Time-dependent laws and initial application of bearing features of bolt-grouting structure in soft rock roadway

Regarding the time-dependent behaviors of the bolting and grouting structure in soft rock roadway, the bearing capacity of bolt-grouting structure is treated as time-dependen value, and the elastic zone, plastic zone and bolt-grouting zone around the roadway are simplified as the stress analysis problem of a thick walled cylinder. Based on an elastic-viscoplastic constitutive model, the formulas for the bearing capacity of bolt-grouting structure are attained. The results show that the needed bearing capacity of bolt-grouting structure to stop rheology and rheological convergence/deformation increases with the increase of the ratio of (original rock stress) to (Tensile yield limit), and the more apparent the rheological features the more the support difficulty. The main reason for support failure and serious rheology is that the needed bearing capacity to stop rheology and rheological deformation increases because of the decrease of support strength and range. The value of the bearing capacity has close relationship with the bolt-grouting parameters, and it is very important that the appropriate bolt-grouting parameters can guarantee the stability of the bolt-grouting structure when rheology ends. The theoretical results reflect well the time-dependent laws of bearing capacity of bolt-grouting structure increasing with the increase of the rheological deformation, and they agree with the field observations, thus playing a great role in the design of bolt-grouting support structure in soft rock roadway.