【作者】 王伟；

【导师】 李小春；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2008， 博士

【摘要】 为满足我国核电快速发展对铀资源的大量需求,解决制约低渗透砂岩型铀矿床原地浸出顺利生产的瓶颈,本文提出了无临空面深层岩体爆破增渗方法,以提高低渗透赋矿岩层的渗透性。建立了爆炸荷载下岩石损伤-渗透率耦合动本构模型。在研究不同装药结构对深层岩体爆破效果的影响的基础上,以内蒙某低渗透砂岩型铀矿床为工程背景,通过无临空面深层岩体爆破增渗模型试验及模型渗流特性试验,探讨了无临空面深层岩体爆破增渗的可行性、增渗效果及增渗机理,得出了一些有益的结论。具体内容如下:1、基于前人提出的损伤模型,本文构建了爆炸荷载下岩石损伤-渗透率耦合动本构模型。本模型抛弃之前模型基于张拉体积应变的拉伸损伤判断准则,且不去区分材料所处的拉压状态,而以某一点主张拉应变之和作为损伤开始积累的判据,以反映差应力引起的材料损伤。同时,假设岩石渗透率各向同性,建立了岩石渗透率的变化和与之相关的损伤状态之间的关系式。本模型简化了问题的描述,使其损伤的物理意义更加明确。2、基于冲击波在交界面两侧压力和速度必须各自相等的连续性条件,求解爆轰产物中适用的反射波方程和介质中适用的冲击波方程,得到药包周围介质中冲击波的初始参数。随后,通过波的传播机理,把集中药包应力波随距离的衰减公式扩展到延长药包,并计算耦合与不耦合装药时距爆心相同距离处岩石中冲击波的参数。由计算结果可知:(1)耦合装药爆破时形成的冲击波压力超过岩石抗压强度极限几十倍以上,药包周围岩石形成粉碎区,爆炸能被大量耗散;(2)与耦合装药相比,不耦合装药可以降低孔壁处岩石中冲击波初始压力。合理的不耦合系数,可使岩石不形成粉碎区,大幅度减少能量耗散;(3)水作为炸药爆轰产物与岩石间的弹性缓冲层,延长了冲击波作用时间,加大了爆炸的作用范围,增加了能量传递。3、以内蒙某低渗透砂岩型铀矿床为工程背景,在模型试验相似理论基础上,设计并实施了无临空面深层岩体爆破增渗初步模型试验和优化模型试验。试验结果表明:(1)耦合装药爆破不适宜在无临空面深层岩体爆破增渗中应用,应采用不耦合装药爆破,并且验证了不耦合介质(水)对爆炸冲击波的弹性缓冲作用;(2)验证了自制PVDF压力传感器的性能,并根据爆炸应力波的实测结果拟合了不同不耦合系数下模型中爆炸应力波幅值随距离衰减的关系式,为无临空面深层岩体爆破增渗方法中合理不耦合系数的选取提供了依据,并且这些关系式可以推广到与模型性质相似的岩石中应用;(3)初步揭示了爆破增渗的作用机理。4、研发了适用于测量模型渗透率的小尺度原位瞬态压力脉冲测试系统,并对爆破后模型进行了渗透率测量试验。试验结果表明:(1)本文提出的无临空面深层岩体爆破增渗方法增渗效果显著,爆破后模型渗透率提高了2～3个数量级;(2)确定了在不耦合装药爆破增渗中合理的不耦合系数范围为1.5～3,不耦合装药爆破增渗的范围大概为70倍的药包半径;(3)表明了爆生气体及微差爆破对渗透率提高的显著作用。5、通过爆破增渗模型试验研究和模型渗透率测量试验研究,揭示了无临空面深层岩体爆破增渗的作用机理:(1)爆炸冲击波致裂及微差爆破增渗机理;(2)不耦合装药爆破增渗机理;(3)空间补偿增渗机理;(4)爆生气体的驱动增渗机理。最后,作者对本文的研究工作做了总结,指出了其中存在的问题,并讨论了今后的研究工作。更多还原

