Analyze And Study Of Anchorage Tunnel Surrounding Rock Vibration Effects Caused By Excavation Blasting

Compared with gravity-anchorage, Tunnel-anchorage only need small excavation amount and low cost, moreover it can utmost protect the ecological environment of construction area, and more and more tunnel-anchorage has been used in the long-span suspension bridge. The excavation blasting quality of Anchorage-tunnel has received increaseing attenuation by bridge engineering field and engineering blasting field, especially the neighborhood and large cross-section anchorage-tunnel are used in long-span suspension bridge, make how to indemnify the integrity and continuity of surrounding rock and sandwiched rock, utmost weaken and even eliminate the damage disturbance of surrounding rock caused by blasting, is the precondition of construction security and quantity to the bridge, and also a scientific technical problem which must be solved in engineering blasting field. Therefore, it’s necessary to study the vibration effect of surrounding rock when anchorage tunnel took excavation blasting.This thesis took the anchorage tunnel of NanXi Yangtze river bridge as background, with many method for example field test, mathematical statistics, numerical simulation to analyze and study the vibration effect of sandwiched rock caused by anchorage tunnel excavation blasting, the main research works and results are reflected as follows。Firstly, based on the difficulties and features of construction and the requirement of the anchorage tunnels, the excavation blasting scheme was designed. Took vibration velocity test when this scheme was carried out. The test results shows that the most vibration intensity of surrounding rock was caused by cutting hole blasting. By contrast the velocity peak of each point when different working face was blasting, found that there was clamping force working on the sandwiched rock when the two anchorage tunnel were in the same depth. And also found, the vibration velocity of sandwiched rock decay rule couldnot described by Sodev’s regression formula.In order to kown the vibration effect of surrounding rock caused by anchorage tunnel excavation blasting entirely, this thesis utilized LS-DYNA established two numeric calculation models, and combined with velocity test results verified that the numeric calculation was reasonable. And the numeric calculation results showed that:In a cross section of advanced-tunnel, the vibration velocity of facing blasting side tunnel arch foot is maximum, the velocity of tunnel side wall is close to the velocity of tunnel arch foot, and the velocity-difference of each position in a section of the advanced tunnel was antidependence to the axial distance between the section and the working face of follow-up tunnel. And also, the numerical results showed that when the follow-up anchorage tunnel excavated at the position27m from the entrance the vibration intensity of sandwiched rock before blasting face was stronger than the vibration intensity behind the face, when the follow-up anchorage tunnel excavated at the position57m from the entrance,dued to clamping force the tunnel arch foot of blasting, facing blasting side maximum vibration velocity appeared in the position behind working face. The numerical results indicated that the vibration velocity of arch foot on the advanced hole working face was smaller than the velocity of arch foot1-5meters scope behind working face, its consistented to the vibration test results.