中文摘要：

膨胀土具有湿胀干缩的特性,在干湿循环作用下土体会产生裂隙,裂隙的发育会破坏土体结构,对土体强度产生影响。通过开展室内膨胀土干湿循环试验和无侧限抗压强度试验,采用数字图像处理技术分析试样表面裂隙,研究膨胀土在干湿循环作用下的开裂特性和纤维加筋对裂隙发育的抑制作用以及强度随裂隙开展的变化规律。结果表明：膨胀土表面裂隙率以及裂隙长度、宽度和分维数等定量指标随着干湿循环次数增加呈双曲线型增大,经历5次循环之后趋于稳定;无侧限抗压强度随干湿循环次数的增加呈双曲线型衰减,经历5次循环之后强度也趋于稳定;强度指标随裂隙率的增加而降低,二者呈线性递减关系。试验过程中纤维土各裂隙指标均小于素膨胀土,而强度均大于素膨胀土,体现了纤维加筋减小膨胀土裂隙性、提高土体强度和整体性的良好效果。

英文摘要：

The characteristics of expanding in the wetting environment and shrinking in the drying environment are significant to expansive soil. Crack occurs under the effects of wetting-drying cycles.Development of crack will destroy the soil structure and weaken the soil strength. Thus,a series of cycle wetting-drying tests and unconfined compressive strength tests were carried out to precisely study the crack properties under the effect of wetting-drying cycle and the effect of fiber reinforcement on the inhibition of crack development and the pattern of strength changing with crack development. The quantitative analysis of the surface fracture of the samples shows that the crack index,length,width and fracted dimension increases with the number of cycle in a hyperbolic type,and the growth trend tends to be stable after 5 cycles.Unconfined compressive strength also decreases with the process of wetting-drying cycles in a hyperbolic type and tends to be stable after 5 cycles. The relationship of crack and strength demonstrates to be negatively correlated.The crack index of fiber-reinforced soil in the tests is lower than that of unreinforced,while strength is higher. It indicates that fiber reinforcement has positive effect on constraining deformation,reducing crack and improving strength and integrity in expansive soil.