Analysis Of Vibration Velocity Maximum Of The Linging Of Existing Tunnel By The Blasting Of The Tunnel Near-by

Since the new tunnel is close to existing tunnel, the seismic wave induced by blasting endangers the safety and stabilization of the surrounding rock and the lining ofexisting tunnel. Base on the XinKulutage tunnel, The principle of finite-element method is used to analyze vibration influence of tunneling blasting on the existing tunnel, and some numerical simulations were carried out with MIDAS/GTS program. The blasting of the new tunnel influence on the deformation, velocity, stress of the existing tunnel were discussed, which considered some cases,such as different blasting lengths,whether it have guiding chamber.In this paper, the value of researching the influence of existing tunnel by the blasting of the tunnel near-by, the blasting on the domestic and international research status and the compare of the new old research method was expounded and generalized detailedly. The stress wave theory and the failure theory of rock blasting was introduced systematically, which included the simulation of blasting vibration, the simplification of boundary, the dynamical finite-element method, the nonlinear analyzing and solving method and so on.Based on the stress wave theory and the failure theory of rock blasting, some different examples about vibration influence of tunneling blasting on the existing tunnel were analyzed by using the transient dynamics method of MIDAS/GTS,which considered some different cases,such as different blasting lengths,whether it have guiding chamber.The vibration velocity, stress and distortion of lining and surrounding rock were analyzed, and some rules and characteristics about the vibration influence of tunneling blasting on the existing tunnel were put forward by analyzing and comparing the different results. Some conclusions were achieved according to the calculated results:(1) In the case of new tunnel blasting vibration, the maximum vibration velocity and displacement occurs from the middle of frontal wall to the bottem of arc, where is highly sensitivity of the blast footage; Along with the arc and below the middle of frontal wall, the vibration and the displacement becomes less and less. The maximum first singal stress occurs from the middle of arc to the bottom of arc, from the bottom of frontal wall to bottom plate, where is highly sensitivity of the blast footage; while the first singal stress of frontal wall is much small, which is opposite to the distribute of the vibration velocity and displacement.(2) Shown from the distribute of response along the existing tunnel vertical caused by the blasting vibration, the vibration velocity of the cross-section near to the source of blasting is high, and vice versa smaller, the largest vertical velocity distribution curve, the maximum displacement curve, the biggest gap stress curve along the existing tunnel is basically symmetric with the central section (the existing cross-section paralleling to the bursting of the tunnel working face). Maximum velocity zones are mainly located in the center section before and after the scope of 5 meters, the largest deformation zone are mainly distributed in the center before and after cross-section area 8 meters, the maximum stress areas are mainly located in the center section before and after the scope of 5 meters.(3) Tunnel lining both peak velocity mainly concentrated in the former 4. And a few more paragraphs later, the slower the vibration attenuation. Therefore in order to reduce the maximum speed of blasting vibration, paragraph 4 to deal with before blasting control.(4) Blasting the same footage, there are holes under the conditions of introduction of new tunnels after blasting both side of the tunnel lining welcome burst response (vibration velocity, displacement, strain, stress) than under the conditions of non-derivative holes much smaller blast. This shows that the new tunnel blasting vibration response caused by the blasting surface blasting the invading folder system conditions. Surface blasting overhead system, the smaller the folder (if hole lead), arising from the tunnel adjacent to both the smaller the vibration response of the blast.(5) When the new tunnel is built, through numerical simulation of elastic-plastic finite element analysis in two-dimension and three-dimension caused by the blasting blasting vibration in different conditions of the 2.0 m, 2.5 m, 3.0 m, 3.5 m and 4.0m blasting footage, to be guided in the absence of conditions, blasting holes the existing tunnel lining threshold velocity is 10.7 cm/s, in a guide hole blasting under the conditions of the existing tunnel lining at the threshold velocity is 11.1 cm/s.