不同卸荷速率下大理岩破裂时效特性与机理研究
发布时间：2018-10-30 10:18
【摘要】：巷道开挖过程中卸荷速率对岩体破裂特性有显著影响,且破裂特性表现出明显的时间效应。针对岩体在卸荷条件下的受力特征,利用颗粒流程序,对脆性大理岩进行围压卸载数值模拟,研究不同卸荷速率下卸荷结束瞬间和卸荷后持续点的岩石试样破裂特性和机理。结果表明:围压卸载过程中,卸荷变形率△ε_i随卸荷速率的增大而减小,且侧向变形比轴向变形更敏感;在卸荷结束瞬间,微裂纹主要集中在试样上下端部并形成剪切破裂带,其中张拉裂纹数目是剪切裂纹的3~6倍,试样的破裂程度S_1随卸荷速率的增大呈指数递减规律变化;在卸荷后持续点,卸荷速率较慢的情况下岩石试样破坏形式为宏观剪切破裂面,卸荷速率较快的情况下岩石试样破坏形式为块体剥落及上下端部颗粒(块体)弹射,试样的破裂程度S_2随卸荷速率的增大呈指数递增规律发展;卸荷速率越快,达到卸荷后持续点时,试样累计释放的颗粒动能越大,岩爆程度越大。
[Abstract]:During the excavation of roadway, the unloading rate has a significant influence on the rock mass rupture characteristics, and the fracture characteristics show obvious time effect. Aiming at the stress characteristics of rock mass under unloading condition, the confining pressure unloading numerical simulation of brittle marble is carried out by using particle flow program, and the fracture characteristics and mechanism of rock specimen at different unloading rates are studied. The results show that the unloading deformation rate 蔚 _ I decreases with the increase of unloading rate, and the lateral deformation is more sensitive than axial deformation. At the end of unloading, the microcracks mainly focus on the upper and lower end of the specimen and form a shear fracture zone, in which the number of tensile cracks is 3 or 6 times that of the shear crack, and the fracture degree S-1 of the specimen varies exponentially with the increase of unloading rate. When the unloading rate is slow, the failure mode of rock specimen is macroscopic shear fracture surface, and the failure form of rock specimen is block spalling and upper and lower end particle (block) ejection when unloading rate is higher. As the unloading rate increases, the fracture degree S _ 2 of the specimen increases exponentially. The faster the unloading rate is, the larger the kinetic energy of particles released by the sample is and the greater the rock burst degree is when it reaches the point of duration after unloading.
【作者单位】： 中南大学资源与安全工程学院;中南大学深部金属矿产开发与灾害控制湖南省重点实验室;
【基金】：国家自然科学基金项目(11472311) 国家重点研发项目(2016YFC0600706)
【分类号】：TD313
，
本文编号：2299724
[Abstract]:During the excavation of roadway, the unloading rate has a significant influence on the rock mass rupture characteristics, and the fracture characteristics show obvious time effect. Aiming at the stress characteristics of rock mass under unloading condition, the confining pressure unloading numerical simulation of brittle marble is carried out by using particle flow program, and the fracture characteristics and mechanism of rock specimen at different unloading rates are studied. The results show that the unloading deformation rate 蔚 _ I decreases with the increase of unloading rate, and the lateral deformation is more sensitive than axial deformation. At the end of unloading, the microcracks mainly focus on the upper and lower end of the specimen and form a shear fracture zone, in which the number of tensile cracks is 3 or 6 times that of the shear crack, and the fracture degree S-1 of the specimen varies exponentially with the increase of unloading rate. When the unloading rate is slow, the failure mode of rock specimen is macroscopic shear fracture surface, and the failure form of rock specimen is block spalling and upper and lower end particle (block) ejection when unloading rate is higher. As the unloading rate increases, the fracture degree S _ 2 of the specimen increases exponentially. The faster the unloading rate is, the larger the kinetic energy of particles released by the sample is and the greater the rock burst degree is when it reaches the point of duration after unloading.
【作者单位】： 中南大学资源与安全工程学院;中南大学深部金属矿产开发与灾害控制湖南省重点实验室;
【基金】：国家自然科学基金项目(11472311) 国家重点研发项目(2016YFC0600706)
【分类号】：TD313
，
本文编号：2299724
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