Study On Controlled Blasting Technology And Vibration Characteristics Of Near Overlapping Tunnel

The construction of drilling and blasting method has greatly improved the efficiency of tunnel engineering,and the control of blasting technology has become the most important part of the project.However,the advantages must have disadvantages,the negative impact of blasting,especially the vibration of overload will be to build(construct)the building of the immeasurable damage.Therefore,the study of blasting vibration propagation law is one of the means to reduce the harmful effect of blasting vibration,and it is also the important content of blasting safety technology research.This article takes the Qingdao metro line Line 2 Liaoyang East Road vehicle base to pull out the entrance of the automobile East Station e exit as the background,on the basis of consulting a large number of relevant literatures and long-term participation in site construction and monitoring,the blasting technology and its vibration characteristics of near make stack tunnel were studied from the aspects of drilling and blasting design,field test,vibration monitoring and data analysis.The "Step+zoning" controlled blasting technology is proposed for the first time,which provides reference for the near make tunnel engineering.In this paper,the regularity of blasting vibration propagation in each district and the distribution of the amplitude and energy of blasting vibration signals are analyzed by using wavelet packet analysis technique.Finally,the concept of safety monitoring and classification of blasting vibration is put forward with 3 factors of vibration velocity,frequency and energy,and the qualitative analysis of the key vibration monitoring position in this project is made.The main conclusions of this thesis are as follows:(1)For the first time,the "Step Zoning Method" was proposed to control blasting technology for the f=3-5 of granite overlapping tunnels with a vertical distance of 3m.Blasting parameters:The upper step cycle footage 0.75m,cutting area,auxiliary 1 zone,auxiliary 2 to distinguish two cycles of three blasting;(2)The maximal value of Vh in the blasting of cutting area appears in the front lm of the working face or the 3m position of the working face,respectively,the relative magnification is:1.79-2.14,1.05-1.22.The Vh maximum of the combined vibration velocity in the auxiliary zone 1 blasting occurs at 3m position in front of the face 1-2m or working face,and the relative magnification is:1.14-1.27 and 1.28?2.08 respectively.The Vh maximum of the combined vibration velocity in the auxiliary Zone 2 blasting occurs at 3m position in front of the face 1?2m or working face,and the relative magnification is:1.04?1.10 and 1.12?1.30 respectively.The maximal value of Vh in the lower bench blasting occurs at 9m or 3m position in front of the working face,and the relative magnification is 1.54-2.41 and 1.30?1.64 respectively.When blasting in cutting area,auxiliary 1 area and auxiliary 2 area,the Vh of blasting working face is generally larger than the front,and the vibration speed magnification is as follows:1.22?1.54,1.02?2.59,1.4?2.71.(3)In the front area of blasting working face:The cutting area and the Auxiliary 1 area blasting,in the vertical direction,the frequency band gradually moves toward the low-frequency with the increase of the horizontal distance,and the low-frequency energy ratio increases and the frequency band Narrows.We should pay attention to the effect of blasting distant low frequency energy on building(construction).When the auxiliary 2 zone and the lower step blasting,the frequency band moves toward the high frequency gradually with the increase of the horizontal distance,and the high-frequency energy ratio increases.The total energy in the vertical direction of blasting vibration signal is generally larger than that of horizontal and horizontal tangential.(4)In the rear area of blasting face:when blasting in the cutting area,in horizontal radial,tangential and vertical direction,the frequency band moves toward the high frequency gradually with the increase of distance,the high frequency energy proportion increases,the frequency band widens.In the horizontal radial,tangential and vertical direction of the auxiliary 1,2 and lower steps,with the increase of distance,the frequency band gradually moves to the low-frequency,and the low-frequency energy increases.Attention should be paid to the impact of blasting distant low-frequency energy on buildings.The total energy of the zonal blasting vibration signal in the vertical direction is generally greater than that of horizontal radial and horizontal tangential.The total energy of each zone blasting vibration signal in 3 directions decreases gradually with the increase of distance.This is basically consistent with the variation of the vibration velocity with distance.(5)The horizontal distance of blasting working face in cutting area is 2m,8m,and the rear 3m is the key position of vibration monitoring.The horizontal distance between 3m,8m and the rear 3m is the key position for vibration monitoring in the 1 area blasting working face.The Auxiliary 2 area Datum Point,the working face rear 3m place is the vibration monitoring key position.The main position of vibration monitoring in the front 6m and rear 3m of the lower bench blasting face.