共查询到20条相似文献，搜索用时 15 毫秒
1.
Stochastic seismic wave interaction with a slippery rock fault is studied, based on the principle of conservation of momentum
at the wave fronts along the fault. By using the displacement discontinuity method, the wave propagation equations are derived
for incident longitudinal-(P-) and shear-(S-) waves, respectively. This is an extension of the study by Li and Ma (2010) for
blast-induced wave propagation across a linear rock joint. Stochastic seismic waves are generated from a frequency spectrum
and used to analyze the seismic wave interaction with a rock fault having a Coulomb-slip behavior. Parametric studies are
carried out to investigate the effect of the intensity and impinging angle of the incident seismic waves on wave propagation
across a slippery rock fault. Results show that the transmission of the incident P-wave is almost not affected by the fault,
on the contrary, this is not the case for an incident S-wave, due to the occurrence of a relative slip which is related to
the impinging angle of the incident S-wave. A quantitative study is presented which is of help in understanding the propagation
and attenuation laws of seismic waves in discontinuous rock masses. 相似文献
2.
Analysis of Wave Propagation Through a Filled Rock Joint 总被引：1，自引：1，他引：0
An analytical and experimental study on a longitudinal wave (P-wave) transmission normally across a filled rock joint is presented in this paper. The dynamic property of the filling material for the artificial rock joints is derived from a series of modified split Hopkinson pressure bar (SHPB) tests. The incident and transmitted waves in granitic pressure bars are calculated by wave separations of the strain gauge readings. The incident wave is approximated by a series of half-sinusoidal waves, and an analytical model on wave propagation across a filled rock joint is then deduced. The derived wave transmission coefficients across the filled joint agree very well with those from the test results. Both the analytical and test results show that the wave transmission coefficients are influenced by the mechanical properties and the input energy of the incident waves. Analytical parametric studies with respect to pre-compaction of the filling material, the frequency and amplitude of the incident wave have also been conducted. 相似文献
3.
A Numerical Study on Wave Transmission Across Multiple Intersecting Joint Sets in Rock Masses with UDEC 总被引：1，自引：1，他引：0
This paper presents a numerical study on wave transmission across jointed rock masses with UDEC, where multiple intersecting joint sets exist. The capability of UDEC of studying wave transmission across rock joints is validated through comparison with analytical solutions and experimental data. Through parametric studies on wave transmission across jointed rock masses, it is found that joint mechanical and spatial parameters including joint normal and shear stiffnesses, nondimensional joint spacing, joint spacing ratio, joint intersecting angle, incident angle, and number of joint sets together determine the wave transmission. And for P wave incidence, compared with other parameters, joint normal stiffness, nondimensional joint spacing, and joint intersecting angle have more significant effects on wave transmission. The physical reasons lying behind those phenomena are explained in detail. Engineering applications and indications of the modeling results are also mentioned. 相似文献
4.
A validation study of the distinct lattice spring model (DLSM) for wave propagation problems is performed. DLSM is a microstructure-based numerical model, which is meshless and has advantages in modelling dynamic problems where stress wave propagation is important. To verify the applicability of DLSM to modelling wave propagation through a discontinuous medium, the virtual wave source (VWS) method is used to obtain analytical solutions for wave propagation across a jointed rock mass. Numerical modelling results of the commercial code UDEC are selected as the reference. The effects of particle size and lattice rotation angle on wave propagation are first studied. Then, the results of wave transmission across a single joint with a different joint stiffness and across multiple parallel joints with different joint spacings are derived with DLSM, UDEC and VWS. These results are in good agreement with each other. Therefore, the capability of DLSM to model P-wave propagation across jointed rock mass is verified, which provides confidence for the further application of DLSM to modelling more complex problems. 相似文献
5.
依据弹性波理论,应力波斜入射线弹性节理时会发生波场分解。根据入射、透射及反射各波形的不同到时,运用离散元软件UDEC模拟应力波在含倾斜节理岩体中的传播并计算其透射、反射系数,并分析其波型转换规律。应力波斜入射单节理时,模拟得到的透射、反射系数随节理刚度、入射角度的变化规律,与已有的理论解是吻合的。应力波斜入射一组平行节理时,随着节理间距的增大,其同类波的透射系数Tpp、Tss先增大后减小,最后趋于稳定值;节理条数越多,Tpp、Tss越小。此外,不同条数的节理,透射系数达到最大值的临界节理间距值基本一致,但趋于稳定时的节理间距值随节理条数的增加而逐渐增大。 相似文献
6.
