Laboratory grouting experiment based CT analysis of grouted soft rocks in deep mines

Because of the complication and concealment of grouted soft rocks in deep mines,no effective method is available to quantitatively analyze the strength and the other behaviors. To solve the problem,firstly,equivalent speci- mens of soft rocks destructed by the high pressure in deep mines are made by the similarity model experiments of triax- ial pressure. Secondly,all the specimens are grouted by self-developed MYZJ-2 pressure grouting system with opti- mized grout ratio. CT scan and uniaxial pressure experiments are,then,conducted to discover the crack state and uni- axial compressive strength of the specimens. Finally,microscopic behaviors of grouted soft rocks in deep mines,inclu- ding strength,development rules and fractal dimension of cracks,have been analyzed based on the experimental data. The results show that after being grouted by superfine cement grout with water cement ratio of 1 ∶ 0. 6 and bentonite cement ratio of 0. 04 ∶ 1,the strength and toughness of destructed soft rocks increases. Thus the residual strength in- creases 40% compared with specimens before grouting. The cracks are mostly filled with the value of fractal dimension reducing from 1. 385 to 1. 074.