Loading and unloading stress paths play critical roles in investigating the deformation and failure of roadway excavation. In this study, tests under four different loading and unloading stress paths were conducted on red sandstone samples, with the aid of a self-developed true triaxial test system. Meanwhile, the deformation and failure characteristics of the samples were monitored during the tests. The following research conclusions were obtained: The octahedral shear stress is linearly correlated with the average effective stress, and the correlation coefficient R² is 0.9825. The Mogi–Coulomb strength criterion is superior to the Drucker–Prager strength criterion in reflecting strength failure characteristics of red sandstone during loading and unloading. Shear failure tends to occur under uniaxial compression, whereas shear–tensile composite failure occurs under loading and unloading conditions. Compared with the true triaxial loading test, loading and unloading tests produce a larger strain in the unloading direction. Under loading and unloading stress paths, with the increase in intermediate principal stress (IPS), the strain in the direction of IPS gradually changes from expansion to compression, and the peak strength gradually increases. The state of IPS affects the failure strength of the sample and reflects the strengthening effect of IPS. This paper boasts a certain value and significance for research on the deformation and failure characteristics of sandstone in the actual in situ stress environment with triaxial dynamic changes.

Considering the harsh environment of deep, fully mechanized working faces and the acutely imbalanced time distribution among excavation, support and anchoring, this paper designed a new type of highly adaptable advance support for fully mechanized roadways that boasts high adaptability, great support strength and a large working space. Firstly, the structure composition and working principle of the advance support were introduced. The structures and mechanical characteristics were then emphatically discussed. Subsequently, with the geological conditions of the 8224-machine roadway in the XT Coal Mine taken as an example, the loads of the advance support were obtained and then imported into the Ansys software to obtain the stress distribution and displacement distribution of the whole advance support and its parts through calculation. Based on the distribution, the stress and strain of the advance support were analyzed. The simulation results are as follows: Under various working conditions, the maximum displacement of the advance support was 4.5 mm, which is negligible compared to the overall size of the support; the maximum stress was 72.8 MPa, which is lower than the yield strength of the material (235 MPa). Therefore, the designed support can bear the pressure from the surrounding rock in the mine. Moreover, the roof beam, which is a weak link in the support, deserves more attention in subsequent engineering designs. This method conduces to not only parallel operations of excavation, support and anchoring, but also to rapid excavation and the safe production of roadways, providing fresh ideas for the advance support for fully mechanized roadways.