为更好地探究灰岩在酸性干湿循环作用下的损伤规律,以桂林岩溶区灰岩作为研究对象,对其开展不同酸性干湿循环作用下的常规三轴压缩试验,分析灰岩损伤后的强度和变形特征。通过建立灰岩在酸性干湿循环-荷载作用下的几何损伤模型,引入Weibull分布函数和复合损伤变量,得到灰岩的统计损伤本构模型。结果表明:在酸性干湿循环作用下,灰岩的内部结构遭到破坏,高循环次数下,弹性模量的劣化增幅更高;模型模拟曲线和试验数据吻合度较高,能够客观地反映灰岩三轴受压破坏的应力-应变全过程和变形特征;灰岩的总损伤演化曲线基本呈“s”型,分为初始损伤阶段、损伤快速发展阶段、损伤减缓发展阶段、完全损伤阶段;在低循环次数下,酸性的增强使得灰岩的脆性出现一定的增强。研究结果可为岩溶区的岩土工程建设、边坡治理等提供参考。

[Objectives] This study focuses on the damage patterns of limestone in karst regions under acidic dry-wet cycles, aiming to explore the effects of the coupled action of acidic environment and dry-wet cycles on the mechanical properties and damage mechanisms of limestone. [Methods] Limestone from the Guilin karst region was selected as the research subject. Dry-wet cycle tests were conducted in acidic solutions with pH values of 3, 5, and 7 to simulate acid rain erosion. The number of cycles was set at 10, 20, and 30. Conventional triaxial compression tests were carried out to obtain stress-strain data and analyze the strength and deformation characteristics of the limestone. By integrating the Weibull distribution function with a composite damage variable, a geometric damage model was established. A statistical damage constitutive model for limestone was derived and its validity was verified using experimental data. [Results] (1)Mechanical degradation behavior: peak stress and elastic modulus exhibited exponential decay with increasing cycle count. The most significant degradation occurred at pH 3, where the elastic modulus decreased by 29.6% after 30 cycles. Notably, at higher cycle counts, the degradation rate in elastic modulus exceeded that of peak strength. (2)Model validation: The theoretical curves of the newly developed constitutive model showed strong agreement with the experimental data, accurately capturing the full stress-strain response of limestone under triaxial compression, including the residual strength phase. (3)Damage evolution mechanism: The total damage curve followed an “S”-shaped four-stage evolution (initial damage, rapid development, slowed development, and complete damage). Lower pH values led to an earlier onset of critical strain. After 10 cycles, the strain at the peak damage rate was significantly reduced, indicating that acidic environments induce increased brittleness in limestone. [Conclusions] The damage constitutive model developed in this study effectively reflects the mechanical behavior and damage evolution of limestone under acidic dry-wet cycles. The research reveals the complex mechanisms of acid-induced damage in limestone, offering new theoretical insights and methods for geotechnical design and slope stability analysis in karst regions, and provides an important reference for evaluating and predicting the performance of limestone materials in practical engineering applications in karst regions.