Slag waste can be effectively used to produce coal–fired slag concrete (CSC), which has economic and environmental benefits. However, CSC in engineering construction will eventually subjected damage. The purpose of this study is investigate the mechanical characteristics damage evolution behaviour specimens under a uniaxial compressive load using acoustic emission (AE) monitoring technology. Through compression testing AE monitoring, stress–strain curve are obtained. Subsequently, model...

Rock destruction under high‐temperature conditions is a key issue for nuclear waste treatment projects, underground coal gasification, and improvement of the use geothermal energy heating. Therefore, in this study, various methods techniques were integrated to study changes mechanical properties, mineral composition, microscopic fracture characteristics Sichuan sandstone treated at 600°C. First, toughness indirect tensile strength untreated sandstones tested by MTS testing machine, double‐K...

It is of great significance to study the reasonable position mining roadway under strip coal pillar for increasing stability roadway, reducing waste resources, and realizing safety production working face. Based on research background face in Jinqiao Coal Mine Jining, Shandong Province, through theoretical analysis, similar material simulation experiment, numerical stress distribution law, plastic failure range, rationality setting different width sections are systematically studied....

The no-pillar mining method is widely used in coal engineering because of its superiority resolving mine pressure hazards and protecting natural resources. In view the geological conditions stable strata a Shandong Coal Zone, novel segmented roadside plugging-filling proposed by introducing filling coefficient into filling. operation process designed with new grouting forming device. Based on relationship between theoretical deflection cantilever beam geometric settlement parallel models,...

Gob-side entry retaining, also termed as non-pillar mining, plays an important role in saving coal resources, high production and efficiency, extending the service life of mine improving investment benefit. Herein, a gob-side retaining method involving use bag filling material for wall construction is proposed based on thin seam mining characteristics. First, mechanical model established, side support resistance 8101 working face calculated. The properties are investigated through...

High temperature can change the mechanical properties of granite, with significant nonlinear characteristics, and at same time its microstructure. Therefore, two kinds granites are used in this paper: one is normal granite other treated 600°C, a detailed comparative study made. The fracture toughness rocks was tested by tests, results were analyzed mechanics model (SEL). At time, order to understand influence high on mineral composition microstructure XRD, optical microscope, SEM observe...

Underhand cut-and-fill stoping is an efficient, sustainable mining method that particularly applicable to complicated conditions in which both the peripheral rocks and orebody are extremely unstable. Considering of shallow, steeply dipping, narrow Canzhuang gold mine Shandong Province, China, a new underhand without sublevel does not use conventional sublevel, access stope, decline proposed. Additionally, novel auxiliary ventilation mode applied achieve high-efficiency ventilation. The...

Aiming at the problem of seepage-stress coupling failure instability cemented gangue-fly ash backfill (CGFB) with defects, triaxial compression test and acoustic emission (AE) monitoring CGFB were carried out in this paper. The strength characteristics defective under analysed,the variation rules AE parameters (ring count, b-value entropy value) process systematically studied. It is found that b-value, defects have a 'mutation' phenomenon, which can be used as precursor feature backfill....

Aiming at the backfill with prefabricated fracture under seepage‐stress coupling, concepts of macrodamage, loaded mesodamage, seepage and total damage were proposed. Based on macroscopic statistical model, coupling effect seepage, stress, initial was considered comprehensively model established. The mechanical properties different water pressures confining tested rationality verified. research shows that are determined by pressure, load, fracture, effect. Fracture have significant effects...

This paper investigates the unstable fracture toughness of specimens different heights using double‐K model for three‐point bending tests on notched concrete beams. It is shown that exhibits a significant size effect. The modified maximum tangential stress (MMTS) criterion used to explain effect toughness. MMTS considers higher order terms Williams series expansion field. results show can reasonably estimate recommended minimum height specimen be 200 mm when beams are determine

Aiming at backfill with crack under the thermo-mechanical (TM) coupling, concepts of macro-damage, loading meso-damage, thermal and total damage were proposed. Based on statistical theory, considering coupling effects temperature, load initial crack, a evolution model TM was established. this, strength criterion mechanical constructed by multivariate function full differential method. The research shows that: (1) theoretical curves are in good agreement test curves, which verifies...

Addressing the challenge of radar detection small targets under sea clutter, target methods based on a three-dimensional feature space have shown effectiveness. However, their application has revealed several problems, including high dependency linear relationships between features for dimensionality reduction, unclear reduction objectives, and spatial divergence samples, which limit performance. To mitigate these challenges, we constructed density distance metric employing copula functions...

Based on cohesive zone model (CZM), a simplified method for estimating the tensile softening curve of quasi-brittle materials is proposed. First, assume that virtual crack opening displacement linearly distributed. According to Castigliano's theorem, proportional function fk(a0,a) proposed, which can obtain Crack Tip Opening Displacement (CTOD) directly from Mouth (CMOD). This simplifies governing equations CZM and be obtained quickly. Finally, effectiveness verified by experiment finite...