Deformation, fracture characteristics and damage constitutive model of soft coal under true triaxial complex stress paths.

Understanding the mechanical properties and damage deterioration mechanisms of soft coal under true triaxial complex stress paths is crucial for predicting and evaluating the stability of the roof during roadway excavation in thick soft coal seams. This study examines the evolution of deformation strength, fracture characteristics, and acoustic emission patterns of soft coal under various initial stress levels and stress paths using true triaxial loading and unloading tests. The research reveals that soft coal undergoes rapid expansion deformation and ultimately fails along the unloading direction, which varies with different stress paths.

Elastoplastic analysis on deformation and failure characteristics of surrounding rock of soft-coal roadway based on true triaxial loading and unloading tests.

Since accidents such as roof caving, rock fragmentation, and severe deformation are particularly likely to occur during roadway excavation in soft and thick coal seams, grasping the range and distribution of deformation and fracturing of surrounding rock is of crucial for evaluating roadway stability and optimizing support design in such coal seams. In this study, based on the stress paths encountered during roadway excavation, true triaxial loading and unloading tests were carried out on soft coal, and the deformation and strength evolutions of soft coal under different intermediate principal stress conditions were analyzed. The test results show that the stress-strain relationship in the pre-peak plasticity-strengthening and post-peak plasticity-weakening stages follows a quadratic function, and the strengeth evolution conforms to the Mogi-Coulomb criterion.

Research on an Intelligent Mining Complete System of a Fully Mechanized Mining Face in Thin Coal Seam.

The mining environment of thin coal seam working faces is generally harsh, the labor intensity is high, and the production efficiency is low. Previous studies have shown that thin coal seam mining finds it difficult to follow machines, does not have complete sets of equipment, has a low degree of automation, and has difficult system co-control, which easily causes production safety accidents. In order to effectively solve the problems existing in thin coal seam mining, Binhu Coal Mine has established intelligent fully mechanized mining and actively explored automatic coal cutting, automatic support following, and intelligent control.

Study of the mechanical characteristics of coal-serial sandstone after high temperature treatment under true triaxial loading.

In this study, a series of true triaxial loading tests were carried out on coal-measure sandstone after high temperature treatment by using a self-developed true triaxial test system combined with acoustic emission (AE) monitoring, and the mass loss, deformation characteristics and loss failure mode of sandstone before and after heat treatment were systematically studied. It is found that the true triaxial mechanical properties of sandstone after high temperature treatment are closely related to temperature, and the peak strength, maximum principal strain, volume strain, minimum fracture angle and elastic modulus, which all showed bimodal changes, and 800 °C is the threshold temperature of the first four parameters. The transition temperature of the elastic modulus is 400 °C.

Experimental Study on Mechanical and Damage Evolution Characteristics of Coal during True Triaxial Cyclic Loading and Unloading.

Research on the mechanical properties and damage evolution of coal during true triaxial cyclic loading and unloading is of great significance for maintaining the long-term safety and stability of underground engineering structures in coal mines. In this paper, firstly, the deformation, strength and fracturing characteristics of coal during true triaxial loading and true triaxial cyclic loading and unloading were analyzed. Then, the residual strain characteristics, energy distribution and evolution of coal were systematically studied.

Comparative Study on the Seepage Characteristics of Gas-Containing Briquette and Raw Coal in Complete Stress-Strain Process.

In this study, triaxial compression and seepage tests were conducted on briquette and raw coal samples using a coal rock mechanics-seepage triaxial test system (TAWD-2000) to obtain the complete stress-strain curves of the two samples under certain conditions. On this basis, the different damage forms of the two coal samples and the effect of their deformation and damage on their permeability were analyzed from the perspective of fine-scale damage mechanics. Moreover, the sensitivity of permeability to external variables and the suddenness of coal and gas outbursts were discussed.

A Mn-N single-atom catalyst embedded in graphitic carbon nitride for efficient CO electroreduction.

Developing effective catalysts based on earth abundant elements is critical for CO electroreduction. However, simultaneously achieving a high Faradaic efficiency (FE) and high current density of CO (j) remains a challenge. Herein, we prepare a Mn single-atom catalyst (SAC) with a Mn-N site embedded in graphitic carbon nitride.