For sustainable utilization of limited coal resources, it is important to increase the recovery rate and reduce mine accidents, especially those occurring in entry (gateroad). Entry stabilities are vital for ventilation, transportation other essential services underground mining. In present study, a finite difference model was built investigate stress evolutions around entry, true triaxial tests were carried out at laboratory explore wall under different mining conditions. The modeling...

Gob-side entry retaining by roof cutting (GERRC) employed in a deep inclined thick coal seam (DITCS) can not only increase economic benefits and recovery, but also optimize surrounding rock structure. In accordance with the principles of GERRC, technology GERRC DITCS is introduced roof-cutting mechanical model proposed to determine key parameters depth angle RC. The results show that greater RC angle, easier caving goaf roof, length cantilever beam increases. should account for dip when...

A non-pillar coal-mining technology with an automatically formed entry is proposed, which reduces the waste of coal resources and underground drivage workload. Three key techniques in this cooperate to achieve automatic formation retaining gob-side entry, realize mining. Constant-resistance large deformation (CRLD) support ensures stability roof; directional presplitting blasting (DPB) separates roof gob a blocking-gangue system (BGSS) integrates caved rock material as effective rib. An...

Abstract Aim (1) To understand the tree root-soil interaction under lateral and moment loading using a physical modelling technique; (2) detect possible factors (e.g. root architecture, water condition, stress level) influencing tree’s push-over behaviour; (3) identify suitable scaling laws to use in modelling. Methods Two 1:20 scaled models with different architectures (namely, deep narrow, shallow wide) were reconstructed 3D printed based on field-surveyed architecture data. Push-over...

Understanding the stability of trees under lateral loads arising from natural hazards (e.g. extreme weather and debris flows) is important, as fallen can become a potential threat to life infrastructure. Two 1 : 20 scale three-dimensional printed analogue root system models, with architectures field-surveyed architecture data, were used simulate push-over behaviour in silty sand different conditions centrifuge. The peak overturning moments obtained verified against data field winching tests....

The nested quadtree based partitioning scheme of HEVC contributes a lot to the coding efficiency improvement, however, it adds significant complexity encoder. This paper introduces fast prediction unit (PU) level depth decision (FPDD) algorithm. It is achieved by making use inherited correlation PU structure between current largest (LCU) and its spatial temporal neighbors. To reduce error propagation, we also propose confidence grading prevent LCUs with bad from being referred others....

Abstract Directional presplit blasting (DPB) technology for an innovative no-pillar mining approach is introduced. First, a mechanical model established to analyze crack initiation and coalescence using the new technology. The explosion pressure formula containing tress concentration factor explains relationship between quantity of explosives coalescence. Subsequently, dynamic finite element simulation method used study stress damage evolution process blasthole wall in ordinary DPB. results...

Gob-side entry retaining (GER) is a hot issue with regard to saving resources and reducing the drivage ratio in longwall mining. This paper investigates an innovative approach of roof presplitting for gob-side (RPGER). RPGER uses directional cumulative blasting split advance. The rock within range caves gob after caved gangue can become natural rib expands be supporting body resisting upper movement. A numerical model was established by discrete element method (DEM), which showed that effect...

The traditional gob-side entry-retaining mining method has problems such as difficulty in roof collapse and large deformation of the entry, which may affect safety mine production. In this study, we introduced a bidirectional blasting technology (BBT) to make smoothly improve method. A theoretical model BBT was established stress propagation analyzed by numerical simulation. then applied composite sandstone condition. Compared with ordinary blasting, concentrated directional cracks can be...

For smaller lateral plant roots in coarse-grained soils, a potentially large relative size of soil particles compared to the may affect their transverse resistance. Even for larger trees, particle effects be important, e.g. when testing 1:N reduced scale models geotechnical centrifuge. The Discrete Element Method (DEM) was used investigate this problem. A rigid root segment under loading plane strain simulated and with Finite (FEM) simulations, where modelled as continuum (no effects). at...

Under the conditions of high ground stress and mining disturbance, strata breakage that is induced by severe. Thus, it critical to investigate structural characteristics key (KS) in deep thick mining. This study introduces an innovative technology, namely, directional blasting fracturing, which energy-gathering tube installed a borehole explosive detonated break roof specified direction. A theory balanced bulk filling established based on requirements developing voussoir beam structure, can...

Severe deformation of surrounding rock and excess-gas are the main problems faced in mining high-gas coal seam. This paper analyzes characteristics mechanical model seam, proposes control technology gas prevention control. Based on this, entry automatically formed by roof cutting (EAFRC) constant resistance large anchor cable (CRLDA) support Shaqu mine put forward. At same time, stress migration law working face under traditional method EAFRC were compared analyzed. Through field engineering...

Abstract For smaller plant roots in coarse-grained soils, large relative size of soil particles compared to can affect their axial resistance. Even for the larger trees, particle effects may be important, e.g. when testing 1: N scale models tree uprooting a geotechnical centrifuge. In this study distinct element method (DEM) was used investigate problem. The sinker root centrifuge model system under loading analysed, with its simulated behaviour finite (FEM) simulations, where modelled as...