Shear strength assessments of residual soil for Ia Pet wind power project in Vietnam

Abstract

The geotechnical parameters are of great importance in wind turbine foundation design. As a case study, laboratory test results of Ia Pet wind power project in Vietnam were analysed to accurately estimate the strength of residual soil, which is classified as high plasticity silt (MH). Due to sample disturbance, the undrained shear strength s u from triaxial unconsolidated undrained shear test (UU) is absolutely underestimated, while su from direct quick shear tests (DSq) and triaxial consolidated undrained shear test (CU) are more representative. Good linear correlations have been found between soil depth and strength obtained from DSq and CU tests. The normalised undrained shear strengths s u/σ v0’ indicate that the residual soil at 0m to 8m is heavily overconsolidated, where s u/σ v0’ is larger than 0.4. Furthermore, the normalised undrained shear strengths s u/σ v0’ presented negative linear correlation of liquidity index, which can be used to quick and cautious estimate the strength of Ia pet residual soil in the future by using liquidity index. The undrained shear strength evaluation using liquidity index is in good agreement with DSq and CU test results, which preliminarily verifies the applicability of expression between s u/σ v0’ and I L.