Multi-echelon support method to limit asymmetry instability in different lithology roadways under high ground stress

•Engineering investigation about asymmetry instability in kilometre-deep roadways.•Elaborate relationship between in-situ rock and the rock-like material.•Correlation analysis of the load-bearing feature and the roadway structural stability.•Control effect of the multi-echelon support on the structural instability of roadway. This paper investigated the effect of a multi-echelon support on the asymmetry structural instability of different lithologykilometre-deep roadways. An engineering background investigation was carried out to determine asymmetry instability in different lithology kilometre-deep roadways using acoustic emission signals of in situ rock and 3D in situ ground stress. The mechanical coupling-bearing structure and multi-echelon support method of the surrounding rock were proposed based on the analysis of the secondary stress distribution and strength degradation of the surrounding rock. A numerical simulation and scale-model experiments were conducted to analyse the asymmetry structural failure mechanism and the effect of a multi-echelon support. The results indicated that the high ground stress created a serious impact on the stability of the coupling-bearing strata, an increase in horizontal ground stress created obvious extensions of the weak bearing stratum and the transfer of the main and key bearing strata. The larger asymmetric deformation phenomena of surrounding rock was often accompanied by wedge-shaped roof caving, serious floor heave and spalling, which indicated the decline of the bearing capacity of the surrounding rock. The redesigned multi-echelon support was shown to reduce the scope of a weak bearing stratum and limit the transfer of the main and key bearing strata, preventing the roadway asymmetry structural instability to a certain degree and relieving plastic flow in the surrounding rock.