Study On Tunneling Blasting Technology For Layered Rock Mass Tunnel

Natural rock masses contain a large number of defects such as joints,faults,and fissures(hereinafter collectively referred to as joints),which make the rock mass have obvious nonlinearity and significant anisotropy.The existence of joints causes stress concentration at the structural plane,and the explosion stress wave The reflection also causes the explosive gas to "leak out" from the joint filler.Especially when there are multiple layers of joints in the rock mass,it is easy to cause uneven distribution of explosive energy,and it is difficult to form a good blasting contour surface and a large blasting block.Shooting and other phenomena.Based on this,the attenuation law of the explosive stress wave in the jointed rock mass after the blasting of the blasthole is theoretically analyzed.At the same time,the finite element program ANASYS-LS/DYNA is used to establish the mechanical model of the layered jointed rock mass,and the thickness and The stress field distribution characteristics of the explosive stress wave in the rock mass when filling the medium,the decay law of the rock mass explosion stress field and peak stress with distance when different charging structures are obtained.The main findings are as follows:(1)The existence of joints hinders the propagation of explosive stress waves.The peak stress after jointing is significantly lower than that of unjointed peak stress.With the increase of joint thickness,the peak stress decreases.The average decay rate is 0.097 MPa./mm;The existence of joints makes the propagation of stress waves have hysteresis,and as the thickness of the joint increases,the propagation delay time of the stress wave is longer,and the average lag time is 1.4 ?s/mm.(2)The joints of different water content have different barrier effects on stress waves.When the thickness of jointed clay is constant,the stress peak of the explosion stress wave through the joint crack decreases with the increase of the water content of the joint filler,and the water content is 25 In the range of%-41%,the stress peak decreases by 0.25MPa for each 1%increase of the average moisture content,the water content is in the range of 41%?50%,and the stress peak decreases by 0.05MPa for every 1%increase of the average moisture content;the stress wave reaches the peak value.The lag time increases as the water content of the joint filler increases,and the average lag time is 0.25 ?s for every 1%increase in moisture content.(3)The existence of joints hinders the expansion of the macroscopic through cracks.The greater the thickness of the joints,the smaller the length of the cracks passing through the joints.(4)When designing the smooth blasting parameters of jointed rock mass tunnel,the influence of joint on the light blasting effect should be fully considered,the distance from the blasthole to the joint should be controlled,and the air space charge should be used to make the explosive energy in the blasthole and the light blast layer as much as possible.The periphery is evenly distributed to achieve a good light burst effect.Figure[58] table[18] reference[56]...