Through An Auxiliary Tunnel And Three Excavated Tunnels To Study The Safety Area And Disaster Early Warning Study Of Them When They Are Excavated And Blasting Each Other

In recent years,underground engineering has developed rapidly,the development of tunnel caverns is also particularly prominent,and because of the limited environment of the underground space,the caverns between most of the caverns are small spaced tunnels or even super small distance tunnels.However,the underground space in Chongqing is an area with better rock conditions.In general,the excavation blasting method is used in the construction,and the cumulative damage of the tunnel caverns with super small spacing in multiple blasting is a prominent problem,and this will lead to the instability of the rock between the caverns in the tunnel caverns.In this paper,we collect data from field,theoretical analysis and numerical simulation,using the restarting function of ANSYS/LS-DYNA software,the excavation blasting of three parallel chambers,such as NO.5 caverns,NO.7 caverns and NO.9 caverns in a section of Chongqing metro line ten,is calculated and analyzed.At the same time,the acoustic velocity of rock mass around the cavern group is tested by RSM-SY5 intelligent acoustic tester,and the data of acoustic velocity of rock mass is collated,and statistical analysis of rock mass acoustic velocity data with representative sections is carried out,and the following conclusions can be drawn from the numerical calculation and the measured data of rock mass in the field:(1)With the excavation of No.5 and No.7 tunnel tunnel and No.9 tunnel and tunnel face,and the number of blasting increases gradually,and the degree of damage is obvious step by step under the condition of multiple blasting near the excavation contour.and the "steps" are gradually reduced from the bottom up.When the measuring point is far away from the excavation contour,the damage degree of the surrounding rock under multiple blasting is only "two steps",after that,and there was no obvious change in the degree of damage.When the monitoring point is about 15 m from the blasting vibration source,the blasting vibration has little effect on the monitoring point.(2)In the case of multiple bursting in the tunnel caverns,and the damage range of the surrounding rock mainly depends on the first blasting,and multiple blasting is mainly an increase in the damage degree of the surrounding rock body,and the increase in the scope of damage is not obvious.Every cavern in the case of multiple blasting,and the damage degree at the top of the cavern is greater than that on both sides of the cavern,but the damage scope on both sides of the cavern is larger than thaton the top of the cavern.(3)According to the cumulative damage degree of the peri rock mass,and the rock mass is divided into different regions,and the range of 0~1.2m at the upper part of the 5 caverns and No.9 caverns and 7 caverns is the broken zone of the surrounding rock,and 1.2~2.4m as crack zone of surrounding rock body of cavern,and beyond the range of 2.4~2.6m,the rock mass is considered as the disturbed zone and the original rock area.The range of 0~1.4m at the wall of 5 caverns and No.9 caverns and No.7caverns is the broken zone of the surrounding rock,and 1.6~2.6m as crack zone of surrounding rock body of cavern,and beyond the range of 2.4~2.8m,the rock mass is considered as the disturbed zone and the original rock area.The left wall of No.7cavern and the right wall of No.5 cavern in the range of 0~1.6m are the fractured rock mass of the rock mass,and 1.6~3.2m as crack zone of surrounding rock body of cavern,In the range of 3.0~3.2m of the side wall of the cavern,the cracks in the right wall of the No.5 hole are connected with the cracks on the left wall of No.7 hole.