Study Of Bearing Characteristic Of Soft And Fractured Roadway Surrounding Rock Anchorage Unit And Its Applications In Engineering

The forming conditions and bearing capacity are vital to stability control of roadwaysurrounding rock with high stress. Research methods such as physical model test, numericalcalculation, theoretical analysis or engineering application verification were applied to thesystematic research of mutual influential mechanism of fractured rock mass and anchor bolts.Main results and conclusion are as below:(1)"Large scale three-dimensional anchorage unit mechanical model test bed" wasdeveloped and improved, which could simulate and control mechanical boundary conditions ofthe processes of prefabricated fractured rock mass and failure of anchorage unit due tocompression. Anchorage unit similar model material which met the requirement of large ratio ofsimilitude and had integrality after failure for fracture observation and fragment statistic wasdeveloped.(2) Fractured rock mass was prefabricated by simulating stress path of roadway excavationand repairmen process, at the base of which, large scale triaxial fractured surrounding rockanchorage unit model test was carried out under conditions of different surrounding rock initialfissure degree, different anchor bolt pretightening force and different anchor bolt density. Thevariation of fractured surrounding rock anchorage unit strength along with anchorage conditionswas obtained. Influential rule of different anchorage conditions to anchorage unit strength,deformation, failure, fractal and energy dissipation characteristics was discussed, which offeredan important foundation to following study of anchorage structure bearing characteristic.(3) The evolution rule of anchorage unit basic mechanical parameter along with plasticstrain was gained by numerical inversion and finally implanted in FLAC3Dcalculation model,from which roadway fractured surrounding rock combined supporting arch bearing capacity andthe law of its influence to surrounding rock stress field were obtained. Combined supporting archbearing capacity, inner and outer stress distribution and peak stress shifting law under thedifferent anchoring condition from numerical calculation were analyzed. The effect law ofanchoring condition and thickness to combined supporting arch bearing capacity and outersurrounding rock stability was obtained.(4) Theoretical analysis models of roadway surrounding rock anchorage structure wereestablished. Basic condition of combined supporting arch (beam) formation and ultimate bearingcapacity expressions of structure instability or strength failure were obtained. The form andevolution law of anchor bolt controlling zone were obtained with the study of fracturing shape ofrock mass around anchor bolt plate and anchorage unit inner stress distribution from anchorageunit physical model test. Basic forming condition and failure pattern criteria of combined supporting arch (beam) was proposed, which provided theoretical foundation for fracturedsurrounding rock anchorage stability control.(5) Finally, based on the above research, the rationality and practicability of researchconclusions of this dissertation were verified by typical repairing engineering of large sectionroadway with soft and fractured surrounding rock.