Technology Of Blasting Excavation And Monitoring In The Shallow-buried Section Of Road Tunnel

With the expanding scale of China’s highway construction，Mountain highwaytunnel construction has been more and more attention by the engineering community.The drill-blasting method as a major construction methods for tunnel engineering, thequality had a direct impact on the safety of tunnel surrounding rock and initial support.Especially for the shallow tunnel, the key technical problems to be solved in theprocess of drill-blasting method of construction of shallow tunnel is the stability of thetunnel entrance in the blasting process, the tunnel construction monitoring and earlywarning, the tunnel blasting vibration effect aspects etc.Relying on huo-lang-yu tunnel of mi-xing road, aiming at the characteristic ofshallow and bad geological conditions of the surrounding rock, the research of threedifferent aspects have been carried out: the dynamic stability analysis in shallowtunnel, advance prediction and3D technology, tunnel blasting principle and controltechnology. By analysis of blasting excavation monitoring, three-dimensionalnumerical simulation of shallow tunnel and the dynamic response and stability oftunnel entrance blasting excavation, using a series of technical measures as strengthensupporting parameters design of surrounding rock above arch foot to ensure the safetyof the shallow tunnel construction. Tunnel monitoring showed that the settlement oftunnel arch crown is small, other safety hazards such as cracks did not appear insurface of tunnel arch crown. Integrated advance prediction and3D technology,optimize construction technology in tunne excavation.With the observations ofvibration monitoring, vault settlement, the hole weeks convergence, choosingreasonable blasting excavation forms and position, monitoring the tunnel blastingvibration effect, optimizing the blasting parameters, can effectively weaken theblasting vibration, but also to ensure a larger circulation footage.In the actual construction process, ensuring production safety of shallow tunnelblasting excavation, the Phenomenons such as under-break of surrounding rock, crackand slip rupture surface did not appear, ove-rbreak are within the control.