岩石静态定向破裂力学机理及其技术研究

发布时间：2018-03-08 13:05

本文选题：静态破碎剂　切入点：各种形状装药孔定向开裂　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：静态爆破技术具有无噪音、无震动、无飞石和无粉尘的优点,被广泛应用于岩土、交通、采矿、水利水电等工程中。针对圆孔装药后的膨胀应力在孔周边呈现均匀分布而无法控制裂纹扩展方向这一问题,展开含不同形状单孔、多孔的静态定向破裂力学机理、实验及其技术研究。通过分析认为:微裂纹是在较高压应力、拉应力和药柱与孔壁之间的摩擦力作用下产生的,然后随着膨胀力的增大,沿着某几条微裂纹扩展成宏观裂纹。建立了含椭圆孔、矩形孔静态膨胀受力的数学模型,通过计算得到:椭圆孔长轴尖角处的应力集中系数达到3-9倍,矩形孔四个尖角处的应力集中系数达到7-9倍。基于此结论,确定了静态定向开裂的两个基本条件:开裂位置确定与膨胀力向垂直于开裂方向集中。利用混凝土易于造孔的特点,分别浇筑了一系列不同几何尺寸的含圆孔、椭圆孔、矩形孔和模拟矩形孔、菱形孔钢模具的混凝土试块,并进行静态破碎试验,结果发现:相对于圆形孔,其他形状的装药孔都有一定的定向作用,并且定向效果:矩形孔弱于菱形孔,菱形孔弱于椭圆孔。研究了多个约束面上含成排圆孔的岩石分割机理,同样也能起到定向作用。同时,利用声发射仪器记录并分析了裂纹扩展的时空分布规律,声发射事件数的密集程度能很好地反应裂纹扩展的路径:从钻孔中部出现较多裂纹,然后向孔口自由面扩展,直至扩展到边沿。利用ANSYS有限元软件对其应力场分布和裂纹扩展进行分析,模拟结果与理论分析、试验结果基本吻合。最后,对实际工程中巷道断面修复、巷道贯通等进行了数值仿真与物理模型实验。
[Abstract]:Static blasting technology has the advantages of no noise, no vibration, no flying stone and no dust, so it is widely used in geotechnical, traffic, mining, In water conservancy and hydropower engineering, aiming at the problem of uniform distribution of expansion stress in the periphery of round hole after charging and the failure to control the direction of crack propagation, the mechanics mechanism of static directional fracture with different shapes and holes is developed. Through the analysis, it is concluded that the microcracks are produced under the action of high pressure stress, tensile stress and friction between the charge column and the hole wall, and then increase with the expansion force. A mathematical model of static expansion force of elliptical hole and rectangular hole is established. The stress concentration factor at the sharp corner of the long axis of elliptical hole is 3-9 times higher than that at the tip of the long axis of elliptical hole. The stress concentration factor at the four sharp corners of a rectangular hole is 7-9 times. Based on this conclusion, two basic conditions of static directional cracking are determined: the crack position is determined and the expansion force is concentrated perpendicular to the crack direction. A series of concrete test blocks with round holes, elliptical holes, rectangular holes, simulated rectangular holes, rhombic holes and steel dies with different geometric sizes were cast, and the static crushing tests were carried out. The results showed that: compared with the circular holes, Other shaped charge holes have some directional effect, and the directional effect is that the rectangular hole is weaker than the rhombic hole, the diamond hole is weaker than the elliptical hole. The mechanism of rock segmentation with rows of circular holes on several constrained surfaces is studied. At the same time, the time-space distribution law of crack propagation is recorded and analyzed by acoustic emission instrument. The density of acoustic emission events can well reflect the path of crack growth: more cracks appear from the middle of borehole. The stress field distribution and crack propagation are analyzed by ANSYS finite element software. The simulation results are in good agreement with the theoretical analysis. Numerical simulation and physical model experiments are carried out on the roadway section repair and tunnel penetration in practical engineering.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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