Method And Application Of Tunnel Blasting Design Based On Intelligent Perception Of Geological Body

Under the advocacy of the "Development Campaign of the Western Regions Strategy" and "the Belt and Road Initiative",the scale of tunnel construction in the northwest of China is steadily on the increase.Most mountain tunnels are excavated by drilling and blasting method,but the phenomenon of over excavation and under excavation,serious damage and destruction of surrounding rock will inevitably occur during the blasting construction,directly affecting the construction safety and increasing the construction cost.Based on the engineering support of Huajiashan tunnel in XKZQ-6 section of Xi ’an to Ankang high-speed,based on theoretical analysis,numerical simulation and field testing methods,the influence law of limestone tunnel under different joint fracture angles on blasting cracks and the law of rock damage evolution under porous millisecond blasting,and proposes a tunnel blasting design method based on intelligent perception of geological body.The optimize the design of tunnel excavation and blasting,and finally achieve the purpose of controlling over excavation and under excavation.The main research work is as follows:(1)A set of parameters of limestone RHT constitutive model are determined by theoretical derivation and geological investigation report.And based on the statistical analysis of rock joint production distribution at the tunnel face of the tunnel site,numerical simulation of rock burst crack expansion under different joint fracture angles,and the variation trends of average blasting induced main crack length were obtained.(2)Through theoretical calculations and finite element analysis software ANSYS/LS-DYNA to analyze the rock damage evolution law under three detonation sequences of flush detonation,hole-by-hole detonation and interval detonation and different differential interval times,and concluded that the burst crack extension length distribution of the intermediate holes detonated first under interval detonation was more uniform,so it can be applied to the auxiliary eye to facilitate rock crushing and reduce the bulk rate.(3)Based on the combination of 3D laser scanning and image processing,a tunnel geological body intelligent perception method is established,which can achieve rapid and accurate acquisition of geological body information.The method is used to collect and analyze the characteristic information of 15 facial surfaces from DK142+185～DK142+239in Huajiashan Tunnel.Based on the intelligent perception information of the geological body,the parameters of the hole and the charge amount are optimized,and a tunnel face is selected to carry out the blasting design after optimization.The results show that the intelligent perception method of the tunnel geological body greatly improves the blasting effect.(4)The rock mass damage range after blasting is tested on site based on 4D ultra HD full intelligent borehole TV,and the evolution characteristics of rock mass excavation damage zone are obtained.Moreover,the rock mass damage zone and excavation disturbance zone are defined based on digital borehole camera.The blasting quality was evaluated by several evaluation indexes of smooth blasting quality,such as smoothness,tunnel over-under-excavated values and gravel fragmentation,which showed the feasibility of the blasting design method based on geological intelligence perception and had certain reference and promotion value for tunnel excavation.