Tunnel2Extended4Expanding Excavation Blasting Vibration Effect And Safety Criterion

With the railways, highways and other transportation projects to developenergetically, at present in the many regions of China,the original two lanetunnel has been unable to meet the demand of transportation and safety. In theexpansion of the process, the topographic and geological conditions,environmental protection and land constraints, usually require two tunnelsspaced as far as possible to reduce or only in the original two lane tunnel onthe basis of the expansion to four lanes. In our country, the tunnel2extended4engineering examples are few, and the small clear distance tunnel under the2diffuser4has no publicly reported. In order to give the Shen HaiExpressway QuanXia section of Damaoshan tunnels built right hole enlargingand excavation blasting to provide theoretical and technical support, thesubject of the use of the site test and numerical simulation method to tunnel2,extended4blasting have been built in highway tunnel with four lanes and2extended4tunnel ’s dynamic response rule, the stability of surrounding rockand its safety criterion of conduct research, the simulation results arecompared with the site test result. The work done and the obtainedachievements are as follows:1, analyzed and summarized the small spacing tunnel2extended4blastingsafety criterion of dynamic response and the research progress and theinadequacy of existence, put forward to settle a way.2, field monitoring of Damaoshan Tunnels2extended4blasting on nearbyexisting highway tunnel with four lanes of the vibration effect of blastingseismic wave, get in the rock and tunnel along the axial propagation:3, based on the cylindrical hole of the tunnel blasting expanding2extended43D numerical model.4, simulated calculation of tunnel enlarging and excavation blasting on theexisting tunnel and expanding excavation tunnel dynamic response andstability of surrounding rock influence, access to the following rules: (1) large span tunnel blasting vibration on the expansion of existing tunneldynamic response, obtained the stress, vibration velocity extremumappearance time and location, summarizes their respective attenuation law;(2) analysis the large span and dig the tunnel overlying layers surroundingrock stability;(3)2extended4tunnel blasting on nearby four lane span existing tunnelvibration effect, summarizes the enlarging and excavation blasting process inboth four lane tunnel velocity and stress field changes, but also on the folderof rock dynamic characteristics are summarized;5, by comparison,it is established considering the effect of frequency oftunnel blasting safety criterion, and verified by an example, the criterion isfeasible. Finally, the improved dynamic stress ratio safety criterion.Research of Damaoshan Tunnels2extended4blasting constructionprovides guidance, and enriches the theory of dynamic response of tunnelblasting.