【作者】 谢冰；

【导师】 李海波；

【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， 2010， 博士

【摘要】 论文结合室内试验、现场试验以及数值模拟的方法对岩体的动态损伤问题和基础爆破安全控制问题进行了研究。通过室内物理力学试验,获得了岩样的宏观与细观力学参数,运用颗粒流软件PFC2D建立了基于颗粒间连接为平行粘接模型的数值试件,这种平行粘接模型能够满足颗粒与颗粒之间传递法向力、切向力与力矩的作用,利用数值试件研究了颗粒的细观力学性质对试件宏观力学性能的影响,得到如下结论：若颗粒间粘接模量越大则颗粒集合体的宏观弹性模量越大,但强度变化无规律性；若颗粒间粘接强度越大则颗粒集合体的宏观强度越大,但其弹性模量几乎不受影响；颗粒粘接的接触半径增大将导致颗粒集合体宏观弹性模量、强度均会提高。通过进行轴压试验,获得了数值试件的应力应变全过程曲线,经过分析整个加载过程中试件的应力、应变、切线模量、动能变化情况可知在试件加载过程中试件的切线模量有一个陡降分界点,对应此刻亦为试件动能陡增分界点,说明试件内部微裂纹开始汇聚,颗粒已经开始出现错动,试件即将失稳破坏,定义此点为损伤分界点,则可得到对应损伤门槛值为D=1-E/E0=0.18,此值与目前《水工建筑物岩石基础开挖工程施工技术规范》(DL/T5389-2007)中按照爆破前后声波波速降低率η=1-(Cp2/Cp1)=10%(此时折算损伤变量值D=1-E/E0=1-(Cp2/Cp1)2=0.19)定义的损伤门槛值较一致。通过弱化颗粒接触点强度的方式建立了用于模拟含节理的数值试件,对比无弱化点与含弱化点数值试件在不同加载速率下的破坏模式,发现接触弱化点的增多将导致材料的宏观力学性质劣化,但随着加载速率的增加,接触缺陷对峰值强度影响的敏感性逐渐减弱。运用动力有限元软件模拟了爆炸荷载,通过对比经验公式可知运用软件所计算的爆炸荷载与经验公式计算结果吻合较好,计算可靠。运用离散元软件UDEC建立了无节理与含节理岩体,将计算得到的爆炸荷载施加于炮孔位置,考察了无节理岩体的爆破损伤特征,结果表明与现场试验岩体爆破前后通过声波降低率所得到的岩体损伤区范围较一致,证明通过UDEC研究岩体爆破损伤区是可行的,进而对节理岩体的爆破损伤问题进行了研究。最后,结合工程实例对岩质基坑爆破开挖过程的损伤区测定与基础爆破开挖的安全控制问题进行了讨论,建立了应对类似工程问题的质量控制流程。更多还原

【Abstract】 Based on laboratory test, field test and numerical simulation, the rock damage by blasting and the problems of security control is studied. Though the Indoor physical and mechanical tests of rock samples, the macro-and micro-mechanics parameter are obtained. By using the particle flow software PFC2D, the numerical specimens is established with the parallel bonded model which allows the normal force, shear force and moment transferring between particle and particle. By studying the influence of micromechanical properties of particles to the macroscopic mechanical properties of the specimen, some conclusions can be draw as follow:the greater the bonding modulus particle has the larger macro-elastic modulus the specimen will has, but the bonding modulus of particles has no influence on the peak strenth of the specimen; the greater the bonding strenth particle has the larger peak strenth the specimen will has, but the bonding strenth of particles has no influence on the elastic modulus of the specimen; the elastic modulus and the peak strength of the specimen will all be increased by increasing the bonding radius of particle.The stress strain curves of the unconfined compression test of the specimen is obtained. By analysis of the changing of the stress, strain, tangent modulus, kinetic energy of the specimen though whole loading process of the test, it can be found that there is a steep drop demarcation point lies in the tangent modulus curve and the point is also the increasing demarcation point of kinetic energy curve. These phenomenon shows that the microcracks in specimens start to gather and particles have started to slip, the damage threshold of D=0.18 can be determined.The numerical specimens with joint is established by weakening the strength of contact points of particles. By analysing the differences of the test between the specimen with joints and with no joints under different loading rate, it can be found that with the increasing of the weakening contact points the mechanical properties of the specimen will degradate, it also shows that with the increasing of loading rate the sensitivity of the peak strength of the specimen gradually is weakened.The blast load is simulated by the dynamic finite element software of ANSYS AUTODYN, and the results is reliable by comparing with the empirical formula.The rock mass with or without joints is established by using the software UDEC. The damage range of the non-jointed rock by blasting agree well with the results got from the field test.All above prove it feasible to study damage zone of rock by using UDEC, and then damage zone of jointed rock is also studied by UDEC.Finally,based on a engineering project the safty control and the measurement of the damage range of the rock foundation excavated by blasting are studied and a quality control procedures for the similar engineering problems is eatablished.更多还原