Geotechnical Engineering

Reflection of P1 wave from free surfaces of double-porosity media

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  • 1. Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education, Zhejiang University, Hangzhou, Zhejiang 310058, China; 2. Research Center of Costal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou, Zhejiang 310058, China; 3. Institute of Geotechnical Engineering, Nanjing Tech University, Nanjing, Jiangsu 210009, China

Received date: 2014-11-24

  Online published: 2018-06-09

Supported by

This work was supported by the National Natural Science Foundation of China (U1234204, 51378463).

Abstract

The bulk waves in double-porosity media and the reflection of P1 wave at the free permeable and impermeable surfaces are theoretically derived and solved. The variations of the amplitude reflection coefficients of the reflecting waves with incident angle and frequency under different surface boundaries, as well as the dispersion and attenuation characteristics of the four kinds of bulk waves, are numerically studied. The results show that: (1) P1, P2, P3 and S waves all show dispersion and attenuation characteristics. Therein, P1 wave propagates fastest with lowest attenuation, and P3 wave attenuates fastest with lowest propagation velocity. (2) As the incident angle of P1 wave increases, the amplitude reflection coefficients of the reflecting P2, P3 and S waves increase at first then decrease, but the case of the reflecting P1 wave is just opposite. Moreover, the permeability of the surface has distinctive effect on the amplitude reflection coefficients of P2 and P3 waves and has slight effect on P1 and S waves. Nevertheless, whether the surface is permeable or impermeable, the changing tendency of the amplitude reflection coefficients is consistent. (3) The amplitude reflection coefficients of the reflecting P2 and P3 waves grow as frequency increases. In contrast with the reflecting P3 wave, for the reflecting P2 wave, the amplitude reflection coefficient in the case of free impermeable surface is larger than that in the case of free permeable surface. (4) For the reflecting P1 wave, with the increase of frequency, the amplitude reflection coefficient in the case of free permeable boundary increases firstly and then decreases, but fluctuates (decrease-increase-decrease) in the case of free impermeable surface. The amplitude reflection coefficients of the reflecting S wave just vary oppositely with the reflecting P1 wave.

Cite this article

HE Peng-fei, XIA Tang-dai, LIU Zhi-jun, CHEN Wei-yun, . Reflection of P1 wave from free surfaces of double-porosity media[J]. Rock and Soil Mechanics, 2016 , 37(6) : 1753 -1761 . DOI: 10.16285/j.rsm.2016.06.028

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