It is complicated in construction geology for the tunneling,so we should support tunnel with self drilling anchor bolt
, self drilling anchor bolt support is currently the most widely used method for high grade highway& tunnelling, also it is the core of the process.Self drilling anchor bolt support as a way of supporting, and there is a fundamental difference in traditional way of support.Traditional way of supporting is often caused by passive collapsed rock mass under loading, but self drilling anchor bolt supporting can actively strengthening rock and soil body, effectively control the deformation, prevents the occurrence of collapse.The main function of self drilling anchor bolt supporting is suspensory action, cut across function, and the roles of composite beams and extrusion strengthening effect.The points about mechanism of action above are as follows:
Suspension action: Put the instability of rock hanging on a solid rock, to prevent slip movement of surrounding rock.Anchor itself in tension, the tension is hanging the weight of the rock mass, in the massive structure or fractured rock mass, the use of self drilling anchor bolt can make loosened zone of loose rock hanging on the stability of rock mass, You can also take over jointed rock block the formation of weak plane cutting together,to prevent it from sliding along the sliding surface.
Cut across function: Put the self drilling anchor bolt into the tunnel roof strata, which is equivalent to increase the fulcrum on the roof, so that the stress of the roof rock mass is reduced, and it plays a role in the maintenance of the tunnel.Of course, the premise of having a good effect is that the top of self drilling anchor bolt must be anchored in solid stability of the rock.
Composite beams:Put self drilling anchor bolt in layered rock, with several thin layers of rock anchorage together, similar to put the overlapped beam into the composite beam overlay, thus enhancing the ability to self-supporting of roof strata,which plays a role in the maintenance of the tunnel.
Extrusion strengthening effect:The self drilling anchor bolt which installated in the surrounding rock after stress, which can be formed in an area around its compression zone, in the anchor system, compression zone overlapping to form a continuous compression zone, thus making the broken rock wholeness or approximate integrity, improve its overall strength and bearing capacity.