A New Classification Method of Mine Goaf Ground Activation Considering High-Speed Railway Influence

Abstract

With the rapid development of high-speed railways in China, it is inevitable that some of the lines will have to traverse through the mine goaf ground, and there is little research on whether the “activation” of the foundation of the mine goaf ground occurs under the influence of train loads. In order to provide a safe and reliable basis for the construction of high-speed railway in mine goaf ground, a new classification method of mine goaf ground activation is proposed considering the stability and railway influence. First, the stability evaluation system of the mine goaf site is established with 3 primary indexes and 12 secondary indexes. The 47 groups’ data of the mine goaf ground site are collected as learning samples. Five machine learning methods including decision tree, discriminant analysis, support vector machine, and classifier ensemble are used to learn and test the data. The optimal algorithm is selected and the stability evaluation model is established to classify the stability of the mine goaf site. Second, influencing factors of railway are graded to establish an extension comprehensive evaluation model. Finally, based on the above two models, a new classification method of high-speed railway goaf ground activation considering the two factors and five sub-factors is proposed. Through the verification of two engineering examples, the prediction result of this method is “easily activation” and the need to treat the goaf area, and the actual construction is also taken to grouting treatment, proving that the method has certain guiding significance for the project.

Evaluation Model on Activation Classification of Coal Mine Goaf Ground Considering High-Speed Railway Loads

“…The catastrophe progression method [16] evolved on the basis of the catastrophe theory [17,18]. Compared with the analytic hierarchy process [19], fuzzy mathematics [20], and other evaluation methods, the primary benefit of utilizing the catastrophe progression approach lies in the fact that it does not need to weigh the indicators at all grades, and the relative importance of each indicator is considered in the evaluation process. It not only reduces the intervention of human subjectivity but also has a relatively simple calculation process.…”

“…To establish a scientific system to evaluate the stability of the coal mine goaf site, it is crucial to thoroughly account for the impact brought about by a diverse array of factors on said site. By referencing the works of He [4], Guo [22], and Ren [23], this paper classifies the control variables affecting the stability of coal mine goaf into four categories: coal mine goaf parameters, engineering geology, hydrological conditions, and external disturbance. The construction of the stability evaluation system of the coal mine goaf site is shown in Figure 1, where the parameters of the goaf are: span (C1), mining depth-to-thickness ratio (C2), area (C3), and specification (C4) (ratio of span to height); engineering geology: rock mass structure (C5), rock quality index (C6), and geological structure (C7); hydrological conditions: underground visible water (C8), and groundwater body (C9); external effects: surrounding mining (C10), adjacent coal mine goaf conditions (C11), and engineering layout (C12).…”

“…The weight coefficient and normalized correlation degree are calculated using Equation (20), resulting in the comprehensive correlation degree of the evaluation object.…”

Experimental and numerical research of crack propagation process and energy dissipation law of grouting specimens under radial impact load

“…The sand layer is a common, poor self-stabilization and hazardous harmful geology, and it induces frequent geological disasters, such as sand collapse, landslide, and surface collapse (Wen et al, 2020a;Ye et al, 2022). Grouting reinforcement can effectively enhance the overall mechanical properties and anti-leakage performance of the sand beds (Liang et al, 2020;Ren et al, 2022). The tensile strength of the sand layer is far less than the compressive strength after grouting reinforcement.…”

Analysis of Uneven Settlement and Deformation of the Existing Railway under the Condition of Mined-out Area after Mining

“…As the railway construction in front, mining work in the later, so some mining work face inevitably goes under the railway. The mined-out area is the area and range affected by ground deformation and failure due to surrounding rock instability, such as displacement, breakage and collapse, whole subsidence and bending of overlying strata after the mining [1]. Because of the high speed of some special railway and the high requirement of foundation stability, it is very important to analyze and evaluate the deformation and stability of railway subgrade when the mining face crosses under the railway [2,3].…”