The Numerical Simulation Of Shotcrete-bolt Support Under High Ground Stress And Blasting Dynamic Load

Blasting engineering is widely used in mine engineering, construction engineering, hydraulic engineering, traffic engineering and civil defence fortifications. Blasting is a special bursting phenomena, and it is a engineering technology which destroy the original structure of something for different purpose of engineering by the energy of the explosive. The favorable economic benefit is obtained by engineering blasting, but at the same time, the explore dynamic load caused by blasting lead to harmful effects for the building and the rock and soil mass nearby. The shotcrete-bolt support is widely used in support engineering, and it is inevitable to be effected by the blasting dynamic load. There is very important engineering significance to research the dynamic response of the shotcrete-bolt support which is under the explore dynamic load.In this paper, the shotcrete-bolt support under high ground stress and blasting dynamic load is studied by way of theoretical analysis, site investigation and numerical simulation. The contents of this paper are outlined in details as following:(1) The time history analysis method of elastic system and elasto-plastic system with different freedom incentived by velocity and acceleration is concluded. The principle of FLAC3D and the frequently-used constitutive model is introduced.(2) The software of FLAC3D is adopted and numerical model of the roadway in Dongguashan Copper mine is created. The results show that: most of the shotcrete is in the plastic state when the the roadway is excavated. Surrounding rock near the shotcreting is also in the plastic state. The roadwayis in the state of bias compression and the plastic zone increased and metastasisd when the orebody is excavated.(3) The dynamic-static coupling numerical model is established, the vertical excitation, horizonal excitation and bidirectional excitation are loaded and the dynamic response of supporting structure is calculated. Under the different excitation, the plastic zone is different; the effect of damage is coupling and superposition, the plastic zone is larger and the change range of rockbolt axial force is bigger under the bidirectional excitation.(4) Analysis and contrast the plastic zone, rockbolt axial force and the roadway displacement of different length rockbolt; import the dynamic load to the static numerical model, analysis the dynamic response of supporting structure of different length rockbolt, the results show that the most reasonable length of rockbolt is 2.2m.(5) Contrast the stress field distribution and the strain field distribution of the different thickness shotcreting, the results show that the damage of surrounding rock is more serious when the shotcreting is too thickness and the thickness of 100mm is suitable.(6) Calculate the numerical model of the steel fiber concrete lining and the concrete lining, the result display that the steel fiber concrete have the better toughnesscan and it can endure higher impact load, steel fiber concrete lining can replace the suspended net concrete lining in roadway support engineering.(7) On the basis of the study, the optimal scheme which can provide references for practical engineering is proposed.The research results of this paper have reference value for the underground engineering with shotcrete-bolt support under high ground stress and blasting dynamic load.