In this study, taking the Sheng’an coal mine as an engineering background, failure characteristics of surrounding rock a roadway under repeated mining in close-distance seam is comprehensively illustrated through field measurements (e.g., drilling imaging), theory analysis and numerical simulation (finite difference method (FDM)). The results show that although return airway 10905 remains intact, apparent roadway’s roof pillar can be observed. addition, expression floor depth caused by upper...

In view of the multi-field coupling effects such as rainfall infiltration, reservoir water level (RWL) seepage, and fissure risk slope disaster increases sharply. This study takes an open-pit mine in China research object. Based on improved Green–Ampt model key objective, infiltration was by combining dynamic changes wet front depth slope. The proposed integrates Darcy's law mass conservation principle establishes mechanism between seepage stress fields. Numerical verification performed...

The overlying strata of the lower coal seam is easy to be collapsed causing roof caving accident at end face mining working under repeated in close-distance seams. In order predict instability face, mechanical model granular arch structure established this study further analyze its main influencing factors. results show that height advancing speed, distance seams, tip-to-face distance, strength surrounding rock and support setting load are factors on face. Subsequently, prediction...

In order to effectively solve the problem of gas concentration overrun in upper corner goaf and tailentry during mining panel 9303 Anshun Coal Mine, based on advantages controllable trajectory wide coverage area directional drilling technology, high long boreholes are arranged extract pressure relief gas. Firstly, principle borehole drainage technology is introduced, fracture evolution overlying strata obtained through using numerical simulation, theoretical calculation, field practice,...

In order to analyze the influence degree of different factors on gas extraction radius, basis coal seam flow theory and elastic mechanics, considering seepage rate change flow, COMSOL Multiphysics numerical simulation software is secondarily developed by using stress-seepage coupling mathematical model rock containing gas. Taking No.2 Juji Coal Mine as an example, effective radius under negative pressure, borehole diameter, time, initial permeability are simulated, respectively. Then,...

During the transportation process of debris flow with large wood (LW), phenomena such as channel blockage and collapse frequently occurs, resulting in increased discharge surges, heightened erosion intensity, amplified damage. Accurately predicted performance is basis evaluating damage disaster mitigation woody flow. In this study, we conducted a series laboratory experiments on erodible gully bed. The experiment results show that final types can be divided into three types: non-blockage,...

Uplift pressure is a critical vertical load on check dam foundations, playing pivotal role in structural design and stability. However, the characteristic of uplift remains complex not fully understood. In this study, specialized test device was designed; 36 tests were conducted to simulate closed dams under varying debris flow conditions. The formation evolution analyzed, along with influences bulk density fine particle contents. Results indicate peak head decreases increasing content,...

In view of the fact that face‐end roof fall under repeated mining close‐distance coal seams seriously affects normal production working face, this paper takes face 17101 as background, different influencing factors caving exposed to are analyzed through field observation mine pressure data, calculation schemes obtained by using orthogonal experiment, subsidence is taken judgment index, UDEC simulation software used calculate when change, and application SPSS statistical for various...

Abstract Borehole destabilization damage is an important factors affecting gas extraction efficiency. To derive the fracture development law, strain, and energy evolution characteristics of different borehole diameters, uniaxial compression experiments were conducted on prefabricated rock specimens with diameters. The results showed that elastic dissipation pore diameters changed process, distribution inside specimens. show as size specimen increases, strain area damaged by tensile gradually...

Abstract The overlying strata of the lower coal seam is easy to be collapsed causing roof caving accident at end face mining working under repeated in close-distance seams. In order predict instability face, mechanical model granular arch structure established this study further analyze its main influencing factors. results show that height advancing speed, distance seams, tip-to-face distance, strength surrounding rock and support setting load are factors on face. Subsequently, prediction...

Supercritical water gasification provides a new approach to the green transformation of coal. Nevertheless, flow behaviour fluid and particles inject into reactor through nozzle still warrant further research. In this paper, three-dimensional numerical simulation particle jet in supercritical environment is carried out using LES-DPM. The simulations focus on effects size, Stokes number, mass flux ratio initial velocity characteristics fluid-solid flow. findings were that as size decreases...