水射流切槽定向爆破模型及实验研究

发布时间：2019-02-15 08:30

【摘要】：穿越复杂地质条件的隧道、小拱角岩台复杂断面开挖以及石材开采等对周边控制成型要求极高的岩石定向断裂控制爆破过程中普遍存在钻孔工作量大、超挖等问题,难以达到设计要求,严重影响施工安全,因此,研究一种巷道低损伤掘进定向断裂新工艺具有重要的现实意义。本文针对周边控制成型要求极高的工程爆破中出现的岩石壁面超挖、围岩破坏严重和钻孔量大的问题,采用岩石断裂力学理论和爆轰理论,对水射流切槽定向爆破法护壁材料消弱应力波作用和射流缝槽聚能效应进行了理论分析,并采用数值模拟和室内实验相结合的方法对理论分析结果进行了验证。论文主要研究成果如下:①基于爆轰理论和岩石断裂力学理论建立水射流切槽定向爆破理论模型。分析了冲击波在界面的反射、透射现象,推导出了护壁材料消弱应力波的公式;结合热激活理论和微裂纹成核理论分析了爆生裂纹的生成、发展过程,推导出了水射流预切槽下的爆生气体准静态作用裂纹扩展公式,最后根据应力波理论分析了爆炸应力波在射流缝槽附近的叠加效应。②分别采用弹塑性材料和压缩损伤材料模型进行了数值模拟。结果表明,护壁材料具有保护围岩的作用,受保护方向损伤最小;缝槽端部裂纹尖端应力强度因子最大,孔壁和缝槽附近区域应力强度因子次之,孔壁稍远区域最小;在爆炸中后期,爆生气体的准静态压力场对裂纹的持续扩展起主导作用,在护壁材料、射流缝的激励机制作用下,绝大部分爆生气体沿射流缝方向聚集,使射流缝方向裂纹受到较大和较长时间的准静态压力作用,因而射流缝附近特别是射流缝端部形成的裂纹最长。③分别采用普通爆破、切槽爆破、护壁爆破和水射流切槽定向爆破4种爆破方式进行了实验。结果表明:与普通爆破相比,护壁爆破能够将受保护方向的应变峰值降低27.98%,而在能量导向方面作用较小;切槽爆破使切槽方向的应变峰值提高了35.06%,但在降低围岩损伤上不如护壁爆破法;水射流切槽定向爆破综合了两种方法的优点,爆破时该方向上的应变峰值比护壁爆破降低了31.04%,在缝槽方向上应变峰值相比切槽爆破升高了35.44%,从而证明水射流切槽定向爆破是一种低损伤定向爆破方式。
[Abstract]:In the process of rock directional fracture controlled blasting, such as tunneling through complex geological conditions, excavation of complex section of small arch corner rock platform and exploitation of stone materials, which require extremely high requirements for peripheral control formation, there are generally problems such as heavy drilling workload and overdigging. It is difficult to meet the design requirements and seriously affect the safety of construction. Therefore, it is of great practical significance to study a new directional fracture technology for roadway driving with low damage. In this paper, the rock fracture mechanics theory and detonation theory are adopted to solve the problems of rock wall overexcavation, serious damage of surrounding rock and large amount of boreholes in engineering blasting with extremely high requirements of peripheral control molding. In this paper, the effect of weak stress wave attenuation and jet slot forming energy effect of water jet trench directional blasting method is theoretically analyzed, and the theoretical analysis results are verified by numerical simulation and laboratory experiments. The main research results are as follows: 1 based on the detonation theory and rock fracture mechanics theory, the theoretical model of water jet tangent directional blasting is established. The reflection and transmission phenomena of shock wave at the interface are analyzed, and the formula for reducing the weak stress wave of the wall protection material is derived. Based on the thermal activation theory and microcrack nucleation theory, the formation and development process of explosive crack are analyzed, and the quasi-static crack propagation formula of exploding gas under pre-cut channel of water jet is derived. Finally, the superposition effect of explosive stress wave near the jet slot is analyzed according to the stress wave theory. 2 numerical simulation is carried out by using the elastic-plastic material model and the compression damage material model, respectively. The results show that the wall protection material has the function of protecting the surrounding rock, and the damage in the protected direction is the least, the stress intensity factor at the crack tip of the slot end is the largest, the stress intensity factor in the region near the hole wall and the slot is the second, and the minimum is in the slightly distant area of the hole wall. In the middle and late stage of explosion, the quasi-static pressure field of explosion gas plays a leading role in the continuous crack propagation. Under the action of wall protection material and the excitation mechanism of jet joint, most of the explosion gas accumulates along the direction of jet seam. The crack in the direction of the jet seam is subjected to large and long time quasi static pressure, so the crack near the jet joint, especially at the end of the jet joint, is the longest. Experiments were carried out on four blasting methods of wall protection blasting and water jet cutting directional blasting. The results show that wall protection blasting can reduce the strain peak value of protected direction by 27.98, but has little effect on energy guidance. The peak value of strain in the cutting direction is increased 35.06, but it is not as good as the wall protection blasting method in reducing the damage of surrounding rock. The water jet trench directional blasting combines the advantages of the two methods. The strain peak value in this direction is lower than that in the wall protection blasting by 31.04, and the strain peak value in the slot direction is 35.4444 higher than that in the slot blasting. It is proved that the directional blasting with water jet cutting is a low damage directional blasting method.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD235

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