Study On Distribution And Support Control Of Plastic Zone In Deep Roadway

The research relies on the NSFC project of “ The research on destruction and stability control of surrounding rock in Large deformation deep tunnel ”.Based on the fully analysis of plastic factors, process and control of plastic malignant extension,the "bolt wire cable and shotcrete+ partical grouting" is proposed and applied in similar roadway,which prove the method has obtained good effects in the field construction.By theoretical analysis and field analysis, it is concluded that the direction of peripheral rock large deformation,dynam-relaxed rock mass and support failure is plastic malignant extension.It is malignant extension,shape and extent of plastic zone decide the failure type of tunnel. Relationship of rock mechanics properties, distribution features of the in-situ stress and plastic zone is close.Based on elastic mechanics, elastic-plastic mechanics, mine pressure theory, analyzes the stress distribution of deep rock,the related calculation formulas is inferred,a corresponding model is established,plastic shape of different coefficients of horizontal pressure is calculated.By theFLAC3 D software, a numerical calculation model is established, the plastic shape of different tunnel cross-section, inhomogeneous stress field,mining pressure field,different section size,different intermediate principal stress and different rock strength is simulated by single factor analysis method. it is concluded that stress field control both plastic shape and size,other factors only control plastic shape.the malignant extension process of plastic zone is simulated by number software,which infer the curve of plastic malignant extension process.By theoretical analysis and FLAC3 D software, it is concluded that the transience of plastic dot decide the process is uncontrollable phase,hugely destructive of malignant extension of plastic decide the process is worthless phase.Because of time based license,the phase of formation of plastic annulus, distortions of plastic annulus and uneven development can be controlled,the best control phase is plastic annulus and distortions of plastic annulus.The relationship between plastic size and anchorage depth is closely related,the control effect of anchorage boundary is worst,the control effect of the anchorage beyond a certain range is best. In addition,the support technology “bolt wire cable and shotcrete+local grouting” is presented by analyzed.The support technology “bolt wire cable and shotcrete+local grouting”is applied in practice, the monitor and analyzed of displacement and fracture development of the rock shows that amount of deformation is little and stable,the crack distribution of the surrounding rocks of roadway is uniformity,which can infer plastic zone is more-or- less uniformly distributed.Tunnel floor heave of bench scale tunnel is better than the tunnel of old plan obvious,shallow rock around the distance of 1.0 meters leads to displacement of bench scale tunnel,the deep surrounding rock of roadways is less affected.As shown above,the support technology “bolt wire cable and shotcrete+local grouting” get an ideal effect,the support technology achieved its control aims of long-term stable of the extended segment of-850 m main haulage way of Qujiang mine.