Abstract In many underground rock projects, masses are subjected to coupled static–cyclic dynamic loading. this paper, tests were carried out on granite specimens using a modified split Hopkinson pressure bar study the characteristics and energy evolution of under impact The results show that both sensitive number repeated impacts confining pressure. Under same pressure, increase factor ( DIF ), elastic modulus, transmitted ratio decreases, while cumulative dissipated energy, specific...

The main Jurassic coal seams of the Ordos Basin northwest mining area have special hosting conditions and complex hydrogeological conditions, high-intensity is likely to cause groundwater loss negative effects on surface ecological environment. research was aimed at predicting height water-flowing fractured zone (WFFZ) in that gave instructions for avoiding water inrush accidents realizing damage reduction during actual procedure mine. In this study, 18 samples measured WFFZ were...

Poly[(glycidyl methacrylate)-co-(glycerol monomethacrylate)]-grafted magnetic microspheres were prepared by graft random copolymerization via ATRP from polymer with dispersed Fe(3)O(4) nanoparticles. Penicillin G acylase (PGA) was immobilized onto the brush-grafted microspheres. The PGA initial glycidyl methacrylate/glycerol monomethacrylate ratios of 40/60 to 60/40 possessed higher catalytic activity than that proportions methacrylate in monomer mixture. showed high thermal stability and...

Due to the increase in length of mining face, pressure characteristics and spatial distribution fully-mechanized faces are different from those typical faces, which leads great challenges roof management intelligent control ultra-long faces. Taking face a medium–thick coal seam northern Shaanxi area as an example using field monitoring data for working resistance hydraulic supports, non-linear prediction method was used extract features dynamic sequence deep learning establish model based on...

Drift‐sand layer is a common weak stratum in mine construction. The construction of the shaft passing over drift‐sand very difficult. Traditional method faces many problems such as long period, high cost, poor working environment, and uncontrollability support effect. In view loose fragile rock mass with great deformation sinking driving engineering penetrating layers coal mine, reaction mechanism shortcomings conventional chemical grouting materials were analyzed. New‐type polymer prepared...

The back-filling body in the gob-side entry retaining is subject to continuous disturbance due repeated mining. In this study, uniaxial and cyclical loading tests of concrete samples were carried out under laboratory conditions study damage evolution characteristics with respect microscopic hydration, deformation properties, energy evolution. results showed that, difference gradation coarse fine aggregates, cemented structure was relatively loose, primary failure modes tensile shearing...

The research was aimed at predicting floor water-inrush risk in coal mines and forewarn of such accidents to guide safe production practice. To this end, a prediction method for water inrush combining the chaotic fruit fly optimization algorithm (CFOA) generalized regression neural network (GRNN) is proposed. Floor predicted by virtue robust nonlinear mapping capability GRNN. However, because effect GRNN influenced smoothing factor, CFOA adopted optimize factor. In way, influences human...

Abstract In the context of ecological conservation and high-quality development in Yellow River Basin, extensive silty slopes have emerged downstream alluvial plain regions owing to engineering construction. These are susceptible rainfall infiltration-induced instability, resulting geological hazards, such as landslides mudslides. This study explored hydrodynamic characteristics spatiotemporal evolution patterns under conditions, focusing on River. Experiments were performed monitor...

With the continuous expansion of application range gob–side entry retaining technology, depth, height, and advancing speed coal seams also increase, which brings great problems to stability control surrounding rock structures retaining. As one main bearing rock, roadway–side support body is a key factor for success In order study deformation characteristics instability mechanism roadway-side body, based on materials gob-side retaining, dynamic test back–filling concrete cracks under uniaxial...

In order to study the dynamic mechanical properties of surrounding rock roadway in deep mines with burst, cyclic impact compression tests sandstone under different velocities were carried out by using split Hopkinson pressure bar (SHPB) test system, and stress-strain curves samples loads relationship between energy dissipation numbers analyzed. The results show that, as loading times increase, initial elastic modulus decreases, peak stress strain increases; average rate increases. cumulative...

Under the influence of repeated mining disturbance, back-filling body for gob-side entry retaining may experience a reduction in bearing capacity or even failure, complicating control surrounding rock stability coal mines. This study employs an electro-hydraulic three-axis servo testing machine and ultrasonic detection system to damage evolution precursor instability response behavior concrete retaining. Specifically, we conduct staged loading experiments on specimens concrete. By analyzing...

Manufactured sand has became progressively the primary source of for construction in China, and performance manufactured shotcrete at early age will be affected by blast loading rock tunnel. This paper mainly presents dynamic behaviours that have not been extensively studied. The results indicate that, Quasi-static uniaxial strength elastic modulus shotcretes increase exponentially with curing ages, both them possess same variation tendency ages: quickly before 7 d, while changes slow down...