节理粗糙度对应力波传播的影响研究

Research of the joint roughness effects on stress wave propagation

考虑节理吻合程度,分析节理粗糙度对应力波传播和节理岩石力学特性的影响规律。使用分离式霍普金森压杆对预制节理试样进行冲击压缩试验,定性研究节理吻合程度对应力波传播的影响,采用投影覆盖法分析节理面,探究分形维数对应力波传播的影响规律。由劈裂试验获得粗糙节理面试样,2个标准试样组合得到光滑节理面试样。试验中控制子弹速度保证入射波的相同,得到以下结论:光滑节理试样的透射系数和等效刚度与完整试样相比衰减约2.1%,表明光滑完全吻合节理对应力波传播影响不大;节理吻合程度相同时,节理粗糙度越大(分形维数2.088～2.214),应力波穿越节理试样的透射系数和等效刚度越小,其中等效刚度近似呈线性减小,透射系数呈二次曲线减小;节理粗糙度相同(分形维数)时,节理吻合程度越小,节理应力波透射系数和试样等效刚度越小,表明节理吻合程度是应力波传播的重要影响因素。

To study the influence of smooth and rough joint on stress wave propagation in rock mass and the mechanical properties of jointed rocks,experimental research was carried out by using split Hopkinson pressure bar(SHPB)system.The effect of joint matching degree coefficient(JMDC)on the stress wave propagation was qualitatively studied.The projection covering method was used to analyze the joint surface,and the influence of fractal dimension on stress wave propagation was studied.Rough joint surface specimens were obtained from the splitting test,and two standard specimens were combined to obtain the smooth joint surface specimens.To get the same incident stress pulse,a series of SHPB experiments were conducted on the rock specimens with smooth joint and rough joint.It was shown that the transmission coefficients and stiffness of smooth joints rock specimen reduce 2.1%compared with intact rock specimen,the smooth joints have little influence on stress wave propagation in the test.The transmission coefficient and stiffness of joint rock specimens were influenced by the difference of joint forms.The greater the joint roughness(the fractal dimension is 2.088–2.214),the smaller the transmission coefficient and stiffness of the rock joint specimen,where the equivalent stiffness is approximately linearly reduced and the transmission coefficient is reduced by a quadratic curve.When joint roughness(fractal dimension)were the same,the smaller the JMDC,the smaller the transmission coefficient and the equivalent stiffness,which indicates that JMDC is an important influencing factor of the stress wave propagation.