Study On The Influence Of Different Composite Parts On The Rockbolt Stress Field By Laboratory Studies

In this paper, by similarity simulation method, the distribution of the stress field of different composite parts of bolting under different bolt numbers and different pre-tightening force are studied, and has achieved the following results:(1)A large scale similarity test rig for testing different composite of bolting was designed and maufactured, and the test rig is shown to have both horizontal and vertical symmetry. (2) For the same component, the pre-tightening force is larger, the corresponding distribution of stress field is wider, and the stress value is greater. (3)When the preload is100kN, the stress distribution of the "non net+single bolt+tray" in three-dimensional space is obtained,the stress isosurfaces are layered, its macroscopic shape is "pomegranate", two high stress concentration zones are formed on the two ends of the anchor bolt, and a tensile stress zone near the anchor section is formed. (4)The stress field distribution of non net/metal mesh/steel mesh "2 bolts+ tray/W steel strip/M steel strip/steel ladder beam/W steel support plate/π steel strip/flat steel strip+100kN preload " are obtained, the stress superposition of the 2 anchors is obvious, and the stress can be connected in the horizontal direction between rock bolts in the surrounding rock. (5) The stress field distribution of "non net/metal mesh/steel mesh 4 bolts+tray "are obtained, when four bolts work together, the bolt and the surrounding rock can form a complete and continuous stress bearing structure with high stress value in the space, the stress isosurface are layered in vertical at the two ends of anchor bolt. (6) Based on the stress distribution in Z=0mm slices, With 30kPa,60kPa,70kPa stress values for reference, The stress field distribution effect of non net/metal mesh/steel mesh "2 bolts+tray/W steel strip/ M steel strip/steel ladder beam/W steel support plate/π steel strip/flat steel strip+100kN preload " are compared, When there is no net, the order is W steel strip、 W steel support plate、 flat steel strip、π steel strip、M steel strip、tray、steel ladder beam; When there is metal mesh, the order is W steel strip、W steel support plate、π steel strip、tray、flat steel strip、M steel strip、steel ladder beam; When there is steel mesh, the order is W steel strip、 W steel support plate、π steel strip、flat steel strip、 tray、M steel strip、 steel ladder beam.(7) The stress diffusion effect of π steel strip/W steel strip/M steel strip in metal mesh and steel mesh are better than non net on the surface of the model, The reason is that the contact relationship between the component and the surrounding rock is changed from " composite part-rock" to " composite part-net-rock", The net can form an interlayer, which increases the "significant" contact area between the middle of composite part and surrounding rock, the advantage of the composite part stiffness can be played.