| The drilling and blasting method is widely used in excavation of underground cavern. In the process of blasting excavation, remaining rock mass has inevitably been disturbed by blasting, especially in the blasting excavation process of small distance of underground caverns, there are disturbing problems for the adjacent rock cavern and the excavating cavern. After surrounding rock mass of the cavern under blasting excavation disturbance, The micro cracks emerge induced by the disturbance in surrounding rock mass, formed the excavation damage zone distributed along the boundary of cavern, named EDZ(Excavation Damage Zone). The Peak vibration velocity are considered as basis for safety estimation of underground caverns under blasting excavating, and the rule of blasting seismic wave propagation can be obtained based on the field blasting vibration test, through it can provide a basis for the following safety measures.Based on the reading of a large number of domestic and foreign literature, combined with the field blasting vibration test in Xiluodu underground diversion tunnels and the middle layer cutting blasting excavating parameters of the diversion tunnel, used dynamic finite element software to study the rule of blasting seismic wave propagation and influence mechanism for EDZ(Excavation Damage Zone) of the adjacent cavern surrounding rock mass by blasting excavation. The main works as follows:(1)Conducted the regression analysis of the measured particle horizontal and vertical vibration velocity of field blasting vibration test blasting by using Sadaovsky empirical formula. The results show that the horizontal particle peak velocity of blasting vibration was large than the vertical particle peak vibration velocity, and the particle horizontal velocity attenuated slowly than vertical velocity. In the subsequent control measures of blasting vibration, it should be taken into consideration that particle horizontal vibration velocity will be controlled in the safety threshold.(2)The numerical simulation software ANSYS/LS-DYNA were conducted to study the propagation of explosion seismic waves between the diversion tunnels, In this paper, two kinds of different material models were used for numerical calculation, the results showed that the numerical simulation results adopting kinematic hardening model which considered strain rate effect were more close to measured data than adopting ideal elastic-plastic model.(3)Carried out the research of surrounding rock mass disturbance of the adjacent tunnels by numerical simulation. In the process of numerical simulation, applied explosion shock loading of partition detonated blast holes in cutting blasting on the rock mass structure, using the cumulative damage theory, to get the evolution law of surrounding rock EDZ(Excavation Damage Zone) of the adjacent tunnel in the cutting blasting excavation process. After single segment holes blasting, in the rock mass area near the blasting holes main caused compressive shear damage, for the far area existing free surface main caused tensile damage. The existing of pre-splitting cracks had reduced the disturbance caused by the blasting excavation on the remaining rock mass.(4) The influence mechanism of the adjacent tunnel surrounding rock mass EDZ caused by cutting blasting as follows:the middle part of adjacent tunnel side wall facing blasting had the largest damaged rock mass range. To ensure the construction safety, it should take monitoring to this region, and the corresponding supporting measures. In the process of cutting blasting process, both sides of the arch and the foundation rock of the adjacent tunnel emerged damaged rock mass area, and the area of adjacent tunnel side wall facing blasting was larger than side wall not facing blasting. The vault and floor of adjacent tunnel also merged damaged rock mass zone, wherein the vault of adjacent tunnel, damaged zone extended to blasting side with the sectional blasting of the cutting blasting. |
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