The surface subsidence caused by mining influences the mine environment and construction safety. In this paper, strata movement and surface subsidence were combined. Based on elasticity and Winkler theory, a prediction method of surface subsidence was established with the primary key stratum as the research object. Using the Tingnan Coal Mine as an example, the mining subsidence of the second panel was predicted. Comparing the predicted results with the measured results, the causes of errors were analyzed and the field of application of the model was clarified. Besides, the geological and mining factors affecting surface subsidence were also analyzed. The results show that the mining subsidence is the surface manifestation of the strata movement. Surface subsidence is affected by the mining area, load, and flexural rigidity of the primary key stratum, foundation modulus of the goaf, and the rock mass. The research results have significance for the planning of the coal resources and the prevention of geological disasters.

Epidemiological studies have revealed an inverse relationship between the incidence of Alzheimer’s disease (AD) and various cancers, including colorectal cancer (CRC). We aimed to determine whether the incidence of CRC is reduced in AD-like mice and whether gut microbiota confers resistance to tumorigenesis through inducing inflammatory tolerance using 16S ribosomal RNA gene sequencing and fecal microbiota transplantation (FMT). AD-like mice experienced a significantly decreased incidence of CRC tumorigenesis induced by azoxymethane–dextran sodium sulfate as evidenced by suppressed intestinal inflammation compared with control mice. However, FMT from age-matched control mice reversed the inhibitory effects on the tumorigenesis of CRC and inflammatory response in AD-like mice. The key bacterial genera in gut microbiota, including Prevotella , were increased in both the AD-like mice and in patients with amnestic mild cognitive impairment (aMCI) but were decreased in patients with CRC. Pretreatment with low-dose Prevotella -derived lipopolysaccharides (LPS) induced inflammatory tolerance both in vivo and in vitro and inhibited CRC tumorigenesis in mice. Imbalanced gut microbiota increased intestinal barrier permeability, which facilitated LPS absorption from the gut into the blood, causing cognitive decline in AD-like mice and patients with aMCI. These data reveal that intestinal Prevotella -derived LPS exerts a resistant effect to CRC tumorigenesis via inducing inflammatory tolerance in the presence of AD. These findings provide biological evidence demonstrating the inverse relationship between the incidence of AD and CRC.

We used the key stratum theory to establish a more realistic thin‐plate mechanical model of elastic foundation clamped boundary and study the fracture mechanism of overlying strata during longwall mining. We analyzed the fracture characteristics and factors affecting fracture of the key stratum combined with the Mohr–Coulomb yield criterion. Besides, we used numerical simulation methods to verify the evolution pattern of the overlying strata fracture. The results show that the fracture mechanisms of the elastic foundation clamped structure’s key stratum varied depending on the position under longwall mining. The advanced coal wall area of the upper surface is a compressive‐shear fracture. The center area of the lower surface is a tensile fracture. With the increase of the excavation length and the load of the key stratum, the central area and the advanced coal wall area of the long side are fractured before the advanced coal wall area of the short side. With the increase of flexural rigidity of the key stratum, the advanced coal wall area of the long side fractures before the central area and the advanced coal wall area of the short side. With the increase of the foundation modulus and the advanced load of the key stratum, the central area fractures before the surrounding advanced coal wall area. The advanced influence distance was positively correlated with the key stratum’s flexural rigidity and advanced load and negatively correlated with the foundation modulus and excavation length. The advanced influence distance was not affected by the load of the key stratum. The numerical simulation results show that, with the increase of the mining area, the fracture trace of overlying strata in goaf extended to the coal wall’s interior. The fracture range of overlying strata is larger than that of the miningd: area. This study has a practical value for water disasters, gas outbursts, and rock strata control.

The fracture characteristics and zoning model of overburden during longwall mining are the basis of coal mine disaster prevention. However, the existing theoretical model is inconsistent with the field measurement. In order to further research into the strata’s fracture characteristics and optimize the overburden’s zoning model, we used the elasticity and Winkler foundation theory to establish first fracture and periodic fracture mechanics models of clamped boundary supported by an elastic foundation with a key stratum as the research object. We analyzed the stress distribution characteristics and fracture evolution pattern of the mining‐induced key stratum. We analyzed the zoning characteristics of mining‐induced overburden and established the zoning model according to different fracture mechanisms. The results show that the key stratum formed a double “O‐X” shaped interconnected fracture zone after the first fracture. The key stratum formed a double “C‐K” shaped interconnected fracture zone after the periodic fracture. We divided the mining‐induced overburden into three zones along the horizontal direction: the original rock zone, the inverted triangular compression‐shear fracture zone, and the trapezoidal tensile fracture zone. The study revealed the mechanism of inverted step fracture in the separation zone, explained the fracture mechanism of the coal pillar support zone, and has significant theoretical value for the prevention and control of water disasters, gas outbursts, and strata movement.

Longwall top coal caving mining is one of the main methods of mining thick coal seams in China. Therefore, carrying out the classification evaluation of top coal caving is of great significance to ensure mining success and reduce the risk of mining technology. In order to realize the classification evaluation of top coal caving, this article introduces the method of using BigML to establish the classification evaluation model of top coal caving. Furthermore, using the data from the CNKI database as sample data, a classification evaluation model of top coal caving is established on BigML. After training, testing, and optimization, the model is used to evaluate the top coal caving in No. 3 coal seam of Gucheng Coal Mine, and the evaluation result is grade 1, which is consistent with the engineering practice. The final research results show that the application of BigML in the classification evaluation of top coal caving is successful; the evaluation of top coal caving through BigML is reliable; BigML provides another scientific reliability way for the classification evaluation of top coal caving.