Research On The Key Technique Of Small Section Hard Rock Tunnel Drifting

Due to its characteristics of low consuming, high tunneling speed, and strongability to adapt, Drilling blasting method has been used in many fields especially inthe small and medium-sized section roadway where the geological conditions arecomplex, and the rock is hard. Drilling, Blasting and Slag tapping are the three keyparts of Roadway excavation, and among the three parts, blasting is the mostimportant one. Based on the Roadway Excavation project of a Cu-Ni ore, this articlefirstly explained the mechanism of rock breaking under the acetion of explosion, thencalculated the Crushing circle radius caused by blasting, and also anANSYS/LS-DYNA^3Dbased Numerical Simulation Analysis about detonationpositions and blasting process is conducted. The main contents and achievements ofthis article are as follows:（1）The Crushing circle radius with diameter charge of42mm and55mm of No.2Rock emulsified explosive in diabase were calculated in this paper. The calculation isbased on the rock crushing principal when explosive detonation happens, explosivesin rocks detonation theory and the shock wave attenuation rule.（2） The hole-bottom detonation and the collar detonation were numericalsimulated with the ANSYS/LS-DYNA^3D. The results show that,1) Stressconcentration phenomenon is closely related to the detonation position, usually, theStress concentration phenomenon appears in the detonation position firstly.2) Thesurface pressure, effective stress, maximum shear stress and major principal stress ofthe collar detonation is higher than that of the hole-bottom detonation, and the actiontime of the collar detonation is short than that of the collar detonation.3) The stresswave of the collar detonation stacks toward the hole-bottom, on the contrast, the stresswave of the hole-bottom stacks toward the hole-collar. All these have proved that thehole-bottom detonation is superior to the collar detonation.（3） The explosion with different blast hole charge diameters（42mm and55mm） are numerical simulated with the help of the ANSYS/LS-DYNA3D, and the resultsindicated that the Crushing circle radius of the above two Charge diameters are rangefrom6cm to8cm and range from12.5cm to15cm respectively.（4） The Mixed parallel and inclined-hole cut blasting parameter and wholesection hole pattern parameters were designed. The one font bit was replaced by theball-tooth bit. All this achieved good results in engineering practice.