本文選題：爆破作用　切入點：射流切槽　出處：《重慶大學》2016年碩士論文

【摘要】：光面(預(yù)裂)爆破常用于隧道爆破開挖,該技術(shù)在隧道爆破施工時能保留較完整的爆破輪廓控制線,減少爆破作用對非開挖巖體的損傷以保持圍巖的穩(wěn)定性。然而,巖石中存在的天然裂隙會對爆破效果產(chǎn)生負面影響,出現(xiàn)超挖及破壞圍巖嚴重等問題,嚴重影響工程進度及隧道建設(shè)質(zhì)量。以光面(預(yù)裂)爆破為基礎(chǔ)的射流切槽爆破則是一種更為有效控制爆破技術(shù),其原理是利用高壓水射流在炮孔兩側(cè)沿爆破開挖輪廓線方向上預(yù)割縫形成射流導(dǎo)向縫槽,誘導(dǎo)爆生裂紋擴展。因此研究巖體裂隙對射流切槽定向爆破效果的影響機制具有重要的工程意義�；诖�,本文在實驗研究獲得高壓水射流切槽炮孔幾何形貌特征的基礎(chǔ)上,結(jié)合斷裂力學理論和爆破理論分析了爆炸荷載作用下射流切槽炮孔的受力狀態(tài)。同時,采用數(shù)值模擬與實驗測試兩種手段系統(tǒng)研究了爆炸荷載作用下不同方位、不同距離裂隙對射流切槽爆破效果的影響規(guī)律。論文主要研究成果如下:(1)采用ANSYS/LS-DYNA模擬研究了不同間距的平行裂隙與水射流縫槽對爆炸應(yīng)用波傳播規(guī)律、巖石位移變化規(guī)律及主裂紋角度變化規(guī)律的影響。結(jié)果顯示:爆炸應(yīng)力波的形狀在爆破初期與切槽炮孔相似,逐漸變?yōu)闄E圓形,最后變?yōu)榻茍A形。應(yīng)力波在裂隙處發(fā)生反射,穿過裂隙發(fā)生時衰減,但仍有部分殘余應(yīng)力波穿過裂隙并作用于上側(cè)巖石;當平行裂隙與射流切槽炮孔的間距較小時,炮孔與裂隙間的巖石會直接被破壞,但隨著炮孔與裂隙之間的距離增大,類似破壞區(qū)域減小;當平行裂隙與射流切槽炮孔的間距較小時,主裂紋角度不明顯。但當平行裂隙與射流切槽炮孔的間距逐漸增大,主裂紋角度逐漸減小。(2)實驗研究了不同角度、不同方位的裂隙對射流切槽爆破裂紋擴展的影響規(guī)律。結(jié)果表明:當裂隙與射流導(dǎo)向縫槽平行時,爆破后所形成爆破空腔的大小隨著裂紋與炮孔中心距離的增大而減小。當裂隙與射流導(dǎo)向縫槽垂直時,裂隙會阻斷爆破裂紋擴展,并在裂隙兩端形成翼裂紋。當射流切槽炮孔與裂隙呈60°角時,爆破空腔大小隨著間距增大而減小,炮孔四周出現(xiàn)環(huán)向裂紋。在4種不同的射流切槽有機玻璃試件中,射流切槽尖端出現(xiàn)的裂紋較多、長度較長,非射流切槽方向中部出現(xiàn)的裂紋較多、長度也較長,射流切槽根部出現(xiàn)的裂紋較少或長度較短。(3)分析得到爆破破壞面積與爆破裂紋之間的相互關(guān)系。通常,當射流切槽炮孔與裂隙的間距增加,爆破破壞面積會逐漸減小,而爆破裂紋長度會增大。主要因是射流切槽炮孔與裂隙的間距增加會改善有機玻璃的力學性能,造成有機玻璃破壞需要更多的爆炸能量,在爆炸能量不變時則會產(chǎn)生更長的裂紋。
[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 擄, 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.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TD235

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