## 1 Introduction  
Accelerated economic growth has led to a significant surge in the demand for mineral resources, necessitating the exploration of deeper resources. This shift results in increasingly complex hydrogeological conditions, often producing substantial amounts of mine water, which can significantly affect mining operations and safety. Water-induced geological disasters, such as landslides, are a major concern in many mining regions. For instance, over 90% of landslides in China are attributed to water [1, 2], with incidents like those at the Fushun West open-pit mine highlighting the risks associated with seepage [3, 4]. Therefore, studying the weakening mechanisms of rock masses under prolonged water immersion is essential for understanding landslide mechanisms and ensuring mine safety. Research on the water-induced softening of sandstone has advanced, with several researchers focusing on a macro perspective, investigating basic mechanical indicators, including compressive strength, tensile strength, energy evolution, and failure modes. [PERSON] et al. investigated how moisture content influences the energy transformation in red sandstone by conducting axial loading and unloading tests. In their research, both the distribution and progression of inherent elastic energy and energy dissipation were assessed [5]. [PERSON] et al. measured both dynamic and static compressive and tensile strengths during variations in water content, providing an explanation of how water content influences the mechanical characteristics of sandstone from dynamic and static perspectives [6]. [PERSON] et al. examined how water content affects the distribution of the deformation characteristics of rocks under multidirectional compression [7; 8], revealing that uneven water distribution primarily impacts cohesion, thereby influencing crack propagation. It is essential to integrate acoustic emission studies with research on fracture morphology and energy release related to water content in sandstone [9; 10; 11; 12; 13; 14]. As research progresses, accurately describing alterations in pore structure becomes critical to understanding the mechanisms of water-rock interactions. Several researchers have employed techniques such as Nuclear Magnetic Resonance (NMR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), ultrasonic testing, and Computed Tomography (CT) imaging to comprehensively evaluate the alterations in mineral composition and pore structure in sandstone [15; 16; 17; 18; 19]. Studies have also examined the effects of acidic and alkaline water on pore structure and cementing materials in sandstone [20; 21]. Therefore, understanding the water-pore-cementing material interactions in sandstone is essential for studying the hydration effects of sandstone. Weakly cemented sandstone is a unique sandstone that has experienced late diagenesis, leading to poor cementation [22]. During groundwater seepage, the framework particles break down into smaller particles, altering the pore structure and increasing the permeability of sandstone [23; 24; 25; 26]. Research on weakly cemented sandstone examines not only its basic macroscopic properties but also its mineral composition and other microscopic aspects, including the relationships between compressive strength, longitudinal wave velocity, strain, elastic modulus, porosity, and changes in mineral composition of the rock samples [27; 28; 29; 30]. To gain a deeper understanding of the impacts of mineral composition on pores, some researchers have conducted comprehensive analyses of the evolution of microscopic pores in weakly cemented sandstone [31; 32; 22; 33]. Despite different conclusions in the macro-, meso-, and micro-level studies of weakly cemented sandstone, its unique properties significantly impact mining operations. Therefore, analyzing the water-rock mechanisms in weakly cemented sandstone continues to be a topic of ongoing research. This study evaluated the weakly cemented sandstone in the southern slope landslide area of the Wulagen Open-pit Mine.