Research On The Vibration Response At The Roadbeds Of Existing Montanic Highway Caused By Under-cross Tunnel Blasting Construction And The Control Of The Response

Because of the limits of geology and terrain and the requirements of line-select,there will be a large number of circumstances where new railway tunnel cross throughthe existing traffic line. As it is applicable to wide and low investment of equipment,mining method is widely used in mountain railway tunnel construction. However, forthe clear distance between undercrossing tunnel and existing traffic line is normallyshort, blasting construction based on mining method will generate seismic wave whichwould seriously threaten the safety and stability of the existing traffic line. Therefore, itis of great significance to research the law of dynamic response caused byundercrossing tunnel’s blasting construction at the existing traffic line and the techniqueto control that response. Based on an engineering background of one part ofundercrossing shanghai-kunming expressway of beiyinpo tunnel, this article uses waysof field research, theoretical analysis and numerical simulation to investigate deeply andsystematically the dynamic response laws of subgrade at existing montanic traffic linecaused the blasting construction of the undercrossing tunnel, and ways to control thatresponse. In this article, the main research contents and conclusions are as followed:Through Numerical simulating get the laws of dynamic response, caused byblasting construction, at the roadbeds of existing traffic line when undercrossing tunneland existing traffic line are in different relative positions.By statistical simulation, gets the maximal velocity at roadbeds of existing highway,caused by blasting construction of undercrossing tunnel, when the charges of couplingcharge structure are different. With mathematical software MATLAB, the mathematicalrelationship between different charges of coupling charge structure and the maximalvibration velocity of roadbeds is concluded. Then, based on requirements of maximalvibration velocity, it would get the maximal charge.It conducts a research about the dynamic response of roadbeds belonging toexisting traffic line under blasting construction with variety conditions of radialnon-coupling coefficient. And it also fits mathematical relationship between differentradial non-coupling coefficient and the shock absorption coefficient with MATLAB.The shock absorption coefficient refers to the ratio of maximal vibration velocity causedby non-coupling and the maximal velocity caused by coupling blasting, when thecharges are the same. By statistical simulation, it gets the dynamic response, caused by differentialblasting at different time intervals, at roadbeds belonging to existing traffic line. It isfound that differential blasting can reduce the velocity remarkably, but the optimumtime interval is not fixed.By statistical simulation gets how the change of the depth and width of slottingaround tunnel will alter the maximal vibration velocity, caused by blasting constructionin under-cross tunnels.