Key Takeaways & Executive Findings
- •• Peak strength and elastic modulus of red sandstone are highly sensitive to immersion height, with reductions of 38% and 23% even at L=1/50H. • Water immersion reduces both energy storage and dissipation capabilities of red sandstone. • Immersion height and duration control the migration and separation of dry-wet interfaces, influencing failure modes. • Low immersion heights pose significant risks to underground rock structures, with the concentration degree of water non-uniform distribution being a key factor in assessing water-induced weakening.
Abstract
To investigate the influence of non-uniform water distribution on the mechanical properties and failure behavior of red sandstone, we designed five immersion heights and durations to achieve varying non-uniform water distribution states. Uniaxial compression tests were conducted on red sandstone under these conditions. The effects of non-uniform water distribution on deformation, failure, strength, and energy characteristics of red sandstone were analyzed. The impact of non-uniform water distribution on the intensity of rock failure was discussed, and the failure mechanism under non-uniform water distribution was revealed. The hazards of low immersion heights on underground rock structures were analyzed. The results demonstrate that peak strength and elastic modulus of red sandstone exhibit high sensitivity to immersion height, with reductions of 38% and 23% respectively even at L=1/50H. Water immersion reduces both energy storage capacity and energy dissipation capability of red sandstone. The immersion height and duration influence the failure mode of red sandstone by controlling the migration and separation of dry-wet interfaces. Low immersion height poses significant risks to underground rock structures (e.g., a 38% strength reduction when L=1/50H), and the concentration degree of water non-uniform distribution is the key factor in assessing the weakening effect of water on rocks.
1. Introduction
Water is not only one of the key factors affecting rock properties, but also the most commonly encountered geological fluid in underground rock engineering. Under the influence of groundwater activity, the mechanical properties of rocks undergo significant changes, severely affecting the stability of underground rock structures such as mine pillars and tunnel surrounding rocks [1,2]. In 1960, Price [3] reported that the uniaxial compressive strength (rc) of rocks decreases with increasing water content. Subsequent extensive research has investigated the effects of water on the uniaxial compressive (UC) mechanical properties of sedimentary rocks [4], igneous rocks [5], metamorphic rocks [6], and rock-like materials [7]. These studies demonstrate that the rc and elastic modulus (E0) of rocks predominantly exhibit either exponential or linear relationships with water content.
Wong et al. [8] reviewed studies on the impact of water on the UC mechanical properties of rocks before 2015 and statistically analyzed the percentage loss of rc across various rock types (see Fig. 1). The results indicate that 81.38% of rocks exhibit a rc loss of less than 60%, while 18.62% demonstrate a loss exceeding 60%. Currently, research on the impact of water on rocks from an energetic perspective is receiving increasing attention. Studies have shown that water can significantly reduce the peak elastic energy and peak dissipated energy of rocks [9]. For example, Khan et al. [10] predicted the early failure points of sandstone with different water contents by analyzing the evolution of the ratios of elastic energy density to dissipated energy density. Zhou et al. [11] pointed out that water inhibits the rockburst tendency of sandstone by red...
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Jiancheng Huang, Yong Luo, Xuefeng Si, Feng Lin, Kun Wang, Jiadong Qiu, Fan Feng, Qing Du (2025). Failure characteristics and mechanisms of uniaxial compressed red sandstone in non-uniform water distribution environment: Effects of immersion height and duration. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.09.008
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Frequently Asked Questions
How does immersion height affect the mechanical properties of red sandstone?
The study found that peak strength and elastic modulus of red sandstone are highly sensitive to immersion height, with reductions of 38% and 23% respectively even at a low immersion height of L=1/50H. This indicates that even partial water immersion can significantly weaken the rock.
What is the role of immersion duration in the failure of red sandstone?
Immersion duration influences the failure mode by controlling the migration and separation of dry-wet interfaces. Longer durations allow more water to penetrate, altering the internal stress distribution and leading to different failure patterns.
How does non-uniform water distribution affect the energy characteristics of red sandstone?
Water immersion reduces both the energy storage capacity and energy dissipation capability of red sandstone. This means the rock can store less elastic energy before failure and dissipate less energy during the failure process, making it more prone to brittle failure.
What are the practical implications of this research for underground rock engineering?
The research highlights that low immersion heights, even as low as 1/50 of the specimen height, can cause a 38% reduction in strength. This poses significant risks to underground structures like mine pillars and tunnel surrounding rocks, emphasizing the need to consider non-uniform water distribution in stability assessments.
What is the key factor in assessing the weakening effect of water on rocks?
The concentration degree of water non-uniform distribution is identified as the key factor. The more concentrated the water distribution, the more significant the weakening effect on rock strength and stiffness.
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