【Abstract】 In order to solve the low permeability of the ores in in-situ leach uranium mining from low-permeability sandstone-type uranium deposits, the method of blasting enhanced permeability of no free surface deep rock mass(abbreviated to BEPDR) is proposed in this thesis to increase the permeability of the ores with low permeability. A coupled damage-permeability dynamic constitutive model of rock under explosive load is developed. Based on studying the influence of different charge configurations on deep rock mass blasting effect, combined with a low-permeability sandstone-type uranium deposits in Inner Mongolia, China, the model tests of BEPDR and seepage characteristics test of the models are carried out, respectively. Then the feasibility, enhanced effect and mechanism of BEPDR are investigated. Some available conclusions are obtained and summarized as follows:1、Based on the evolved damage models, a coupled damage-permeability dynamic constitutive model of rock under explosive load is developed in this thesis. In this model it is assumed that the damage is initiated and controlled by the sum of all the principal tensile strains in place of volumetric strain at a point. The later was used in the evolved damage models to control the damage. This model doesn’t distinguish whether the material is in tension state or in compression state and simulates the damage induced by differential stress. Moreover, in this model it is also assumed that the permeability of rock is isotropy and the relational expression between of damage growth and permeability variation in brittle rocks is proposed.2、Based on the succession conditions at the interface on both sides of which the pressures and velocities must be equal,the initial shock-wave parameters of the medium surrounding a charge are given by calculating the equations valid for the reflected wave in the detonation products and the equations valid for the shock wave in the medium. Damping equation of stress waves, which is damped with increased distance of wave front from the vibration source, is extended from spherical charges to cylindrical charges based on the propagation theory of wave. Then the shock-wave parameters of the rock having the same distance from the detonation source are worked out in the case of decoupled charges and coupled charges. The conclusions obtained as follows:(1) the shock-wave pressure is tens or hundreds of times larger than compressive ultimate strength of rock,then the crush zone comes into being in the rock surrounding a charge. So blasting energy are vastly dissipated;(2) in contrast with couple charge blasting,decouple charge blasting could decrease the initial shock-wave pressure of bore wall’s rock. If the reasonable coefficient of decouple charge is adopted, the crush zone will disappear and the dissipation of energy will decrease;(3) water, between detonation products and rock, is indicated as an elastic buffer which protracts action time of shock wave, enlarges the action region of shock wave and increases the propagation of energy.3、Combined with a low-permeability sandstone-type uranium deposits in Inner Mongolia, China, based on the similarity theory of the model test, the preliminary model tests of BEPDR and the optimized model tests of BEPDR are designed and implemented. According to the results of the model tests, the conclusions obtain as follows: (1) blasting with coupling charging is not appropriate for BEPDR and the decoupling charging is recommended, moreover, elastic buffering effect of the decoupling medium(water) on the explosion wave is verified; (2) characteristic of homemade PVDF pressure transducer is proved, the damping relationships between blasting stress waves amplitude and distance of the wave front from the blasting source in the case of different decouple coefficients are fitting according to experimental results and this formulas could be applied in the rocks that their lithology is similar to the model; (3) the mechanism of the permeability increase of the BEPDR is preliminary revealed.4、Small-scale in situ transient pulse test system that could measure the permeability of the blasted models is developed. According to the results of the permeability of the blasted models, the conclusions obtain as follows: (1) the effect of the proposed method BEPDR on the increase of the permeability is remarkable, and compared with the permeability of original models, the permeability of blasted models is increased two or three orders of magnitude; (2) the reasonable decoupling coefficient should be within the range of 1.5~3 for the decoupling charging blast and the incidence of increasing permeability is about 70 times of the radius of charge; (3) the influence of the explosive gases and short delay blasting on the permeability is considerable.5、According to model tests of BEPDR and permeability tests of the models, the mechanism of the permeability increase of the BEPDR is revealed as follows: (1) blasting shock wave created cracks and short delay blasting action mechanism; (2) decouple charge blasting action mechanism; (3) space compensating action mechanism; (4) blasting gases driving action mechanism.At last, the research work are generalized, and the problems which need further study in the future are discussed.更多还原