ANALYSIS OF TIME-SPACE EFFECTS OF CONSTRUCTION BEHAVIOR OF DEEP SOFT ROCK TUNNEL

With the rapid development of transportation,it is inevitable to excavate tunnel in the deep rock mass,and the problems of special engineering geology in deep rock mass will be much more distinct.The 3D nonlinear viscoelasticity numerical simulation and analysis are conducted on time-space effect of mechanical behaviors and deformation characteristics of deep soft rock mass during the tunnel construction;and the calculation results are compared with the field data.Considering rheological effect and time-space effect of deep soft rock tunnel,the results of show that the effect of excavation face is primary in the advancing face zone and the stress of surrounding rocks gradually releases from the excavation face.Rheological effect plays a key role out of the influence range of the spatial effect of excavation face.According to the characteristics of deep soft rock tunnel,support structure should be established as soon as possible in order to ameliorate the stress in surrounding rock circle,to reduce disturbance and to improve the self-bearing capability of the surrounding rock.Because of the distinct rheological property of soft and weak rocks,the secondary support structure must be established in time to bear the rheological pressure.Thus,the large displacement could be restricted by the secondary support structure.The present research enriches the theory of construction mechanics of underground structures and has wide application prospects in engineering.