Non-coal pillar mining with roadway formed automatically (RFANM) is a new mining approach, which demonstrates revolutionary significance because it does not require making roadway before mining and coal pillar retaining. In order to explore the stability of the surrounding rock structure in RFANM, the deformation of the surrounding rock was theoretically analyzed and simulated based on three different fracture positions of the main roof. It was concluded that reasonable control of temporary support strength in roadway is of great importance to control the deformation of the entry. The deformation process of surrounding rock under different fracture positions in RFANM was simulated by using the Universal Discrete Element Code (UDEC). The results of the numerical simulation showed that the main roof was fractured at the solid coal side or gob side; the deformation of the roadway was small. The fracture condition of the main roof at the gob side required a higher effect of roof slitting or temporary support from the roadway. Through drilling and peeping at the retained roadway, it was judged that the main roof was broken inside the coal wall. Field monitoring results revealed that the deformation of the roadway can be effectively controlled.

A vinyl acetate ethylene modified cement based thin spray on liner was tested to clarify how curing temperature, relative humidity, and age control tensile behaviour and sandstone interfacial bonding. A single factor design was used. Temperature levels of 20, 30, 40, 50, and 60 ◦C were applied at 30% RH for 7 d. Humidity levels of 30%, 45%, 60%, 75%, and 90% RH were applied at 20 ◦C for 7 d. Ages of 7 to 35 d were examined at 20 ◦C and 30% RH. Tensile responses were measured on dog bone specimens. Interfacial bonding was quantified using pull off type tests on sandstone composites. Tensile strength showed an optimum with temperature, increasing from 1.72 MPa at 20 ◦C to 3.14 MPa at 40 ◦C and then decreasing to 2.26 MPa at 60 ◦C, while failure strain decreased from 7.55% to 6.04%. Peak interfacial bond strength also peaked at 40 ◦C, rising from 1.10 MPa to 1.96 MPa, and bond energy reached 3107.9 N·mm. Humidity caused a threshold type deterioration. Tensile strength dropped to 0.79 MPa at 90% RH, whereas failure strain increased to 16.88%. The interface was more humidity sensitive, with peak bond strength decreasing to 0.33 MPa and bond energy decreasing to 849.4 N·mm at 90% RH. The results highlight that high humidity makes the interface the controlling weakness, while moderate temperature improves early performance when moisture is controlled.

Utilizing calcined coal gangue (CCG) as a replacement for clay in limestone-calcined clay cement (LC3) reduces economic costs and carbon emissions while enabling resource utilization of coal gangue. This study systematically characterizes freeze-thaw cycles (FTCs) damage in High-performance concrete made from LC3-CCG through surface damage evolution, internal pore distribution, energy dissipation patterns, and service life assessment. Key results demonstrate: compared with the metakaolin (MK) control group, LC3-60-CCG exhibits higher particle distribution coefficient values and strength loss rates but lower mass loss rates; surface damage manifests both shallow-layer concentration and deep-layer penetration, with micro-fractal dimension being most significantly affected; FTCs failure initiates via pore penetration through mortar matrices between aggregates, while surface spalling propagates along external pores. Increasing FTCs elevate the intersection strain value of elastic and dissipated strain energy curves, intensifying conjugate shear trends; laboratory predictions indicate LC3-60-CG achieves 910 maximum FTCs, exceeding LC3-60-MK's frost resistance lifespan.