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In this paper, the formation mechanism of a slightly inclined bedding mudstone landslide in the overlying mountain of the coal mining subsidence area of the Tanshan Coal Mine in Ningxia, China, is studied. By means of geotechnical investigation, indoor geotechnical tests, theoretical analysis and other technical means, we find the geological environment background of the study area and obtain the physical and mechanical property indexes of the mining landslide in the Tanshan Coal Mine. By combining the numerical simulation of discrete elements and finite elements, the macro deformation and failure law of the mining mudstone landslide and the displacement and stress nephogram of the failure process are discussed. The results show that the slightly inclined bedding mudstone landslide in the Tanshan Coal Mine is 850 m long from east to west, 500 m wide from north to south and 10,875,000 m3 in volume. It is composed of Jurassic mudstone and is a traction landslide caused by the coal mining subsidence area. The formation of the landslide is affected by internal factors and inducing factors. The internal factors are mainly geotechnical types and engineering geological properties, and the inducing factors are mainly coal mining activities and rainfall. By analyzing and summarizing the calculation process of the slope model prior to the landslide in 2D-Block and GeoStudio numerical simulation software, the sliding process of the slightly inclined bedding mudstone landslide in the Tanshan Coal Mine is divided into four stages: slope creep, slope deformation, landslide movement and landslide accumulation. GeoStudio software is used to calculate the stability of the Tanshan Coal Mine landslide under natural and rainfall conditions. The landslide is in a stable state under natural conditions and is basically stable under rainfall conditions. By comparing the calculation results of the limit equilibrium method and the finite element limit equilibrium method, we find that the calculated stability coefficient is more accurate when the appropriate constitutive model is selected. The research results have important reference significance for the prevention and control of the gently inclined bedding mudstone landslide of the overlying mountain in the coal mining subsidence area of the Loess Plateau.

Fiber-reinforced soils have been of great interest to experimenters for building foundations' strength performance, time, and economy. This paper investigates the effects of water content and polypropylene fiber dosage and length on loess's unconfined compressive strength (UCS) according to the central composite response surface design test procedure. The water content is 11%-25%, the mass ratio of fiber to soil is 0.1%-0.9%, and the fiber length ranges from 6-18 mm. The response surface method (RSM) developed full quadratic models of different variables with response values. After analysis of variance (ANOVA), the mathematical model developed in this study was statistically significant (p ≤ 0.05) and applicable to the optimization process. The optimization results showed that the optimal water content values, fiber amount, and fiber length were 16.41%, 0.579%, and 14.90 mm, respectively. The unconfined compressive strength of the optimized specimens was increased by 288.017 kPa. The research results can reference the design and construction of fiber-reinforced soil in practical projects such as road base engineering and foundation engineering.

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