Soft Rock Deformation And Failure Characteristic And Yield Bolt Support Technology Research

Along with our national coal mine has been being mined from shallow to deep miningstep by step, many complicated geological conditions of coal mining depth is overkilometers, strata conditions have also been transitted from hard rock into soft rock.Compared to the hard rock, soft rock tunnel and surrounding rock deformated irregularlywith complicated impact conditions. So the mechanism of deformation in soft rock tunnelexcavation research become urgently needs to solve the problem.Based on the supporting theory of soft rock tunnel, combining the parameters ofsurrounding rock of Shigetai coal mine auxiliary transportation lane71202-1and thesupporting status of it, plus using FLAC3D numerical simulation software to performsimulation analysis of surrounding rock deformation and supporting effect comparison,this paper provides the in-depth research about the characteristics of deformation in softrock tunnel excavation and supporting technology for pressure. By applying the results tothe experiment of roadway to improve the supporting engineering, positive effect isachieved and the safety of mine production is ensured. The main research results of thispaper are as follows:(1) Analyse the deformation of high stress soft rock tunnel excavation in domestic andoverseas research and a large number of Shigetai coal field engineering data; conclude thatthe soft rock mechanics and engineering properties, classification and characteristics ofsoft rock roadways deformation: deformation time is long, shape deformated largely,deformation rate is fast, etc.(2) Select the Shigetai coal mine auxiliary transportation lane71202-1as theexperimental analysis of roadway, together with the actual survey data such as size, rockproperties of roadway, mine pressure and use the simulation software FLAC3D to performnumerical simulation analysis to find out the horizontal and vertical stress and deformationbased on these stress as well as the plastic zone formation reasons. According to thesimulation results, it is found that the surrounding rock of roadway bear the stress from theoriginal surrounding rock vertically, which leads to the failure of plasticity under thecondition of roof and floor deformation and then results in the Shear failure by the influence of shoulders and feet, later stress effect spreads to horizontal two sides andcombine with the horizontal stress of deep rock, the damage of two sides is made.Thesimulation results are basically identical with the actual survey results, therefore, theresults provide the good theoretical basis to slove the problem of the type of soft rockdeformation.(3) Based on the supporting failure problem of auxiliary transportation lane71202-1original traditional rigid bolt support system, this research decides to choose yield boltinstead of choosing traditional rigid anchor bolt. yield bolt principle is presented in thispaper as well as conduct the experiment research over yield bolt components and auxiliarycomponents. Select yield pipe as yield component and use120NM damping nut and"sandwich" gasket as auxilary component.(4) Using FLAC3D software to compare and analyse the supporting effect inexperimental roadway between original supporting form and new type yield supportingform, it can be seen that deformation significantly shrink and deformation rate slowedmarkedly with the increase of the time. On the premise of yield bolt support, plus the useof anchor parameters selected by FLAC3D, compare different conditions, such as the boltrow spacing, pre-tightening force and length, to find out optimum bolt parameters andmake the yield supporting system achieve the best coupling point so that the mineproduction safety is ensured.(5) Given on the fact that Shigetai coal mine auxiliary transportation lane71202-1hadproblems of large roof breakage area and bolt fracture, this paper applying the outcomes ofnumerical simulation to the actual tunnel and reform the supporting project, also monitorthe supporting effect.By comparing pre-and post-reform in each60days, the effects arebasically identical with results from computer simulation: vertical and horizontaldeformation rate gradually decreased with increasing time,deformation shape is alsoensured with effective control, which make sure the operation safety in efficient way.