Composite grouting reinforcement technology for deep roadway surrounding rock

The single grouting method and grouting material can not achieve an ideal grouting effect under the complex geological conditions of deep roadway surrounding rock. In order to solve this problem, a composite grouting reinforcement technology for deep roadway surrounding rock is proposed. Taking the 3210 isolated island working face of a mine in Shanxi Province as an example, this paper expounds on the principle and application of the composite grouting reinforcement technology. Firstly, combined with the geomechanical test results of the field test area and the physical and mechanical parameters of coal and rock mass, the range of each cracked zone of 3210 return air roadway is calculated. Secondly, based on the crack characteristics of surrounding rock zones, three-step grouting technology is proposed. The technology includes shallow low-pressure infiltration grouting, deep high-pressure cracking grouting and supplementary grouting. The depth of each borehole in the three-step grouting technology is determined according to the scope of each zone. Then, the corresponding grouting materials are selected according to the crack development degree and crack opening scale in each zone. The inorganic cement grouting materials should be used in high permeability zones. The ultra-fine cement grouting materials should be used in medium permeability zones. The polymer chemical grouting materials should be used for supplementary grouting in low permeability zones. Finally, according to the field grouting test, the grouting pressure parameters of different crack zones are determined. The grouting reinforcement effect of 3210 return air roadway is comprehensively judged by using three indexes. The three indexes include the anchoring force of grouting reinforcement rock mass, the uniaxial compressive strength of grouting reinforcement rock mass, and the integrity of surrounding rock mass. After adopting the composite grouting reinforcement technology, the anchoring force of the roadway side coal body is increased by 144%, reaching 230 kN. The uniaxial compressive strengths of the roof and roadway surrounding rock increase by 10.9% and 18.5% respectively, reaching 50.68 MPa and 23.37 MPa respectively. The wave velocity of the roadway side coal body increases by 15.2%, reaching 750 m/s. From the deformation rate and deformation amount of surrounding rock in grouted area and ungrouted area, the composite grouting reinforcement technology has achieved a good effect.