【摘要】：隨著淺部資源的耗盡,越來越多的煤礦進入深部開采。鉆孔爆破在煤礦采掘中廣泛應(yīng)用,如巷道掘進爆破、厚硬頂板強制放頂、瓦斯增透等。其中,厚硬頂板強制放頂是在厚層堅硬巖石中進行深孔柱狀裝藥爆破、沒有自由面,其施工設(shè)計多以經(jīng)驗為主。而眾多文獻表明,在深部地層中巖層受高地應(yīng)力作用,炸藥爆炸作用范圍與淺部地層不同。本文以此為背景,通過模型實驗和數(shù)值模擬相結(jié)合的方法對沖擊荷載作用下高地應(yīng)力巖體的破壞形式及機理進行研究。通過查閱大量國內(nèi)外文獻,并結(jié)合應(yīng)力波理論發(fā)現(xiàn),高地應(yīng)力場巖體爆破時在沖擊荷載作用后會產(chǎn)生一個卸載波,并且隨著地應(yīng)力的增大而愈發(fā)明顯;故認為在高地應(yīng)力場巖體爆破,除了爆炸沖擊波和爆生氣體的直接作用,還包含卸載波在爆腔周圍反射拉伸形成的裂隙。本文以此為基礎(chǔ),開展爆破模型試驗,模擬沖擊荷載作用后高地應(yīng)力巖體在卸載波作用下的破壞損傷情況。模型實驗采用抗壓強度30MPa水泥砂漿材料模擬巖體、直徑Φ400mm的鋼管模擬巖體在深部的夾制作用,利用直徑Φ5mm,長1000mm的鋁纖維導(dǎo)爆索模擬柱狀裝藥產(chǎn)生沖擊波,以沖擊波在鋼管-水泥砂漿交界面處的反射模擬巖體中的卸載波。在炮孔周圍布置應(yīng)變片測點、采用超動態(tài)應(yīng)變儀采集應(yīng)變波,以分析炮孔周圍應(yīng)力場分布;同時預(yù)埋電極、借助并行電法進行爆破后模型體的損傷范圍測試。采用LS-DYNA有限元軟件,對約束條件下深孔柱狀裝藥爆破破巖過程進行分析,研究約束條件下模型體中沖擊波的傳播歷程和裂紋的擴展過程,以探究高應(yīng)力場巖體深孔柱狀裝藥裂隙擴展和損傷機理。主要得到以下結(jié)論:1)水泥砂漿中裂紋的萌生和擴展相較于應(yīng)力波的傳播有明顯的滯后效應(yīng)。2)通過鋼套管約束作用下水泥砂漿的深孔爆破模型試驗驗證了爆炸卸載波在深部高地應(yīng)力巖體中形成裂隙和損傷的可能性。3)根據(jù)爆破前后電阻率分布圖,并結(jié)合數(shù)值模擬結(jié)果發(fā)現(xiàn)由卸載波形成的裂紋并不與爆破后的炮孔貫穿,其形成機理與爆生裂紋明顯不同,炮孔周圍的損傷是壓碎和軸向拉伸形成的徑向裂紋,而卸載波裂紋主要是因徑向拉伸形成的軸向裂紋,且二者并不貫穿。4)以薩氏公式為基礎(chǔ),結(jié)合數(shù)值模擬中爆破振動峰值隨爆心距變化的分布規(guī)律,擬合得到深孔爆破模型的爆破振動衰減的經(jīng)驗公式。5)根據(jù)混凝土、巖石等材料的應(yīng)變率效應(yīng),并結(jié)合數(shù)值模擬中深孔爆破模型的應(yīng)力波衰減規(guī)律,提出用于爆破工程現(xiàn)場的損傷破壞范圍評估方法。
[Abstract]:With the depletion of shallow resources, more and more coal mines enter deep mining. Borehole blasting is widely used in coal mining, such as roadway excavation blasting, thick and hard roof forced roof release, gas penetration and so on. Among them, the thick hard roof forced caving is to carry on the deep hole cylindrical charge blasting in the thick layer hard rock, has no free surface, its construction design is mostly based on the experience. Many literatures show that the explosive explosion range is different from that in shallow strata because of the high ground stress in the deep strata. In this paper, the failure form and mechanism of high ground stress rock mass under impact load are studied by the combination of model experiment and numerical simulation. By consulting a large number of literatures at home and abroad and combining with the theory of stress wave, it is found that a unloading wave will be produced after rock mass blasting with high in-situ stress field under impact load, and it becomes more and more obvious with the increase of in-situ stress. Therefore, it is considered that in high stress field rock mass blasting, in addition to the direct action of blast shock wave and explosive gas, it also contains the crack formed by the reflection and tension of unloading wave around the explosion cavity. On this basis, the blasting model test is carried out to simulate the damage of high ground stress rock mass under unloading wave. In the model experiment, the compressive strength 30MPa cement mortar is used to simulate the rock mass, and the diameter 桅 400mm pipe is used to simulate the rock mass in the deep layer. The shock wave is produced by using the aluminum fiber detonating cable with diameter 桅 5 mm and long 1000mm to simulate the cylindrical charge. The unloading wave of rock mass is simulated by the reflection of shock wave at the interface between steel pipe and cement mortar. Strain gauge measurement points are arranged around the hole, strain waves are collected by super dynamic strain meter to analyze the distribution of stress field around the hole, and the damage range of the model body after blasting is measured with the help of the parallel electric method and the embedded electrode. LS-DYNA finite element software is used to analyze the rock breaking process of deep hole cylindrical charge blasting under constraint conditions, and the propagation history of shock wave and the crack propagation process in the model body under constraint conditions are studied. In order to explore the crack propagation and damage mechanism of deep hole cylindrical charge in high stress field rock mass. The main conclusions are as follows: (1) crack initiation and propagation in cement mortar have obvious hysteresis effect compared with stress wave propagation. 2) through the model test of deep hole blasting of cement mortar confined by steel casing, explosion unloading is verified. According to the distribution map of resistivity before and after blasting, the possibility of wave forming crack and damage in deep rock mass with high ground stress is 3. Combined with the numerical simulation results, it is found that the crack formed by unloading wave is not through the hole after blasting, and its formation mechanism is obviously different from that of explosion crack, and the damage around the hole is a radial crack formed by crushing and axial tension. However, the unloading wave crack is mainly caused by axial crack formed by radial tension, and both of them are not through 4. 4) on the basis of Saarde's formula, combined with the distribution law of the peak value of blasting vibration with the change of the distance between the blast center and the center of explosion in numerical simulation, According to the strain rate effect of concrete, rock and other materials, combined with the numerical simulation of the attenuation law of stress wave in the model of deep hole blasting, the empirical formula of attenuation of blasting vibration of deep hole blasting model is obtained by fitting. A method for evaluating the damage range of blasting engineering site is presented.
【學(xué)位授予單位】：安徽理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TD235

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1 徐軒;深孔柱狀裝藥爆破模型試驗與數(shù)值模擬研究[D];安徽理工大學(xué);2017年

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本文編號：2189382