Innovative ultrafine silica-based HFQSAD grouting materials applied for water blocking and reinforcing fractured rock mass in roadways with dispersed water spraying

Abstract

Dispersed water spraying occurs at roof during the excavation of coal mine roadways. This reduces the load-bearing capacity of surrounding rocks and leads to fractures in the support structures, posing a significant challenge in coal mining. Grouting is a commonly used method to seal water-conducting fractures. Therefore, the work presented the development of a novel ultrafine silica-based high-fluidity quick-setting anti-aqueous dispersions (HFQSAD) grouting material for water blocking and reinforcing fractured rock mass. Additionally, an effective construction process was proposed for controlling dispersed water spraying at the roof of roadways. Results showed that ultrafine silica-based HFQSAD grouting materials had high fluidity, quick setting, strong anti-aqueous dispersion, and good durability. The optimal mixture ratio was determined based on fluidity, initial setting time, uniaxial compressive strength (UCS) at 3 days, and anti-aqueous dispersions. The formulation consisted of a water-cement ratio of 0.45, 0.45 % water reducer, 0.45 % accelerator, 0.2 % PAM, 0.7 % HPMC, and 1 % organosilicon defoamer. According to the independently developed model of dynamic water grouting, the grouting material could seal dynamic water channels and reinforce fractured rock mass. Finally, a new grouting construction process was proposed, utilizing the strategy of "first interception and then blocking for full section treatment" to address water spraying at the roof of the main belt roadway of the west wing in Shanxian Energy Coal Mine. This method could reduce water spraying by 95.2 %, which sealed dispersed water spraying at roof. The effectiveness and feasibility of the ultrafine silicon-based HFQSAD grouting materials and construction process in treating water spraying were confirmed.