Research On The Application Of Pilot Hole In Presplit Blasting For The Slope Treatment Of Yingku Mountain

Due to unreasonable mining in the early stage,abandoned open-pit mines have left a large number of high and steep slopes,which will lead to landslides,collapses and other geological disasters.It is a prominent problem that needs to be solved urgently for the restoration and management of mine geological environment.In the environmental restoration project of abandoned mine in the pressure kushan mountain,the high and steep slope with serious overcut and undercut due to irregular mining has brought difficulty to slope cutting and load reduction,which also restricts the construction progress and cost,and is not good for the later greening operation.Pre-splitting blasting technology has many advantages,such as controlling the smoothness of rock wall,reducing the damage degree of surrounding rock and effectively controlling the blasting vibration.It is widely used in open pit mine,water conservancy and hydropower,highway engineering and other fields.Due to the characteristic that the blasting energy is released along the weak surface,some scholars proposed to use the guide hole to guide the blasting energy release,so as to obtain better effect of pre-splitting crack formation.But the current domestic study is less,so this article combined with the national natural science fund project(52064003),through theoretical analysis and numerical calculation method,to explore the pre-splitting blasting under the guide hole stress distribution and the law of blasting energy release,the impact on the guide hole blasting parameters were analyzed,and aimed at Ya Ku mountain ecological restoration projects,optimization measures are proposed for field test and engineering application,has certain theoretical significance and practical engineering value.Through the research,the main achievements are as follows:(1)The general mechanical process of rock mass blasting fracture-forming theory is described,and based on this theory,the main development process of rock mass blasting theoretical model is summarized.Based on the elastic mechanics and fracture mechanics,the stress distribution and fracture-forming characteristics of the surrounding rock of the guide hole wall are discussed.(2)Through ANSYS/LS-DYNA numerical calculation software,the guide hole action blasting model was established.Through the stress nephogram,stress-time history curve and final state damage nephogram,it was found that the guide hole had obvious advantages in the stress superposition effect and crack forming effect,and with the increase of the aperture,the stress superposition effect and the strength of the reflected tensile wave also increased.With the increase of the decoupling coefficient,the connecting stress between holes decreases gradually.Through numerical calculation and field tests,it is considered that selecting the decoupling coefficient 1.5 is the best blasting effect in presplit-splitting blasting of pressure reservoir hill.Studies have also shown that for pitch 1.6 m,1.8 m,the thickness of shear between the hole is relatively thin,shearing area between the two bottom hole and the formation rate faster,shear fracture damage is hard to continue to the depths of the rock mass near extension,on the contrary,pitch under 2.0 m,2.2 m parameters did not show a rapid shear failure pattern,gradually to internal excessive damage is to present a certain Angle,The efficiency of energy conversion to damage is high.(3)According to the actual treatment situation of the abandoned mine in Pressure Kushan,different hole spacing was selected to carry out the pre-splitting blasting test with guiding hole action.Test shows that the aperture (?) 120 mm,not the pitch of coupling coefficient is 1.5,2.2 m under blasting parameters,to keep the damage degree of rock mass,the smallest average slope half hole forming rate of 83.3%,not flatness to reduce about 60%,and compared with the buffer blasting,the pre-splitting blasting technology three biggest blasting vibration vector synthesis downhill 57%,better able to reduce the blasting vibration damage,and obtain good engineering application in the governance project,improve the engineering construction progress,reduce the operation cost,has a certain practical significance.