Stress wave attenuation across fractured rock masses is a great concern of underground structure safety. When the wave amplitude is large, fractures experience nonlinear deformation during the wave propagation. This paper presents a study on normal transmission of P‐wave across parallel fractures with nonlinear deformational behaviour (static Barton–Bandis model). The results show that the magnitude of transmission coefficient is a function of incident wave amplitude, nondimensional fracture spacing and number of fractures. Two important indices of nondimensional fracture spacing are identified, and they divide the area of nondimensional fracture spacing into three parts (individual fracture area, transition area and small spacing area). In the different areas, the magnitude of transmission coefficient has different trends with nondimensional fracture spacing and number of fractures. In addition, the study reveals that under some circumstances, the magnitude of transmission coefficient increases with increasing number of fractures, and is larger than 1. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
7.
Transmission of Elastic P-waves across Single Fractures with a Nonlinear Normal Deformational Behavior 总被引：13，自引：5，他引：13
Summary This paper presents a theoretical study on normally incident elastic P-wave transmission across single dry fractures with
a nonlinear normal deformational behavior. The effects of nonlinear fracture normal behavior on P-wave transmission are examined
without the mixture of fracture shear behavior. The linear displacement discontinuity model for wave propagation across fractures
is extended to a nonlinear model – the hyperbolic elastic model (BB model). Numeric solutions of magnitudes of transmission
(|T
non|) and reflection (|R
non|) coefficients, for normally incident P-wave transmission across the nonlinear deformable fractures, are obtained and related
to the closure behavior of fractures. Parametric studies are conducted to acquire an insight into the effects of the nonlinear
fracture normal deformation on P-wave transmission, in terms of initial normal stiffness and the ratio of current maximum
closure to maximum allowable closure of the fractures, as well as the incident wave amplitude and frequency. Comparisons between
the linear and nonlinear models are presented. It is shown that, |T
lin| and |R
lin| for the linear model are special solutions of |T
non| and |R
non| for the nonlinear model, when the incident wave amplitude is so low that the current maximum closure of fracture incurred
during the wave transmission is much smaller, relative to the maximum allowable closure. In addition, the nonlinear fracture
behavior gives rise to a phenomenon of higher harmonics during the wave transmission across the fracture. The higher harmonics
contribute to the increase of |T
non| from |T
lin|. 相似文献
8.
基于弹性波在冻结饱和多孔介质与单相弹性介质中的传播理论,研究了平面P波在饱和冻土介质与单相弹性介质分界面上的透反射问题。利用Helmholtz矢量分解定理,根据分界面上的边界条件,获得了平面P波从单相弹性介质入射到饱和冻土介质分界面上透反射振幅比的理论表达式。通过数值计算,分析了在不同入射频率、胶结参数、孔隙率、饱和度和接触参数下,弹性波的透反射振幅比随入射角变化的关系。研究结果表明：P波从单相弹性介质垂直入射到饱和冻土介质分界面上时只有反射P波和3种透射P波产生,当掠入射时只产生反射而没有透射现象发生。入射频率、胶结参数、孔隙率、饱和度以及接触参数等参数对反射波和透射波的振幅比影响显著。 相似文献
9.
地震AVO （amplitude versus offset）技术是一项利用振幅信息研究岩性、检测油气的地震勘探技术。常规方法基于Zoeppritz方程计算模型界面处的反射系数,而实际地下非均匀介质中地震反射特征不仅与入射角度、物性差异有关,还与入射波频率、地层厚度、薄互层结构等因素有关。为此,应用传播矩阵理论充分考虑与这些因素有关的调谐干涉等传播效应,针对实际数据计算非均匀地下介质的高精度合成地震记录,对比Zoeppritz方程、Shuey二项近似方程、Shuey三项近似方程以及传播矩阵算法的模拟效果。研究发现：在小角度入射时Zoeppritz方程、Shuey二项近似方程和Shuey三项近似方程的反射振幅和波形基本一致,大角度入射时Zoeppritz方程与Shuey三项近似方程接近;Zoeppritz算法的模拟结果在小角度入射和浅层情况下与传播矩阵算法差别较小,而在大角度入射和深层情况下与传播矩阵差别较大,说明层间多次波的调谐干涉等传播效应不可忽略。 相似文献
10.
