【摘要】 针对膨胀土在自然降水-蒸发循环作用下，土体产生显著的胀缩变形过程中裂隙不断萌生并扩展，极易引发边坡崩裂、失稳等工程灾害问题，以河南省南阳市膨胀土为研究对象，对干湿循环作用下裂隙膨胀土的压缩模量劣化问题进行研究，通过1～3次干湿循环试验结合CT扫描技术，分析裂隙发育特征及其对压缩模量的影响。试验结果表明：干湿循环次数显著加剧裂隙扩展，首次循环仅形成局部微裂隙，第二次循环裂隙最大深度达55 mm,第三次循环裂隙完全贯穿试样(65 mm),且裂隙率自上而下递减。通过改进侧限压缩装置，揭示了压缩过程的三阶段规律，并发现压缩模量随循环次数增加而系统性降低，主要归因于裂隙导致的有效承载面积减小及咬合力减弱。随着压缩过程进行，经历较多干湿循环的试样因其初始裂隙网络更发达、连通性更强，压缩模量的提升幅度显著受限，体现了干湿循环对土体压缩特性的累积损伤效应。更多还原

【Abstract】 Expansive soils containing significant amounts of hydrophilic minerals(e.g., montmorillonite and illite) undergo substantial swell-shrink deformation under natural precipitation-evaporation cycles. During this process, desiccation cracks initiate and propagate progressively, readily inducing engineering hazards such as slope cracking and instability. This work investigates the deterioration of compression modulus in cracked expansive soils subjected to W-D cycles, using soil samples from Nanyang City, Henan Province. Through 1～3 W-D cycles combined with CT scanning technology, the crack propagation characteristics and their impacts on compression modulus were quantitatively analyzed. Experimental results demonstrate that cyclic wetting-drying significantly aggravates crack development: initial cycle produces only localized micro-cracks, the second cycle extends cracks to 55 mm maximum depth, while the third cycle generates fully penetrating cracks(65 mm) with surface-to-base decreasing crack ratio distribution. Using a modified confined compression device, three-stage compression characteristics were identified, showing systematic reduction of compression modulus with increasing cycles, primarily attributed to reduced effective bearing area and weakened interparticle bonding caused by cracking. As the compression process proceeds, samples that have undergone more W-D cycles exhibit a significantly limited increase in compression modulus due to their more developed and interconnected initial crack network. This reflects the cumulative damage effect of W-D cycles on the compressive characteristics of the soil.更多还原