Zhao Weisheng, Han Lijun, Yan Shuai, He Wei
School of Architectural Engineering, Neijiang Normal University, Neijiang, 641112, China.
State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology, Xuzhou, 221116, China.
Sci Rep. 2025 Jul 9;15(1):24770. doi: 10.1038/s41598-025-11033-7.
The hygroscopic behavior of mudstone and its water content significantly influence the stability of underground engineering structures. This study investigated the hygroscopic behavior of mudstone under coupled temperature and humidity conditions and its effect on mechanical properties through hygroscopicity experiments and uniaxial compression tests. A hygroscopic mathematical model was developed, and the physical significance of the model's coefficients was clarified. Additionally, coefficient of variation (CV) analysis was conducted to examine water content deviations during the hygroscopic process. The results indicated that the equilibrium water content (EWC) exhibited a three-stage growth pattern with increasing humidity: rapid growth (0‒20% RH), slow growth (20‒60% RH), and accelerated growth (60‒100% RH), whereas it decreased with increasing temperature, although the rate of decrease slowed progressively. The EWC of small samples (φ15 mm), which can reach 12.22%, was much greater than that of standard mechanical samples (φ50 mm), whose EWC was less than 4%. A low-humidity environment (≤ 80%RH) or a relatively high temperature (e.g., 30℃) effectively reduced water content deviations. An increasing water content resulted in a linear decline in the uniaxial compressive strength (UCS) and elastic modulus (E), with humidity accelerating mechanical degradation, whereas at high humidity levels, increasing the temperature had a moderate positive effect on the mechanical properties. Humidity was the dominant factor influencing the hygroscopic behavior of mudstone, and reducing the environmental humidity significantly decreased the EWC, improving the mechanical properties of mudstone. On the basis of these findings, a high-temperature and low-humidity environmental optimization strategy was proposed to mitigate the adverse effects of hygroscopic behavior on mechanical properties and to enhance the long-term stability of engineering structures. This study revealed the nonlinear hygroscopic-mechanical behavior of mudstone under coupled temperature and humidity conditions, providing a scientific basis for environmental temperature and humidity regulation and structural stability optimization in underground engineering.
泥岩的吸湿行为及其含水量对地下工程结构的稳定性有显著影响。本研究通过吸湿实验和单轴压缩试验，研究了泥岩在温度和湿度耦合条件下的吸湿行为及其对力学性能的影响。建立了吸湿数学模型，阐明了模型系数的物理意义。此外，进行了变异系数（CV）分析，以研究吸湿过程中的含水量偏差。结果表明，平衡含水量（EWC）随湿度增加呈现三阶段增长模式：快速增长（0‒20%RH）、缓慢增长（20‒60%RH）和加速增长（60‒100%RH），而随温度升高而降低，尽管降低速率逐渐减缓。小尺寸样品（φ15mm）的EWC可达12.22%，远大于标准力学样品（φ50mm）的EWC，后者小于4%。低湿度环境（≤80%RH）或相对较高温度（如30℃）可有效降低含水量偏差。含水量增加导致单轴抗压强度（UCS）和弹性模量（E）线性下降，湿度加速力学性能劣化，而在高湿度水平下，升高温度对力学性能有适度的积极影响。湿度是影响泥岩吸湿行为的主导因素，降低环境湿度可显著降低EWC，改善泥岩力学性能。基于这些发现，提出了高温低湿环境优化策略，以减轻吸湿行为对力学性能的不利影响，提高工程结构的长期稳定性。本研究揭示了泥岩在温度和湿度耦合条件下的非线性吸湿-力学行为，为地下工程中的环境温度和湿度调节以及结构稳定性优化提供了科学依据。
