Study On Expansive Slurry Grouting Reinforcement Mechanical Characteristics Of The Fractured Roof In The Mining Field

Grouting reinforcement as an important means of fractured rock support can effectively improve the mechanical strength of the composites.Based on the theoretical basis that the rock is stronger in the three-way stress state than in the one-way stress state,the expansive slurry grouting reinforcement technology is proposed for the ordinary slurry at the fractured roof plate of the mining field,which only provides the bonding effect in the reinforcement process and the problem of dry shrinkage after solidification.In order to analyze the effect of reinforcement of the roof slab of the fault-bearing quarry with expansive slurry grouting,rock mechanics tests,similar simulations and numerical simulations were carried out,and the following research results were obtained.(1)Indoor shear and numerical simulation tests of slurry reinforcement with ordinary slurry and expansive slurry were carried out to analyze the internal pores of the slurry,shear strength,damage form of the slurry-rock composite rock mass with different slurry reinforcement materials,as well as the stress change and plastic zone distribution inside the slurry-rock composite during the shear process.Based on the Mohr-Coulomb criterion,the variation of mechanical parameters of slurry-rock composite rock mass under different grout reinforcement conditions is analyzed,and the reinforcement mechanism of expansive slurry grouting is revealed.Compared to ordinary slurry,expansive slurry increased the shear strength of the slurry-rock composite rock mass by 30.53%.The reinforcement effects were very significant.(2)The shear tests of slurry-rock composite rock masses with different slurry thicknesses,initial normal stresses and fracture roughness under expansive slurry grouting reinforcement were carried out,and the changes in shear strength,stressdisplacement curves,damage forms and AE energy characteristics of the slurry-rock composite rock masses under the control of a single factor were analysed by means of AE and DIC characterisation.With the increase of different influencing factors,the shear strength of the slurry-rock composite shows a "log-like","linear-like" and "exponential-like" increase respectively.The friction at the slurry-rock contact surface is a key factor in changing the shear strength of composite rock masses,but different influences act in different ways,resulting in significantly different mechanical properties.(3)Similar simulations and numerical simulations of expansive slurry and ordinary slurry grouting reinforcement at the fractured roof plate of the mining field were carried out to analyse the displacement,the trend of stress changes in the surrounding rock under different slurry grouting reinforcement.Compared to ordinary slurry reinforcement,the expansive slurry enhances the overall mechanical strength and bearing capacity of the fractured roof plate of the mining field by first squeezing and then sticking,and reduces the stress and displacement of the roof and the surrounding rocks of the mining pillar.The horizontal compression of the expansive stresses transfers the self-weight stress acting on the quarry from the overlying rock to more unmined surrounding rock,and reducing the possibility of deformation and instability of the surrounding rock of the mine pillar.Expansive slurry reinforcement can further enhance the effect of grouting.