This paper investigates in detail the nature of diffraction of plane P waves around a canyon in poroelastic half-space, and studies the effects of incident frequency, drainage condition, porosity, etc, on the diffract...This paper investigates in detail the nature of diffraction of plane P waves around a canyon in poroelastic half-space, and studies the effects of incident frequency, drainage condition, porosity, etc, on the diffraction of waves. It is shown that the surface displacement amplitudes of the drained case are close to those of the undrained case, however, the surface displacement amplitudes of the dry case are very different from those of the saturated （either drained or undrained） cases. There are large phase shift between the dry case and the saturated cases, as well as slightly longer resultant wavelengths for the undrained case than those for the drained case and longer resultant wavelengths for the drained case than those for the dry case. For small porosity the surface displacement amplitudes for the saturated cases are almost identical to those for the dry case; while for large porosity, the effect of drainage condition becomes significant, and the surface displacement amplitudes for the undrained case are larger than those for the drained case. As the incident frequency increases, the effect of porosity becomes significant, and more significant for the undrained case than that for the drained case. As the porosity increases, the pore pressures increase significantly but their oscillations become smoother. As the incident frequency increases, the pore pressures become more complicated.展开更多
Submerged floating tunnel (SFT) is a novel type traffic structure for crossing long strait and deep lakes. To investigate the dynamic pressure acting on an SFT under compression (P) wave incidence, a theoretical analy...Submerged floating tunnel (SFT) is a novel type traffic structure for crossing long strait and deep lakes. To investigate the dynamic pressure acting on an SFT under compression (P) wave incidence, a theoretical analysis model considering marine sediment effect has been proposed. Based on displacement potential functions, the reflection and refraction coefficients of P wave in different media are derived. Numerical examples are employed to illustrate the effects of the thickness of sediment layer, the incident P wave angle, the tether stiffness and spacing, and the permeability of the sediment on the dynamic pressure loading on the SFT. The results show that dynamic pressure is related to the saturation of sediment and affected by the thickness of sediment. The partially saturated sediment will amplify the dynamic pressure loading on the SFT, and the resonance frequency increases a little with the fully saturated sediment. Besides, increasing the tether stiffness and decreasing in the tether spacing will lead to a dynamic pressure falling. Deepening the SFT position and reducing the permeability of the sediment are effective measures to reduce dynamic pressure acting on the SFT.展开更多
基金support from the Program for New Century Excellent Talents in University (NCET-05-0248)the Key Program for Applied Basic Research of Tianjin Municipality (07JCZDJC10100)
文摘This paper investigates in detail the nature of diffraction of plane P waves around a canyon in poroelastic half-space, and studies the effects of incident frequency, drainage condition, porosity, etc, on the diffraction of waves. It is shown that the surface displacement amplitudes of the drained case are close to those of the undrained case, however, the surface displacement amplitudes of the dry case are very different from those of the saturated （either drained or undrained） cases. There are large phase shift between the dry case and the saturated cases, as well as slightly longer resultant wavelengths for the undrained case than those for the drained case and longer resultant wavelengths for the drained case than those for the dry case. For small porosity the surface displacement amplitudes for the saturated cases are almost identical to those for the dry case; while for large porosity, the effect of drainage condition becomes significant, and the surface displacement amplitudes for the undrained case are larger than those for the drained case. As the incident frequency increases, the effect of porosity becomes significant, and more significant for the undrained case than that for the drained case. As the porosity increases, the pore pressures increase significantly but their oscillations become smoother. As the incident frequency increases, the pore pressures become more complicated.
基金This work was supported by the National Natural Science Foundation of China (Grants 51541810 and 51279178)the Fundamental Research Funds for the Central Universities (Grant 2018QNA4032).
文摘Submerged floating tunnel (SFT) is a novel type traffic structure for crossing long strait and deep lakes. To investigate the dynamic pressure acting on an SFT under compression (P) wave incidence, a theoretical analysis model considering marine sediment effect has been proposed. Based on displacement potential functions, the reflection and refraction coefficients of P wave in different media are derived. Numerical examples are employed to illustrate the effects of the thickness of sediment layer, the incident P wave angle, the tether stiffness and spacing, and the permeability of the sediment on the dynamic pressure loading on the SFT. The results show that dynamic pressure is related to the saturation of sediment and affected by the thickness of sediment. The partially saturated sediment will amplify the dynamic pressure loading on the SFT, and the resonance frequency increases a little with the fully saturated sediment. Besides, increasing the tether stiffness and decreasing in the tether spacing will lead to a dynamic pressure falling. Deepening the SFT position and reducing the permeability of the sediment are effective measures to reduce dynamic pressure acting on the SFT.
