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Journal : Indonesian Geotechnical Journal

Interpolation method for spatial distribution of clay content within residual soil Alfrendo Satyanaga; Aswin Lim; Nurly Gofar
Indonesian Geotechnical Journal Vol. 1 No. 1 (2022): Vol.1 , No.1, April 2022
Publisher : Himpunan Ahli Teknik Tanah Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (679.507 KB) | DOI: 10.56144/igj.v1i1.5

Abstract

Residual soil is covering some parts of the tropical country such as Singapore. It is commonly known that residual soil is associated with variability either horizontally or vertically. As a result, it is necessary to have a method to determine the distribution of soil properties to minimize the need to have an excessive amount of boreholes before the commencement of the construction project. This paper presents the suitable interpolation method for the spatial distribution of clay content across Singapore island. The common term related to the spatial distribution of soil properties is called digital soil map. The selection of the best method to generate this map depends on different factors. Therefore, each case requires a thorough evaluation and comparison based on the interpolation results. Singapore's digital elevation model and its boundary were utilized in this study. A digital soil map was developed using ArcGIS software based on two interpolation methods such as ordinary kriging, and the inverse distance weighted method. These two methods were cross-validated and compared based on the regression analysis of the analyses results. Cross-validation was performed to verify the correctness of the mentioned interpolation methods. In order to validate the interpolation results, the mean error and the root mean square error were used. The results suggest that ordinary kriging could be used as a suitable method to generate the spatial distribution of clay content obtained from boreholes in Singapore.
Two-Dimensional Finite Element Analysis of Piled Raft Coefficient Settlement Ratio on Clays Christian William Munaba; Aswin Lim; Arif Yunando Soen
Indonesian Geotechnical Journal Vol. 1 No. 2 (2022): Vol.1 , No.2, August 2022
Publisher : Himpunan Ahli Teknik Tanah Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (555.218 KB) | DOI: 10.56144/igj.v1i2.15

Abstract

Nowadays, designing a piled raft foundation is challenging because the behavior is three-dimensional. For some engineers, a three-dimensional analysis might not be affordable due to more costly than a two-dimensional analysis. In this study, 2D Finite element analysis – axisymmetric was used to study the piled raft foundation. The pile diameter and pile length were varied to investigate the relation between piled raft coefficient and load-settlement. In addition, the load transfer mechanism between the raft part and the pile part in clayey soils is also examined. The results show the longer the pile and the larger the diameter, the greater the load carried by the pile and the smaller the settlement. Increase in pile length by 5 m, resulting in a load transfer of 2% to 6% from a raft to pile, and reduced settlement by 2% to 3%. Furthermore, A 0.5 m increase in pile diameter results in an 8% to 25% load transfer from a raft to pile, and a 2% to 7% reduction in a settlement. The soil consistency affects the load distribution and settlement of the pile-raft foundation system. The higher the soil consistency, the smaller the amount transferred to the pile, and the higher the effectiveness of the pile in reducing the settlement that occurs.
Influence of Underconsolidating Soil on Effective Stress Path in a Deep Excavation Case Albert Sebastian; Lim, Aswin
Indonesian Geotechnical Journal Vol. 4 No. 3 (2025): Vol. 4, No. 3, December 2025
Publisher : Himpunan Ahli Teknik Tanah Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56144/igj.v4i3.133

Abstract

This study investigates the influence and impact of clay soil that is presumed to be undergoing consolidation process on an unbraced shallow excavation system. The excavation geometry spans up to 160 meters with a maximum depth of 5.25 meters. A concrete sheet pile wall was installed at the front side of the excavation, supported by additional tie beams connected to square precast piles behind the wall. Based on soil investigation data, residual excess pore water pressures were identified within the underconsolidating clay layer at depths between 3 to 12 meters. These residual pore pressures contribute additional loading to the retaining wall system. A back analysis was conducted to obtain appropriate soil parameters to be used for PLAXIS 2D modelling. The finite element analysis results were compared with inclinometer data to validate the back analysis. Modeling of the underconsolidating condition was performed by manually inputting the pore water pressure into the initial condition. Results show that under underconsolidating conditions, the maximum wall deflection reached 190 mm, whereas under hydrostatic conditions, it was only 100 mm. Additionally, a parametric study was carried out to examine the relationship between the degree of consolidation and wall deflection. The findings indicate that a higher degree of consolidation leads to reduced wall deflection. To investigate the stress changes on the wall due to underconsolidating soil, a stress path analysis was performed to understand the stress history around the excavation. It was found that in underconsolidating conditions, the average effective stress tends to be lower and the deviatoric stress higher, resulting in a stress path that is closer to the failure line.