| Da Nanhu mine has the typical characteristics of western mining area. The roof and floor of roadway is weakly consolidated rock with the characteristics of poor cementation and low strength. Rock strength weakened further under the influence of the roof aquifer, leading to the difficulty in roadway support and the adverse effects of the safe and efficient mining. To address such problem, multiple methodologies including rock testing, mechanical analysis, numerical modeling, and case study were used in this work. Combining with mine actual production of Da Nanhu mine, the surrounding rock control technology for weak cementation roadway of water-enriched roof was carried out. The key findings in this work can be summarized as:(1) The water-bearing layers feature of water-enriched roof and the change rule of physical and mechanical properties of weakly consolidated rock mass under the action of water were obtained, followed by the results of rock testing and case study. Weakly consolidated rock contains lots of water absorption and swelling clay minerals, and there are many holes and cracks in the interior. It is easily sliming, disintegrating and weathering under the influence of water, leading to the weakening of rock mass strength. The parameters of uniaxial compressive strength, cohesion and internal friction angle gradually decay with the increase of water content of rock mass, and the function relation between rock mechanical parameters and water content was established.(2) The stability of roadway surrounding rock under the action of water was obtained. The roof aquifer is the key factor to cause the deformation and failure of the roadway. With the increase of water content in roof rock, it caused the roadway deformation intensified, the plastic zone extends to the deep surrounding rock, the bearing capacity of the surrounding rock is reduced, and the range of the two stress concentration area is enlarged in the group.(3) Under different water content, the distribution characteristics of support stress field, the range of effective compressive stress and the change of axial force of the bolt t were analyzed. The weakening effect of roof water on reliability of anchorage structure was revealed by these studies. The increase of the water content of surrounding rock is not conducive to the diffusion of pre-tightening force and the increase of axial force of the bolt’s free segment, leading to the narrowing of the scope of compressive stress and the reduction of the strength generated in the surrounding rock. It influenced the whole performance of the anchorage structure, and weakened the strength of the bolt support. Based on the field test, the attenuation law of the anchorage performance of the anchor and cable with time under the effect of water was obtained.(4) According to the characteristics of roadway roof aquifer, the roadway is classified and the appropriate supporting form and supporting parameters were determined. It could reduce the weakening effect of water on roof strata by necessary drainage and water blocking measures. The subsection control technology of surrounding rock in weak cementation roadway of water-enriched roof was successful application to the 111801 roadway of auxiliary transport in the Da Nanhu mine, and achieved good technical and economic results. |
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