Field evaluation and behavior of the soil improved using dynamic replacement

Abstract

The Dynamic Replacement (DR) technique has been used successfully to improve soft soils. It uses the dynamic compaction energy to drive granular materials down into the soils, forming a pillar of 2–2.5 m diameter. In this paper, a 30,000 m2 study is used to evaluate the performance of the technique. Cone penetration tests (CPTs) were carried out before ground improvement to analyze the soil and select the appropriate technique. Post improvement CPTs (inside and between pillars) and load tests were carried out to confirm that the design requirements (bearing capacity and settlement) are met. It is proposed to use the Schmertmann [1] and Schmertmann et al. [2] method for calculating the settlements. However, to make it applicable to the case of DR for clayey soils, a methodology is proposed to calculate an equivalent tip resistance based on the DR replacement ratio. The values of the equivalent tip resistance are used to calculate the equivalent modulus of elasticity of the soil for settlement calculations. A finite element model has been built to simulate the revised formula, and the calculated settlements have shown a good agreement with the conducted measurements and the finite element model results as well. Keywords: Dynamics, Site investigation, Geotechnical engineering