Supporting technology research of concrete filled steel tubular support in extremely soft rock mining area

摘要

Inner Mongolia's xilingol league area of chagannaoer's main inclined shaft is extremely soft rock roadway with the properties of 0.12 ～ 5.12MPa in uniaxial compressive strength of rock, 60.6% in clay mineral content and 82% of clay mineral composition is montmorillonite, and with the feature of argillation and expansion by absorbing water in surrounding rock. The two previous supporting schemes for this roadway were double16a I-beam and 650mm concrete layer as the first scheme, and close U36 steel stents as the repairing scheme, respectively. Both of them were failed to control deformation failure of surrounding rock. In this paper, a new supporting scheme was proposed by testing mechanics parameters and mineral composition of surrounding rock, analyzing hydraulic properties of surrounding rock and deformation failure, and evaluating surrounding rock load. This new scheme consists of high strength pressure-bearing ring supporting technology based on concrete filled steel tubular support and surrounding rock partial pressure-releasing technology. Aiming at deformation of side walls of the main inclined shaft roadway, a test was carried out to study the bending resistance of the support and improve the support. The industrial test showed that the new supporting scheme can effectively control the deformation of the main inclined shaft surrounding rock and realize long-term stability of roadway.