| With less shallow mineral resources,mineral resources gradually enter deep mining,and more and more kilometers deep Wells appear.In the process of deep mining,high ground stress is often accompanied,and the mechanical properties of rock mass are obviously different from those of shallow mines.In view of the new excavation problems faced,it is urgent to solve its safety,and systematically study the change law of its stress field and failure law.It is necessary to start from the research of the basic unloading mechanism,strengthen the similar simulation or field test of the unloading effect of excavation,explore the dynamic adjustment mechanism during excavation,the damage research of surrounding rock during excavation and after excavation,and play a practical reference role in the stability control of surrounding rock.Taking deep blasting excavation as the research object,using various means,building and making test platform independently,taking the initiative to cross-learn other disciplines,adopting theoretical analysis,test and numerical simulation techniques,and based on theoretical analysis,establishing dynamic unloading mechanical model of deep rock mass excavation under dynamic load,combining dynamic loading excavation test of similar materials with numerical simulation research methods.The stability of surrounding rock is analyzed from the Angle of excavation radius,rock lithology,unloading rate and different initial stresses influencing the stress field of surrounding rock,and then the unloading mechanism of dynamic load excavation is revealed from the whole level of rock to surrounding rock.The main research work is as follows:(1)The SHPB impact test was carried out to study the rock mechanical properties and the regularity of block distribution under the dynamic load impact condition,and the rock fracture of different lengths was studied in combination with the shock wave attenuation law,which provided references for further research on the surrounding rock cracking mechanism and surrounding rock damage under the action of blasting,and revealed the rock dynamic load characteristics.(2)The problem of roadway excavation in uniform stress field is regarded as a plane strain problem.Based on the unloading theory in elastic dynamics and the unloading model of explosion load and ground stress established,the dynamic stress field generated under the coupling action of ground stress and explosion load is solved by means of the residue theorem and the hysteresis of inverse Laplace transformation.This paper discusses the interaction between explosion load and geostress dynamic unloading in time and space,and reveals the unloading mechanism under the coupling action of explosion load and geostress.(3)Based on the law of conservation of energy and the change of unloading stress field,the dynamic adjustment process of surrounding rock energy during blasting excavation is analyzed.The change of surrounding rock energy during excavation is not a monotonous increase or decrease,but a fluctuating process,and the adjustment mechanism of unloading energy during dynamic load excavation is revealed.(4)Based on the self-developed similar simulation test system for dynamic disturbance of roadway surrounding rock,the dynamic load is simulated by dropping hammer impact,and the unloading effect of excavation of circular roadway with high ground stress is studied,including the stress change of surrounding rock,crack propagation and failure mode of surrounding rock during unloading.The influence of different unloading factors such as excavation radius,rock lithology and initial stress on the stress,strain field and damage distribution of surrounding rock is analyzed,and the failure law of dynamic excavation unloading under high ground stress is revealed.(5)Establish a finite element model of roadway under dynamic load excavation,focus on in-depth study of surrounding rock damage distribution law caused by dynamic load excavation under different initial stresses,different excavation rates,different lithology and different excavation radius,determine the distribution characteristics of surrounding rock damage zone under different unloading factors,and reveal the rock mass damage law under the transient unloading action of explosion load and ground stress.(6)Monitoring surrounding rock damage by blasting excavation in deep roadway through industrial field tests,and revealing the damage area and damage law of surrounding rock blasting excavation in Luling Mine through acoustic testing and drilling visitation.Figure [104] Table [8] Reference [186]... |
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