基于弹性波在非饱和多孔介质与单相弹性介质中的传播理论,考虑在非饱和土地基中设置一定厚度的复合多层波阻板（复合多层波阻板以3层为例）,利用Helmholtz矢量分解定理,推导了非饱和土地基中S波通过复合多层波阻板的透射、反射振幅比的解析解。通过数值算例,分析了层间波阻板剪切模量和密度等物理力学参数对非饱和土地基中S波通过复合多层波阻板时传播特性的影响规律。结果表明：复合多层波阻板中层间波阻板材料的剪切模量和密度对透反射系数影响显著。复合多层波阻板是一种有效的隔振屏障,严格控制层间波阻板的剪切模量和密度可以获得最佳隔振效果,这为复合多层波阻板在地基振动控制领域中的应用提供理论指导。 相似文献
11.
节理面透射模型及其隔振性能研究 总被引：3，自引：1，他引：2
振动波入射到节理界面上,与软弱断层一样会产生波场的分解,能够起到隔振作用。根据线性变形节理的透反射规律研究发现,隔振后各点的波场可由透射P波与透射S波叠加而成,其能量分配服从Zoeppritz方程,不连续位移造成了透射波的衰减;法向刚度增加透射纵波系数会增加,而切向刚度与透射纵波无关,法向与切向刚度对透射S波均有影响,刚度增加透射S波振幅逐渐降低,逐步逼近于0;由于透射后波场相互干涉,不同波场延时不同,透射合成波与入射波相比,振幅降低,持续时间增加,波形尾段有畸变;总能量系数与节理面的刚度无关,而随入射角增加不断降低。 相似文献
12.
考虑节理质量对应力波传播的影响,运用波的位移位函数推导了谐波在厚黏弹性节理的透、反射系数计算公式,采用波形相关系数描述子波穿过黏弹性节理的波形变化,讨论具有一定厚度的黏弹性节理简化位移不连续模型的适用条件。设厚黏弹性节理模型和位移不连续模型的透射波波形相关系数为0.9时对应的节理厚度为临界厚度,岩体与节理的阻抗比对临界厚度的影响很小;临界厚度随子波中心频率增大呈负指数减小,入射角越大,临界厚度随中心频率减小得越慢。试验数据分析表明：当节理厚度为0.03 m时,采用位移不连续模型和厚黏弹性模型计算得到的节理力学参数非常接近,随节理厚度和子波中心频率增加,运用位移不连续模型的计算结果偏差越大,试验结果与理论分析是一致的。 相似文献
13.
根据Biot波动理论,采用复变函数与多级坐标法,求解了P波作用下饱和土体中地下输流管道的波动散射方程,分析了管道中流体介质性质、入射波角度及管道埋深等对地下输流管道周边动应力集中系数及孔压集中系数分布的影响。计算结果表明：在低频弹性波入射时,管道周边动应力集中系数及孔压集中系数分布相对均匀,而随入射频率的增加,其分布变得复杂化,但其峰值有所减小;中低频波入射作用下,管道内为水、石油介质时,动应力集中系数和孔压集中系数较空气介质时小,而在高频波作用时情况相反;对于管道内流体介质为水时,随着入射角度的变化,应力集中分布也沿一定角度的方向发生转动,入射波自管道下方垂直入射时,管道周边动应力集中系数峰值相对较大;随埋深的增加,动应力集中系数和孔压集中系数均呈震荡减小的趋势。 相似文献
14.
Ahmadreza Hedayat Laura J. Pyrak-Nolte Antonio Bobet 《Rock Mechanics and Rock Engineering》2014,47(5):1575-1587
Seismic wave transmission and digital image correlation (DIC) are employed to study slip processes along frictional discontinuities. A series of biaxial compression experiments are performed on gypsum specimens with non-homogeneous contact surfaces. The specimens are composed of two blocks with perfectly mated contact surfaces with a smooth surface with low frictional strength on the upper half and a rough surface with high frictional strength on the lower half. Compressional, P, and shear, S, wave pulses were transmitted through the discontinuity while digital images of the specimen surface were acquired during the test. A distinct peak in the amplitude of transmitted wave occurs prior to the peak shear strength and is considered a “precursor” to the failure. Precursors indicate that slip initiates from the smooth surface and extends to the rough surface as the shear load is increased. From the DIC data, slip is identified as a jump in the displacement field along the fracture that initiates from the smooth surface and propagates to the rough surface. Precursors are associated with an increase in the rate of slip across the discontinuity and are a measure of the reduction in the fracture shear stiffness. 相似文献
15.
