Investigation on failure behavior of collapse column in China’s coal mine based on discontinuous deformation numerical method

Abstract

Karst collapse column is a serious geological disaster in China’s coal mines. There are various karst collapse columns in coal mine areas, such as Huainan, Huaibei, Xingtai, Lu’an. And they have seriously affected mining safety and geological environment. The present research is focused on analyzing subsidence mechanism and dynamic collapse process. Based on mechanical analysis of thin plate theory, a detailed model of collapse column slipping and bending fracture is constructed to gather the critical conditions of the collapse column roof. The sensitivity parameters analysis shows that both the radius and roof thickness of cave have a great influence on the sliding instability and bending fracture. Meanwhile, the buried depth also affects bending failure. The discontinuous deformation analysis (DDA) method is used to simulate and analyze the collapse process. The numerical results indicate that the stability of inverted funnel collapse column is dominated by the bending stress of roof strata. The movement of columnar collapse column is mainly caused by sliding instability. However, the funnel collapse column is relatively stable, and does not change in the same condition. The displacement field analysis shows that the collapse range of inverted funnel collapse column is obviously larger than that of columnar collapse column, in which its maximum displacement is approximately 1.5 times that of the columnar collapse column. There is no large area collapse on the upper part of the funnel collapse column, and the block system is relatively stable. The principal stress field analysis proves the above results.

Experimental Study of Pore Permeability Characteristics Based On Variable-Mass System In Karst Collapse Pillars

“…This structure can penetrate through the Ordovician tuff, mudstone, and coal layers [21]. When the pressurized water pressure within the Ordovician aquifer is greater than the principal stress of the key layer, the destruction of the column within the surrounding high permeability region will occur [22][23][24]. At this stage, many scholars mainly use series of sudden water models, and the lithological distribution perspective to precisely analyze the sudden water mechanism.…”

Prediction of Fracture Evolution and Groundwater Inrush from Karst Collapse Pillars in Coal Seam Floors: A Micromechanics-Based Stress-Seepage-Damage Coupled Modeling Approach

“…(i) Using a finite element mesh, the model geometry is discretized into a series of MREVs, and the hydromechanical parameters and microcrack parameters for each of the MREVs are initialized (ii) The loading condition of the model is discretized into several small subload steps in the time domain, and the model is loaded sequentially by subload (iii) During each subload step, all hydromechanical parameters of the rock are constant, and a finite element method based on the full coupling analysis is adopted to calculate the average stress field, average pore pressure field, average strain field, and average seepage velocity field for each MREV of the model (iv) According to the stress state of each MREV of the rock obtained by finite element calculation, the 5 Geofluids stress intensity factor at the microcrack tip of each group in each MREV is calculated by Equation (11), and the propagation length of each microcrack is calculated (v) Equations (7), (14), and (15) The above implementation procedure is programmed using a combination of MATLAB and COMSOL software to replicate the dynamic processes of damage and fracture as well as the seepage evolution behavior of the rock under hydromechanical coupling. This program enables more realistic and visual numerical simulations of the process and mechanism of groundwater inrush from KCPs in coal seam floors.…”

“…Ma et al [13] studied groundwater inrush disasters caused by seepage instabilities in KCPs. Zuo et al [14,15] studied the failure behavior of KCPs using a discrete element method. Ma et al [16] investigated the particle erosion effect on the groundwater inrush mechanism of a KCP by using FLAC 3D software and a stress-seepage coupling model.…”

Mechanism Analysis of Delayed Water Inrush from Karst Collapse Column during Roadway Excavation Based on Seepage Transition Theory: A Case Study in PanEr Coal Mine

“…In the early stage, scholars studied the morphological characteristics and pointed out that the cross-sectional morphology was mainly round, oval, and triangular [7][8][9]. It is usually cylindrical or conical in profile and in serrated contact with the surrounding rocks.…”