Abstract With the increase in mining depth and deterioration of surrounding rock conditions, large deformation failure deep roadway is still very common. To solve support problem, it necessary to understand mechanism roadway. This paper presents a case study on behavior design Tangyang mine by field tests numerical simulations. The mass properties were first evaluated based data mechanical parameters specimens. Then, model was established calibrated microparameters. features cracking...

Colloidal plasmonic metal nanoparticles are capable of surface-enhanced Raman scattering (SERS) for various analytical fields. Despite steady efforts to establish hot spots and obtain optimal SERS signals, it remains a challenge ensure the accessibility high density enhancing activity. Here, pyramid silicon was utilized as template fabricate graphene oxide (GO)/silver (AgNPs)/pyramid polymethyl methacrylate (PMMA) three-dimension (3D) flexible structure. Micrographs displayed hybrid...

The stability of deep coal roadways with large sections and thick top is a typical challenge in many mines China. innovative Universal Discrete Element Code (UDEC) trigon block adopted to create numerical model based on case study at the Dongtan mine China better understand failure mechanism control this kind roadway. process an unsupported roadway simulated, results suggest that deformation roof more serious than sides floor, especially center roof. radial stress released intense tangential...

Abstract Jointed rock masses are a common phenomenon in engineering and vulnerable to cyclic loads caused by earthquakes, blasts, traffic loads. Therefore, it is crucial comprehend the fatigue characteristics of jointed under dynamic disturbance for long‐term stability assessments structures. This paper aims investigate effects distinct joint inclinations pre‐cyclic loading on strength failure rock‐like specimens using experiments numerical simulations. The results indicate that decreases...

Abstract Slabbing failure and strain rock burst are the main patterns during excavation construction phases of deep tunnels in hard brittle rock, which cause unexpected equipment damage casualties. This study presents a numerical simulation with an unloading central hole within specimen laboratory scale. A combined finite element/discrete element method (FEM/DEM) reproduces crack initiation, propagation, coalescence around entire process. The influence sectional shapes, rates holes, situ...

The mechanical characteristics of rock are greatly influenced by hydrochemical corrosion. chemical corrosion impact and deformation properties the meso-pore structure under action different solutions for stability evaluation mass engineering high theoretical relevance applied value. Based on actual data, a support vector machine (SVM) constitutive model based artificial bee colony algorithm (ABC) optimization is constructed in this article. porosity (chemical deterioration), confining...

The behavior of gob-side entry under dynamic pressure is totally different from the one driven after movement overlying strata above adjacent coalface goaf. will experience severe roof lateral structural adjustments caused by mining. Thus deformation and failure characteristics narrow coal pillar along gob should be carefully considered. On basis data obtained in a thin seam pressure, measures to reinforce are put forward. In addition, non-harmonious controlling rock structures...

To explore solutions for reinforcement problems of broken rock masses in deep roadways, it is necessary to study the performance cement-based grout and its effect. In this study, grouting-reinforced specimens with different particle sizes coal were made, which revealed effect grouting on bearing capacity mechanism secondary damage instability reinforced specimens. First, was determined that appropriate water–cement ratio (W/C) meet field conditions 0.45. Second, uniaxial compression 0.45 W/C...

Abstract The application of gob-side entry retaining (GER) in steeply pitching seam longwall mining with a hard roof has always been difficult problem. Based on the simplified beam mechanical model, traditional by packing (GERP) structure evolution process and its problems use seams are analyzed. Therefore, based unique characteristics gangue rolling accumulating seam, this contribution proposes an innovative method cutting (GERRC) details technical process. structures GERRC GERP compared....

Obtaining the bursting liability is essential for rock burst mitigation. To reasonably evaluate of coal in deep mining, a new modified energy index considering rebound and damage effects proposed. Then, uniaxial compressive tests gypsum–rock combination specimens with different types are conducted researching evolution liability. Third, traditional KE KED compared. At last, reasonability verified through PFC2D simulation. Results show: (1) When evaluating coal–rock combination, must be...

In the mining process of an underground coal mine, dynamic load often causes great damage to roadway and affects normal mine. this paper, deformation surrounding rocks under static different disturbance intensities is studied by numerical simulation. The results show that same condition, greater strength is, more obvious roof displacement subsidence is. With increase in propagation distance, amplitude waveform decreases gradually. Under intensity, variation with frequencies studied....

The collapse of overlying rocks caused by the instability residual coal pillars during lower seam mining significantly impacts its safety. This paper focuses on gentle dipping group and utilizes discrete element method (DEM) as basis to comprehensively consider multiple factors through orthogonal experiments. In so doing it reveals influence mechanisms various at a close distance under pillar. Firstly, process in gently-dipping seams was simulated analyzed based case study Baoping mine....

ABSTRACT Nonpersistent joints are prevalent in engineering rock masses and sensitive to cyclic loads induced by geological movements disturbances. Therefore, studying the fatigue mechanisms of with nonpersistent under compressive is crucial for ensuring rational design long‐term stability structures. Based on laboratory experiments, this study employed discrete element method create specimens different joints, uniaxial loading tests were conducted these maximum stress levels. The results...

Physical model tests were first performed to investigate the failure pattern of multiple pillar-roof support system. It was observed in physical tests, pillars design with same mechanical parameters #1, cracking occurred simultaneously panel and roof above barrier pillars. When 2 5 lost bearing capacity, collapse supported by those occurred. #2 a relatively weaker pillar (pillar 3) among six found that whole system divided into two independent systems crack, subsidence events during loading...

Abstract In this study, we present a comprehensive investigation of the ground stability gob‐side entry by roof cutting in relation to mining stage, based on field measurements, theoretical analysis, numerical simulation, and situ practice. Differing from normal mode entry, mining‐induced stress strain evolution under (GSERC) is extremely complex, unreasonable support can cause serious deformation collapse GSERC. Taking Dadougou coal mine as engineering background, response, rock mechanics...

Accurately characterizing the mechanical behavior and fracture mechanisms of rock containing holes under dynamic loads is essential for ensuring stability underground structures. In this study, to enhance understanding processes in specimens with cavities subjected impacts, experimental numerical studies focusing on influence borehole geometry strain rate are conducted. The results reveal that affects specimens’ strength peak strain. However, degree such diminishes as diameter increases two...

Understanding the deformation failure behavior of composite rock strata has important implications for deep underground engineering construction. Based on uniaxial compression laboratory test specimens containing holes, microscopic parameters in particle discrete element simulation are firstly calibrated. Then, mechanical properties and characteristics with holes under different confining pressures studied. The results show that dip angles have significant effects peak strength elastic...

The large-section gob-side tailentry of the sublevel caving face often deforms heavily in horizontal direction when driving and mining deep mines, especially side solid coal, so it is difficult to support needs several maintenances for enough space.The control mechanism technology put forward based on location main roof's lateral fracture decrease large deformation.And field test monitoring roadway done 1306 coalface Dongtan Mine.It proved that tailentry's deformation obviously reduced..

This study was aimed at the large deformation phenomenon of rock mass surrounding gob‐side entry driven in a 20 m extra‐thick coal seam. Taking tailgate 8211 as engineering background, numerical investigation employed to analyze law entry. The results are follows. (1) Because immediate roof composed weak with thickness 17 m, vulnerable fail effect overlying strata pressure; thus, visual subsidence maximum convergence 800 mm observed field. (2) bearing capacity pillar significantly less than...