摘要:
为了探究非线性斜交节理岩体中纵波的传播特性,采用理论分析、对比验证、数值计算相结合的方法,首先引用双曲线节理模型,基于应力波与线性节理的交互作用关系,根据叠加原理推导纵波入射非线性斜交节理的传播方程,其次依据文献的入射纵波参数与节理岩体条件,计算透反射系数发现结果非常接近,验证本文理论模型是准确可行的,然后选取δ函数的辅助函数作为入射纵波,通过参数研究分析纵波波形、持时以及节理刚度对斜交节理岩体中纵波传播特性的影响规律。研究结果表明:δ函数的辅助函数入射斜交节理时具有明显地幅值降低、幅值时刻滞后以及持时延长的现象,更能体现纵波短时内的突变特性和非线性衰减特征;斜交节理岩体中入射纵波持时的增加会明显提高P波的透射性能,稍微降低P波和S波的反射特性,但是对S波的透射影响非常薄弱;纵波传播至斜交节理时P波易透射微反射,S波易反射微透射,随着kn0和ks的增加,反射系数Rsc呈下凹曲面型衰减,透射系数Tpc呈上凸曲面型递增,P波的透射性能与节理法向刚度相关性密切,S波的反射特性受斜交节理中第2条节理影响显著。本文研究成果有益于开展天然节理岩体的力学特性和动力响应研究。
Abstract:
In order to explore the propagation characteristics of P wave in nonlinear oblique joints rock mass, the method combing theoretical analysis, comparative verification and numerical calculation is adopted. Firstly, the hyperbolic joint model with normal nonlinear deformation and tangential linear deformation is introduced. Based on the interaction relationship between stress wave and linear joint, the propagation equation of P wave incident oblique joints is deduced according to the wave theory, Snell theorem, conservation principle of wave front momentum, displacement discontinuity theory and superposition principle. Then, based on the parameters of incident P wave and the conditions of jointed rock mass in literature, the transmission and reflection coefficients are calculated and found to be very close, which verified the accuracy and feasibility of the theoretical model. Furthermore, the auxiliary function of δ function is selected as the incident P wave to analysis influence rule of waveform, duration and joint stiffness on the propagation characteristics of P wave in oblique joints rock mass through parameter research. The results indicated that the phenomenon of amplitude reduction, amplitude-time delay and duration extension is significant when the auxiliary function of δ function incident on oblique joints, which can better reflect the mutation characteristics and nonlinear attenuation feature of P wave in short time. The duration of incident P wave in oblique joints rock mass can significantly improve the transmission performance of P wave and slightly reduce the reflection characteristics of P wave and S wave. But the increase of duration is very weak impact on the transmission of S wave. P waves are prone to transmission but difficult to reflection and S waves are prone to reflection but difficult to transmission when P wave transmit to oblique joints. As kn0 and ks increase, the reflection coefficient Rsc decay in concave surface shape, while the transmission coefficient Tpc increase in convex surface shape. The transmission performance of P wave is closely related to the normal stiffness of joint, while the reflection characteristics of S wave is significantly affected by the second joint in the oblique joints. The research results are beneficial for developing the mechanical properties and dynamic response of natural jointed rock mass.