ISSN 1000-3665 CN 11-2202/P

    轴向冲击下含孔洞岩样的动态力学特性与能量特征数值研究

    Numerical study on dynamic mechanical properties and energy characteristics of rock samples with holes under axial impacts

    • 摘要: 岩石因天然作用和人类活动会形成各种类型的孔洞缺陷,为探究含孔洞岩样在冲击荷载作用下的力学特性和能量演化规律,首先基于有限元软件ANSYS/LS-DYNA与Holmquist-Johnson-Cook(HJC)本构模型,对含不同面积的圆形和方形开孔岩样进行动态冲击数值模拟研究。接着,分析了孔洞形状与孔洞面积对岩样的强度和变形特征的影响,并考察了不同类型的开孔岩样的裂纹发展与破坏特征。最后,分别阐释了不同类型岩样在冲击破坏过程中的能量转化机制。结果表明:含孔洞岩样的峰值应力和弹性模量均低于完整岩样,且随孔洞面积的增大分别呈指数和线性函数衰减;在冲击荷载下,含孔洞岩样的开裂时间早于完整岩样,岩样的破碎程度与孔洞面积呈正相关,且在同样孔洞面积下方形孔洞岩样破坏程度比圆形孔洞岩样更剧烈;随着孔洞面积的增大,岩样的透射能逐渐减小,耗散能逐渐增大,圆形和方形孔洞岩样的能耗密度均呈线性增长趋势。孔洞对岩样的劣化作用明显,且方形孔洞劣化强于圆形孔洞,能量演化规律与破坏模式密切相关。本文研究成果可为动态载荷下岩体工程建设及防灾减灾等提供参考。

       

      Abstract: Various types of pore defects are formed in rocks due to natural effects and human activities, in order to investigate the mechanical properties and energy evolution of rock samples with pores under impact loads, the dynamic compression numerical simulations using the finite element software ANSYS/LS-DYNA and the Holmquist-Johnson-Cook (HJC) constitutive model were conducted. These simulations involved rock samples with varying pore areas, featuring both circular and square pores. Then, the influence of pore shape and area on the strength and deformation characteristics of rock samples is analyzed, and the characteristics of crack development in rock samples with different pore size and shape are examined. Finally, the energy conversion mechanism during the impact-induced failure for various types of rock samples is elucidated. The results show that the peak stress and elastic modulus of rock samples with pores are consistently lower than those of intact rock samples, and they decrease exponentially and linearly with the increase of pore area, respectively. Under the impact load, the cracking time of the rock sample with pores is earlier than that of the intact rock sample. The degree of fragmentation of rock samples is positively correlated with pore area. Under the same pore area, square pores had a more significant deteriorating effect on the rock samples compared to round pores. With the increase of pore area, the transmitted energy decreases gradually, and the dissipated energy increases gradually. The energy consumption density of both round and square pore samples showed a linear increase. The deterioration of the rock samples by the pores is obvious, and the deterioration of the square pores is stronger than that of the round pores, and the energy evolution law is closely related to the damage pattern. The research results of this paper can provide references for rock engineering construction and disaster prevention and mitigation under dynamic loads.

       

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