Due to the proposal of China’s carbon neutrality target, the traditional fossil energy industry continues to decline, and the proportion of new energy continues to increase. New energy power systems have high requirements for peak shaving and energy storage, but China’s current energy storage facilities are seriously insufficient in number and scale. The unique features of abandoned mines offer considerable potential for the construction of large-scale pumped storage power stations. Several countries have reported the conversion of abandoned mines to pumped storage plants, and a pilot project for the conversion of an underground reservoir group has been formalized in China. A feasibility study that considered the natural conditions, mine conditions, safety conditions, and economic benefits revealed that the construction of pumped storage power stations using abandoned mines could ameliorate several economic, ecological, and social problems, including resource utilization, ecological restoration, and population resettlement. The construction of pumped storage power stations using abandoned mines not only utilizes underground space with no mining value (reduced cost and construction period), but also improves the peak-load regulation and energy storage urgently needed for the development of power grid systems. Combined with the underground space and surface water resources of the Shitai Mine in Anhui, China, a plan for the construction of a pumped storage power station was proposed. The challenges faced by the current project were evaluated, further research suggested, and demonstration projects established in order to help achieve carbon peaking and carbon neutrality goals.

The mechanics behaviors, failure modes and acoustic emission characteristics of rectangular green sandstone specimens containing a single joint with various inclination degree under different confining pressure have been determined in this article. The samples were tested over a confining pressure range of 0 to 40 MPa, and the inclination of the joint was varied between 0° and 50°. The test results indicated that: Mohr–Coulomb criterion is fit to peak strength of intact samples and residual strength of jointed samples with 40°. But the peak strength of jointed sample with 40° increases nonlinearly with confining pressure, which can be fitted by Hoek–Brown criterion. And the confining pressure has a reduction effect on anisotropy for jointed rock. When the inclination angle was less than 40°, the joint has a small negative influence on the strength and deformation of the jointed sample, as the inclination angle increased from 40° to 50°, a drop decrease in peak strength and Young’s modulus can be observed. The failure modes can be classified into T-mode, S-mode and SD-mode. Finally, the evolution laws of AE count for green sandstone specimens has been discussed.

In order to effectively address stability control technology issues of soft surrounding rock roadways in deep mines. This study analyses the deformation and failure characteristics of the surrounding rock of a −962 m horizontal track roadway with original support conditions based on a severe deformation case that occurred in a mine. Upon establishing a mechanical model of surrounding rock failure zoning for circular roadways, which is based on the relationship between the stress–strain curve of soft rocks and the secondary stress distribution and strength of surrounding rock, this study explores the influence of rock strength indicators, disturbance degree, and support resistance on the stress distribution of the surrounding rock. The failure or instability mechanism of high-stress soft and weak surrounding rock is revealed on this basis. A multi-stage strengthening combined support technology is proposed, which consists of “high-strength prestressed anchor bolt (cable) supports as the core, deep and shallow hole groutings as the foundation, bottom angle, and floor anchorage grouting reinforcements as the key.” Moreover, numerical simulation and engineering practice optimize and verify the support scheme. The results show that after adopting the multi-stage strengthening combined support technology, the deformation of the surrounding rock of the roadways was only 12.6~14.3% of that under the original supporting parameters, and the deformation rate was still less than 0.2 mm/d even after 40 days. The proposed surrounding rock support method realizes the stability control of the roadway, which also has specific reference significance for similar projects.

Utilizing underground coal gasification cavities for carbon capture and sequestration provides a potentially economic and sustainable solution to a vexing environmental and energy problem. The thermal influence on creep properties and long-term permeability evolution around the underground gasification chamber is a key issue in UCG-CCS operation in containing fugitive emissions. We complete multi-step loading and unloading creep tests with permeability measurement at confining stresses of 30 MPa on pre-cracked sandstone specimens thermally heat-treated to 250, 500, 750 and 1000 °C. Observations indicate a critical threshold temperature of 500 °C required to initiate thermally-induced cracks with subsequent strength reduction occurring at 750 °C. Comparison of histories of creep, visco-elastic and visco-plastic strains highlight the existence of a strain jump at a certain deviatoric stress level—where the intervening rock bridge between the twin starter-cracks is eliminated. As the deviatoric stress level increases, the visco-plastic strains make up an important composition of total creep strain, especially for specimens pre-treated at higher temperatures, and the development of the visco-plastic strain leads to the time-dependent failure of the rock. The thermal pre-treatment produces thermal cracks with their closure resulting in increased instantaneous elastic strains and instantaneous plastic strains. With increasing stress ratio, the steady-state creep rates increase slowly before the failure stress ratio but rise suddenly over the final stress ratio to failure. However, the pre-treatment temperature has no clear and apparent influence on steady creep strain rates. Rock specimens subject to higher pre-treatment temperatures exhibit higher permeabilities. The pre-existing cracks close under compression with a coplanar shear crack propagating from the starter-cracks and ultimately linking these formerly separate cracks. In addition, it is clear that the specimens pre-treated at higher temperatures accommodate greater damage.