Analytical study of ground motion caused by seismic wave propagation across faulted rock masses 
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下载免费PDF全文 Studying seismic wave propagation across rock masses and the induced ground motion is an important topic, which receives considerable attention in design and construction of underground cavern/tunnel constructions and mining activities. The current study investigates wave propagation across a rock mass with one fault and the induced ground motion using a recursive approach. The rocks beside the fault are assumed as viscoelastic media with seismic quality factors, Qp and Qs. Two kinds of interactions between stress waves and a discontinuity and between stress waves and a free surface are analyzed, respectively. As the result of the wave superposition, the mathematical expressions for induced ground vibration are deduced. The proposed approach is then compared with the existing analysis for special cases. Finally, parametric studies are carried out, which includes the influences of fault stiffness, incident angle, and frequency of incident waves on the peak particle velocities of the ground motions. 相似文献
16.
Analysis of Blast Wave Interaction with a Rock Joint 总被引：8，自引：3，他引：5
The interaction between rock joints and blast waves is crucial in rock engineering when rock mass is suffered from artificial or accidental explosions, bursts or weapon attacks. Based on the conservation of momentum at the wave fronts and the displacement discontinuity method, quantitative analysis for the interaction between obliquely incident P- or S-blast wave and a linear elastic rock joint is carried out in the present study, so as to deduce a wave propagation equation. For some special cases, such as normal or tangential incidence, rigid or weak joint, the analytical solution of the stress wave interaction with a rock joint is obtained by simplifying the wave propagation equation. By verification, it is found that the transmission and reflection coefficients from the wave propagation equation agree very well with the existing results. Parametric studies are then conducted to evaluate the effects of the joint stiffness and incident waves on wave transmission and reflection. The wave propagation equation derived in the present study can be straightforwardly extended for different incident waveforms and nonlinear rock joints to calculate the transmitted and reflected waves without mathematical methods such as the Fourier and inverse Fourier transforms. 相似文献
17.
基于多相孔隙介质弹性理论,给出了非饱和土中不同弹性波的传播方程。根据分界面上的边界条件,建立了各势函数波幅值之间的关系式,讨论了入射剪切波在不同饱和度土层分界面上的反射与透射问题。在无限空间非饱和土体中存在3种压缩波和1种剪切波,因此,当剪切波传播到不同饱和度的非饱和土层分界面上将分别在上、下土层激发产生4种反射波和4种透射波。推导出不同反射波和透射波的振幅比例系数和能量比例系数的理论表达式,并且在此基础上进行数值分析。在数值算例中分别研究了各反射波与透射波的能量比例系数（即能量反射率和能量透射率）受入射频率、入射角度以及上、下土层土体饱和度变化的影响情况。计算结果表明：各能量反射率和能量透射率不仅与入射角和入射频率有关,而且其受上、下土层饱和度变化的影响也同样不能忽视。 相似文献
18.
基于单相弹性介质与非饱和多孔介质中波的传播理论和Snell定律,研究了P1波从非饱和土介质中入射到波阻板（wave impeding block,WIB）时的传播特性。推导了P1波在非饱和土地基中通过波阻板后反射波和透射波振幅比的解析解,分析了反射波振幅比和透射波振幅比与波阻板的剪切模量、密度以及入射角、入射频率、饱和度等各种参数的关系曲线,从而得到这些参数对非饱和土地基中波阻板隔振效果的影响规律。数值结果表明：波阻板隔振屏障的剪切模量和密度对其隔振性能影响较为显著,当波阻板剪切模量和密度在一定范围内时波阻板隔振屏障可获得较好的隔振性能;入射角对波阻板隔振性能影响较大,而入射频率对其隔振效果影响很小。 相似文献
19.
20.
爆破强震扰动影响下受软弱结构面控制型边坡易出现滑移破坏,其破坏机制研究是滑坡灾害防护的重要内容.利用波函数解析方法建立了应力波入射岩-结构面-岩模型,分析了爆破P波透反射规律与软弱结构面应力响应,结合自主研发的爆破应力波扰动结构面剪切强度仪得到了抗剪强度劣化规律,构建结构面动应力与扰动后抗剪强度量化关系,提出结构面内部剪切强度失效模型.研究表明:计算模型的P波在两个界面产生的透射系数均随着入射角增加而降低;振动台加载后软弱结构面的剪切强度存在明显的劣化,加载振幅为0.2 mm时,内聚力由68.75 kPa降低至9.69 kPa.结合建立的剪切强度失效模型与试验得到的剪切强度劣化规律,确定振幅在0.15 mm内时软弱结构面的安全性可以得到保证. 相似文献