山地灾害与地表过程重点实验室知识库

夹层是常见的地质结构,在地震或爆破荷载作用下,夹层对应力波的传播以及对岩体的响应具有重要的影响。以往对应力波在夹层介质中传播的研究多集中于夹层对应力波的隔振或透射性能,而对应力波在夹层中的多次折、反射过程中能量的演化规律缺乏讨论,对夹层介质的应力响应与破坏没有开展较好地分析。通过理论方法对应力波在夹层内部传播过程中的能量系数的变化规律进行了研究,分析了岩体介质波阻抗和应力波入射角对夹层内外介质中累积波动能量系数的影响规律,以及平面型边坡中软弱夹层的应力响应特征和动态稳定性。研究发现,应力波在夹层内部往复反射过程中,夹层内剩余应力波能量随折、反射发生次数呈指数曲线下降,第4次折、反射后产生的应力波能量可以忽略;夹层内外介质中应力波的累积能量系数的差异随着夹层内外介质波阻抗的相对差异的增大而增大。在平面谐波入射下,边坡内部的夹层中的剪应力和抗剪强度呈波动变化;相对P波,SV波入射会产生较高水平的剪应力,对边坡稳定性影响最大。且SV波入射时,边坡的安全系数对夹层的倾角变化更为敏感,随倾角增大而迅速降低。

The intercalation is a common geological structure,and it significantly influences the stress wave propagation and its response to rock mass under the seismic or blasting loads.In the past studies,the researches focus on vibration isolation performance and transmissivity of stress wave propagation at intercalation.However,the energy evolution of stress wave in the process of multiple refraction and reflection in intercalation are seldom investigated,and the stress response and failure of intercalation have not been well analysed.Therefore,the variation laws of energy coefficients in the propagation process of stress waves were studied by theoretical analysis.The influence of the wave impedance of rock mass and the angle of incidence of stress wave to the accumulated energy coefficients of stress wave in the intercalation are analysed,as well as the intercalation stress response and the dynamic safety coefficients of a plane failure slope.As a result,the residual energy coefficients of stress wave decreased exponentially with the times of refraction and reflection during the stress wave propagation in the intercalation.It was found that the residual energy of stress waves could be neglected after the fourth refraction and reflection.The differences in accumulated energy coefficients of stress waves in the different media increased with the relative differences of wave impedance between the intercalation and surrounding rock.Under the incident of the plane harmonic wave,the shear stress and shear strength in the intercalation exhibited a fluctuation of the same frequency as the incident wave.Compared to P-wave incident,SV-wave incident generated greater shear stress in the intercalation,and caused the greatest impact on the slope stability.When the SV-wave was incident,the safety factor of the slope was more sensitive to the dip angle of intercalation than that when P-wave incident,and the safety factor decreased more rapidly with the increase of the dip angle.