Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering

Abstract 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 thro...

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Main Authors: Weisheng Zhao, Lijun Han, Shuai Yan, Wei He
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-11033-7
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author Weisheng Zhao
Lijun Han
Shuai Yan
Wei He
author_facet Weisheng Zhao
Lijun Han
Shuai Yan
Wei He
author_sort Weisheng Zhao
collection DOAJ
description Abstract 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.
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spelling doaj-art-897f26dd92df4a39b40e57124bd5bdfc2025-08-20T04:01:51ZengNature PortfolioScientific Reports2045-23222025-07-0115111610.1038/s41598-025-11033-7Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineeringWeisheng Zhao0Lijun Han1Shuai Yan2Wei He3School of Architectural Engineering, Neijiang Normal UniversityState Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and TechnologyState Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and TechnologySchool of Architectural Engineering, Neijiang Normal UniversityAbstract 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.https://doi.org/10.1038/s41598-025-11033-7MudstoneHygroscopic behaviorTemperature and humidity conditionsMechanical degradationUnderground engineering
spellingShingle Weisheng Zhao
Lijun Han
Shuai Yan
Wei He
Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering
Scientific Reports
Mudstone
Hygroscopic behavior
Temperature and humidity conditions
Mechanical degradation
Underground engineering
title Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering
title_full Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering
title_fullStr Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering
title_full_unstemmed Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering
title_short Experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering
title_sort experimental study on nonlinear hygroscopic and strength behavior of mudstone under coupled temperature and humidity conditions for underground engineering
topic Mudstone
Hygroscopic behavior
Temperature and humidity conditions
Mechanical degradation
Underground engineering
url https://doi.org/10.1038/s41598-025-11033-7
work_keys_str_mv AT weishengzhao experimentalstudyonnonlinearhygroscopicandstrengthbehaviorofmudstoneundercoupledtemperatureandhumidityconditionsforundergroundengineering
AT lijunhan experimentalstudyonnonlinearhygroscopicandstrengthbehaviorofmudstoneundercoupledtemperatureandhumidityconditionsforundergroundengineering
AT shuaiyan experimentalstudyonnonlinearhygroscopicandstrengthbehaviorofmudstoneundercoupledtemperatureandhumidityconditionsforundergroundengineering
AT weihe experimentalstudyonnonlinearhygroscopicandstrengthbehaviorofmudstoneundercoupledtemperatureandhumidityconditionsforundergroundengineering