裂隙岩体射流切槽爆破数值模拟及实验研究

发布时间：2018-03-31 05:31

本文选题：爆破作用　切入点：射流切槽　出处：《重庆大学》2016年硕士论文

【摘要】：光面(预裂)爆破常用于隧道爆破开挖,该技术在隧道爆破施工时能保留较完整的爆破轮廓控制线,减少爆破作用对非开挖岩体的损伤以保持围岩的稳定性。然而,岩石中存在的天然裂隙会对爆破效果产生负面影响,出现超挖及破坏围岩严重等问题,严重影响工程进度及隧道建设质量。以光面(预裂)爆破为基础的射流切槽爆破则是一种更为有效控制爆破技术,其原理是利用高压水射流在炮孔两侧沿爆破开挖轮廓线方向上预割缝形成射流导向缝槽,诱导爆生裂纹扩展。因此研究岩体裂隙对射流切槽定向爆破效果的影响机制具有重要的工程意义。基于此,本文在实验研究获得高压水射流切槽炮孔几何形貌特征的基础上,结合断裂力学理论和爆破理论分析了爆炸荷载作用下射流切槽炮孔的受力状态。同时,采用数值模拟与实验测试两种手段系统研究了爆炸荷载作用下不同方位、不同距离裂隙对射流切槽爆破效果的影响规律。论文主要研究成果如下:(1)采用ANSYS/LS-DYNA模拟研究了不同间距的平行裂隙与水射流缝槽对爆炸应用波传播规律、岩石位移变化规律及主裂纹角度变化规律的影响。结果显示:爆炸应力波的形状在爆破初期与切槽炮孔相似,逐渐变为椭圆形,最后变为近似圆形。应力波在裂隙处发生反射,穿过裂隙发生时衰减,但仍有部分残余应力波穿过裂隙并作用于上侧岩石;当平行裂隙与射流切槽炮孔的间距较小时,炮孔与裂隙间的岩石会直接被破坏,但随着炮孔与裂隙之间的距离增大,类似破坏区域减小;当平行裂隙与射流切槽炮孔的间距较小时,主裂纹角度不明显。但当平行裂隙与射流切槽炮孔的间距逐渐增大,主裂纹角度逐渐减小。(2)实验研究了不同角度、不同方位的裂隙对射流切槽爆破裂纹扩展的影响规律。结果表明:当裂隙与射流导向缝槽平行时,爆破后所形成爆破空腔的大小随着裂纹与炮孔中心距离的增大而减小。当裂隙与射流导向缝槽垂直时,裂隙会阻断爆破裂纹扩展,并在裂隙两端形成翼裂纹。当射流切槽炮孔与裂隙呈60°角时,爆破空腔大小随着间距增大而减小,炮孔四周出现环向裂纹。在4种不同的射流切槽有机玻璃试件中,射流切槽尖端出现的裂纹较多、长度较长,非射流切槽方向中部出现的裂纹较多、长度也较长,射流切槽根部出现的裂纹较少或长度较短。(3)分析得到爆破破坏面积与爆破裂纹之间的相互关系。通常,当射流切槽炮孔与裂隙的间距增加,爆破破坏面积会逐渐减小,而爆破裂纹长度会增大。主要因是射流切槽炮孔与裂隙的间距增加会改善有机玻璃的力学性能,造成有机玻璃破坏需要更多的爆炸能量,在爆炸能量不变时则会产生更长的裂纹。
[Abstract]:Smooth (pre-splitting) blasting is often used in tunnel blasting excavation. This technique can keep a complete blasting contour control line in tunnel blasting construction and reduce the damage caused by blasting to non-excavated rock mass in order to maintain the stability of surrounding rock.However, the existence of natural cracks in the rock will have a negative impact on the blasting effect, such as overdigging and serious damage to surrounding rock, which will seriously affect the progress of the project and the quality of tunnel construction.The jet cutting blasting based on smooth surface blasting is a more effective blasting control technique. The principle is that the high pressure water jet is used to pre-cut the two sides of the blasting hole along the direction of the outline of blasting excavation to form the jet guide slot.Induced crack propagation.Therefore, it is of great engineering significance to study the influence mechanism of rock fissure on the effect of jet cutting directional blasting.Based on this, based on the experimental study, the geometrical morphology of high pressure water jet notched holes is obtained. Combined with the theory of fracture mechanics and blasting theory, the stress state of jet notched holes under explosive loading is analyzed in this paper.At the same time, numerical simulation and experimental test were used to systematically study the effect of different directions and distances of fracture on the blasting effect of jet cutting.The main research results are as follows: (1) the effects of parallel fractures and water jet slots with different spacing on the propagation of applied wave, rock displacement and main crack angle are studied by ANSYS/LS-DYNA simulation.The results show that the shape of the explosive stress wave is similar to that of the cut hole in the early stage of blasting, and gradually becomes elliptical, and finally becomes round.The stress wave is reflected at the fissure and attenuates when it passes through the fissure, but there are still some residual stress waves passing through the fissure and acting on the upper rock.The rock between the hole and the fissure will be destroyed directly, but with the increase of the distance between the hole and the fissure, the similar failure area will decrease, and the angle of the main crack is not obvious when the distance between the parallel fissure and the jet-cut hole is small.However, when the distance between the parallel fissure and the jet-cut hole increases gradually, the main crack angle decreases gradually.) the effect of different angles and different directions on the crack propagation in the jet-cut blasting is studied.The results show that when the fissure is parallel to the jet guide slot, the size of the blasting cavity decreases with the increase of the distance between the crack and the center of the hole.When the crack is perpendicular to the jet guide slot, the crack will block the propagation of the blasting crack and form the wing crack at the two ends of the crack.When the angle between the hole and the fissure is 60 掳, the size of the blasting cavity decreases with the increase of the distance, and the circumferential crack appears around the hole.In the four kinds of fluid-cut plexiglass specimens, the cracks at the tip of the jet groove are more and the length is longer, and the crack in the middle of the non-jet groove direction is more and the length is longer.The relationship between blasting damage area and blasting crack is obtained by means of the analysis of fewer cracks or shorter length at the root of jet notch.Usually, when the distance between the hole and the fissure increases, the blasting damage area will gradually decrease, and the blasting crack length will increase.The main reason is that the increase of the spacing between the hole and the fissure of the jet groove will improve the mechanical properties of the plexiglass and cause the destruction of the plexiglass to require more explosive energy and the longer crack will occur when the explosion energy is constant.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD235

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