Micromechanics of soil responses in cyclic simple shear tests

نویسندگان

  • Liang Cui
  • Subhamoy Bhattacharya
  • George Nikitas
چکیده

Offshore wind turbine (OWT) foundations are subjected to a combination of cyclic and dynamic loading arising from wind, wave, rotor and blade shadowing. Under cyclic loading, most soils change their characteristics including stiffness, which may cause the system natural frequency to approach the loading frequency and lead to unplanned resonance and system damage or even collapse. To investigate such changes and the underlying micromechanics, a series of cyclic simple shear tests were performed on the RedHill 110 sand with different shear strain amplitudes, vertical stresses and initial relative densities of soil. The test results showed that: (a) Vertical accumulated strain is proportional to the shear strain amplitude but inversely proportional to relative density of soil; (b) Shear modulus increases rapidly in the initial loading cycles and then the rate of increase diminishes and the shear modulus remains below an asymptote; (c) Shear modulus increases with increasing vertical stress and relative density, but decreasing with increasing strain amplitude. Coupled DEM simulations were performed using PFC2D to analyse the micromechanics underlying the cyclic behaviour of soils. Micromechanical parameters (e.g. fabric tensor, coordination number) were examined to explore the reasons for the various cyclic responses to different shear strain amplitudes or vertical stresses. Both coordination number and magnitude of fabric anisotropy contribute to the increasing shear modulus.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Evaluating the Liquefaction Potential of Soil in the South and Southeast of Tehran based on the Shear Wave Velocity through Empirical Relationships

The liquefaction resistance of soil can be evaluated using laboratory tests such as cyclic simple shear, cyclic triaxial, cyclic torsional shear as well as field methods like Standard Penetration Test (SPT), Cone Penetration Test (CPT) and Shear Wave Velocity (Vs). In this regard, this study attempts to compare the results of the SPT based on the simplified procedure proposed by Seed and Idriss...

متن کامل

The Small Strain Effects to the Shear Strength and Maximum Stiffness of Post-Cyclic Degradation of Hemic Peat Soil

The laboratory tests for measuring the effects of small strain to the shear strength and maximum stiffness development of post-cyclic degradation of hemic peat are reviewed in this paper. A series of laboratory testing has been conducted to fulfil the objective of this research to study the post-cyclic behaviour of peat soil and focuses on the small strain characteristics. For this purpose, a n...

متن کامل

TOPOLOGY OPTIMIZATION OF PERFORATED STEEL PLATE SHEAR WALLS WITH THICK PLATE IN SIMPLE FRAMES

In this paper, topology optimization (TO) is applied to determine the form, size and location of holes for the special form of perforated steel plate shear wall (PSPSW). The proposed model is based on the recently presented particular form of PSPSW that is called the ring-shaped steel plate shear wall. The strain energy is selected as the objective function in the optimization. Simple Isotropic...

متن کامل

The Validity Assessment of Laboratory Shear Modulus Using In-Situ Seismic Piezocone Test Results

Seismic piezocone device (SCPTu) together with Resonant Column and Cyclic Triaxial test apparatus are employed to measure small strain shear modulus (G0) of carbonate sandy and clayey soils of southern coasts of Iran. A large area of southern regions of Iran is formed from clay, silt and sand. In this study, maximum shear modulus that is derived from both field (by seismic piezocone) and labora...

متن کامل

A Hyperbolic Model for Stress-strain Behavior of Unsaturated Soils

A new simple shear apparatus is fabricated which is capable of applying monotonic and cyclic load on soil specimens. A series of tests was conducted to study the pore pressures (or suction), volume change, and shear behavior of the soil samples with anisotropic consolidation pressure. The simple shear apparatus is capable of controlling as well as measuring pore-air and pore-water pressure in t...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2017