## 1 Introduction  
As the mechanization of comprehensive coal mining machinery advances and concentrated production in mining areas is realized, the production capacity of mines has been continuously increasing. This progress has raised the bar for the automation and continuity of coal production. Underground coal bunkers, serving as a pivotal nexus connecting various production links in coal mines, are essential for the sustained and efficient operation of the underground transport system [1]. Due to the adhesion properties of raw coal [2, 3, 4], combined with the presence of moisture and gangue, promote agglomeration and wall adhesion. This can lead to substantial build-up on bunker walls or even complete blockages [5], which hampers the efficiency of coal bunker utilization and disrupts the normal flow of production and transportation within the mine. Consequently, research into the adhesion properties of raw coal and the characteristics of adhesive blockages in coal bunkers is of paramount theoretical and practical importance. Such research is fundamental to resolving the issue of adhesive blockages in underground coal bunkers and ensuring their safe and efficient operation. The adhesion properties of raw coal are critical parameters that characterize its flowability. In coal bunkers, raw coal predominantly exists in particulate form. Currently, numerous experts and scholars have conducted in-depth studies on the adhesion properties between these particles from macroscopic and microscopic perspectives. [PERSON] et al. (2016) used the Jenike shear test to study the impact of particle shape on adhesion properties and flowability, concluding that particles closer to spherical shapes with greater surface roughness exhibit poorer flowability. [PERSON] et al. (2017) examined the influence of brown coal's particle size distribution on its flowability, finding that the cohesion of brown coal is significantly affected by particle size distribution. [PERSON] et al. (2018) measured the adhesion property parameters of sawdust, brown coal, and hard coal, determining their flow functions. [PERSON] et al. (2019) suggested that particle motion involves friction, which is mainly influenced by normal force and the coefficient of friction. [PERSON] et al. (2010) and [PERSON] et al. (2011) concluded that particle adhesion is dependent on van der Waals forces and liquid bridge forces, proposing a formula to calculate interparticle adhesion force. [PERSON] (2012), [PERSON] (2013); [PERSON] (2013), and [PERSON] (2015) attributed the agglomeration of moist particles to the formation of liquid bridges between water and coal particles, with higher moisture content leading to more liquid bridges and greater difficulty in separating the coal material. The aforementioned studies primarily investigated the adhesion properties between particles by considering factors such as particle shape, size distribution, and moisture content, achieving significant progress. However, these studies predominantly focused on the adhesion behavior of specific types of coal or powdered materials. In contrast, raw coal in coal bunkers typically exists under compaction conditions, and its adhesion properties are not only influenced by the inherent attributes of the particles but are also closely related to the degree of compaction. Additionally, raw coal exhibits a tendency to adhere to the bunker walls, yet studies on the adhesion properties at the coal-wall interface remain insufficient. To comprehensively uncover the true adhesion behavior of underground raw coal, it is essential to systematically investigate the combined effects of factors such as moisture content, compaction level, and interfacial interactions. Regarding the adhesive clogging problem in bunkers, numerous scholars have also conducted extensive research from various perspectives, including material flow velocity, flow pattern, and bunker wall pressure (2016; 2017; 2018; 2019). Among them, [PERSON] et al.