• Research on the mechanism and models of earthquake triggering by dynamic disturbance is reviewed. • The drawbacks of the available research works on earthquake triggering are pointed out. • Some suggestions on scientific issues of earthquake triggering for future research are proposed.
• This study explored the influence of burial depth and time effect on the energy evolution of four-dimensional (4D) supported surrounding rock by performing elastic strain energy calculation and finite element analysis. 4D support was originally launched by the authors. • The results indicate that the combined support mode of 4D roof support and conventional side support is highly applicable for the stability control of surrounding rock of deep roadways with a burial depth exceeding 520 m, in that it can effectively restrain the area and depth of plastic deformation of surrounding rock. • Moreover, 4D anchor cable support limits the accumulation range and rate of elastic strain energy, which is more conducive to the long-term stability control of roadway surrounding rock than conventional support. • 4D support can effectively reduce the convergence deformation of roadway surrounding rock, and maintain stability for a long time, thus meeting the requirements of safety in coal mining sites.
• Combination of a carbon sink material such as biochar and automated irrigation technology is proposed for regulating soil water content. • 1-D column tests were conducted to determine optimal biochar content required for regulating water content within the desired range of field capacity. • Water usage is minimal for biochar content between 1% to 3%. This is due to enhancement of soil water retention capacity by biochar. • Excess biochar (5% content) can also lead to development of fungi mold on surface of soil and higher water usage.
• Ultrafine cement, ultrafine fly ash, ultrafine slag, and additives (superplasticizer, AUA, gypsum, and retarder) are used to develop highly efficient composite ultrafine cement (CUC). • Rheological properties, chemical compositions, microstructure characteristics, and mechanical properties of CUC grouts are presented. • The new high-efficiency CUC grouts are used to reinforce the broken surrounding rock and to confirm that grouting can effectively reinforce the surrounding rock.
• The development of the dynamic rock mechanics instrument is clarified, and the three major shortcomings of the existing instruments are summarized. • Based on the conventional triaxial instrument, the first generation of the TFD-2000/D triaxial instrument was developed, which can apply disturbing load independently, implementing the function of cyclic disturbance and combined dynamic and static disturbances. • The second generation of the TFD-2000/D triaxial instrument is improved to achieve variable amplitude cyclic loading, low-frequency high-level ground stress loading, and cyclic dynamic disturbance alternating with creep.
• A data set of China’s (ultra-)mafic magmatic mine was presented, including 1233 polygons. • The spatiotemporal extension of mines was conceptualized to mirror the mining-related economic and political realities in China.
• The effects of thermal damage and the loading rate on dynamic splitting mechanical properties and fracture surface morphological characteristics of granite were determined. • The surface roughness index Z2 in the axial and radial directions of the Brazilian splitting sample was calculated. • Prediction models of dynamic splitting parameters based on Z22r are proposed.
• In this study, a preliminary site selection method for underground hydrogen storage in salt cavern was established. • Dynamic demands for hydrogen energy were considered as key influencing factors. • The significance of each index in the site evaluation method for underground hydrogen storage in salt mines was investigated. • The Pingdingshan salt mine was identified as a suitable location for underground hydrogen storage in China.