Rubberized concrete (RC) has attracted more attention these years as it is an economical and environmental‐friendly construction material. Normally, the uniaxial compressive strength (UCS) of RC needs to be evaluated before application. In this study, evolutionary random forest model (BRF) combining (RF) beetle antennae search (BAS) algorithms was proposed, which can used for establishing relationship between UCS its key variables. A total number 138 cases were collected from literature...

Abstract Roadway stability in extremely soft coal mass is a typical challenge deep underground mines, as the most widely adopted support structure such rock bolting, compound system normally fails. This paper proposed novel prereinforcement method for roadway, that is, jet grouting (JG) technique, to improve quality of surrounding and form stable namely grouted coalcrete. The field laboratory tests were conducted evaluating applicability JG mechanical parameters A numerical model was...

Predictive model and formula of jacking force has been well-established for circular pipe in the past decades. However, frictional mechanism pipe–soil–slurry prediction rectangular not well understood. Nowadays, is widely used, because its over 20% larger effective usable area than that as underground facilities, with same cross-sectional area. Nevertheless, corresponding models thrust are lacking. In order to further understand slurry jacking, five classical analytical calculation have...

In maintaining the efficiency of coal mining, stability roadway plays a significant role, as it is closely related to production and safety personnel. deep underground mines, rheological deformation normally occurs, which affects its service life. To address this problem, in paper, novel high-efficiency Jet Grouting (JG) technique was presented, control effect on investigated. A creep test specimen laboratory scale performed, behavior revealed. The rheology mass surrounding further analyzed...

For large underground coal mines producing 10 million tons a year, rapid excavation and stability of deep roadways are pivotal to ensure sustainable, safe, efficient production. This paper provides case study Hulusu Coal Mine in Inner Mongolia, where roadway speed was insufficient meet production needs. Moreover, deformation the roofs severe. To achieve control roadways, new support system proposed constructed at depth 640 m. The consisted long flexible bolts pretensioned high levels spaced...

Controlling floor heave plays an important role in the stability of mining roadways that is pivotal to sustainable, safe, and efficient development coal resources underground mines. In order propose highly economical methods controlling heave, numerical simulation, laboratory physical engineering practice were carried out reveal mechanism reinforcing roof sidewalls control roadway, return airway 15208, Xinjing Coal Mine Yanquan area China. The simulation demonstrated surrounding rock roadway...

Rapid excavation could mitigate the imbalance relationship between speed and production needs that plays a pivotal role in sustainable development of large underground coal mines. This paper provides case study on Bolter Miner Excavation Technology (BMRET) Menkeqing Coal Mine, which has high 13 million tons per year Inner Mongolia. The temporal characterization procedures is analyzed detail based field monitoring data. improvement roadway driving process efficiency under new support design...

The stability of underground openings is pivotal to sustainable safe mining in coal mines. To determine the and tunneling safety issues 800-m-deep through large fault zones argillaceous rocks Guqiao Coal Mine East China, pilot industrial test, laboratory experimentation, field measurements were used analyze deformations failure characteristics surrounding rock, influence factors excavation openings, study control countermeasures. main influencing include zones, high situ stress, poor...

It is of significance to study the damage and destruction rock under cyclic loading in geotechnical engineering. We determined trends evolution sandstone constant-amplitude tiered unloading uniaxial compression. The results show that (1) variation acoustic-emission events was consistent with stress curves 89% all occurred during cycling stages. observed Kaiser effect more notable cycling. (2) variable increased sharply stages its increment 0.07 higher for than Sandstone exhibited greater...

Uniaxial cyclic loading‐unloading compression experiments with schemes of six loading rates and unloading were carried out on the combined testing platform. Impact rock AE characteristics was revealed. Results show that increasing resulted in decreasing total rings entire deformation failure process. Increasing rate decreased at stages, stages same cycle. Total counts had a negative linear relationship to rates. The stage active period phenomena, impacts more apparent. Especially when...

This laboratory study investigated the damage evolution of sandstone specimens under two types cyclic loading by monitoring and analyzing changes in elastic moduli ultrasonic velocities during loading. During low‐level loading, stiffness degradation method was unable to describe accumulations but velocity measurements clearly reflected development. A crack density parameter is introduced order interpret tangential modulus velocities. The results show following. (1) Low‐level enhanced...

Goaf-side roadway driving with narrow coal pillars could obviously improve resource recovery rates compared traditional large, wide pillars, and this is pivotal to the sustainable development of underground mines. However, it very difficult control stability goaf-side driving, especially in deep, thick seams large high working faces. In order entry face 210106 deep seam Xinji No. 2 Coal Mine Anhui Province China, we carried out field investigations, theoretical calculations, numerical...

Zhuji coalmine, a typical deep underground coalmine located in Huainan city, Anhui province of China, is characterised by rich gas, high situ stress and low permeability. These geotechnical conditions cause serious problems including outburst, excessive gas emissions the upper corner coal face, resource recovery resulting from large remaining pillars when using conventional mining methods. Retained gob-side gateroad (RGSG) proposed to resolve these eliminating extracting simultaneously. To...

Abstract To inhibit the destructive evolution of HfB 2 ‐SiC coating during oxidation, La O 3 was added to modify oxygen‐blocking capability coating. The effect content on oxygen barrier capacity investigated. addition 5 vol.% lowered oxidation activity and strengthened inert coating, which made permeability maximum weight change rate decrease by 30.32% 73.97%, respectively. Due solid solution reaction dispersed , HfO SiO nanoparticles, a stable Hf‐B‐La‐Si‐O multiphase glass formed surface...

The longevity of grouting has a significant effect on the safe and sustainable operation many engineering projects. A 500-day experiment was carried out to study long-term mechanical behavior nano silica sol grouting. activated with different proportions NaCl catalyst cured under fluctuating temperature humidity conditions. parameters grout samples were tested using an electrohydraulic uniaxial compression tester improved Vicat instrument. Scanning electron microscope, X-ray diffraction,...

Rock burst is a typical dynamic disaster in deep underground coal mining. Based on the support problems of roadways fully mechanized caving face 401111 Hujiahe Coal Mine suffering from rock Shaanxi Province China, failure law and influencing factors surrounding roadway are analyzed. The results show that deformation shows characteristics elastic, plastic transformation, rheology, expansion. At same time, it has roadway, such as fast speed, long duration, asymmetric deformation, large loose...

A new experimental method for characterizing the porosity of loose media subjected to overburden pressure is proposed based on functional relationships between porosity, true density, and bulk density. This used test total coal particles from Guobei mine in Huaibei mining area, China, terms influence particle size porosity. The results indicate that under 20 MPa situ stress about 10.22%. obey an attenuated exponential function, while a power function. greatly reduced sensitivity high with...

Understanding the acoustic emission effects on bolts under cyclic loading is of great significance for support roadways. The presented research focuses characteristics loading. following main conclusions were drawn: (1) With a higher frequency, counts rate increases, while total energy released in given path decreases. (2) A fitting formula established according to relationship between tension amplitude and cumulative counts, which can analyze magnitude level load. (3) damage factor load...