Theory And Technology Research Of Setting Pressure Relief Hole On High Stress Soft Rock Tunnel

Now the high stress soft rock roadway can sum up the several aspects:one is the passive rigid support; two is the combined support; three is the rigid-flexible coupling support; four is the pressure relief support.Although these four support methods have achieved certain supporting effect in soft rock roadway with high stress, the roadway is unstable because of the limited support strength, larger excavation, serious disturbance and damage to surrounding rock and higher shop visit rate.In order to solve essentially the problem of high stress soft rock roadway support, this paper developed a new set pore pressure release material using in high stress soft rock roadway, and put forward a new support ideas and support technology of hole pressure releif which has good supporting effect,high comprehensive bearing capacity, the stability of surrounding rock and small excavation. The main research results are as follows:(1) A new support concept that relief materials receiving hole is in the high stress soft rock roadway is proposed based on the available supporting technicals and existing problems for high stress soft rock roadway.(2) The suitable raw materials for pressure relief materials are selected by comparing the fly ash, coal gangue and copying steel fiber though X ray fluorescence (XRF), the cylinder pressure strength test, softening coefficient, stability test, consistency test and water absorption test.(3) Through the compressive strength test, the micro-CT, scanning electron microscope, corrosion resistance and fatigue resistance experiment, from the two aspects of microscopic structure and macroscopic mechanics, analyzing the compressive strength and density of these pressure relief materials including unsaturated polyester resin fiber, fiber cement, epoxy resin fiber and phenolic resin fiber, compaction pressure material,the best pressure relief material is unsaturated polyester resin fiber and Mix:1:4.8:0.35, adding2%copying steel fiber.(4) Through analyzing the hole shape and hole rate of pressure release materia, a new relief materials receiving hole is determined which is unsaturated polyester resin fiber with round hole,35%hole rate,18holes, and whose main mechanics are also determined.(5) Based on the research on elastic-plastic theory and energy theory of high stress soft rock roadway, this paper analyzes the pressure relief mechanism of porous pressure relief material; analyzing the relationship among stress, pressure relief of surrounding rock and support;analyzing the relationship between deformation of surrounding rock and the pressure relief quantity of porous material; having a conclusion that preset broken zone can effectively reduce the broken zone radius in high stress soft rock roadway;proposing the optimum amount of pressure relief of porous pressure release material and the theory on preset crushing zone in high stress soft rock roadway.(6) Based on the structural model of hole pressue relief in the high stress soft rock roadway, through the similar simulation and numerical simulation study of the porous pressure relief in supporting, a new support method and once roadway technology suitable for high stress soft rock roadway.