Experimental Investigation On Blasting Fatigue Behavior Of Defected Source

Water jet grooving directional fracture control Blasting improves the quality of traditional blasting and solves the problem of mechanical engraving,However,due to the existence of various structural planes in the rock mass,the law of the expansion of the blasting bursts in the event of these structural planes will inevitably change.At the same time,the instantaneous nature of the explosive load and the complexity of the nonlinear response of the blasting rock mass make the research on the directional fracture blasting of the water jet grouting so far,and the theoretical analysis method needs to be developed and perfected.Therefore,it is of theoretical and practical significance to study the effect of defective media on the directional blasting of jet grooving.In this paper,the mechanism of directional bursting of water jet grooving is analyzed by using fracture mechanics and blasting theory.The propagation law of explosive stress wave is simulated by ANSYS/LS-DYNA numerical simulation software under different spacing fissures.The propagation mechanism of the bursting crack and the propagation mechanism of the stress wave are analyzed by the blasting test of the plexiglass medium with different orientation prefabricated fissures,and the results of this paper are as follows:(1)Based on the theory of fracture mechanics and blasting,the stress distribution around the borehole of the jet grouting is analyzed,and the expression of the stress intensity factor of the crack propagation in the grooving direction under the blasting load is obtained,and the mechanism of the directional blasting of the water jet grouting is revealed.The propagation law of stress wave is analyzed in the crack.(2)The propagation law of stress wave,the propagation law and distribution law of the crack,the change of the main crack angle,the propagation law of the stress wave are obtained by numerical simulation software,the results show as follows: the propagation of the stress wave is affected by the grooving and the prefabricated fissure.,the guiding effect of the pre-explosion groov is obvious.The stress wave is concentrated in the direction of the grooving,and the stress wave in the explosion is affected by the prefabricated fissure,and lead to stress concentration at the fissure;The burst crack is affected by the grooving and the prefabricated fissure.The initial stage of the burst is affected by the grooving,and the crack is cracked in the direction of the end of the slot.The expansion of the crack in the middle stage is deflected to the preform fissure position by the prefabricated fissures;The angle of the main crack is increased first and then decreases with the increase of the spacing,which is mainly reflected in the effect of the prefabricated fracture angle on the crack propagation.(3)The propagation law of the stress wave and the distribution of the cracked crack were obtained by setting the blasting experiments of the prefabricated fissures(14 groups)plexiglass with different angles and different pitches.The distribution of the cracked crack included the total number of cracks,the main crack at the end of the cutting and the root Length changes and so on.The results show.as follows: With the increase of the prefabricated fissure spacing,the total number of cracks decreases,the length of the main crack at the end of the incision increases,and the length of the main crack decreases;With the increase of the prefabricated fissure angle,the length of the main crack at the end of the grooved end increases,and the length of the main crack in the grooved root is increased first and then decreased by the change of the prefabricated crack angle;The jet grooving has a guiding effect on the expansion of the crack,which promotes the propagation of the crack in the direction of the grooving.The prefabricated fissure has obvious effect on the crack propagation at the close distance,which is mainly reflected in the main crack at the end of the slot The crack at the root and the prefabricated fissure penetrate,and the main crack at the root of the grout will reflect the stress wave energy due to the presence of the prefabricated fissure,and the degree of accumulation of the stress wave around the borehole is enhanced,that is,Leading to the formation of annular cracks in some stress wave superimposed areas,plexiglass specimen tensile damage;The effect of prefabricated fissures at different angles on the crack propagation is difference,and the prefabricated fissure angle is larger to promote the crack propagation.