Theoretical analysis and numerical simulation on the coupled support technology of concrete-filled steel tube and bolt-cable in deep roadway

Abstract

Coupled support technology for concrete-filled steel tube support (CFSTS) and bolt-cable (BC) used in deep roadways often fails, and increasing the length of BC is a waste of material. Therefore, changing the pre-tightening force of BC to improve the force state in CFSTS is proposed in this paper. Firstly, the damage modes of CFSTS were investigated, and the internal forces in CFSTS contained cable were obtained using the elastic centre method. And the results indicated the cable could reduce the internal force in CFSTS to ensure its high bearing capacity. And then, the numerical calculation models with different lateral pressure coefficients and coupled support conditions were established. Further, the stress and displacement law for the roadway and the support body under different lateral pressures and different support schemes, and increasing the pre-tightening force for bolt-cable in different angle ranges was investigated. And the results show that the best “CFSTS + BC” coupled support effect could be achieved with pre-tightening forces for bolts and cables of 60 and 100 kN, respectively, and the optimal reinforcement angle range is 15°–45°. Finally, “CFSTS + BC” coupled support technology was applied in the field.

Keywords

concrete-filled steel tube support / bolt-cable / coupled support / internal force / pre-tightening force / angle ranges

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