Mechanical Properties And Engineering Application Of Wet Shotcrete In Coal Mine

At present domestic shotcrete support common dry spray method construction process. Dry spray concrete compressive strength is generally only20MPa, long-term supporting effect is poor, and difficult to guarantee the stability of roadway. Bond strength is low, prone to "cutting type" damage, the sealing effect of surrounding rock is not ideal; The poorly of toughness leads to the spray layer easier to crack, flake; Spray layer thickness, flexibility is poor, difficult to adapt to the deformation of surrounding rock. In order to solve the above problems existing in the supporting, throughout experimental research、theoretical analysis and field test the article analyses basic mechanical properties of wet shotcrete and the supporting application in coal mine. The main research work and achievements are as follows:(1) Definiting ratio of project for encasing material through additive’s performance analysis. The early laboratory wet shotcrete strength, compressive strength, tensile strength, bond strength test, and compared with wet shotcrete mechanics performance analysis, addition to support strength and stability of wet shotcrete.(2) Study on large scale concrete flexural strength, and the relationship between the load and deflection; Forced deformation of shotcrete layer carries out a comparative analysis on the three stages; Analyzed both has good flexibility, and has enough supporting force of spray layer thickness control。(3) Studied the overall effect between dry spray support and wet shotcrete, based on the shotcrete supporting role in the overall study, The application of the theory of composite straight beam and derivation under arbitrary distribution load spray layer and interface balance differential equation, the relationship between the strain of surrounding rock. Study on the basis of the principle of wet shotcrete supporting design, proposes the partition supporting design technology, to ensure support effect.(4) The wet shotcrete supporting engineering has been applicated in Tong xin coal mine. Field application effect shows that wet spray field dust concentration is far lower than that of dry spray field, spring back rate is decreased, the wet shotcrete support is safe and reliable, increased labor productivity of roadway support.