Performance Evaluation and Numerical Modeling of Embankment over Soft Clayey Soil Improved with Chemico-Pile

Abstract

The stabilization of soft clay is one of the most important construction techniques in geotechnical engineering. The injection method using chemical grouting in the ground has been widely used to improve soft ground. Chemical admixture stabilization (with lime and cement as the chemical admixture) has been extensively used in both shallow and deep stabilization to improve the inherent properties of soil, such as strength and deformation behavior. These methods involve mixing soil with chemicals. The other technique—the so-called chemico-lime pile or chemico-pile method—involves forming columns of chemically treated lime in the soil without mixing. This method is widely used in Japan and Singapore and is a fast, effective, and well-recognized way of improving soil with soft clay deposits. The chemico-pile method has been used in a full-scale test embankment project at the Nong Ngo Hao site near Bangkok, Thailand. The site is part of the second Bangkok International Airport project, located in the Samutprakan Province, 30 km east of the Bangkok metropolis. Both laboratory and field investigations were performed to evaluate the effectiveness of lime columns on soft soil. In situ cone penetration tests were performed to evaluate the reduction in compressibility and the increase in the shear strength of the soils. Numerical modeling using the finite element program PLAXIS was employed to model the chemico-pile–supported embankment. This paper presents the improved effect of chemico-pile on soft clay, discusses the improved embankment behavior seen in the field data, and compares the field data with numerical modeling results for pore water pressure, vertical settlements, and lateral movements.