastic-brittle damage stage with the increase of tensile stress and the decrease of freezing temperature; the splitting tensile strength has strong temperature sensitivity and increases approximately linearly with the decrease of freezing temperature; the size effect leads to the variability of sample strength, and the splitting tensile strengths are in the order of 5-10, 5-20, 10-15, and 15-20 mm particle size samples.