## Abstract

The small-strain shear modulus depends on stress in uncemented soils. In effect, the shear-wave velocity, which is often used to calculate shear stiffness, follows a power equation with the mean effective stress in the polarization plane V_{s}=α(σ'_{m}/1 kPa)^{β}, where the α factor is the velocity at 1 kPa, and the β exponent captures the velocity sensitivity to the state of stress. The small-strain shear stiffness, or velocity, is a constant-fabric measurement at a given state of stress. However, parameters α and β are determined by fitting the power equation to velocity measurements conducted at different effective stress levels, so changes in both contact stiffness and soil fabric are inherently involved. Therefore, the α and β parameters should be linked to soil compressibility C_{C}. Compiled experimental results show that the a factor decreases and the b exponent increases as soil compressibility C_{C} increases, and there is a robust inverse relationship between α and β for all sediments: β≈0.73-0.27 log[α/(m/s)]. Velocity data for a jointed rock mass show similar trends, including a power-type stress-dependent velocity and inverse correlation between α and β however, the α-β trend for jointed rocks plots above the trend for soils.

Original language | English (US) |
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Article number | 06014011 |

Journal | Journal of Geotechnical and Geoenvironmental Engineering |

Volume | 140 |

Issue number | 10 |

DOIs | |

State | Published - Oct 1 2014 |

Externally published | Yes |

## Keywords

- Compression index
- Contact effects
- Coordination number
- Granular fabric
- Shear-wave velocity
- Velocity-stress power relations

## ASJC Scopus subject areas

- General Environmental Science
- Geotechnical Engineering and Engineering Geology